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Author name code: allende-prieto
ADS astronomy entries on 2022-09-14
author:"Allende Prieto, Carlos"
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Title: White Dwarf Binaries across the H-R Diagram
Authors: Anguiano, Borja; Majewski, Steven R.; Stassun, Keivan G.;
Badenes, Carles; Daher, Christine Mazzola; Dixon, Don; Allende Prieto,
Carlos; Schneider, Donald P.; Price-Whelan, Adrian M.; Beaton,
Rachael L.
2022AJ....164..126A Altcode: 2022arXiv220713992A
We created the APOGEE-GALEX-Gaia catalog to study white dwarf (WD)
binaries. This database aims to create a minimally biased sample
of WD binary systems identified from a combination of GALEX, Gaia,
and APOGEE data to increase the number of WD binaries with orbital
parameters and chemical compositions. We identify 3414 sources as WD
binary candidates, with nondegenerate companions of spectral types
between F and M, including main-sequence stars, main-sequence binaries,
subgiants, sub-subgiants, red giants, and red clump stars. Among our
findings are (a) a total of 1806 systems having inferred WD radii R
< 25 R <SUB>⊕</SUB>, which constitute a more reliable group of
WD binary candidates within the main sample; (b) a difference in the
metallicity distribution function between WD binary candidates and the
control sample of most luminous giants (M <SUB> H </SUB> < -3.0);
(c) the existence of a population of sub-subgiants with WD companions;
(d) evidence for shorter periods in binaries that contain WDs compared
to those that do not, as shown by the cumulative distributions of APOGEE
radial velocity shifts; (e) evidence for systemic orbital evolution in a
sample of 252 WD binaries with orbital periods, based on differences in
the period distribution between systems with red clump, main-sequence
binary, and sub-subgiant companions and systems with main-sequence or
red giant companions; and (f) evidence for chemical enrichment during
common envelope (CE) evolution, shown by lower metallicities in wide
WD binary candidates (P > 100 days) compared to post-CE (P <
100 days) WD binary candidates.
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Title: HORuS transmission spectroscopy and revised planetary
parameters of KELT-7 b
Authors: Tabernero, H. M.; Zapatero Osorio, M. R.; Allende Prieto,
C.; González-Álvarez, E.; Sanz-Forcada, J.; López-Gallifa, A.;
Montes, D.; del Burgo, C.; González Hernández, J. I.; Rebolo, R.
2022MNRAS.515.1247T Altcode: 2022arXiv220611548T; 2022MNRAS.tmp.1869T
We report on the high-resolution spectroscopic observations of two
planetary transits of the hot Jupiter KELT-7b (M<SUB>p</SUB> = 1.28
± 0.17M<SUB>Jup</SUB>, T<SUB>eq</SUB> = 2028 K) observed with the
High Optical Resolution Spectrograph (HORuS) mounted on the 10.4-m
Gran Telescopio Canarias (GTC). A new set of stellar parameters are
obtained for the rapidly rotating parent star from the analysis of
the spectra. Using the newly derived stellar mass and radius, and the
planetary transit data of the Transiting Exoplanet Survey Satellite
(TESS) together with the HORuS velocities and the photometric and
spectroscopic data available in the literature, we update and improve
the ephemeris of KELT-7b. Our results indicate that KELT-7 has an angle
λ = -10.55 ± 0.27 deg between the sky projections of the star's spin
axis and the planet's orbital axis. By combining this angle and our
newly derived stellar rotation period of 1.38 ± 0.05 d, we obtained a
3D obliquity ψ = 12.4 ± 11.7 deg (or 167.6 deg), thus reinforcing that
KELT-7 is a well-aligned planetary system. We search for the presence of
Hα, Li I, Na I, Mg I, and Ca II features in the transmission spectrum
of KELT-7b but we are only able to determine upper limits of 0.08-1.4
per cent on their presence after accounting for the contribution of
the stellar variability to the extracted planetary spectrum. We also
discuss the impact of stellar variability on the planetary data. Our
results reinforce the importance of monitoring the parent star when
performing high-resolution transmission spectroscopy of the planetary
atmosphere in the presence of stellar activity.
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Title: Absolute dimensions and apsidal motion of the eclipsing
binaries V889 Aquilae and V402 Lacertae
Authors: Baroch, D.; Giménez, A.; Morales, J. C.; Ribas, I.; Herrero,
E.; Perdelwitz, V.; Jordi, C.; Granzer, T.; Allende Prieto, C.
2022A&A...665A..13B Altcode: 2022arXiv220613121B
Context. Double-lined eclipsing binaries allow the direct determination
of masses and radii, which are key for testing stellar models. With
the launch of the TESS mission, many well-known eclipsing binaries
have been observed at higher photometric precision, permitting the
improvement of the absolute dimension determinations. <BR /> Aims:
Using TESS data and newly obtained spectroscopic observations, we aim
to determine the masses and radii of the eccentric eclipsing binary
systems V889 Aql and V402 Lac, together with their apsidal motion
parameters. <BR /> Methods: We simultaneously modelled radial velocity
curves and times of eclipse for each target to precisely determine
the orbital parameters of the systems, which we used to analyse the
light curves and then obtain their absolute dimensions. We compared
the obtained values with those predicted by theoretical models. <BR
/> Results: We determined masses and radii of the components of
both systems with relative uncertainties lower than 2%. V889 Aql is
composed of two stars with masses 2.17 ± 0.02 M<SUB>⊙</SUB> and
2.13 ± 0.01 M<SUB>⊙</SUB> and radii 1.87 ± 0.04 R<SUB>⊙</SUB>
and 1.85 ± 0.04 R<SUB>⊙</SUB>. We find conclusive evidence of
the presence of a third body orbiting V889 Aql with a period of 67
yr. Based on the detected third light and the absence of signal in
the spectra, we suggest that this third body could in turn be a binary
composed of two ∼1.4 M<SUB>⊙</SUB> stars. V402 Lac is composed of
two stars with masses 2.80 ± 0.05 M<SUB>⊙</SUB> and 2.78 ± 0.05
M<SUB>⊙</SUB> and radii 2.38 ± 0.03 R<SUB>⊙</SUB> and 2.36 ±
0.03 R<SUB>⊙</SUB>. The times of minimum light are compatible with
the presence of a third body for this system too, although its period
is not yet fully sampled. In both cases we have found a good agreement
between the observed apsidal motion rates and the model predictions.
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Title: DESI Observations of the Andromeda Galaxy: Revealing the
Immigration History of our Nearest Neighbor
Authors: Dey, Arjun; Najita, Joan R.; Koposov, S. E.; Josephy-Zack,
J.; Maxemin, Gabriel; Bell, Eric F.; Poppett, C.; Patel, E.; Beraldo e
Silva, L.; Raichoor, A.; Schlegel, D.; Lang, D.; Meisner, A.; Myers,
Adam D.; Aguilar, J.; Ahlen, S.; Allende Prieto, C.; Brooks, D.;
Cooper, A. P.; Dawson, K. S.; de la Macorra, A.; Doel, P.; Font-Ribera,
A.; Garcia-Bellido, Juan; Gontcho, S. Gontcho A; Guy, J.; Honscheid,
K.; Kehoe, R.; Kisner, T.; Kremin, A.; Landriau, M.; Le Guillou, L.;
Levi, Michael E.; Li, T. S.; Martini, Paul; Miquel, R.; Moustakas,
J.; Nie, Jundan; Palanque-Delabrouille, N.; Prada, F.; Schlafly,
E. F.; Sharples, Ray M.; Tarle, Gregory; Ting, Yuan-Sen; Tyas, L.;
Valluri, M.; Wechsler, Risa H.; Zou, H.
2022arXiv220811683D Altcode:
We present DESI observations of the inner halo of M31, which reveal
the kinematics of a recent merger - a galactic immigration event -
in exquisite detail. Of the 11,416 sources studied in 3.75 hours
of on-sky exposure time, 7,438 are M31 sources with well measured
radial velocities. The observations reveal intricate coherent kinematic
structure in the positions and velocities of individual stars: streams,
wedges, and chevrons. While hints of coherent structures have been
previously detected in M31, this is the first time they have been seen
with such detail and clarity in a galaxy beyond the Milky Way. We find
clear kinematic evidence for shell structures in the Giant Stellar
Stream, the NE Shelf and Western Shelf regions. The kinematics are
remarkably similar to the predictions of dynamical models constructed
to explain the spatial morphology of the inner halo. The results are
consistent with the interpretation that much of the substructure in the
inner halo of M31 is produced by a single galactic immigration event 1 -
2 Gyr ago. Significant numbers of metal-rich stars are present in all
of the detected substructures, suggesting that the immigrating galaxy
had an extended star formation history. We also investigate the ability
of the shells and Giant Stellar Stream to constrain the gravitational
potential of M31, and estimate the mass within a projected radius of 125
kpc to be ${\rm log_{10}}\, M_{\rm NFW}(<125\,{\rm kpc})/M_\odot =
11.78_{-0.10}^{+0.13}$. The results herald a new era in our ability
to study stars on a galactic scale and the immigration histories
of galaxies.
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Title: The Gaia-ESO Public Spectroscopic Survey: Motivation,
implementation, GIRAFFE data processing, analysis, and final data
products
Authors: Gilmore, G.; Randich, S.; Worley, C. C.; Hourihane, A.;
Gonneau, A.; Sacco, G. G.; Lewis, J. R.; Magrini, L.; Francois, P.;
Jeffries, R. D.; Koposov, S. E.; Bragaglia, A.; Alfaro, E. J.; Allende
Prieto, C.; Blomme, R.; Korn, A. J.; Lanzafame, A. C.; Pancino, E.;
Recio-Blanco, A.; Smiljanic, R.; Van Eck, S.; Zwitter, T.; Bensby, T.;
Flaccomio, E.; Irwin, M. J.; Franciosini, E.; Morbidelli, L.; Damiani,
F.; Bonito, R.; Friel, E. D.; Vink, J. S.; Prisinzano, L.; Abbas,
U.; Hatzidimitriou, D.; Held, E. V.; Jordi, C.; Paunzen, E.; Spagna,
A.; Jackson, R. J.; Maiz Apellaniz, J.; Asplund, M.; Bonifacio, P.;
Feltzing, S.; Binney, J.; Drew, J.; Ferguson, A. M. N.; Micela, G.;
Negueruela, I.; Prusti, T.; Rix, H. -W.; Vallenari, A.; Bergemann,
M.; Casey, A. R.; de Laverny, P.; Frasca, A.; Hill, V.; Lind, K.;
Sbordone, L.; Sousa, S. G.; Adibekyan, V.; Caffau, E.; Daflon, S.;
Feuillet, D. K.; Gebran, M.; Gonzalez Hernandez, J. I.; Guiglion,
G.; Herrero, A.; Lobel, A.; Merle, T.; Mikolaitis, S.; Montes, D.;
Morel, T.; Ruchti, G.; Soubiran, C.; Tabernero, H. M.; Tautvaisiene,
G.; Traven, G.; Valentini, M.; Van der Swaelmen, M.; Villanova, S.;
Viscasillas Vazquez, C.; Bayo, A.; Biazzo, K.; Carraro, G.; Edvardsson,
B.; Heiter, U.; Jofre, P.; Marconi, G.; Martayan, C.; Masseron, T.;
Monaco, L.; Walton, N. A.; Zaggia, S.; Aguirre Borsen-Koch, V.; Alves,
J.; Balaguer-Nunez, L.; Barklem, P. S.; Barrado, D.; Bellazzini, M.;
Berlanas, S. R.; Binks, A. S.; Bressan, A.; Capuzzo-Dolcetta, R.;
Casagrande, L.; Casamiquela, L.; Collins, R. S.; D'Orazi, V.; Dantas,
M. L. L.; Debattista, V. P.; Delgado-Mena, E.; Di Marcantonio, P.;
Drazdauskas, A.; Evans, N. W.; Famaey, B.; Franchini, M.; Fremat, Y.;
Fu, X.; Geisler, D.; Gerhard, O.; Gonzalez Solares, E. A.; Grebel,
E. K.; Gutierrez Albarran, M. L.; Jimenez-Esteban, F.; Jonsson, H.;
Khachaturyants, T.; Kordopatis, G.; Kos, J.; Lagarde, N.; Ludwig,
H. -G.; Mahy, L.; Mapelli, M.; Marfil, E.; Martell, S. L.; Messina,
S.; Miglio, A.; Minchev, I.; Moitinho, A.; Montalban, J.; Monteiro,
M. J. P. F. G.; Morossi, C.; Mowlavi, N.; Mucciarelli, A.; Murphy,
D. N. A.; Nardetto, N.; Ortolani, S.; Paletou, F.; Palous, J.;
Pickering, J. C.; Quirrenbach, A.; Re Fiorentin, P.; Read, J. I.;
Romano, D.; Ryde, N.; Sanna, N.; Santos, W.; Seabroke, G. M.; Spina,
L.; Steinmetz, M.; Stonkute, E.; Sutorius, E.; Thevenin, F.; Tosi,
M.; Tsantaki, M.; Wright, N.; Wyse, R. F. G.; Zoccali, M.; Zorec,
J.; Zucker, D. B.
2022arXiv220805432G Altcode:
The Gaia-ESO Public Spectroscopic Survey is an ambitious project
designed to obtain astrophysical parameters and elemental abundances
for 100,000 stars, including large representative samples of the
stellar populations in the Galaxy, and a well-defined sample of 60
(plus 20 archive) open clusters. We provide internally consistent
results calibrated on benchmark stars and star clusters, extending
across a very wide range of abundances and ages. This provides a
legacy data set of intrinsic value, and equally a large wide-ranging
dataset that is of value for homogenisation of other and future
stellar surveys and Gaia's astrophysical parameters. This article
provides an overview of the survey methodology, the scientific aims,
and the implementation, including a description of the data processing
for the GIRAFFE spectra. A companion paper (arXiv:2206.02901)
introduces the survey results. Gaia-ESO aspires to quantify both
random and systematic contributions to measurement uncertainties. Thus
all available spectroscopic analysis techniques are utilised, each
spectrum being analysed by up to several different analysis pipelines,
with considerable effort being made to homogenise and calibrate the
resulting parameters. We describe here the sequence of activities up to
delivery of processed data products to the ESO Science Archive Facility
for open use. The Gaia-ESO Survey obtained 202,000 spectra of 115,000
stars using 340 allocated VLT nights between December 2011 and January
2018 from GIRAFFE and UVES. The full consistently reduced final data set
of spectra was released through the ESO Science Archive Facility in late
2020, with the full astrophysical parameters sets following in 2022.
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Title: Information content of BP/RP spectra in Gaia DR3
Authors: Witten, Callum E. C.; Aguado, David S.; Sanders, Jason L.;
Belokurov, Vasily; Evans, N. Wyn; Koposov, Sergey E.; Allende Prieto,
Carlos; De Angeli, Francesca; Irwin, Mike J.
2022MNRAS.tmp.2163W Altcode: 2022arXiv220512271W
Gaia Data Release 3 has provided the astronomical community with
the largest stellar spectroscopic survey to date (> 220 million
sources). The low resolution (R~50) blue photometer (BP) and red
photometer (RP) spectra will allow for the estimation of stellar
atmospheric parameters such as effective temperature, surface gravity
and metallicity. We create mock Gaia BP/RP spectra and use Fisher
information matrices to probe the resolution limit of stellar parameter
measurements using BP/RP spectra. The best-case scenario uncertainties
that this analysis provides are then used to produce a mock-observed
stellar population in order to evaluate the false positive rate
(FPR) of identifying extremely metal-poor (EMP) stars. We conclude
that the community will be able to confidently identify metal-poor
stars at magnitudes brighter than G = 16 using BP/RP spectra. At
fainter magnitudes true detections will start to be overwhelmed by
false positives. When adopting the commonly-used G < 14 limit for
metal-poor star searches, we find a FPR for the low-metallicity regimes
[Fe/H] < -2, -2.5 and -3 of just 14%, 33% and 56% respectively,
offering the potential for significant improvements on previous
targeting campaigns. Additionally, we explore the chemical sensitivity
obtainable directly from BP/RP spectra for Carbon and α-elements. We
find an absolute Carbon abundance uncertainty of σ<SUB>A(C)</SUB>
< 1 dex for Carbon-enriched metal-poor (CEMP) stars, indicating
the potential to identify a CEMP stellar population for follow-up
confirmation with higher resolution spectroscopy. Finally, we find
that large uncertainties in α-element abundance measurements using
BP/RP spectra means that efficiently obtaining these abundances will
be challenging.
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Title: Overview of the DESI Milky Way Survey
Authors: Cooper, Andrew P.; Koposov, Sergey E.; Allende Prieto,
Carlos; Manser, Christopher J.; Kizhuprakkat, Namitha; Myers, Adam
D.; Dey, Arjun; Gaensicke, Boris T.; Li, Ting S.; Rockosi, Constance;
Valluri, Monica; Najita, Joan; Deason, Alis; Raichoor, Anand; Wang,
Mei-Yu; Ting, Yuan-Sen; Kim, Bokyoung; Carrillo, Andreia; Wang,
Wenting; Beraldo e Silva, Leandro; Han, Jiwon Jesse; Ding, Jiani;
Sanchez-Conde, Miguel; Aguilar, Jessica N.; Ahlen, Steven; Bailey,
Stephen; Belokurov, Vasily; Brooks, David; Cunha, Katia; Dawson, Kyle;
de la Macorra, Axel; Doel, Peter; Eisenstein, Daniel J.; Fagrelius,
Parker; Fanning, Kevin; Font-Ribera, Andreu; Forero-Romero, Jaime E.;
Gaztanaga, Enrique; Gontcho, Satya Gontcho A; Guy, Julien; Honscheid,
Klaus; Kehoe, Robert; Kisner, Theodore; Kremin, Anthony; Landriau,
Martin; Levi, Michael E.; Martini, Paul; Meisner, Aaron M.; Miquel,
Ramon; Moustakas, John; Nie, Jundan; Palanque-Delabrouille, Nathalie;
Percival, Will J.; Poppett, Claire; Prada, Francisco; Rehemtulla,
Nabeel; Schlafly, Edward; Schlegel, David; Schubnell, Michael;
Sharples, Ray M.; Tarle, Gregory; Wechsler, Risa H.; Weinberg, David
H.; Zhou, Zhimin; Zou, Hu
2022arXiv220808514C Altcode:
We describe the Milky Way Survey (MWS) that will be undertaken with the
Dark Energy Spectroscopic Instrument (DESI) on the Mayall 4m Telescope
at the Kitt Peak National Observatory. Over the next 5 years DESI
MWS will observe approximately 7 million stars at Galactic latitudes
|b|>20 deg, with an inclusive target selection scheme focused
on the thick disk and stellar halo. MWS will also include several
high-completeness samples of rare stellar types, including white dwarfs,
low-mass stars within 100pc of the Sun, and horizontal branch stars. We
summarize the potential of DESI to advance understanding of Galactic
structure and stellar evolution. We introduce the final definitions
of the main MWS target classes and estimate the number of stars in
each class that will be observed. We describe our pipelines to derive
radial velocities, atmospheric parameters and chemical abundances. We
use ~500,000 spectra of unique stellar targets from the DESI Survey
Validation program (SV) to demonstrate that our pipelines can measure
radial velocities to approximately 1 km/s and [Fe/H] accurate to
approximately 0.2 dex for typical stars in our main sample. We find
stellar parameter distributions from 100 sq. deg. of SV observations
with >90% completeness on our main sample are in good agreement
with expectations from mock catalogues and previous surveys.
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Title: BACCHUS Analysis of Weak Lines in APOGEE Spectra (BAWLAS)
Authors: Hayes, Christian R.; Masseron, Thomas; Sobeck, Jennifer;
Garcia-Hernandez, D. A.; Allende Prieto, Carlos; Beaton, Rachael L.;
Cunha, Katia; Hasselquist, Sten; Holtzman, Jon A.; Jonsson, Henrik;
Majewski, Steven R.; Shetrone, Matthew; Smith, Verne V.; Almeida,
Andres
2022arXiv220800071H Altcode:
Elements with weak and blended spectral features in stellar spectra
are challenging to measure and require specialized analysis methods
to precisely measure their chemical abundances. In this work, we
have created a catalog of approximately 120,000 giants with high
signal-to-noise APOGEE DR17 spectra, for which we explore weak and
blended species to measure Na, P, S, V, Cu, Ce, and Nd abundances and
$^{12}$C/$^{13}$C isotopic ratios. We employ an updated version of
the BACCHUS (Brussels Automatic Code for Characterizing High accUracy
Spectra) code to derive these abundances using the stellar parameters
measured by APOGEE's DR17 ASPCAP pipeline, quality flagging to identify
suspect spectral lines, and a prescription for upper limits. Combined
these allow us to provide our BACCHUS Analysis of Weak Lines in
APOGEE Spectra (BAWLAS) catalog of precise chemical abundances for
these weak and blended species that agrees well with literature and
improves upon APOGEE abundances for these elements, some of which
are unable to be measured with APOGEE's current, grid-based approach
without computationally expensive expansions. This new catalog can be
used alongside APOGEE and provide measurements for many scientific
applications ranging from nuclear physics to Galactic chemical
evolution and Milky Way population studies. To illustrate this we
show some examples of uses for this catalog, such as, showing that we
observe stars with enhanced s-process abundances or that we can use
the our $^{12}$C/$^{13}$C ratios to explore extra mixing along the
red giant branch.
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Title: The Gaia-ESO Public Spectroscopic Survey: Implementation,
data products, open cluster survey, science, and legacy
Authors: Randich, S.; Gilmore, G.; Magrini, L.; Sacco, G. G.; Jackson,
R. J.; Jeffries, R. D.; Worley, C. C.; Hourihane, A.; Gonneau, A.;
Viscasillas Vàzquez, C.; Franciosini, E.; Lewis, J. R.; Alfaro, E. J.;
Allende Prieto, C.; Blomme, T. Bensby R.; Bragaglia, A.; Flaccomio, E.;
François, P.; Irwin, M. J.; Koposov, S. E.; Korn, A. J.; Lanzafame,
A. C.; Pancino, E.; Recio-Blanco, A.; Smiljanic, R.; Van Eck, S.;
Zwitter, T.; Asplund, M.; Bonifacio, P.; Feltzing, S.; Binney, J.;
Drew, J.; Ferguson, A. M. N.; Micela, G.; Negueruela, I.; Prusti,
T.; Rix, H. -W.; Vallenari, A.; Bayo, A.; Bergemann, M.; Biazzo, K.;
Carraro, G.; Casey, A. R.; Damiani, F.; Frasca, A.; Heiter, U.; Hill,
V.; Jofré, P.; de Laverny, P.; Lind, K.; Marconi, G.; Martayan, C.;
Masseron, T.; Monaco, L.; Morbidelli, L.; Prisinzano, L.; Sbordone,
L.; Sousa, S. G.; Zaggia, S.; Adibekyan, V.; Bonito, R.; Caffau,
E.; Daflon, S.; Feuillet, D. K.; Gebran, M.; González Hernández,
J. I.; Guiglion, G.; Herrero, A.; Lobel, A.; Maíz Apellániz,
J.; Merle, T.; Mikolaitis, S.; Montes, D.; Morel, T.; Soubiran,
C.; Spina, L.; Tabernero, H. M.; Tautvaišienė, G.; Traven, G.;
Valentini, M.; Van der Swaelmen, M.; Villanova, S.; Wright, N. J.;
Abbas, U.; Aguirre Børsen-Koch, V.; Alves, J.; Balaguer-Núnez,
L.; Barklem, P. S.; Barrado, D.; Berlanas, S. R.; Binks, A. S.;
Bressan, A.; Capuzzo--Dolcetta, R.; Casagrande, L.; Casamiquela, L.;
Collins, R. S.; D'Orazi, V.; Dantas, M. L. L.; Debattista, V. P.;
Delgado-Mena, E.; Di Marcantonio, P.; Drazdauskas, A.; Evans, N. W.;
Famaey, B.; Franchini, M.; Frémat, Y.; Friel, E. D.; Fu, X.; Geisler,
D.; Gerhard, O.; González Solares, E. A.; Grebel, E. K.; Gutiérrez
Albarrán, M. L.; Hatzidimitriou, D.; Held, E. V.; Jiménez-Esteban,
F.; Jönsson, H.; Jordi, C.; Khachaturyants, T.; Kordopatis, G.; Kos,
J.; Lagarde, N.; Mahy, L.; Mapelli, M.; Marfil, E.; Martell, S. L.;
Messina, S.; Miglio, A.; Minchev, I.; Moitinho, A.; Montalban, J.;
Monteiro, M. J. P. F. G.; Morossi, C.; Mowlavi, N.; Mucciarelli, A.;
Murphy, D. N. A.; Nardetto, N.; Ortolani, S.; Paletou, F.; Palouus, J.;
Paunzen, E.; Pickering, J. C.; Quirrenbach, A.; Re Fiorentin, P.; Read,
J. I.; Romano, D.; Ryde, N.; Sanna, N.; Santos, W.; Seabroke, G. M.;
Spagna, A.; Steinmetz, M.; Stonkuté, E.; Sutorius, E.; Thévenin,
F.; Tosi, M.; Tsantaki, M.; Vink, J. S.; Wright, N.; Wyse, R. F. G.;
Zoccali, M.; Zorec, J.; Zucker, D. B.; Walton, N. A.
2022arXiv220602901R Altcode:
In the last 15 years different ground-based spectroscopic surveys
have been started (and completed) with the general aim of delivering
stellar parameters and elemental abundances for large samples of
Galactic stars, complementing Gaia astrometry. Among those surveys,
the Gaia-ESO Public Spectroscopic Survey (GES), the only one performed
on a 8m class telescope, was designed to target 100,000 stars using
FLAMES on the ESO VLT (both Giraffe and UVES spectrographs), covering
all the Milky Way populations, with a special focus on open star
clusters. This article provides an overview of the survey implementation
(observations, data quality, analysis and its success, data products,
and releases), of the open cluster survey, of the science results and
potential, and of the survey legacy. A companion article (Gilmore et
al.) reviews the overall survey motivation, strategy, Giraffe pipeline
data reduction, organisation, and workflow. The GES has determined
homogeneous good-quality radial velocities and stellar parameters for a
large fraction of its more than 110,000 unique target stars. Elemental
abundances were derived for up to 31 elements for targets observed with
UVES. Lithium abundances are delivered for about 1/3 of the sample. The
analysis and homogenisation strategies have proven to be successful;
several science topics have been addressed by the Gaia-ESO consortium
and the community, with many highlight results achieved. The final
catalogue has been released through the ESO archive at the end of
May 2022, including the complete set of advanced data products. In
addition to these results, the Gaia-ESO Survey will leave a very
important legacy, for several aspects and for many years to come.
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Title: TOI-178: a window into the formation and evolution of
planetary systems
Authors: Hooton, Matthew J.; Fisher, Chloe; Alibert, Yann; Hara,
Nathan; Heng, Kevin; Leleu, Adrien; Palle, Enric; Wilson, Thomas
G.; Adibekyan, Vardan; Allart, Romain; Barros, Susana C. C.; Billot,
Nicolas; Boué, Gwenaël; Bourrier, Vincent; Brandeker, Alexis; Bruno,
Giovanni; Correia, Alexandre C. M.; Demory, Brice-Olivier; Ehrenreich,
David; Espinoza, Néstor; Fossati, Luca; Fridlund, Malcolm; Haldemann,
Jonas; Hoyer, Sergio; Kitzmann, Daniel; Lavie, Baptiste; Lendl, Monika;
Lillo-Box, Jorge; Morris, Brett; Osborn, Hugh; Oshagh, Mahmoudreza;
Persson, Carina; Pozuelos, Francisco J.; Allende-Prieto, Carlos;
Santos, Nuno; Schneider, Jean; Sozzetti, Alessandro
2022BAAS...54e.394H Altcode:
Laplacian resonant chains — where astronomical bodies are in mean
motion resonance with two or more other bodies — are rare phenomena
observed in systems such as the TRAPPIST-1 exoplanets and the Galilean
moons of Jupiter. Laplacian chains are an important tool to study
the history of planetary systems occupying this configuration, as the
fragility of the chain significantly constrains the possible pathways
through which the planets can form and evolve. Whilst initial TESS
observations suggested that TOI-178 — a nearby system of exoplanets
orbiting a relatively cool K-dwarf — hosted the first known planets
occupying a horseshoe-coorbital configuration, follow-up observations by
CHEOPS, NGTS and SPECULOOS revealed a compact system of six transiting
exoplanets all smaller than Neptune: five of which form a chain of
Laplacian resonance. Precise measurements of the host's radial velocity
using the ESPRESSO spectrograph revealed uncommon planet-to-planet
density variations: a stark departure from the monotonic decrease
in density with orbital separation common to most systems. JWST time
awarded in Cycle 1 to acquire transmission spectroscopy of planets b,
d and g promises to make the evolution of the TOI-178 planets amongst
the best-understood of any planetary system for the foreseeable future.
---------------------------------------------------------
Title: Overview of the Instrumentation for the Dark Energy
Spectroscopic Instrument
Authors: Abareshi, B.; Aguilar, J.; Ahlen, S.; Alam, Shadab; Alexander,
David M.; Alfarsy, R.; Allen, L.; Allende Prieto, C.; Alves, O.;
Ameel, J.; Armengaud, E.; Asorey, J.; Aviles, Alejandro; Bailey,
S.; Balaguera-Antolínez, A.; Ballester, O.; Baltay, C.; Bault,
A.; Beltran, S. F.; Benavides, B.; BenZvi, S.; Berti, A.; Besuner,
R.; Beutler, Florian; Bianchi, D.; Blake, C.; Blanc, P.; Blum, R.;
Bolton, A.; Bose, S.; Bramall, D.; Brieden, S.; Brodzeller, A.;
Brooks, D.; Brownewell, C.; Buckley-Geer, E.; Cahn, R. N.; Cai, Z.;
Canning, R.; Carnero Rosell, A.; Carton, P.; Casas, R.; Castander,
F. J.; Cervantes-Cota, J. L.; Chabanier, S.; Chaussidon, E.; Chuang,
C.; Circosta, C.; Cole, S.; Cooper, A. P.; da Costa, L.; Cousinou,
M. -C.; Cuceu, A.; Davis, T. M.; Dawson, K.; de la Cruz-Noriega, R.;
de la Macorra, A.; de Mattia, A.; Della Costa, J.; Demmer, P.; Derwent,
M.; Dey, A.; Dey, B.; Dhungana, G.; Ding, Z.; Dobson, C.; Doel, P.;
Donald-McCann, J.; Donaldson, J.; Douglass, K.; Duan, Y.; Dunlop, P.;
Edelstein, J.; Eftekharzadeh, S.; Eisenstein, D. J.; Enriquez-Vargas,
M.; Escoffier, S.; Evatt, M.; Fagrelius, P.; Fan, X.; Fanning, K.;
Fawcett, V. A.; Ferraro, S.; Ereza, J.; Flaugher, B.; Font-Ribera,
A.; Forero-Romero, J. E.; Frenk, C. S.; Fromenteau, S.; Gänsicke,
B. T.; Garcia-Quintero, C.; Garrison, L.; Gaztañaga, E.; Gerardi,
F.; Gil-Marín, H.; Gontcho, S. Gontcho A; Gonzalez-Morales, Alma
X.; Gonzalez-de-Rivera, G.; Gonzalez-Perez, V.; Gordon, C.; Graur,
O.; Green, D.; Grove, C.; Gruen, D.; Gutierrez, G.; Guy, J.; Hahn,
C.; Harris, S.; Herrera, D.; Herrera-Alcantar, Hiram K.; Honscheid,
K.; Howlett, C.; Huterer, D.; Iršič, V.; Ishak, M.; Jelinsky, P.;
Jiang, L.; Jimenez, J.; Jing, Y. P.; Joyce, R.; Jullo, E.; Juneau,
S.; Karaçaylı, N. G.; Karamanis, M.; Karcher, A.; Karim, T.; Kehoe,
R.; Kent, S.; Kirkby, D.; Kisner, T.; Kitaura, F.; Koposov, S. E.;
Kovács, A.; Kremin, A.; Krolewski, Alex; L'Huillier, B.; Lahav,
O.; Lambert, A.; Lamman, C.; Lan, Ting-Wen; Landriau, M.; Lane, S.;
Lang, D.; Lange, J. U.; Lasker, J.; Le Guillou, L.; Leauthaud, A.;
Le Van Suu, A.; Levi, Michael E.; Li, T. S.; Magneville, C.; Manera,
M.; Manser, Christopher J.; Marshall, B.; McCollam, W.; McDonald, P.;
Meisner, Aaron M.; Mezcua, J. Mena-Fernández M.; Miller, T.; Miquel,
R.; Montero-Camacho, P.; Moon, J.; Martini, J. Paul; Meneses-Rizo, J.;
Moustakas, J.; Mueller, E.; Muñoz-Gutiérrez, Andrea; Myers, Adam D.;
Nadathur, S.; Najita, J.; Napolitano, L.; Neilsen, E.; Newman, Jeffrey
A.; Nie, J. D.; Ning, Y.; Niz, G.; Norberg, P.; Noriega, Hernán E.;
O'Brien, T.; Obuljen, A.; Palanque-Delabrouille, N.; Palmese, A.;
Zhiwei, P.; Pappalardo, D.; Peng, X.; Percival, W. J.; Perruchot,
S.; Pogge, R.; Poppett, C.; Porredon, A.; Prada, F.; Prochaska, J.;
Pucha, R.; Pérez-Fernández, A.; Pérez-Ráfols, I.; Rabinowitz, D.;
Raichoor, A.; Ramirez-Solano, S.; Ramírez-Pérez, César; Ravoux, C.;
Reil, K.; Rezaie, M.; Rocher, A.; Rockosi, C.; Roe, N. A.; Roodman,
A.; Ross, A. J.; Rossi, G.; Ruggeri, R.; Ruhlmann-Kleider, V.; Sabiu,
C. G.; Safonova, S.; Said, K.; Saintonge, A.; Salas Catonga, Javier;
Samushia, L.; Sanchez, E.; Saulder, C.; Schaan, E.; Schlafly, E.;
Schlegel, D.; Schmoll, J.; Scholte, D.; Schubnell, M.; Secroun,
A.; Seo, H.; Serrano, S.; Sharples, Ray M.; Sholl, Michael J.;
Silber, Joseph Harry; Silva, D. R.; Sirk, M.; Siudek, M.; Smith, A.;
Sprayberry, D.; Staten, R.; Stupak, B.; Tan, T.; Tarlé, Gregory; Sien
Tie, Suk; Tojeiro, R.; Ureña-López, L. A.; Valdes, F.; Valenzuela,
O.; Valluri, M.; Vargas-Magaña, M.; Verde, L.; Walther, M.; Wang,
B.; Wang, M. S.; Weaver, B. A.; Weaverdyck, C.; Wechsler, R.; Wilson,
Michael J.; Yang, J.; Yu, Y.; Yuan, S.; Yèche, Christophe; Zhang,
H.; Zhang, K.; Zhao, Cheng; Zhou, Rongpu; Zhou, Zhimin; Zou, H.; Zou,
J.; Zou, S.; Zu, Y.
2022arXiv220510939A Altcode:
The Dark Energy Spectroscopic Instrument (DESI) has embarked on an
ambitious five-year survey to explore the nature of dark energy with
spectroscopy of 40 million galaxies and quasars. DESI will determine
precise redshifts and employ the Baryon Acoustic Oscillation
method to measure distances from the nearby universe to z >
3.5, as well as measure the growth of structure and probe potential
modifications to general relativity. In this paper we describe the
significant instrumentation we developed for the DESI survey. The new
instrumentation includes a wide-field, 3.2-deg diameter prime-focus
corrector that focuses the light onto 5020 robotic fiber positioners
on the 0.812 m diameter, aspheric focal surface. The positioners and
their fibers are divided among ten wedge-shaped petals. Each petal is
connected to one of ten spectrographs via a contiguous, high-efficiency,
nearly 50 m fiber cable bundle. The ten spectrographs each use a pair of
dichroics to split the light into three channels that together record
the light from 360 - 980 nm with a resolution of 2000 to 5000. We
describe the science requirements, technical requirements on the
instrumentation, and management of the project. DESI was installed at
the 4-m Mayall telescope at Kitt Peak, and we also describe the facility
upgrades to prepare for DESI and the installation and functional
verification process. DESI has achieved all of its performance goals,
and the DESI survey began in May 2021. Some performance highlights
include RMS positioner accuracy better than 0.1", SNR per \sqrtÅ >
0.5 for a z > 2 quasar with flux 0.28e-17 erg/s/cm^2/A at 380 nm
in 4000s, and median SNR = 7 of the [OII] doublet at 8e-17 erg/s/cm^2
in a 1000s exposure for emission line galaxies at z = 1.4 - 1.6. We
conclude with highlights from the on-sky validation and commissioning
of the instrument, key successes, and lessons learned. (abridged)
---------------------------------------------------------
Title: The Robotic Multi-Object Focal Plane System of the Dark Energy
Spectroscopic Instrument (DESI)
Authors: Silber, Joseph Harry; Fagrelius, Parker; Fanning, Kevin;
Schubnell, Michael; Aguilar, Jessica Nicole; Ahlen, Steven; Ameel,
Jon; Ballester, Otger; Baltay, Charles; Bebek, Chris; Beard, Dominic
Benton; Besuner, Robert; Cardiel-Sas, Laia; Casas, Ricard; Castander,
Francisco Javier; Claybaugh, Todd; Dobson, Carl; Duan, Yutong; Dunlop,
Patrick; Edelstein, Jerry; Emmet, William T.; Elliott, Ann; Evatt,
Matthew; Gershkovich, Irena; Guy, Julien; Harris, Stu; Heetderks,
Henry; Heetderks, Ian; Honscheid, Klaus; Illa, Jose Maria; Jelinsky,
Patrick; Jelinsky, Sharon R.; Jimenez, Jorge; Karcher, Armin; Kent,
Stephen; Kirkby, David; Kneib, Jean-Paul; Lambert, Andrew; Lampton,
Mike; Leitner, Daniela; Levi, Michael; McCauley, Jeremy; Meisner,
Aaron; Miller, Timothy N.; Miquel, Ramon; Mundet, Juliá; Poppett,
Claire; Rabinowitz, David; Reil, Kevin; Roman, David; Schlegel,
David; Serrano, Santiago; Van Shourt, William; Sprayberry, David;
Tarlé, Gregory; Sien Tie, Suk; Weaverdyck, Curtis; Zhang, Kai;
Azzaro, Marco; Bailey, Stephen; Becerril, Santiago; Blackwell, Tami;
Bouri, Mohamed; Brooks, David; Buckley-Geer, Elizabeth; Peñate
Castro, Jose; Derwent, Mark; Dey, Arjun; Dhungana, Govinda; Doel,
Peter; Eisenstein, Daniel J.; Fahim, Nasib; Garcia-Bellido, Juan;
Gaztañaga, Enrique; Gontcho, Satya Gontcho A; Gutierrez, Gaston;
Hörler, Philipp; Kehoe, Robert; Kisner, Theodore; Kremin, Anthony;
Kronig, Luzius; Landriau, Martin; Le Guillou, Laurent; Martini,
Paul; Moustakas, John; Palanque-Delabrouille, Nathalie; Peng, Xiyan;
Percival, Will; Prada, Francisco; Allende Prieto, Carlos; Gonzalez de
Rivera, Guillermo; Sanchez, Eusebio; Sanchez, Justo; Sharples, Ray;
Soares-Santos, Marcelle; Schlafly, Edward; Weaver, Benjamin Alan;
Zhou, Zhimin; Zhu, Yaling; Zou, Hu
2022arXiv220509014S Altcode:
A system of 5,020 robotic fiber positioners was installed in 2019 on
the Mayall Telescope, at Kitt Peak National Observatory. The robots
automatically re-target their optical fibers every 10 - 20 minutes,
each to a precision of several microns, with a reconfiguration time
less than 2 minutes. Over the next five years, they will enable the
newly-constructed Dark Energy Spectroscopic Instrument (DESI) to measure
the spectra of 35 million galaxies and quasars. DESI will produce
the largest 3D map of the universe to date and measure the expansion
history of the cosmos. In addition to the 5,020 robotic positioners and
optical fibers, DESI's Focal Plane System includes 6 guide cameras, 4
wavefront cameras, 123 fiducial point sources, and a metrology camera
mounted at the primary mirror. The system also includes associated
structural, thermal, and electrical systems. In all, it contains
over 675,000 individual parts. We discuss the design, construction,
quality control, and integration of all these components. We include
a summary of the key requirements, the review and acceptance process,
on-sky validations of requirements, and lessons learned for future
multi-object, fiber-fed spectrographs.
---------------------------------------------------------
Title: Strong CO absorption features in massive ETGs
Authors: Eftekhari, Elham; La Barbera, Francesco; Vazdekis, Alexandre;
Allende Prieto, Carlos; Knowles, Adam Thomas
2022MNRAS.512..378E Altcode: 2022MNRAS.tmp..488E; 2022arXiv220208651E
Massive Early-Type Galaxies (ETGs) in the local Universe are believed to
be the most mature stage of galaxy evolution. Their stellar population
content reveals the evolutionary history of these galaxies. However,
while state-of-the-art Stellar Population Synthesis (SPS) models
provide an accurate description of observed galaxy spectra in the
optical range, the modelling in the Near-Infrared (NIR) is still in
its infancy. Here, we focus on NIR CO absorption features to show,
in a systematic and comprehensive manner, that for massive ETGs,
all CO indices, from H through to K band, are significantly stronger
than currently predicted by SPS models. We explore and discuss
several possible explanations of this 'CO mismatch', including the
effect of intermediate-age, asymptotic-giant-branch-dominated, stellar
populations, high-metallicity populations, non-solar abundance ratios,
and the initial mass function. While none of these effects is able
to reconcile models and observations, we show that ad hoc 'empirical'
corrections, taking into account the effect of CO-strong giant stars in
the low-temperature regime, provide model predictions that are closer
to the observations. Our analysis points to the effect of carbon
abundance as the most likely explanation of NIR CO line-strengths,
indicating possible routes for improving the SPS models in the NIR.
---------------------------------------------------------
Title: SEGUE-2: Old Milky Way Stars Near and Far
Authors: Rockosi, Constance M.; Lee, Young Sun; Morrison, Heather L.;
Yanny, Brian; Johnson, Jennifer A.; Lucatello, Sara; Sobeck, Jennifer;
Beers, Timothy C.; Allende Prieto, Carlos; An, Deokkeun; Bizyaev,
Dmitry; Blanton, Michael R.; Casagrande, Luca; Eisenstein, Daniel
J.; Gould, Andrew; Gunn, James E.; Harding, Paul; Ivans, Inese I.;
Jacobson, H. R.; Janesh, William; Knapp, Gillian R.; Kollmeier,
Juna A.; Lépine, Sébastien; López-Corredoira, Martín; Ma,
Zhibo; Newberg, Heidi J.; Pan, Kaike; Prchlik, Jakub; Sayers, Conor;
Schlesinger, Katharine J.; Simmerer, Jennifer; Weinberg, David H.
2022ApJS..259...60R Altcode:
The Sloan Extension for Galactic Understanding and Exploration 2
(SEGUE-2) obtained 128,288 low-resolution spectra (R ~ 1800) of
118,958 unique stars in the first year of the Sloan Digital Sky
Survey III (2008-2009). SEGUE-2 targeted prioritized distant halo
tracers (blue horizontal-branch stars, K giants, and M giants) and
metal-poor or kinematically hot populations. The main goal of SEGUE-2
was to target stars in the distant halo and measure their kinematics
and chemical abundances to learn about the formation and evolution
of the Milky Way. We present the SEGUE-2 field placement and target
selection strategies. We discuss the success rate of the targeting
based on the SEGUE-2 spectra and other spectroscopic and astrometric
surveys. We describe the final SEGUE-2/SDSS-III improvements to the
stellar parameter determinations based on the SEGUE Stellar Parameter
Pipeline. We report a (g - i) color-effective temperature relation
calibrated to the IRFM. We evaluate the accuracy and uncertainties
associated with these stellar parameters by comparing with fundamental
parameters, a sample of high-resolution spectra of SEGUE stars analyzed
homogeneously, stars in well-studied clusters, and stars observed
in common by the APOGEE survey. The final SEGUE spectra, calibration
data, and derived parameters described here were released in SDSS-III
Data Release 9 and continue to be included in all subsequent SDSS Data
Releases. Because of its faint limiting magnitude and emphasis on the
distant halo, the public SEGUE-2 data remain an important resource
for the spectroscopy of stars in the Milky Way.
---------------------------------------------------------
Title: The Seventeenth Data Release of the Sloan Digital Sky Surveys:
Complete Release of MaNGA, MaStar, and APOGEE-2 Data
Authors: Abdurro'uf; Accetta, Katherine; Aerts, Conny; Silva
Aguirre, Víctor; Ahumada, Romina; Ajgaonkar, Nikhil; Filiz Ak,
N.; Alam, Shadab; Allende Prieto, Carlos; Almeida, Andrés; Anders,
Friedrich; Anderson, Scott F.; Andrews, Brett H.; Anguiano, Borja;
Aquino-Ortíz, Erik; Aragón-Salamanca, Alfonso; Argudo-Fernández,
Maria; Ata, Metin; Aubert, Marie; Avila-Reese, Vladimir; Badenes,
Carles; Barbá, Rodolfo H.; Barger, Kat; Barrera-Ballesteros, Jorge
K.; Beaton, Rachael L.; Beers, Timothy C.; Belfiore, Francesco;
Bender, Chad F.; Bernardi, Mariangela; Bershady, Matthew A.; Beutler,
Florian; Bidin, Christian Moni; Bird, Jonathan C.; Bizyaev, Dmitry;
Blanc, Guillermo A.; Blanton, Michael R.; Boardman, Nicholas Fraser;
Bolton, Adam S.; Boquien, Médéric; Borissova, Jura; Bovy, Jo; Brandt,
W. N.; Brown, Jordan; Brownstein, Joel R.; Brusa, Marcella; Buchner,
Johannes; Bundy, Kevin; Burchett, Joseph N.; Bureau, Martin; Burgasser,
Adam; Cabang, Tuesday K.; Campbell, Stephanie; Cappellari, Michele;
Carlberg, Joleen K.; Wanderley, Fábio Carneiro; Carrera, Ricardo;
Cash, Jennifer; Chen, Yan-Ping; Chen, Wei-Huai; Cherinka, Brian;
Chiappini, Cristina; Choi, Peter Doohyun; Chojnowski, S. Drew; Chung,
Haeun; Clerc, Nicolas; Cohen, Roger E.; Comerford, Julia M.; Comparat,
Johan; da Costa, Luiz; Covey, Kevin; Crane, Jeffrey D.; Cruz-Gonzalez,
Irene; Culhane, Connor; Cunha, Katia; Dai, Y. Sophia; Damke, Guillermo;
Darling, Jeremy; Davidson, James W., Jr.; Davies, Roger; Dawson, Kyle;
De Lee, Nathan; Diamond-Stanic, Aleksandar M.; Cano-Díaz, Mariana;
Sánchez, Helena Domínguez; Donor, John; Duckworth, Chris; Dwelly,
Tom; Eisenstein, Daniel J.; Elsworth, Yvonne P.; Emsellem, Eric;
Eracleous, Mike; Escoffier, Stephanie; Fan, Xiaohui; Farr, Emily;
Feng, Shuai; Fernández-Trincado, José G.; Feuillet, Diane; Filipp,
Andreas; Fillingham, Sean P.; Frinchaboy, Peter M.; Fromenteau,
Sebastien; Galbany, Lluís; García, Rafael A.; García-Hernández,
D. A.; Ge, Junqiang; Geisler, Doug; Gelfand, Joseph; Géron, Tobias;
Gibson, Benjamin J.; Goddy, Julian; Godoy-Rivera, Diego; Grabowski,
Kathleen; Green, Paul J.; Greener, Michael; Grier, Catherine J.;
Griffith, Emily; Guo, Hong; Guy, Julien; Hadjara, Massinissa;
Harding, Paul; Hasselquist, Sten; Hayes, Christian R.; Hearty, Fred;
Hernández, Jesús; Hill, Lewis; Hogg, David W.; Holtzman, Jon A.;
Horta, Danny; Hsieh, Bau-Ching; Hsu, Chin-Hao; Hsu, Yun-Hsin; Huber,
Daniel; Huertas-Company, Marc; Hutchinson, Brian; Hwang, Ho Seong;
Ibarra-Medel, Héctor J.; Chitham, Jacob Ider; Ilha, Gabriele S.;
Imig, Julie; Jaekle, Will; Jayasinghe, Tharindu; Ji, Xihan; Johnson,
Jennifer A.; Jones, Amy; Jönsson, Henrik; Katkov, Ivan; Khalatyan,
Arman, Dr.; Kinemuchi, Karen; Kisku, Shobhit; Knapen, Johan H.;
Kneib, Jean-Paul; Kollmeier, Juna A.; Kong, Miranda; Kounkel, Marina;
Kreckel, Kathryn; Krishnarao, Dhanesh; Lacerna, Ivan; Lane, Richard
R.; Langgin, Rachel; Lavender, Ramon; Law, David R.; Lazarz, Daniel;
Leung, Henry W.; Leung, Ho-Hin; Lewis, Hannah M.; Li, Cheng; Li,
Ran; Lian, Jianhui; Liang, Fu-Heng; Lin, Lihwai; Lin, Yen-Ting;
Lin, Sicheng; Lintott, Chris; Long, Dan; Longa-Peña, Penélope;
López-Cobá, Carlos; Lu, Shengdong; Lundgren, Britt F.; Luo, Yuanze;
Mackereth, J. Ted; de la Macorra, Axel; Mahadevan, Suvrath; Majewski,
Steven R.; Manchado, Arturo; Mandeville, Travis; Maraston, Claudia;
Margalef-Bentabol, Berta; Masseron, Thomas; Masters, Karen L.;
Mathur, Savita; McDermid, Richard M.; Mckay, Myles; Merloni, Andrea;
Merrifield, Michael; Meszaros, Szabolcs; Miglio, Andrea; Di Mille,
Francesco; Minniti, Dante; Minsley, Rebecca; Monachesi, Antonela;
Moon, Jeongin; Mosser, Benoit; Mulchaey, John; Muna, Demitri; Muñoz,
Ricardo R.; Myers, Adam D.; Myers, Natalie; Nadathur, Seshadri; Nair,
Preethi; Nandra, Kirpal; Neumann, Justus; Newman, Jeffrey A.; Nidever,
David L.; Nikakhtar, Farnik; Nitschelm, Christian; O'Connell, Julia E.;
Garma-Oehmichen, Luis; Luan Souza de Oliveira, Gabriel; Olney, Richard;
Oravetz, Daniel; Ortigoza-Urdaneta, Mario; Osorio, Yeisson; Otter,
Justin; Pace, Zachary J.; Padilla, Nelson; Pan, Kaike; Pan, Hsi-An;
Parikh, Taniya; Parker, James; Peirani, Sebastien; Peña Ramírez,
Karla; Penny, Samantha; Percival, Will J.; Perez-Fournon, Ismael;
Pinsonneault, Marc; Poidevin, Frédérick; Poovelil, Vijith Jacob;
Price-Whelan, Adrian M.; Bárbara de Andrade Queiroz, Anna; Raddick,
M. Jordan; Ray, Amy; Rembold, Sandro Barboza; Riddle, Nicole; Riffel,
Rogemar A.; Riffel, Rogério; Rix, Hans-Walter; Robin, Annie C.;
Rodríguez-Puebla, Aldo; Roman-Lopes, Alexandre; Román-Zúñiga,
Carlos; Rose, Benjamin; Ross, Ashley J.; Rossi, Graziano; Rubin,
Kate H. R.; Salvato, Mara; Sánchez, Sebástian F.; Sánchez-Gallego,
José R.; Sanderson, Robyn; Santana Rojas, Felipe Antonio; Sarceno,
Edgar; Sarmiento, Regina; Sayres, Conor; Sazonova, Elizaveta; Schaefer,
Adam L.; Schiavon, Ricardo; Schlegel, David J.; Schneider, Donald P.;
Schultheis, Mathias; Schwope, Axel; Serenelli, Aldo; Serna, Javier;
Shao, Zhengyi; Shapiro, Griffin; Sharma, Anubhav; Shen, Yue; Shetrone,
Matthew; Shu, Yiping; Simon, Joshua D.; Skrutskie, M. F.; Smethurst,
Rebecca; Smith, Verne; Sobeck, Jennifer; Spoo, Taylor; Sprague,
Dani; Stark, David V.; Stassun, Keivan G.; Steinmetz, Matthias;
Stello, Dennis; Stone-Martinez, Alexander; Storchi-Bergmann, Thaisa;
Stringfellow, Guy S.; Stutz, Amelia; Su, Yung-Chau; Taghizadeh-Popp,
Manuchehr; Talbot, Michael S.; Tayar, Jamie; Telles, Eduardo; Teske,
Johanna; Thakar, Ani; Theissen, Christopher; Tkachenko, Andrew; Thomas,
Daniel; Tojeiro, Rita; Hernandez Toledo, Hector; Troup, Nicholas W.;
Trump, Jonathan R.; Trussler, James; Turner, Jacqueline; Tuttle,
Sarah; Unda-Sanzana, Eduardo; Vázquez-Mata, José Antonio; Valentini,
Marica; Valenzuela, Octavio; Vargas-González, Jaime; Vargas-Magaña,
Mariana; Alfaro, Pablo Vera; Villanova, Sandro; Vincenzo, Fiorenzo;
Wake, David; Warfield, Jack T.; Washington, Jessica Diane; Weaver,
Benjamin Alan; Weijmans, Anne-Marie; Weinberg, David H.; Weiss, Achim;
Westfall, Kyle B.; Wild, Vivienne; Wilde, Matthew C.; Wilson, John C.;
Wilson, Robert F.; Wilson, Mikayla; Wolf, Julien; Wood-Vasey, W. M.;
Yan, Renbin; Zamora, Olga; Zasowski, Gail; Zhang, Kai; Zhao, Cheng;
Zheng, Zheng; Zheng, Zheng; Zhu, Kai
2022ApJS..259...35A Altcode: 2021arXiv211202026A
This paper documents the seventeenth data release (DR17) from the
Sloan Digital Sky Surveys; the fifth and final release from the
fourth phase (SDSS-IV). DR17 contains the complete release of the
Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey,
which reached its goal of surveying over 10,000 nearby galaxies. The
complete release of the MaNGA Stellar Library accompanies this data,
providing observations of almost 30,000 stars through the MaNGA
instrument during bright time. DR17 also contains the complete release
of the Apache Point Observatory Galactic Evolution Experiment 2 survey
that publicly releases infrared spectra of over 650,000 stars. The
main sample from the Extended Baryon Oscillation Spectroscopic Survey
(eBOSS), as well as the subsurvey Time Domain Spectroscopic Survey data
were fully released in DR16. New single-fiber optical spectroscopy
released in DR17 is from the SPectroscipic IDentification of ERosita
Survey subsurvey and the eBOSS-RM program. Along with the primary data
sets, DR17 includes 25 new or updated value-added catalogs. This paper
concludes the release of SDSS-IV survey data. SDSS continues into its
fifth phase with observations already underway for the Milky Way Mapper,
Local Volume Mapper, and Black Hole Mapper surveys.
---------------------------------------------------------
Title: The chemical characterisation of halo substructure in the
Milky Way based on APOGEE
Authors: Horta, Danny; Schiavon, Ricardo P.; Mackereth, J. Ted;
Weinberg, David H.; Hasselquist, Sten; Feuillet, Diane; O'Connell,
Robert W.; Anguiano, Borja; Allende-Prieto, Carlos; Beaton, Rachael
L.; Bizyaev, Dmitry; Cunha, Katia; Geisler, Doug; García-Hernández,
D. A.; Holtzman, Jon; Jönsson, Henrik; Lane, Richard R.; Majewski,
Steve R.; Mészáros, Szabolcs; Minniti, Dante; Nitschelm, Christian;
Shetrone, Matthew; Smith, Verne V.; Zasowski, Gail
2022arXiv220404233H Altcode:
Galactic haloes in a $\Lambda$-Cold Dark Matter ($\Lambda$CDM)
universe are predicted to host today a swarm of debris resulting from
cannibalised dwarf galaxies that have been accreted via the process of
hierarchical mass assembly. The chemo-dynamical information recorded
in the Galactic stellar populations associated with such systems helps
elucidate their nature, placing constraints on the mass assembly history
of the Milky Way. Using data from the APOGEE and \textit{Gaia} surveys,
we examine APOGEE targets belonging to the following substructures in
the stellar halo: Heracles, \textit{Gaia}-Enceladus/Sausage (GES),
Sagittarius dSph, the Helmi stream, Sequoia, Thamnos, Aleph, LMS-1,
Arjuna, I'itoi, Nyx, Icarus, and Pontus. We examine the distributions
of all substructures in chemical space, considering the abundances
of elements sampling various nucleosynthetic pathways. Our main
findings include: {\it i)} the chemical properties of GES, Heracles,
the Helmi stream, Sequoia, Thamnos, LMS-1, Arjuna, and I'itoi match
qualitatively those of dwarf satellites of the Milky Way, such as
the Sagittarius dSph; {\it ii)} the abundance pattern of the recently
discovered inner Galaxy substructure Heracles differs statistically
from that of populations formed {\it in situ}. Heracles also differs
chemically from all other substructures; {\it iii)} the abundance
patterns of Sequoia (selected in various ways), Arjuna, LMS-1, and
I'itoi are indistinguishable from that of GES, indicating a possible
common origin; {\it iv)} the abundance patterns of the Helmi stream and
Thamnos substructures are different from all other halo substructures;
{\it v)} the chemical properties of Nyx and Aleph are very similar to
those of disc stars, implying that these substructures likely have an
\textit{in situ} origin.
---------------------------------------------------------
Title: APOGEE detection of N-rich stars in the tidal tails of
Palomar 5
Authors: Phillips, Siân G.; Schiavon, Ricardo P.; Mackereth, J. Ted;
Allende Prieto, Carlos; Anguiano, Borja; Beaton, Rachael L.; Cohen,
Roger E.; García-Hernández, D. A.; Geisler, Douglas; Horta, Danny;
Jönsson, Henrik; Kisku, Shobhit; Lane, Richard R.; Majewski, Steven
R.; Mason, Andrew; Minniti, Dante; Schultheis, Mathias; Taylor, Dominic
2022MNRAS.510.3727P Altcode: 2021arXiv211202117P; 2021MNRAS.tmp.3197P
Recent results from chemical tagging studies using Apache Point
Observatory Galactic Evolution Experiment data suggest a strong link
between the chemical abundance patterns of stars found within globular
clusters (GC), and chemically peculiar populations in the Galactic
halo field. In this paper, we analyse the chemical compositions
of stars within the cluster body and tidal streams of Palomar 5, a
GC that is being tidally disrupted by interaction with the Galactic
gravitational potential. We report the identification of nitrogen-rich
(N-rich) stars both within and beyond the tidal radius of Palomar 5,
with the latter being clearly aligned with the cluster tidal streams;
this acts as confirmation that N-rich stars are lost to the Galactic
halo from GCs, and provides support to the hypothesis that field N-rich
stars identified by various groups have a GC origin.
---------------------------------------------------------
Title: VizieR Online Data Catalog: NIR APOGEE radial velocities of
Draco C1 (Lewis+, 2020)
Authors: Lewis, H. M.; Anguiano, B.; Stassun, K. G.; Majewski, S. R.;
Arras, P.; Sarazin, C. L.; Li, Z. -Y.; de, Lee N.; Troup, N. W.;
Allende Prieto, C. A.; Badenes, C.; Cunha, K.; Garcia-Hernandez,
D. A.; Nidever, D. L.; Palicio, P. A.; Simon, J. D.; Smith, V. V.
2022yCat..19009043L Altcode:
We utilize multi-epoch, high-resolution (R~22500) near-infrared (NIR;
1.51-1.70um) spectra from the APOGEE spectrograph, taken via APOGEE-2 as
part of the Sloan Digital Sky Survey (SDSS-IV; see III/284). <P />Draco
C1 was included on multiple plate designs, each receiving six or more
visits to date. As a result, the red giant (RG) component of the Draco
C1 system (2MASS J17195764+5750054) has been observed 46 times over
the duration of the APOGEE-2 survey, with those visits spanning >3yr
(2016 April through 2019 June). <P />(1 data file).
---------------------------------------------------------
Title: VizieR Online Data Catalog: Sloan Digital Sky Surveys (SDSS),
Release 16 (DR16) (Ahumada+, 2020)
Authors: Ahumada, R.; Allende Prieto, C.; Almeida, A.; et al.
2022yCat.5154....0A Altcode:
Data Release 16 (DR16) is the fourth data release of the fourth phase of
the Sloan Digital Sky Survey (SDSS-IV). DR16 contains SDSS observations
through August 2018. <P />The principal changes from previous versions
are summarized at http://www.sdss.org/dr16/whatsnew/ <P />(1 data file).
---------------------------------------------------------
Title: Retrieving the transmission spectrum of HD 209458b using
CHOCOLATE: a new chromatic Doppler tomography technique
Authors: Esparza-Borges, E.; Oshagh, M.; Casasayas-Barris, N.;
Pallé, E.; Chen, G.; Morello, G.; Santos, N. C.; Seidel, J. V.;
Sozzetti, A.; Allart, R.; Figueira, P.; Bourrier, V.; Lillo-Box,
J.; Borsa, F.; Zapatero Osorio, M. R.; Tabernero, H.; Demangeon,
O. D. S.; Adibekyan, V.; González Hernández, J. I.; Mehner, A.;
Allende Prieto, C.; Di Marcantonio, P.; Alibert, Y.; Cristiani, S.;
Lo Curto, G.; Martins, C. J. A. P.; Micela, G.; Pepe, F.; Rebolo,
R.; Sousa, S. G.; Suárez Mascareño, A.; Udry, S.
2022A&A...657A..23E Altcode: 2021arXiv211002028E
Multiband photometric transit observations or low-resolution
spectroscopy (spectro-photometry) are normally used to retrieve the
broadband transmission spectra of transiting exoplanets in order to
assess the chemical composition of their atmospheres. In this paper
we present an alternative approach for recovering the broadband
transmission spectra using chromatic Doppler tomography based on
physical modeling through the SOAP tool: CHOCOLATE (CHrOmatiC line
prOfiLe tomogrAphy TEchnique). To validate the method and examine
its performance, we use observational data recently obtained with
the ESPRESSO instrument to retrieve the transmission spectra of the
archetypal hot Jupiter HD 209458b. Our findings indicate that the
recovered transmission spectrum is in good agreement with the results
presented in previous studies, which used different methodologies
to extract the spectrum, achieving similar precision. We explored
several atmospheric models and inferred from spectral retrieval that
a model containing H<SUB>2</SUB>O and NH<SUB>3</SUB> is the preferred
scenario. The CHOCOLATE methodology is particularly interesting for
future studies of exoplanets around young and active stars or moderate
to fast rotating stars, considering SOAP's ability to model stellar
active regions and the fact that the rotational broadening of spectral
lines favors its application. Furthermore, CHOCOLATE will allow the
broad transmission spectrum of a planet to be retrieved using high-S/N,
high-resolution spectroscopy with the next generation of extremely
large telescopes, where low-resolution spectroscopy will not always
be accessible. <P />Based on guaranteed time observations collected at
the European Southern Observatory (ESO) under ESO program 1102.C-0744
by the ESPRESSO Consortium.
---------------------------------------------------------
Title: A stellar stream remnant of a globular cluster below the
metallicity floor
Authors: Martin, Nicolas F.; Venn, Kim A.; Aguado, David S.;
Starkenburg, Else; González Hernández, Jonay I.; Ibata, Rodrigo A.;
Bonifacio, Piercarlo; Caffau, Elisabetta; Sestito, Federico; Arentsen,
Anke; Allende Prieto, Carlos; Carlberg, Raymond G.; Fabbro, Sébastien;
Fouesneau, Morgan; Hill, Vanessa; Jablonka, Pascale; Kordopatis,
Georges; Lardo, Carmela; Malhan, Khyati; Mashonkina, Lyudmila I.;
McConnachie, Alan W.; Navarro, Julio F.; Sánchez-Janssen, Rubén;
Thomas, Guillaume F.; Yuan, Zhen; Mucciarelli, Alessio
2022Natur.601...45M Altcode: 2022arXiv220101309M
Stellar ejecta gradually enrich the gas out of which subsequent stars
form, making the least chemically enriched stellar systems direct
fossils of structures formed in the early Universe<SUP>1</SUP>. Although
a few hundred stars with metal content below 1,000th of the
solar iron content are known in the Galaxy<SUP>2-4</SUP>, none of
them inhabit globular clusters, some of the oldest known stellar
structures. These show metal content of at least approximately 0.2%
of the solar metallicity ([Fe /H ]≳−2.7 )?. This metallicity
floor appears universal<SUP>5,6</SUP>, and it has been proposed that
protogalaxies that merged into the galaxies we observe today were
simply not massive enough to form clusters that survived to the present
day<SUP>7</SUP>. Here we report observations of a stellar stream, C-19,
whose metallicity is less than 0.05% of the solar metallicity ([F e /
H ]=−3.38 ±0.06 (s t a t i s t i c a l )±0.20 (s y s t e m a t i
c ))?. The low metallicity dispersion and the chemical abundances of
the C-19 stars show that this stream is the tidal remnant of the most
metal-poor globular cluster ever discovered, and is significantly below
the purported metallicity floor: clusters with significantly lower
metallicities than observed today existed in the past and contributed
their stars to the Milky Way halo.
---------------------------------------------------------
Title: VizieR Online Data Catalog: Updated radial velocities from
Gaia DR2 (Seabroke+, 2021)
Authors: Seabroke, G. M.; Fabricius, C.; Teyssier, D.; Sartoretti, P.;
Katz, D.; Cropper, M.; Antoja, T.; Benson, K.; Smith, M.; Dolding,
C.; Gosset, E.; Panuzzo, P.; Thevenin, F.; Allende Prieto, C.;
Blomme, R.; Guerrier, A.; Huckle, H.; Jean-Antoine, A.; Haigron, R.;
Marchal, O.; Baker, S.; Damerdji, Y.; David, M.; Fremat, Y.; Janssen,
K.; Jasniewicz, G.; Lobel, A.; Samaras, N.; Plum, G.; Soubiran, C.;
Vanel, O.; Zwitter, T.; Ajaj, M.; Caffau, E.; Chemin, L.; Royer, F.;
Brouillet, N.; Crifo, F.; Guy, L. P.; Hambly, N. C.; Leclerc, N.;
Mastrobuono-Battisti, A.; Viala, Y.
2021yCat..36530160S Altcode:
EDR3 status of high-velocity stars in the negative and positive tail
of DR2's radial velocity distribution. <P />(2 data files).
---------------------------------------------------------
Title: HD 22496 b: The first ESPRESSO stand-alone planet discovery
Authors: Lillo-Box, J.; Faria, J. P.; Suárez Mascareño, A.;
Figueira, P.; Sousa, S. G.; Tabernero, H.; Lovis, C.; Silva, A. M.;
Demangeon, O. D. S.; Benatti, S.; Santos, N. C.; Mehner, A.; Pepe,
F. A.; Sozzetti, A.; Zapatero Osorio, M. R.; González Hernández,
J. I.; Micela, G.; Hojjatpanah, S.; Rebolo, R.; Cristiani, S.;
Adibekyan, V.; Allart, R.; Allende Prieto, C.; Cabral, A.; Damasso,
M.; Di Marcantonio, P.; Lo Curto, G.; Martins, C. J. A. P.; Megevand,
D.; Molaro, P.; Nunes, N. J.; Pallé, E.; Pasquini, L.; Poretti, E.;
Udry, S.
2021A&A...654A..60L Altcode: 2021arXiv210900226L
Context. The ESPRESSO spectrograph is a new powerful tool developed
to detect and characterize extrasolar planets. Its design allows an
unprecedented radial velocity precision (down to a few tens of cm
s<SUP>−1</SUP>) and long-term thermomechanical stability. <BR />
Aims: We present the first stand-alone detection of an extrasolar
planet by blind radial velocity search using ESPRESSO; our aim is to
show the power of the instrument in characterizing planetary signals at
different periodicities in long observing time spans. <BR /> Methods:
We used 41 ESPRESSO measurements of HD 22496 obtained within a time
span of 895 days with a median photon noise of 18 cm s<SUP>−1</SUP>. A
radial velocity analysis was performed to test the presence of planets
in the system and to account for the stellar activity of this K5-K7
main-sequence star. For benchmarking and comparison, we attempted
the detection with 43 archive HARPS measurements and in this work we
compare the results yielded by the two datasets. We also used four
TESS sectors to search for transits. <BR /> Results: We find radial
velocity variations compatible with a close-in planet with an orbital
period of P = 5.09071 ± 0.00026 days when simultaneously accounting for
the effects of stellar activity on longer timescales (P<SUB>rot</SUB>
= 34.99<SUB>−0.53</SUB><SUP>+0.58</SUP> days). We characterize the
physical and orbital properties of the planet and find a minimum mass
of 5.57<SUB>−0.68</SUB><SUP>+0.73</SUP> M<SUB>⊕</SUB>, right in
the dichotomic regime between rocky and gaseous planets. Although
not transiting according to TESS data, if aligned with the
stellar spin axis, the absolute mass of the planet must be below 16
M<SUB>⊕</SUB>. We find no significant evidence for additional signals
in the data with semi-amplitudes above 56 cm s<SUP>−1</SUP> at 95%
confidence. <BR /> Conclusions: With a modest set of radial velocity
measurements, ESPRESSO is capable of detecting and characterizing
low-mass planets and constraining the presence of planets in the
habitable zone of K dwarfs down to the rocky-mass regime. <P />Full
Table B.2 is only available at the CDS via anonymous ftp to <A
href="http://cdsarc.u-strasbg.fr">cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/654/A60">http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/654/A60</A>
<P />Based on Guaranteed Time Observations collected at the European
Southern Observatory (ESO) under ESO programs 1102.C-074, 1104.C-0350,
and 106.21M2 by the ESPRESSO Consortium.
---------------------------------------------------------
Title: VizieR Online Data Catalog: HD 22496 b ESPRESSO RVs
(Lillo-Box+, 2021)
Authors: Lillo-Box, J.; Faria, J. P.; Suarez-Mascareno, A.; Figueira,
P.; Sousa, S. G.; Tabernero, H.; Lovis, C.; Silva, A. M.; Demangeon,
O. D. S.; Benatti, S.; Santos, N. C.; Mehner, A.; Pepe, F. A.;
Sozzetti, A.; Zapatero Osorio, M. R.; Gonzalez Hernandez, J. I.;
Micela, G.; Hojjatpanah, S.; Rebolo, R.; Cristiani, S.; Adibekyan,
V.; Allart, R.; Allende Prieto, C.; Cabral, A.; Damasso, M.; di
Marcantonio, P.; Lo Curto, G.; Martins, C. J. A. P.; Megevand, D.;
Molaro, P.; Nunes, N. J.; Palle, E.; Pasquini, L.; Poretti, E.;
Udry, S.
2021yCat..36540060L Altcode:
Detection and characterization of the exoplanet HD 22496 b with ESPRESSO
data. <P />(1 data file).
---------------------------------------------------------
Title: Symbiotic Stars in the Apache Point Observatory Galactic
Evolution Experiment Survey: The Case of LIN 358 and SMC N73
(LIN 445a)
Authors: Washington, Jasmin E.; Lewis, Hannah M.; Anguiano, Borja;
Majewski, Steven R.; Chojnowski, S. Drew; Smith, Verne V.; Stassun,
Keivan G.; Allende Prieto, Carlos; Cunha, Katia; Nidever, David L.;
García-Hernández, D. A.; Pan, Kaike
2021ApJ...918...19W Altcode: 2021arXiv210708309W
LIN 358 and SMC N73 are two symbiotic binaries in the halo of the Small
Magellanic Cloud, each composed of a hot white dwarf accreting from
a cool giant companion. In this work, we characterize these systems
using a combination of spectral energy distribution (SED)-fitting
to the extant photometric data spanning a broad wavelength range
(X-ray/ultraviolet to near-infrared), detailed analysis of the Apache
Point Observatory Galactic Evolution Experiment (APOGEE) spectra for
the giant stars, and orbit fitting to high quality radial velocities
from the APOGEE database. Using the calculated Roche lobe radius for
the giant component and the mass ratio for each system, it is found that
LIN 358 is likely undergoing mass transfer via wind Roche lobe overflow,
while the accretion mechanism for SMC N73 remains uncertain. This work
presents the first orbital characterization for both of these systems
(yielding periods of >270 and >980 days, respectively, for SMC
N73 and LIN 358) and the first global SED fitting for SMC N73. In
addition, variability was identified in APOGEE spectra of LIN 358
spanning 17 epochs over two years that may point to a time variable
accretion rate as the product of an eccentric orbit.
---------------------------------------------------------
Title: Warm terrestrial planet with half the mass of Venus transiting
a nearby star
Authors: Demangeon, O. D. S.; Zapatero Osorio, M. R.; Alibert, Y.;
Barros, S. C. C.; Adibekyan, V.; Tabernero, H. M.; Antoniadis-Karnavas,
A.; Camacho, J. D.; Suárez Mascareño, A.; Oshagh, M.; Micela,
G.; Sousa, S. G.; Lovis, C.; Pepe, F. A.; Rebolo, R.; Cristiani, S.;
Santos, N. C.; Allart, R.; Allende Prieto, C.; Bossini, D.; Bouchy, F.;
Cabral, A.; Damasso, M.; Di Marcantonio, P.; D'Odorico, V.; Ehrenreich,
D.; Faria, J.; Figueira, P.; Génova Santos, R.; Haldemann, J.; Hara,
N.; González Hernández, J. I.; Lavie, B.; Lillo-Box, J.; Lo Curto,
G.; Martins, C. J. A. P.; Mégevand, D.; Mehner, A.; Molaro, P.; Nunes,
N. J.; Pallé, E.; Pasquini, L.; Poretti, E.; Sozzetti, A.; Udry, S.
2021A&A...653A..41D Altcode: 2021arXiv210803323D
In recent years, the advent of a new generation of radial velocity
instruments has allowed us to detect planets with increasingly
lower mass and to break the one Earth-mass barrier. Here we report
a new milestone in this context by announcing the detection of the
lowest-mass planet measured so far using radial velocities: L 98-59
b, a rocky planet with half the mass of Venus. It is part of a system
composed of three known transiting terrestrial planets (planets b-d). We
announce the discovery of a fourth nontransiting planet with a minimum
mass of 3.06<SUB>−0.37</SUB><SUP>+0.33</SUP> M<SUB>⊕</SUB> and
an orbital period of 12.796<SUB>−0.019</SUB><SUP>+0.020</SUP>
days and report indications for the presence of a fifth
nontransiting terrestrial planet. With a minimum mass of
2.46<SUB>−0.82</SUB><SUP>+0.66</SUP> M<SUB>⊕</SUB> and an orbital
period 23.15<SUB>−0.17</SUB><SUP>+0.60</SUP> days, this planet, if
confirmed, would sit in the middle of the habitable zone of the L 98-59
system. L 98-59 is a bright M dwarf located 10.6ṗc away. Positioned
at the border of the continuous viewing zone of the James Webb
Space Telescope, this system is destined to become a corner stone for
comparative exoplanetology of terrestrial planets. The three transiting
planets have transmission spectrum metrics ranging from 49 to 255, which
undoubtedly makes them prime targets for an atmospheric characterization
with the James Webb Space Telescope, the Hubble Space Telescope,
Ariel, or ground-based facilities such as NIRPS or ESPRESSO. With
an equilibrium temperature ranging from 416 to 627 K, they offer
a unique opportunity to study the diversity of warm terrestrial
planets without the unknowns associated with different host stars. L
98-59 b and c have densities of 3.6<SUB>−1.5</SUB><SUP>+1.4</SUP>
and 4.57<SUB>−0.85</SUB><SUP>+0.77</SUP> g cm<SUP>−3</SUP>,
respectively, and have very similar bulk compositions with a
small iron core that represents only 12 to 14% of the total
mass, and a small amount of water. However, with a density of
2.95<SUB>−0.51</SUB><SUP>+0.79</SUP> g cm<SUP>−3</SUP> and despite a
similar core mass fraction, up to 30% of the mass of L 98-59 d might be
water. <P />Full Table B.1 is only available at the CDS via anonymous
ftp to <A href="http://cdsarc.u-strasbg.fr">cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/653/A41">http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/653/A41</A>
<P />Based in part on Guaranteed Time Observations collected at the
European Southern Observatory under ESO programme(s) 1102.C-0744,
1102.C-0958, and 1104.C-0350 by the ESPRESSO Consortium.
---------------------------------------------------------
Title: J-PLUS: Searching for very metal-poor star candidates using
the SPEEM pipeline
Authors: Andrés Galarza, Carlos; Daflon, Simone; Placco, Vinicius
M.; Allende-Prieto, Carlos; Borges Fernandes, Marcelo; Yuan,
Haibo; López-Sanjuan, Carlos; Lee, Young Sun; Solano, Enrique;
Jiménez-Esteban, F.; Sobral, David; Alvarez Candal, Alvaro; Pereira,
Claudio B.; Akras, Stavros; Martín, Eduardo; Jiménez Teja, Yolanda;
Cenarro, Javier; Cristóbal-Hornillos, David; Hernández-Monteagudo,
Carlos; Marín-Franch, Antonio; Moles, Mariano; Varela, Jesús;
Vázquez Ramió, Héctor; Alcaniz, Jailson; Dupke, Renato; Ederoclite,
Alessandro; Sodré, Laerte, Jr.; Angulo, Raul E.
2021arXiv210911600A Altcode:
We explore the stellar content of the Javalambre Photometric Local
Universe Survey (J-PLUS) Data Release 2 and show its potential
to identify low-metallicity stars using the Stellar Parameters
Estimation based on Ensemble Methods (SPEEM) pipeline. SPEEM is a
tool to provide determinations of atmospheric parameters for stars
and separate stellar sources from quasars, using the unique J-PLUS
photometric system. The adoption of adequate selection criteria
allows the identification of metal-poor star candidates suitable for
spectroscopic follow-up. SPEEM consists of a series of machine learning
models which uses a training sample observed by both J-PLUS and the
SEGUE spectroscopic survey. The training sample has temperatures
Teff between 4\,800 K and 9\,000 K; $\log g$ between 1.0 and 4.5,
and $-3.1<[Fe/H]<+0.5$. The performance of the pipeline has
been tested with a sample of stars observed by the LAMOST survey
within the same parameter range. The average differences between the
parameters of a sample of stars observed with SEGUE and J-PLUS, which
were obtained with the SEGUE Stellar Parameter Pipeline and SPEEM,
respectively, are $\Delta Teff\sim 41$ K, $\Delta \log g\sim 0.11$
dex, and $\Delta [Fe/H]\sim 0.09$ dex. A sample of 177 stars have
been identified as new candidates with $[Fe/H]<-2.5$ and 11 of them
have been observed with the ISIS spectrograph at the William Herschel
Telescope. The spectroscopic analysis confirms that $64\%$ of stars have
$[Fe/H]<-2.5$, including one new star with $[Fe/H]<-3.0$. SPEEM
in combination with the J-PLUS filter system has shown the potential
to estimate the stellar atmospheric parameters (Teff, $\log g$, and
[Fe/H]). The spectroscopic validation of the candidates shows that
SPEEM yields a success rate of $64\%$ on the identification of very
metal-poor star candidates with $[Fe/H]<-2.5$.
---------------------------------------------------------
Title: Gaia Early Data Release 3. Updated radial velocities from
Gaia DR2
Authors: Seabroke, G. M.; Fabricius, C.; Teyssier, D.; Sartoretti, P.;
Katz, D.; Cropper, M.; Antoja, T.; Benson, K.; Smith, M.; Dolding,
C.; Gosset, E.; Panuzzo, P.; Thévenin, F.; Allende Prieto, C.;
Blomme, R.; Guerrier, A.; Huckle, H.; Jean-Antoine, A.; Haigron, R.;
Marchal, O.; Baker, S.; Damerdji, Y.; David, M.; Frémat, Y.; Janßen,
K.; Jasniewicz, G.; Lobel, A.; Samaras, N.; Plum, G.; Soubiran, C.;
Vanel, O.; Zwitter, T.; Ajaj, M.; Caffau, E.; Chemin, L.; Royer, F.;
Brouillet, N.; Crifo, F.; Guy, L. P.; Hambly, N. C.; Leclerc, N.;
Mastrobuono-Battisti, A.; Viala, Y.
2021A&A...653A.160S Altcode: 2021arXiv210802796S
Context. Gaia's Early Third Data Release (EDR3) does not contain new
radial velocities because these will be published in Gaia's full third
data release (DR3), expected in the first half of 2022. To maximise
the usefulness of EDR3, Gaia's second data release (DR2) sources
(with radial velocities) are matched to EDR3 sources to allow their
DR2 radial velocities to also be included in EDR3. This presents
two considerations: (i) a list of 70 365 sources with potentially
contaminated DR2 radial velocities has been published; and (ii) EDR3
is based on a new astrometric solution and a new source list, which
means sources in DR2 may not be in EDR3. <BR /> Aims: The two aims of
this work are: (i) investigate the list in order to improve the DR2
radial velocities being included in EDR3 and to avoid false-positive
hypervelocity candidates; and (ii) match the DR2 sources (with radial
velocities) to EDR3 sources. <BR /> Methods: Thetwo methods of this
work are: (i) unpublished, preliminary DR3 radial velocities of sources
on the list, and high-velocity stars not on the list, are compared
with their DR2 radial velocities to identify and remove contaminated
DR2 radial velocities from EDR3; and (ii) proper motions and epoch
position propagation is used to attempt to match all sources with radial
velocities in DR2 to EDR3 sources. The comparison of DR2 and DR3 radial
velocities is used to resolve match ambiguities. <BR /> Results: EDR3
contains 7 209 831 sources with a DR2 radial velocity, which is 99.8%
of sources with a radial velocity in DR2 (7 224 631). 14 800 radial
velocities from DR2 are not propagated to any EDR3 sources because
(i) 3871 from the list are found to either not have a DR3 radial
velocity or it differs significantly from its DR2 value, and five
high-velocity stars not on the list are confirmed to have contaminated
radial velocities, in one case because of contamination from the
non-overlapping Radial Velocity Spectrometer windows of a nearby, bright
star; and (ii) 10 924 DR2 sources could not be satisfactorily matched to
any EDR3 sources, so their DR2 radial velocities are also missing from
EDR3. <BR /> Conclusions: The reliability of radial velocities in EDR3
has improved compared to DR2 because the update removes a small fraction
of erroneous radial velocities (0.05% of DR2 radial velocities and 5.5%
of the list). Lessons learnt from EDR3 (e.g. bright star contamination)
will improve the radial velocities in future Gaia data releases. The
main reason for radial velocities from DR2 not propagating to EDR3
is not related to DR2 radial velocity quality. It is because the DR2
astrometry is based on one component of close binary pairs, while
EDR3 astrometry is based on the other component, which prevents these
sources from being unambiguously matched.
---------------------------------------------------------
Title: An extension of the MILES library with derived T<SUB>eff</SUB>,
log g, [Fe/H], and [α/Fe]
Authors: García Pérez, A. E.; Sánchez-Blázquez, P.; Vazdekis,
A.; Allende Prieto, C.; Milone, A. de C.; Sansom, A. E.; Gorgas, J.;
Falcón-Barroso, J.; Martín Navarro, I.; Cacho, R.
2021MNRAS.505.4496G Altcode: 2021MNRAS.tmp..304G
Extragalactic astronomy and stellar astrophysics are intrinsically
related. In fact, the determination of important galaxy properties such
as stellar masses, star formation histories, or chemical abundances
relies on the ability to model their stellar populations. One important
ingredient of these models is stellar libraries. Empirical libraries
must have a good coverage of T<SUB>eff</SUB>, [Z/H], and surface
gravity, and have these parameters reliably determined. MILES is
one of the most widely used empirical libraries. Here, we present an
extension of this library with 205 new stars especially selected to
cover important regions of the parameter space, including metal-poor
stars down to [Fe/H] ~ -1.0. We describe the observations and data
reductions as well as a new determination of the stellar parameters,
including [α/Fe] ratio. The new MILES library contains 1070 stars
with homogeneous and reliable determination of [Fe/H], T<SUB>eff</SUB>,
log g, and [α/Fe] ratio.
---------------------------------------------------------
Title: sMILES: a library of semi-empirical MILES stellar spectra
with variable [α/Fe] abundances
Authors: Knowles, Adam T.; Sansom, A. E.; Allende Prieto, C.;
Vazdekis, A.
2021MNRAS.504.2286K Altcode: 2021arXiv210404822K; 2021MNRAS.tmp..968K
We present a new library of semi-empirical stellar spectra that is based
on the empirical Medium resolution Isaac Newton Library of Empirical
Spectra (MILES) library. A new, high-resolution library of theoretical
stellar spectra is generated that is specifically designed for use in
stellar population studies. We test these models across their full
wavelength range against other model libraries and find reasonable
agreement in their predictions of spectral changes due to atmospheric
α-element variations, known as differential corrections. We also
test the models against the MILES and MaStar libraries of empirical
stellar spectra and also find reasonable agreements, as expected from
previous work. We then use the abundance pattern predictions of the new
theoretical stellar spectra to differentially correct MILES spectra
to create semi-empirical MILES (sMILES) star spectra with abundance
patterns that differ from those present in the Milky Way. The final
result is five families of 801 sMILES stars with [α/Fe] abundances
ranging from -0.20 to 0.60 dex at MILES resolution (FWHM = $2.5\,$Å)
and wavelength coverage ($3540.5\!-\!7409.6\,$Å). We make the sMILES
library publicly available.
---------------------------------------------------------
Title: The APOGEE Data Release 16 Spectral Line List
Authors: Smith, Verne V.; Bizyaev, Dmitry; Cunha, Katia; Shetrone,
Matthew D.; Souto, Diogo; Allende Prieto, Carlos; Masseron, Thomas;
Mészáros, Szabolcs; Jönsson, Henrik; Hasselquist, Sten; Osorio,
Yeisson; García-Hernández, D. A.; Plez, Bertrand; Beaton, Rachael
L.; Holtzman, Jon; Majewski, Steven R.; Stringfellow, Guy S.; Sobeck,
Jennifer
2021AJ....161..254S Altcode: 2021arXiv210310112S
The updated H-band spectral-line list (from λ15000-17000) adopted by
the Apache Point Observatory Galactic Evolution Experiment (APOGEE)
for the SDSS-IV Data Release 16 (DR16) is presented in this work. The
APOGEE line list is a combination of atomic and molecular lines,
with data drawn from laboratory, theoretical, and astrophysical
sources. Oscillator strengths and damping constants are adjusted
using high signal-to-noise, high-resolution spectra of the Sun, and α
Boo (Arcturus), as "standard stars." Updates to the DR16 line list,
as compared to the previous DR14 version, include the addition of
molecular H<SUB>2</SUB>O and FeH lines, as well as a much larger (by
a factor of ∼4) atomic line list, including a significantly greater
number of transitions with hyperfine splitting. More recent references
and line lists for the crucial molecules, CO and OH, as well as for
C<SUB>2</SUB> and SiH, are also included. In contrast to DR14, DR16
contains measurable lines from the heavy neutron-capture elements
cerium (as Ce II), neodymium (as Nd II), and ytterbium (as Yb II),
as well as one line from rubidium (as Rb I), which may be detectable
in a small fraction of APOGEE red giants.
---------------------------------------------------------
Title: Six transiting planets and a chain of Laplace resonances
in TOI-178
Authors: Leleu, A.; Alibert, Y.; Hara, N. C.; Hooton, M. J.; Wilson,
T. G.; Robutel, P.; Delisle, J. -B.; Laskar, J.; Hoyer, S.; Lovis,
C.; Bryant, E. M.; Ducrot, E.; Cabrera, J.; Delrez, L.; Acton, J. S.;
Adibekyan, V.; Allart, R.; Allende Prieto, C.; Alonso, R.; Alves,
D.; Anderson, D. R.; Angerhausen, D.; Anglada Escudé, G.; Asquier,
J.; Barrado, D.; Barros, S. C. C.; Baumjohann, W.; Bayliss, D.;
Beck, M.; Beck, T.; Bekkelien, A.; Benz, W.; Billot, N.; Bonfanti,
A.; Bonfils, X.; Bouchy, F.; Bourrier, V.; Boué, G.; Brandeker,
A.; Broeg, C.; Buder, M.; Burdanov, A.; Burleigh, M. R.; Bárczy,
T.; Cameron, A. C.; Chamberlain, S.; Charnoz, S.; Cooke, B. F.;
Corral Van Damme, C.; Correia, A. C. M.; Cristiani, S.; Damasso, M.;
Davies, M. B.; Deleuil, M.; Demangeon, O. D. S.; Demory, B. -O.;
Di Marcantonio, P.; Di Persio, G.; Dumusque, X.; Ehrenreich, D.;
Erikson, A.; Figueira, P.; Fortier, A.; Fossati, L.; Fridlund, M.;
Futyan, D.; Gandolfi, D.; García Muñoz, A.; Garcia, L. J.; Gill,
S.; Gillen, E.; Gillon, M.; Goad, M. R.; González Hernández, J. I.;
Guedel, M.; Günther, M. N.; Haldemann, J.; Henderson, B.; Heng, K.;
Hogan, A. E.; Isaak, K.; Jehin, E.; Jenkins, J. S.; Jordán, A.; Kiss,
L.; Kristiansen, M. H.; Lam, K.; Lavie, B.; Lecavelier des Etangs,
A.; Lendl, M.; Lillo-Box, J.; Lo Curto, G.; Magrin, D.; Martins,
C. J. A. P.; Maxted, P. F. L.; McCormac, J.; Mehner, A.; Micela, G.;
Molaro, P.; Moyano, M.; Murray, C. A.; Nascimbeni, V.; Nunes, N. J.;
Olofsson, G.; Osborn, H. P.; Oshagh, M.; Ottensamer, R.; Pagano, I.;
Pallé, E.; Pedersen, P. P.; Pepe, F. A.; Persson, C. M.; Peter, G.;
Piotto, G.; Polenta, G.; Pollacco, D.; Poretti, E.; Pozuelos, F. J.;
Queloz, D.; Ragazzoni, R.; Rando, N.; Ratti, F.; Rauer, H.; Raynard,
L.; Rebolo, R.; Reimers, C.; Ribas, I.; Santos, N. C.; Scandariato,
G.; Schneider, J.; Sebastian, D.; Sestovic, M.; Simon, A. E.; Smith,
A. M. S.; Sousa, S. G.; Sozzetti, A.; Steller, M.; Suárez Mascareño,
A.; Szabó, Gy. M.; Ségransan, D.; Thomas, N.; Thompson, S.; Tilbrook,
R. H.; Triaud, A.; Turner, O.; Udry, S.; Van Grootel, V.; Venus, H.;
Verrecchia, F.; Vines, J. I.; Walton, N. A.; West, R. G.; Wheatley,
P. J.; Wolter, D.; Zapatero Osorio, M. R.
2021A&A...649A..26L Altcode: 2021arXiv210109260L
Determining the architecture of multi-planetary systems is one of the
cornerstones of understanding planet formation and evolution. Resonant
systems are especially important as the fragility of their orbital
configuration ensures that no significant scattering or collisional
event has taken place since the earliest formation phase when
the parent protoplanetary disc was still present. In this context,
TOI-178 has been the subject of particular attention since the first
TESS observations hinted at the possible presence of a near 2:3:3
resonant chain. Here we report the results of observations from CHEOPS,
ESPRESSO, NGTS, and SPECULOOS with the aim of deciphering the peculiar
orbital architecture of the system. We show that TOI-178 harbours
at least six planets in the super-Earth to mini-Neptune regimes,
with radii ranging from 1.152<SUB>−0.070</SUB><SUP>+0.073</SUP>
to 2.87<SUB>−0.13</SUB><SUP>+0.14</SUP> Earth radii and periods
of 1.91, 3.24, 6.56, 9.96, 15.23, and 20.71 days. All planets but
the innermost one form a 2:4:6:9:12 chain of Laplace resonances,
and the planetary densities show important variations from planet
to planet, jumping from 1.02<SUB>−0.23</SUB><SUP>+0.28</SUP> to
0.177<SUB>−0.061</SUB><SUP>+0.055</SUP> times the Earth's density
between planets c and d. Using Bayesian interior structure retrieval
models, we show that the amount of gas in the planets does not vary
in a monotonous way, contrary to what one would expect from simple
formation and evolution models and unlike other known systems in a
chain of Laplace resonances. The brightness of TOI-178 (H = 8.76 mag,
J = 9.37 mag, V = 11.95 mag) allows for a precise characterisation of
its orbital architecture as well as of the physical nature of the six
presently known transiting planets it harbours. The peculiar orbital
configuration and the diversity in average density among the planets
in the system will enable the study of interior planetary structures
and atmospheric evolution, providing important clues on the formation
of super-Earths and mini-Neptunes.
---------------------------------------------------------
Title: VizieR Online Data Catalog: TOI-178 six transiting planets
(Leleu+, 2021)
Authors: Leleu, A.; Alibert, Y.; Hara, N. C.; Hooton, M. J.; Wilson,
T. G.; Robutel, P.; Delisle, J. -B.; Laskar, J.; Hoyer, S.; Lovis,
C.; Bryant, E. M.; Ducrot, E.; Cabrera, J.; Delrez, L.; Acton, J. S.;
Adibekyan, V.; Allart, R.; Allende Prieto, C.; Alonso, R.; Alves,
D. Anderson D. R.; Angerhausen, D.; Anglada Escude, G.; Asquier,
J.; Barrado, D.; Barros, S. C. C.; Baumjohann, W.; Bayliss, D.;
Beck, M.; Beck, T.; Bekkelien, A.; Benz, W.; Billot, N.; Bonfanti,
A.; Bonfils, X.; Bouchy, F.; Bourrier, V.; Boue, G.; Brandeker,
A.; Broeg, C.; Buder, M.; Burdanov, A.; Burleigh, M. R.; Barczy,
T.; Cameron, A. C.; Chamberlain, S.; Charnoz, S.; Cooke, B. F.;
Corral van Damme, C.; Correia, A. C. M.; Cristiani, S.; Damasso, M.;
Davies, M. B.; Deleuil, M.; Demangeon, O. D. S.; Demory, B. -O.;
di Marcantonio, P.; di Persio, G.; Dumusque, X.; Ehrenreich, D.;
Erikson, A.; Figueira, P.; Fortier, A.; Fossati, L.; Fridlund, M.;
Futyan, D.; Gandolfi, D.; Garcia Munoz, A.; Garcia, L. J.; Gill,
S.; Gillen, E.; Gillon, M.; Goad, M. R.; Gonzalez Hernandez, J. I.;
Guedel, M.; Guenther, M. N.; Haldeman, N. J.; Henderson, B.; Heng, K.;
Hogan, A. E.; Isaak, K.; Jehin, E.; Jenkins, J. S.; Jordan, A.; Kiss,
L.; Kristiansen, M. H.; Lam, K.; Lavie, B.; Lecavelier Des Etangs,
A.; Lendl, M.; Lillo-Box, J.; Lo Curto, G.; Magrin, D.; Martins,
C. J. A. P.; Maxted, P. F. L.; McCormac, J.; Mehner, A.; Micela, G.;
Molaro, P.; Moyano, M.; Murray, C. A.; Nascimbeni, V.; Nunes, N. J.;
Olofsson, G.; Osborn, H. P.; Oshagh, M.; Ottensamer, R.; Pagano, I.;
Palle, E.; Pedersen, P. P.; Pepe, F. A.; Persson, C. M.; Peter, G.;
Piotto, G.; Polenta, G.; Pollacco, D.; Poretti, E.; Pozuelos, F. J.;
Queloz, D.; Ragazzoni, R.; Rando, N.; Ratti, F.; Rauer, H.; Raynard,
L.; Rebolo, R.; Reimers, C.; Ribas, I.; Santos, N. C.; Scandariato,
G.; Schneider, J.; Sebastian, D.; Sestovic, M.; Simon, A. E.; Smith,
A. M. S.; Sousa, S. G.; Sozzetti, A.; Steller, M.; Suarez Mascareno,
A.; Szabo, Gy. M.; Segransan, D.; Thomas, N.; Thompson, S.; Tilbrook,
R. H.; Triaud, A.; Turner, O.; Udry, S.; Van Grootel, V.; Venus, H.;
Verrecchia, F.; Vines, J. I.; Walton, N. A.; West, R. G.; Wheatley,
P. J.; Wolter, D.; Zapatero Osorio, M. R.
2021yCat..36490026L Altcode:
Raw and detrended data from CHEOPS, NGTS, SPECULOOS and TESS; raw data
from ESPRESSO. <P />(15 data files).
---------------------------------------------------------
Title: TLUSTY and SYNSPEC Users's Guide IV: Upgraded Versions 208
and 54
Authors: Hubeny, Ivan; Allende Prieto, Carlos; Osorio, Yeisson;
Lanz, Thierry
2021arXiv210402829H Altcode:
We present a brief description of the newly upgraded versions of the
programs TLUSTY, version 208, and SYNSPEC, version 54. TLUSTY is used
to generate model stellar atmospheres or accretion disks, and SYNSPEC
produces detailed synthetic spectra and/or opacity tables. This paper
complements published guides that provide a detailed description
of earlier versions of the codes, TLUSTY205, and SYNSPEC51. The
main upgrades include the flexible construction of opacity tables
in SYNSPEC, and their use in producing hybrid models with TLUSTY},
with important species treated in NLTE, while the bulk of opacity of
atomic and molecular lines and continua are considered in LTE using
a pre-calculated opacity table. There is also a number of additional
changes and upgrades that increase the versatility and flexibility of
these codes.
---------------------------------------------------------
Title: Unearthing the fossilized Andromeda galaxy: a spectroscopic
pilot survey of M31 giants
Authors: Mackereth, John Edward; Allende-Prieto, Carlos; Nataf,
David Moise; Schiavon, Ricardo
2021jwst.prop.2301M Altcode:
Galaxy evolution models are strongly underpinned by anchoring
constraints made locally in the Milky Way. In this proposal, we aim
to perform a pilot study toward providing a secondary local anchor in
the form of a detailed mapping in element abundances of the stellar
populations of the Andromeda galaxy, M31. Primarily, we will use NIRSpec
spectroscopy of giant stars to study element abundances in the old
disk of M31, establishing whether it plays host to a dichotomy in the
ratio of its alpha-element abundances relative to Iron. Such a feature
is readily observed in the Milky Way, and thought to be indicative
of an early and rapid assembly of its mass. These pilot observations
towards larger spectroscopic surveys of the M31 disk will allow us to
discriminate between the myriad models which are now proposed for the
origin of this feature in the Milky Way. This will place the first
stake of true galactic archaeology in Andromeda, opening the door to
more detailed future studies which will attempt to reconstruct the
star formation history and more fully constrain the history of mass
assembly in our nearest giant disk.
---------------------------------------------------------
Title: TOI-178: the best laboratory for testing planetary formation
theories
Authors: Hooton, Matthew; Adibekyan, Vardan; Alibert, Yann; Allart,
Romain; Allende-Prieto, Carlos; Barros, Susana Cristina Cabral; Billot,
Nicolas; Boue, Gwenael; Bourrier, Vincent; Brandeker, Alexis; Bruno,
Giovanni; Correia, Alexandre C. M.; Demory, Brice-Olivier; Ehrenreich,
David; Espinoza, Nestor; Fisher, Chloe; Fossati, Luca; Fridlund,
Malcolm; Haldemann, Jonas; Hara, Nathan; Heng, Kevin; Hoyer, Sergio;
Kitzmann, Daniel; Leleu, Adrien; Lavie, Baptiste; Lendl, Monika;
Morris, Brett M.; Osborn, Hugh; Oshagh, Mahmoudreza; Palle, Enric;
Persson, Carina; Pozuelos-Romero, Francisco Jose; Santos, Nuno C.;
Schneider, Jean; Sozzetti, Alessandro; Wilson, Thomas G.
2021jwst.prop.2319H Altcode:
The atmospheric characterisation of multiple exoplanets in the same
system can provide a window into the processes that underpinned their
formation and evolution. The planetary C/O ratios are of particular
interest as they encode information about where the planet formed with
respect to different ice lines, but precise measurements of this using
current instrumentation have proved challenging. Recent observations
have revealed that the nearby late K-type star TOI-178 hosts a compact
system of at least six transiting exoplanets with R < 3 Earth radii,
five of which form a chain of Laplacian resonances. Alongside the fact
that the large planet-to-planet density variations present in the system
appear difficult to theoretically explain, its resonant chain and large
atmospheric signal sizes provide a well-constrained laboratory to test
the main formation theories. We propose to use JWST/NIRSpec in BOTS
mode with the G395M grating to observe single transits of TOI-178 b,
d, and g, providing an atmospheric characterisation of planets that
span the full range of known orbital separations from the host. Amongst
other things, our mock retrievals suggest that the strong constraints
that we will be able to place on the abundances of H2O, CO, CO2, and
CH4 will enable a precise derivation of the C/O for each planet. The
combination of these measurements will facilitate the first detailed
observational study using the C/O to test whether multiple planets in
the same system formed in situ or migrated to their current positions.
---------------------------------------------------------
Title: The atmosphere of HD 209458b seen with ESPRESSO. No detectable
planetary absorptions at high resolution
Authors: Casasayas-Barris, N.; Palle, E.; Stangret, M.; Bourrier, V.;
Tabernero, H. M.; Yan, F.; Borsa, F.; Allart, R.; Zapatero Osorio,
M. R.; Lovis, C.; Sousa, S. G.; Chen, G.; Oshagh, M.; Santos, N. C.;
Pepe, F.; Rebolo, R.; Molaro, P.; Cristiani, S.; Adibekyan, V.;
Alibert, Y.; Allende Prieto, C.; Bouchy, F.; Demangeon, O. D. S.; Di
Marcantonio, P.; D'Odorico, V.; Ehrenreich, D.; Figueira, P.; Génova
Santos, R.; González Hernández, J. I.; Lavie, B.; Lillo-Box, J.;
Lo Curto, G.; Martins, C. J. A. P.; Mehner, A.; Micela, G.; Nunes,
N. J.; Poretti, E.; Sozzetti, A.; Suárez Mascareño, A.; Udry, S.
2021A&A...647A..26C Altcode: 2021arXiv210104094C
We observed two transits of the iconic gas giant HD 209458b between
380 and 780 nm, using the high-resolution ESPRESSO spectrograph. The
derived planetary transmission spectrum exhibits features at all
wavelengths where the parent star shows strong absorption lines,
for example, Na I, Mg I, Fe I, Fe II, Ca I, V I, Hα, and K I. We
interpreted these features as the signature of the deformation of the
stellar line profiles due to the Rossiter-McLaughlin effect, combined
with the centre-to-limb effects on the stellar surface, which is in
agreement with similar reports recently presented in the literature. We
also searched for species that might be present in the planetary
atmosphere but not in the stellar spectra, such as TiO and VO, and
obtained a negative result. Thus, we find no evidence of any planetary
absorption, including previously reported Na I, in the atmosphere of HD
209458b. The high signal-to-noise ratio in the transmission spectrum
(~1700 at 590 nm) allows us to compare the modelled deformation
of the stellar lines in assuming different one-dimensional stellar
atmospheric models. We conclude that the differences among various
models and observations remain within the precision limits of the
data. However, the transmission light curves are better explained when
the centre-to-limb variation is not included in the computation and only
the Rossiter-McLaughlin deformation is considered. This demonstrates
that ESPRESSO is currently the best facility for spatially resolving the
stellar surface spectrum in the optical range using transit observations
and carrying out empirical validations of stellar models. <P />Based
on Guaranteed Time Observations collected at the European Southern
Observatory under ESO programme 1102.C-0744 by the ESPRESSO Consortium.
---------------------------------------------------------
Title: Analysis of Previously Classified White Dwarf-Main-sequence
Binaries Using Data from the APOGEE Survey
Authors: Corcoran, Kyle A.; Lewis, Hannah M.; Anguiano, Borja;
Majewski, Steven R.; Kounkel, Marina; McDonald, Devin J.; Stassun,
Keivan G.; Cunha, Katia; Smith, Verne; Allende Prieto, Carlos; Badenes,
Carles; De Lee, Nathan; Mazzola, Christine N.; Longa-Peña, Penélope;
Roman-Lopes, Alexandre
2021AJ....161..143C Altcode: 2020arXiv201212997C
We present analyses of near-infrared spectroscopic data from the Apache
Point Observatory Galactic Evolution Experiment (APOGEE) survey for
45 previously confirmed or candidate white dwarf-main-sequence (WDMS)
binaries identified by the optical Sloan Digital Sky Survey (SDSS)
and LAMOST surveys. Among these 45 systems, we classify three as having
red giant primaries in the LAMOST sample and 14 as young stellar object
contaminants in the photometrically identified SDSS sample. From among
the subsample of 28 systems that we confirm to have MS primaries, we
derive and place limits on orbital periods and velocity amplitudes for
14. Seven systems have significant velocity variations that warrant
a post-common-envelope (PCE) binary classification, four of which
are newly classified, three of which are newly confirmed, and five
for which we can derive full orbital parameters. If confirmed, one
of these newly discovered systems (2M14544500+4626456) will have the
second-longest orbital period reported for a typical compact PCE WDMS
binary (P = 15.1 days). In addition to the seven above, we also recover
and characterize with APOGEE data the well-known PCE WDMS systems EG
UMa and HZ 9. We also investigate the overall metallicity distribution
of the WDMS sample, which is a parameter space not often explored
for these systems. Of note, we find one system (2M14244053+4929580)
to be extremely metal-poor ([Fe/H] = - 1.42) relative to the rest of
the near-solar sample. Additionally, the PCE systems in our sample are
found to be, on average, higher in metallicity than their wide-binary
counterparts, though we caution that with this small number of systems,
the sample may not be representative of the overall distribution of
WDMS systems.
---------------------------------------------------------
Title: HIRES, the High-resolution Spectrograph for the ELT
Authors: Marconi, A.; Abreu, M.; Adibekyan, V.; Aliverti, M.; Allende
Prieto, C.; Amado, P.; Amate, M.; Artigau, E.; Augusto, S.; Barros,
S.; Becerril, S.; Benneke, B.; Bergin, E.; Berio, P.; Bezawada,
N.; Boisse, I.; Bonfils, X.; Bouchy, F.; Broeg, C.; Cabral, A.;
Calvo-Ortega, R.; Canto Martins, B. L.; Chazelas, B.; Chiavassa,
A.; Christensen, L.; Cirami, R.; Coretti, I.; Covino, S.; Cresci,
G.; Cristiani, S.; Cunha Parro, V.; Cupani, G.; de Castro Leão,
I.; Renan de Medeiros, J.; Furlande Souza, M. A.; Di Marcantonio,
P.; Di Varano, I.; D'Odorico, V.; Doyon, R.; Drass, H.; Figueira,
P.; Belen Fragoso, A.; Uldall Fynbo, J. P.; Gallo, E.; Genoni,
M.; González Hernández, J.; Haehnelt, M.; Hlavacek-Larrondo, J.;
Hughes, I.; Huke, P.; Humphrey, A.; Kjeldsen, H.; Korn, A.; Kouach,
D.; Landoni, M.; Liske, J.; Lovis, C.; Lunney, D.; Maiolino, R.; Malo,
L.; Marquart, T.; Martins, C.; Mason, E.; Molaro, P.; Monnier, J.;
Monteiro, M.; Mordasini, C.; Morris, T.; Mucciarelli, A.; Murray,
G.; Niedzielski, A.; Nunes, N.; Oliva, E.; Origlia, L.; Pallé,
E.; Pariani, G.; Parr-Burman, P.; Peñate, J.; Pepe, F.; Pinna,
E.; Piskunov, N.; Rasilla Piñeiro, J. L.; Rebolo, R.; Rees, P.;
Reiners, A.; Riva, M.; Romano, D.; Rousseau, S.; Sanna, N.; Santos,
N.; Sarajlic, M.; Shen, T. -C.; Sortino, F.; Sosnowska, D.; Sousa,
S.; Stempels, E.; Strassmeier, K.; Tenegi, F.; Tozzi, A.; Udry,
S.; Valenziano, L.; Vanzi, L.; Weber, M.; Woche, M.; Xompero, M.;
Zackrisson, E.; Zapatero Osorio, M. R.
2021Msngr.182...27M Altcode: 2020arXiv201112317M
HIRES will be the high-resolution spectrograph at optical and
near-infrared (NIR) wavelengths for ESO's Extremely Large Telescope
(ELT). It will consist of three fibre-fed spectrographs providing a
wavelength coverage of 0.4-1.8 µm (with a goal of 0.35-1.8 µm) at a
spectral resolution of ~ 100 000. Fibre-feeding allows HIRES to have
several interchangeable observing modes, including a single-conjugate
adaptive optics (SCAO) module and a small diffraction-limited integral
field unit in the NIR. It will therefore be able to operate in both
seeing- and diffraction-limited modes. HIRES will address a wide range
of science cases spanning nearly all areas of research in astrophysics
and even fundamental physics. Some of the top science cases will be
the detection of biosignatures from exoplanet atmospheres, finding the
fingerprints of the first generation of stars (Pop III), tests on the
stability of Nature's fundamental couplings, and the direct detection
of the cosmic acceleration. The HIRES consortium is composed of more
than 30 institutes from 14 countries, forming a team of more than 200
scientists and engineers.
---------------------------------------------------------
Title: Searching for the Alpha-Abundance Bimodality in the M31 Disk
Authors: Nidever, David; Gilbert, Karoline; Tollerud, Erik;
Allende-Prieto, Carlos; Cunha, Katia; Debattista, Victor P.; Escala,
Ivanna; Fardal, Mark; Garver, Bethany Ray; Guhathakurta, Puragra;
Hamanowicz, Aleksandra; Kirby, Evan; Quirk, Amanda; Smith, Verne V.;
Sohn, Sangmo Tony; Ting, Yuan-Sen; Wojno, Jennifer
2021jwst.prop.2609N Altcode:
The recent era of large, ground-based abundance surveys has unraveled
the chemical structures of our Milky Way galaxy. The most striking
abundance feature is the alpha-abundance bimodality. The low-alpha
stars are younger (1-8 Gyr) while the high-alpha stars are older
(8-12 Gyr) and have a thicker distribution. There are a number of
different models that attempt to explain this chemical feature, but so
far none have been strongly favored by the data. However, they do make
different predictions about the prevalence of the alpha-bimodality
in Milky Way-mass galaxies. Therefore, we propose to take NIRSpec
MSA medium-resolution (R=2700), high-S/N observations of ~130 red
giant branch stars in the M31 disk with which we will measure precise
metallicity and alpha-abundances (to ~0.03 dex) and search for an
alpha-bimodality. These first precise elemental abundances in the M31
disk will double our sample of MW-mass galaxies with which to compare
and constraint the models. This will allow us to take a big step forward
in our understanding of the most important chemical process at work
in our galaxy. In addition, we will use the abundance information, in
combination with accurate star formation histories from the PHAT survey,
to probe the chemical evolution of the M31 disk in more detail using
one-zone chemical evolution models that will allow us to constrain the
star formation efficiency, inflow and outflow rates, and initial mass
function. This pilot program will demonstrate the utility of NIRSpec
for obtaining individual elemental abundances to explore the chemical
enrichment of stellar populations lying well beyond the Milky Way in
the Local Group.
---------------------------------------------------------
Title: Fundamental physics with ESPRESSO: Towards an accurate
wavelength calibration for a precision test of the fine-structure
constant
Authors: Schmidt, Tobias M.; Molaro, Paolo; Murphy, Michael T.; Lovis,
Christophe; Cupani, Guido; Cristiani, Stefano; Pepe, Francesco A.;
Rebolo, Rafael; Santos, Nuno C.; Abreu, Manuel; Adibekyan, Vardan;
Alibert, Yann; Aliverti, Matteo; Allart, Romain; Allende Prieto,
Carlos; Alves, David; Baldini, Veronica; Broeg, Christopher; Cabral,
Alexandre; Calderone, Giorgio; Cirami, Roberto; Coelho, João; Coretti,
Igor; D'Odorico, Valentina; Di Marcantonio, Paolo; Ehrenreich,
David; Figueira, Pedro; Genoni, Matteo; Génova Santos, Ricardo;
González Hernández, Jonay I.; Kerber, Florian; Landoni, Marco;
Leite, Ana C. O.; Lizon, Jean-Louis; Lo Curto, Gaspare; Manescau,
Antonio; Martins, Carlos J. A. P.; Megévand, Denis; Mehner, Andrea;
Micela, Giuseppina; Modigliani, Andrea; Monteiro, Manuel; Monteiro,
Mario J. P. F. G.; Mueller, Eric; Nunes, Nelson J.; Oggioni, Luca;
Oliveira, António; Pariani, Giorgio; Pasquini, Luca; Redaelli,
Edoardo; Riva, Marco; Santos, Pedro; Sosnowska, Danuta; Sousa,
Sérgio G.; Sozzetti, Alessandro; Suárez Mascareño, Alejandro;
Udry, Stéphane; Zapatero Osorio, Maria-Rosa; Zerbi, Filippo
2021A&A...646A.144S Altcode: 2020arXiv201113963S
Observations of metal absorption systems in the spectra of
distant quasars allow one to constrain a possible variation of the
fine-structure constant throughout the history of the Universe. Such
a test poses utmost demands on the wavelength accuracy and previous
studies were limited by systematics in the spectrograph wavelength
calibration. A substantial advance in the field is therefore expected
from the new ultra-stable high-resolution spectrograph ESPRESSO,
which was recently installed at the VLT. In preparation of the
fundamental physics related part of the ESPRESSO GTO program, we
present a thorough assessment of the ESPRESSO wavelength accuracy
and identify possible systematics at each of the different steps
involved in the wavelength calibration process. Most importantly,
we compare the default wavelength solution, which is based on the
combination of Thorium-Argon arc lamp spectra and a Fabry-Pérot
interferometer, to the fully independent calibration obtained from a
laser frequency comb. We find wavelength-dependent discrepancies of
up to 24 m s<SUP>-1</SUP>. This substantially exceeds the photon noise
and highlights the presence of different sources of systematics, which
we characterize in detail as part of this study. Nevertheless, our
study demonstrates the outstanding accuracy of ESPRESSO with respect
to previously used spectrographs and we show that constraints of a
relative change of the fine-structure constant at the 10<SUP>-6</SUP>
level can be obtained with ESPRESSO without being limited by wavelength
calibration systematics.
---------------------------------------------------------
Title: The contribution of N-rich stars to the Galactic stellar halo
using APOGEE red giants
Authors: Horta, Danny; Mackereth, J. Ted; Schiavon, Ricardo P.;
Hasselquist, Sten; Bovy, Jo; Allende Prieto, Carlos; Beers, Timothy
C.; Cunha, Katia; García-Hernández, D. A.; Kisku, Shobhit S.; Lane,
Richard R.; Majewski, Steven R.; Mason, Andrew C.; Nataf, David M.;
Roman-Lopes, Alexandre; Schultheis, Mathias
2021MNRAS.500.5462H Altcode: 2020MNRAS.tmp.3381H; 2020MNRAS.500.5462H; 2020arXiv200801097H
The contribution of dissolved globular clusters (GCs) to the stellar
content of the Galactic halo is a key constraint on models for GC
formation and destruction, and the mass assembly history of the Milky
Way. Earlier results from APOGEE pointed to a large contribution of
destroyed GCs to the stellar content of the inner halo, by as much
as 25 ${{\ \rm per\ cent}}$, which is an order of magnitude larger
than previous estimates for more distant regions of the halo. We set
out to measure the ratio between nitrogen-rich (N-rich) and normal
halo field stars, as a function of distance, by performing density
modelling of halo field populations in APOGEE DR16. Our results show
that at 1.5 kpc from the Galactic Centre, N-rich stars contribute a
much higher 16.8$^{+10.0}_{-7.0}\, {{\ \rm per\ cent}}$ fraction to
the total stellar halo mass budget than the 2.7$^{+1.0}_{-0.8}\, {{\
\rm per\ cent}}$ ratio contributed at 10 kpc. Under the assumption that
N-rich stars are former GC members that now reside in the stellar halo
field, and assuming the ratio between first and second population GC
stars being 1:2, we estimate a total contribution from disrupted GC
stars of the order of 27.5$^{+15.4}_{-11.5}\, {{\ \rm per\ cent}}$
at r = 1.5 kpc and 4.2$^{+1.5}_{-1.3}\, {{\ \rm per\ cent}}$ at r =
10 kpc. Furthermore, since our methodology requires fitting a density
model to the stellar halo, we integrate such density within a spherical
shell from 1.5 to 15 kpc in radius, and find a total stellar mass
arising from dissolved and/or evaporated GCs of M<SUB>GC,total</SUB>
= 9.6$^{+4.0}_{-2.6}\, \times$ 10<SUP>7</SUP> M⊙.
---------------------------------------------------------
Title: ESPRESSO high-resolution transmission spectroscopy of WASP-76 b
Authors: Tabernero, H. M.; Zapatero Osorio, M. R.; Allart, R.; Borsa,
F.; Casasayas-Barris, N.; Demangeon, O.; Ehrenreich, D.; Lillo-Box,
J.; Lovis, C.; Pallé, E.; Sousa, S. G.; Rebolo, R.; Santos,
N. C.; Pepe, F.; Cristiani, S.; Adibekyan, V.; Allende Prieto, C.;
Alibert, Y.; Barros, S. C. C.; Bouchy, F.; Bourrier, V.; D'Odorico,
V.; Dumusque, X.; Faria, J. P.; Figueira, P.; Génova Santos, R.;
González Hernández, J. I.; Hojjatpanah, S.; Lo Curto, G.; Lavie,
B.; Martins, C. J. A. P.; Martins, J. H. C.; Mehner, A.; Micela,
G.; Molaro, P.; Nunes, N. J.; Poretti, E.; Seidel, J. V.; Sozzetti,
A.; Suárez Mascareño, A.; Udry, S.; Aliverti, M.; Affolter, M.;
Alves, D.; Amate, M.; Avila, G.; Bandy, T.; Benz, W.; Bianco, A.;
Broeg, C.; Cabral, A.; Conconi, P.; Coelho, J.; Cumani, C.; Deiries,
S.; Dekker, H.; Delabre, B.; Fragoso, A.; Genoni, M.; Genolet, L.;
Hughes, I.; Knudstrup, J.; Kerber, F.; Landoni, M.; Lizon, J. L.;
Maire, C.; Manescau, A.; Di Marcantonio, P.; Mégevand, D.; Monteiro,
M.; Monteiro, M.; Moschetti, M.; Mueller, E.; Modigliani, A.; Oggioni,
L.; Oliveira, A.; Pariani, G.; Pasquini, L.; Rasilla, J. L.; Redaelli,
E.; Riva, M.; Santana-Tschudi, S.; Santin, P.; Santos, P.; Segovia,
A.; Sosnowska, D.; Spanò, P.; Tenegi, F.; Iwert, O.; Zanutta, A.;
Zerbi, F.
2021A&A...646A.158T Altcode: 2020arXiv201112197T
<BR /> Aims: We report on ESPRESSO high-resolution transmission
spectroscopic observations of two primary transits of the highly
irradiated, ultra-hot Jupiter-sized planet, WASP-76b. We investigated
the presence of several key atomic and molecular features of interest
that may reveal the atmospheric properties of the planet. <BR />
Methods: We extracted two transmission spectra of WASP-76b with R ≈
140 000 using a procedure that allowed us to process the full ESPRESSO
wavelength range (3800-7880 Å) simultaneously. We observed that at
a high signal-to-noise ratio, the continuum of ESPRESSO spectra shows
`wiggles', which are likely caused by an interference pattern outside
the spectrograph. To search for the planetary features, we visually
analysed the extracted transmission spectra and cross-correlated
the observations against theoretical spectra of different atomic and
molecular species. <BR /> Results: The following atomic features are
detected: Li I, Na I, Mg I, Ca II, Mn I, K I, and Fe I. All are detected
with a confidence level between 9.2 σ (Na I) and 2.8 σ (Mg I). We did
not detect the following species: Ti I, Cr I, Ni I, TiO, VO, and ZrO. We
impose the following 1 σ upper limits on their detectability: 60,
77, 122, 6, 8, and 8 ppm, respectively. <BR /> Conclusions: We report
the detection of Li I on WASP-76b for the first time. In addition,
we confirm the presence of Na I and Fe I as previously reported in
the literature. We show that the procedure employed in this work can
detect features down to the level of ~0.1% in the transmission spectrum
and ~10 ppm by means of a cross-correlation method. We discuss the
presence of neutral and singly ionised features in the atmosphere of
WASP-76b. <P />Based on guaranteed time observations collected at the
European Southern Observatory under ESO programme 1102.C-0744 by the
ESPRESSO Consortium.
---------------------------------------------------------
Title: First Scientific Results from HORuS and GTC
Authors: Allende-Prieto, C.; Aguado, D. S.; Rebolo, R.; González
Hernández, J. I.; Calvo, J.; Gómez, M.; Peñate, J.; Joven, E.;
Osorio, Y. M.; Tabernero, H. M.; Gracia, F.
2021AAS...23713906A Altcode:
We present the first science results from the High Optical Resolution
Spectrograph (HORuS), a cross-dispersed echelle spectrograph now
in operation on the 10.4-m Gran Telescopio Canarias (GTC). The
spectrograph provides a FWHM resolving power of 25,000 and coverage
between 370 and 690 nm. HORuS has been mostly built with parts from
a previous instrument, with a number of upgrades including a train
of monolithic prisms for cross-dispersion, a fiber link, and a new
CCD. The commissioning of HORuS was completed in March 2019 and over
the past three semesters the instrument has been used to observe stars
orbiting black holes, transiting exoplanets, planetary nebulae, star
clusters in nearby galaxies, stellar streams, and extremely metal-poor
stars. This presentation will highlight the varied results reported
in the first publications using HORuS data.
---------------------------------------------------------
Title: Analyzing Abundances of R-process Elements in Metal Poor
Stars Utilizing GTC Spectra
Authors: Moore, V.; Ezzeddine, R.; Allende Prieto, C.
2021AAS...23734305M Altcode:
The r-process involves a heavy atomic nucleus seed undergoing
rapid neutron capture to create a heavier element. This can only
be achieved in environments of high free neutron density and high
temperature. The site(s) of the r-process have been debated for a
long time. Theoretical investigations have suggested neutron star
mergers, collapsars and magneto-rotational supernovae as possible
contenders. The electromagnetic counterpart of the first ever observed
neutron star merger, GW170817, has confirmed the presence of r-process
rich ejecta. However, no detailed r-process abundance measurements could
be made. Evidence of the r-process can be seen in metal-poor stars such
as those in the halo of the Milky Way. We present chemical abundance
analysis of metal-poor stars observed using the 10m Gran Telescopio
Canarias (GTC) in the Canary Islands, Spain. This is the first set
of data to be analyzed for r-process from the high resolution optical
echelle spectrograph HORuS on the GTC. I have used the spectroscopic
analysis tool Spectroscopy Made Hard to determine the abundances of
neutron capture elements from the high resolution spectra of a sample
of r-process enhanced stars. The results of our analysis are used to
better constrain the origins of the r-process and its sites.
---------------------------------------------------------
Title: The GTC gains high spectral resolution
Authors: Allende Prieto, Carlos
2021NatAs...5..105A Altcode:
HORuS, a new high-resolution spectrograph for the Gran Telescopio
Canarias, will facilitate an expanded range of optical and near-infrared
studies, explains Instrument Scientist Carlos Allende Prieto.
---------------------------------------------------------
Title: Evidence from APOGEE for the presence of a major building
block of the halo buried in the inner Galaxy
Authors: Horta, Danny; Schiavon, Ricardo P.; Mackereth, J. Ted;
Pfeffer, Joel; Mason, Andrew C.; Kisku, Shobhit; Fragkoudi, Francesca;
Allende Prieto, Carlos; Cunha, Katia; Hasselquist, Sten; Holtzman, Jon;
Majewski, Steven R.; Nataf, David; O'Connell, Robert W.; Schultheis,
Mathias; Smith, Verne V.
2021MNRAS.500.1385H Altcode: 2020MNRAS.500.1385H; 2020arXiv200710374H
We report evidence from APOGEE for the presence of a new
metal-poor stellar structure located within ∼4 kpc of the Galactic
Centre. Characterized by a chemical composition resembling those of
low-mass satellites of the Milky Way, this new inner Galaxy structure
(IGS) seems to be chemically and dynamically detached from more
metal-rich populations in the inner Galaxy. We conjecture that this
structure is associated with an accretion event that likely occurred in
the early life of the Milky Way. Comparing the mean elemental abundances
of this structure with predictions from cosmological numerical
simulations, we estimate that the progenitor system had a stellar mass
of ∼5 × 10<SUP>8</SUP> M<SUB>⊙</SUB>, or approximately twice the
mass of the recently discovered Gaia-Enceladus/Sausage system. We
find that the accreted:in situ ratio within our metal-poor ([Fe/H]
< -0.8) bulge sample is somewhere between 1:3 and 1:2, confirming
predictions of cosmological numerical simulations by various groups.
---------------------------------------------------------
Title: The S2 stream: the shreds of a primitive dwarf galaxy
Authors: Aguado, David S.; Myeong, G. C.; Belokurov, Vasily; Evans,
N. Wyn; Koposov, Sergey E.; Allende Prieto, Carlos; Lanfranchi,
Gustavo A.; Matteucci, Francesca; Shetrone, Matthew; Sbordone, Luca;
Navarrete, Camila; González Hernández, Jonay I.; Chanamé, Julio;
Peralta de Arriba, Luis; Yuan, Zhen
2021MNRAS.500..889A Altcode: 2020MNRAS.tmp.3033A; 2020arXiv200711003A; 2020MNRAS.500..889A
The S2 stream is a kinematically cold stream that is plunging
downwards through the Galactic disc. It may be part of a hotter
and more diffuse structure called the Helmi stream. We present a
multi-instrument chemical analysis of the stars in the metal-poor S2
stream using both high- and low-resolution spectroscopy, complemented
with a re-analysis of the archival data to give a total sample of 62
S2 members. Our high-resolution program provides α-elements (C, Mg,
Si, Ca, and Ti), iron-peak elements (V, Cr, Mn, Fe, Ni), n-capture
process elements (Sr, Ba), and other elements such as Li, Na, Al,
and Sc for a subsample of S2 objects. We report coherent abundance
patterns over a large metallicity spread (~1 dex) confirming that the
S2 stream was produced by a disrupted dwarf galaxy. The combination of
S2's α-elements displays a mildly decreasing trend with increasing
metallicity, which can be tentatively interpreted as a 'knee' at
[Fe/H] < -2. At the low-metallicity end, the n-capture elements in
S2 may be dominated by r-process production; however, several stars are
Ba-enhanced but unusually poor in Sr. Moreover, some of the low-[Fe/H]
stars appear to be carbon-enhanced. We interpret the observed abundance
patterns with the help of chemical evolution models that demonstrate
the need for modest star formation efficiency and low wind efficiency
confirming that the progenitor of S2 was a primitive dwarf galaxy.
---------------------------------------------------------
Title: ESPRESSO at VLT. On-sky performance and first results
Authors: Pepe, F.; Cristiani, S.; Rebolo, R.; Santos, N. C.; Dekker,
H.; Cabral, A.; Di Marcantonio, P.; Figueira, P.; Lo Curto, G.; Lovis,
C.; Mayor, M.; Mégevand, D.; Molaro, P.; Riva, M.; Zapatero Osorio,
M. R.; Amate, M.; Manescau, A.; Pasquini, L.; Zerbi, F. M.; Adibekyan,
V.; Abreu, M.; Affolter, M.; Alibert, Y.; Aliverti, M.; Allart, R.;
Allende Prieto, C.; Álvarez, D.; Alves, D.; Avila, G.; Baldini,
V.; Bandy, T.; Barros, S. C. C.; Benz, W.; Bianco, A.; Borsa, F.;
Bourrier, V.; Bouchy, F.; Broeg, C.; Calderone, G.; Cirami, R.; Coelho,
J.; Conconi, P.; Coretti, I.; Cumani, C.; Cupani, G.; D'Odorico, V.;
Damasso, M.; Deiries, S.; Delabre, B.; Demangeon, O. D. S.; Dumusque,
X.; Ehrenreich, D.; Faria, J. P.; Fragoso, A.; Genolet, L.; Genoni,
M.; Génova Santos, R.; González Hernández, J. I.; Hughes, I.; Iwert,
O.; Kerber, F.; Knudstrup, J.; Landoni, M.; Lavie, B.; Lillo-Box, J.;
Lizon, J. -L.; Maire, C.; Martins, C. J. A. P.; Mehner, A.; Micela, G.;
Modigliani, A.; Monteiro, M. A.; Monteiro, M. J. P. F. G.; Moschetti,
M.; Murphy, M. T.; Nunes, N.; Oggioni, L.; Oliveira, A.; Oshagh, M.;
Pallé, E.; Pariani, G.; Poretti, E.; Rasilla, J. L.; Rebordão,
J.; Redaelli, E. M.; Santana Tschudi, S.; Santin, P.; Santos, P.;
Ségransan, D.; Schmidt, T. M.; Segovia, A.; Sosnowska, D.; Sozzetti,
A.; Sousa, S. G.; Spanò, P.; Suárez Mascareño, A.; Tabernero, H.;
Tenegi, F.; Udry, S.; Zanutta, A.
2021A&A...645A..96P Altcode: 2020arXiv201000316P
Context. ESPRESSO is the new high-resolution spectrograph of ESO's Very
Large Telescope (VLT). It was designed for ultra-high radial-velocity
(RV) precision and extreme spectral fidelity with the aim of performing
exoplanet research and fundamental astrophysical experiments with
unprecedented precision and accuracy. It is able to observe with any
of the four Unit Telescopes (UTs) of the VLT at a spectral resolving
power of 140 000 or 190 000 over the 378.2 to 788.7 nm wavelength
range; it can also observe with all four UTs together, turning the
VLT into a 16 m diameter equivalent telescope in terms of collecting
area while still providing a resolving power of 70 000. <BR /> Aims:
We provide a general description of the ESPRESSO instrument, report on
its on-sky performance, and present our Guaranteed Time Observation
(GTO) program along with its first results. <BR /> Methods: ESPRESSO
was installed on the Paranal Observatory in fall 2017. Commissioning
(on-sky testing) was conducted between December 2017 and September
2018. The instrument saw its official start of operations on October
1, 2018, but improvements to the instrument and recommissioning runs
were conducted until July 2019. <BR /> Results: The measured overall
optical throughput of ESPRESSO at 550 nm and a seeing of 0.65″ exceeds
the 10% mark under nominal astroclimatic conditions. We demonstrate
an RV precision of better than 25 cm s<SUP>-1</SUP> during a single
night and 50 cm s<SUP>-1</SUP> over several months. These values being
limited by photon noise and stellar jitter shows that the performance is
compatible with an instrumental precision of 10 cm s<SUP>-1</SUP>. No
difference has been measured across the UTs, neither in throughput
nor RV precision. <BR /> Conclusions: The combination of the large
collecting telescope area with the efficiency and the exquisite spectral
fidelity of ESPRESSO opens a new parameter space in RV measurements,
the study of planetary atmospheres, fundamental constants, stellar
characterization, and many other fields. <P />Based on GTOs collected
at the European Southern Observatory under ESO program(s) 1102.C-0744,
1102.C-0958 and 1104.C-0350 by the ESPRESSO Consortium.
---------------------------------------------------------
Title: Atmospheric Rossiter-McLaughlin effect and transmission
spectroscopy of WASP-121b with ESPRESSO
Authors: Borsa, F.; Allart, R.; Casasayas-Barris, N.; Tabernero,
H.; Zapatero Osorio, M. R.; Cristiani, S.; Pepe, F.; Rebolo, R.;
Santos, N. C.; Adibekyan, V.; Bourrier, V.; Demangeon, O. D. S.;
Ehrenreich, D.; Pallé, E.; Sousa, S.; Lillo-Box, J.; Lovis, C.;
Micela, G.; Oshagh, M.; Poretti, E.; Sozzetti, A.; Allende Prieto, C.;
Alibert, Y.; Amate, M.; Benz, W.; Bouchy, F.; Cabral, A.; Dekker, H.;
D'Odorico, V.; Di Marcantonio, P.; Figueira, P.; Genova Santos, R.;
González Hernández, J. I.; Lo Curto, G.; Manescau, A.; Martins,
C. J. A. P.; Mégevand, D.; Mehner, A.; Molaro, P.; Nunes, N. J.;
Riva, M.; Suárez Mascareño, A.; Udry, S.; Zerbi, F.
2021A&A...645A..24B Altcode: 2020arXiv201101245B
Context. Ultra-hot Jupiters are excellent laboratories for the study
of exoplanetary atmospheres. WASP-121b is one of the most studied;
many recent analyses of its atmosphere report interesting features at
different wavelength ranges. <BR /> Aims: In this paper we analyze one
transit of WASP-121b acquired with the high-resolution spectrograph
ESPRESSO at VLT in one-telescope mode, and one partial transit
taken during the commissioning of the instrument in four-telescope
mode. <BR /> Methods: We take advantage of the very high S/N data
and of the extreme stability of the spectrograph to investigate the
anomalous in-transit radial velocity curve and study the transmission
spectrum of the planet. We pay particular attention to the removal
of instrumental effects, and stellar and telluric contamination. The
transmission spectrum is investigated through single-line absorption
and cross-correlation with theoretical model templates. <BR /> Results:
By analyzing the in-transit radial velocities we were able to infer
the presence of the atmospheric Rossiter-McLaughlin effect. We measured
the height of the planetary atmospheric layer that correlates with the
stellar mask (mainly Fe) to be 1.052 ± 0.015 R<SUB>p</SUB> and we also
confirmed the blueshift of the planetary atmosphere. By examining the
planetary absorption signal on the stellar cross-correlation functions
we confirmed the presence of a temporal variation of its blueshift
during transit, which could be investigated spectrum-by-spectrum
thanks to the quality of our ESPRESSO data. We detected significant
absorption in the transmission spectrum for Na, H, K, Li, Ca II,
and Mg, and we certified their planetary nature by using the 2D
tomographic technique. Particularly remarkable is the detection of
Li, with a line contrast of ~0.2% detected at the 6σ level. With the
cross-correlation technique we confirmed the presence of Fe I, Fe II,
Cr I, and V I. Hα and Ca II are present up to very high altitudes in
the atmosphere (~1.44 R<SUB>p</SUB> and ~2 R<SUB>p</SUB>, respectively),
and also extend beyond the transit-equivalent Roche lobe radius of the
planet. These layers of the atmosphere have a large line broadening that
is not compatible with being caused by the tidally locked rotation of
the planet alone, and could arise from vertical winds or high-altitude
jets in the evaporating atmosphere. <P />Based in part on Guaranteed
Time Observations collected at the European Southern Observatory under
ESO programme 1102.C-0744 by the ESPRESSO Consortium.
---------------------------------------------------------
Title: Integration and early testing of WEAVE: the next-generation
spectroscopy facility for the William Herschel Telescope
Authors: Dalton, Gavin; Trager, Scott; Abrams, Don Carlos; Bonifacio,
Piercarlo; Aguerri, J. Alfonso L.; Vallenari, Antonella; Bishop,
Georgia; Middleton, Kevin; Benn, Chris; Dee, Kevin; Mignot, Shan;
Lewis, Ian; Pragt, Johannes; Pico, Sergio; Walton, Nicholas; Rey,
Juerg; Allende Prieto, Carlos; Lhomé, Emilie; Balcells, Marc; Terrett,
David; Brock, Matthew; Ridings, Andy; Skvarč, Jure; Verheijen, Marc;
Steele, Iain; Stuik, Remko; Kroes, Gabby; Tromp, Neils; Kragt, Jan;
Lesman, Dirk; Mottram, Chris; Bates, Stuart; Gribbin, Frank; Burgal,
Jose Alonso; Herreros, José Miguel; Delgado, José Miguel; Martin,
Carlos; Cano, Diego; Navarro, Ramon; Irwin, Mike; Peralta de Arriba,
Luis; O'Mahoney, Neil; Bianco, Andrea; Moleinezhad, Alireza; ter
Horst, Rik; Molinari, Emilio; Lodi, Marcello; Guerra, José; Baruffalo,
Andrea; Carrasco, Esperanza; Farcas, Szigfrid; Schallig, Ellen; Hughes,
Sarah; Hill, Vanessa; Smith, Dan; Drew, Janet; Poggianti, Bianca;
Iovino, Angela; Pieri, Mat; Jin, Shoko; Dominguez Palmero, Lillian;
Fariña, Cecilia; Martín, Adrian; Worley, Clare; Murphy, David;
Guest, Steve; Morris, Huw; Elswijk, Eddy; de Haan, Menno; Hanenburg,
Hiddo; Salasnich, Bernardo; Mayya, Divakara; Izazaga-Pérez, Rafael;
Gafton, Emanuel; Caffau, Elisabetta; Horville, David; Paz Chinchón,
Francisco; Falcon-Barosso, Jesus; Gänsicke, Boris; San Juan, Jose;
Hernandez, Nauzet
2020SPIE11447E..14D Altcode:
We present an update on the overall integration progress of the
WEAVE next-generation spectroscopy facility for the William Herschel
Telescope (WHT), now scheduled for first light in early-2021, with
almost all components now arrived at the observatory. We also present
a summary of the current planning behind the 5-year initial phase of
survey operations, and some detailed end-to-end science simulations
that have been implemented to evaluate the final on-sky performance
after data processing. WEAVE will provide optical ground-based follow
up of ground-based (LOFAR) and space-based (Gaia) surveys. WEAVE
is a multi-object and multi-IFU facility utilizing a new 2-degree
prime focus field of view at the WHT, with a buffered pick-and-place
positioner system hosting 1000 multi-object (MOS) fibres, 20 mini
integral field units, or a single large IFU for each observation. The
fibres are fed to a single (dual-beam) spectrograph, with total of
16k spectral pixels, located within the WHT GHRIL enclosure on the
telescope Nasmyth platform, supporting observations at R~5000 over
the full 370-1000nm wavelength range in a single exposure, or a high
resolution mode with limited coverage in each arm at R~20000.
---------------------------------------------------------
Title: K2-111: an old system with two planets in near-resonance
Authors: Mortier, A.; Zapatero Osorio, M. R.; Malavolta, L.;
Alibert, Y.; Rice, K.; Lillo-Box, J.; Vanderburg, A.; Oshagh, M.;
Buchhave, L.; Adibekyan, V.; Delgado Mena, E.; Lopez-Morales, M.;
Charbonneau, D.; Sousa, S. G.; Lovis, C.; Affer, L.; Allende Prieto,
C.; Barros, S. C. C.; Benatti, S.; Bonomo, A. S.; Boschin, W.; Bouchy,
F.; Cabral, A.; Collier Cameron, A.; Cosentino, R.; Cristiani, S.;
Demangeon, O. D. S.; Di Marcantonio, P.; D'Odorico, V.; Dumusque, X.;
Ehrenreich, D.; Figueira, P.; Fiorenzano, A.; Ghedina, A.; González
Hernández, J. I.; Haldemann, J.; Harutyunyan, A.; Haywood, R. D.;
Latham, D. W.; Lavie, B.; Lo Curto, G.; Maldonado, J.; Manescau, A.;
Martins, C. J. A. P.; Mayor, M.; Mégevand, D.; Mehner, A.; Micela,
G.; Molaro, P.; Molinari, E.; Nunes, N. J.; Pepe, F. A.; Palle, E.;
Phillips, D.; Piotto, G.; Pinamonti, M.; Poretti, E.; Riva, M.; Rebolo,
R.; Santos, N. C.; Sasselov, D.; Sozzetti, A.; Suárez Mascareño,
A.; Udry, S.; West, R. G.; Watson, C. A.; Wilson, T. G.
2020MNRAS.499.5004M Altcode: 2020MNRAS.tmp.3119M; 2020arXiv201001993M
This paper reports on the detailed characterization of the K2-111
planetary system with K2, WASP, and ASAS-SN photometry, as well as
high-resolution spectroscopic data from HARPS-N and ESPRESSO. The
host, K2-111, is confirmed to be a mildly evolved (log g = 4.17),
iron-poor ([Fe/H] = -0.46), but alpha-enhanced ([α/Fe]=0.27),
chromospherically quiet, very old thick disc G2 star. A global fit,
performed by using PyORBIT, shows that the transiting planet, K2-111
b, orbits with a period P<SUB>b</SUB> = 5.3518 ± 0.0004 d and has
a planet radius of $1.82^{+0.11}_{-0.09}$ R<SUB>⊕</SUB> and a
mass of $5.29^{+0.76}_{-0.77}$ M<SUB>⊕</SUB>, resulting in a bulk
density slightly lower than that of the Earth. The stellar chemical
composition and the planet properties are consistent with K2-111 b
being a terrestrial planet with an iron core mass fraction lower than
the Earth. We announce the existence of a second signal in the radial
velocity data that we attribute to a non-transiting planet, K2-111 c,
with an orbital period of 15.6785 ± 0.0064 d, orbiting in near-3:1
mean motion resonance with the transiting planet, and a minimum
planet mass of 11.3 ± 1.1 M<SUB>⊕</SUB>. Both planet signals are
independently detected in the HARPS-N and ESPRESSO data when fitted
separately. There are potentially more planets in this resonant system,
but more well-sampled data are required to confirm their presence and
physical parameters.
---------------------------------------------------------
Title: ELT-HIRES, the high resolution spectrograph for the ELT:
the Phase A study and the path to construction
Authors: Marconi, A.; Abreu, M.; Adibekyan, V.; Aliverti, M.; Allende
Prieto, C.; Amado, P.; Amate, M.; Artigau, E.; Augusto, S.; Barros, S.;
Becerril, S.; Benneke, B.; Bergin, E.; Berio, P.; Bezawada, N.; Boisse,
I.; Bonfils, X.; Bouchy, F.; Broeg, C.; Cabral, A.; Calvo-Ortega,
R.; Canto Martins, B. L.; Chazelas, B.; Chiavassa, A.; Christensen,
L.; Cirami, R.; Coretti, I.; Covino, S.; Cresci, G.; Cristiani, S.;
Cunha Parro, V.; Cupani, G.; D'Odorico, V.; de Castro Leão, I.;
de Medeiros, J. R.; de Souza, M.; Di Marcantonio, P.; Di Varano, I.;
Doyon, R.; Drass, H.; Figueira, P.; Fragoso, A.; Fynbo, J.; Gallo,
E.; Genoni, M.; González Hernández, J.; Gratton, R.; Haehnelt, M.;
Hansen, C.; Hlavacek-Larrondo, J.; Hughes, I.; Huke, P.; Humphrey,
A.; Kjeldsen, H.; Korn, A.; Kouach, D.; Landoni, M.; Liske, J.;
Lovis, C.; Lunney, D.; Maiolino, R.; Malo, L.; Marquart, T.; Martins,
C. J. A. P.; Maslowski, P.; Mason, E.; Micela, G.; Molaro, P.; Monnier,
J.; Monteiro, M.; Mordasini, C.; Morris, T.; Mucciarelli, A.; Murray,
G.; Niedzielski, A.; Niemczura, E.; Nisini, B.; Nunes, N.; Oliva,
E.; Origlia, L.; Pallé, E.; Pariani, G.; Parr-Burman, P.; Pasquini,
L.; Peñate, J.; Pepe, F.; Pietrzynski, G.; Pinna, E.; Piskunov,
N.; Pollo, A.; Rasilla, J.; Rebolo, R.; Rees, P.; Reiners, A.; Riva,
M.; Romano, D.; Rousseau, S.; Sanna, N.; Sarajlic, M.; Shen, T. -C.;
Sortino, F.; Sosnowska, D.; Sousa, S.; Stempels, E.; Strassmeier, K.;
Tenegi, F.; Tozzi, A.; Udry, S.; Valenziano, L.; Vanzi, L.; Weber,
M.; Woche, M.; Xompero, M.; Zackrisson, E.; Zapatero Osorio, M. R.
2020SPIE11447E..26M Altcode:
HIRES is the high-resolution spectrograph of the European Extremely
Large Telescope at optical and near-infrared wavelengths. It consists
of three fibre-fed spectrographs providing a wavelength coverage of
0.4-1.8 µm (goal 0.35-2.4 µm) at a spectral resolution of 100,000. The
fibre-feeding allows HIRES to have several, interchangeable observing
modes including a SCAO module and a small diffraction-limited IFU
in the NIR. Therefore, it will be able to operate both in seeing-
and diffraction-limited modes. Its modularity will ensure that HIRES
can be placed entirely on the Nasmyth platform, if enough mass and
volume is available, or part on the Nasmyth and part in the Coud`e
room. ELT-HIRES has a wide range of science cases spanning nearly all
areas of research in astrophysics and even fundamental physics. Among
the top science cases there are the detection of biosignatures from
exoplanet atmospheres, finding the fingerprints of the first generation
of stars (PopIII), tests on the stability of Nature's fundamental
couplings, and the direct detection of the cosmic acceleration. The
HIRES consortium is composed of more than 30 institutes from 14
countries, forming a team of more than 200 scientists and engineers.
---------------------------------------------------------
Title: Broadband transmission spectroscopy of HD 209458b with
ESPRESSO: evidence for Na, TiO, or both
Authors: Santos, N. C.; Cristo, E.; Demangeon, O.; Oshagh, M.; Allart,
R.; Barros, S. C. C.; Borsa, F.; Bourrier, V.; Casasayas-Barris, N.;
Ehrenreich, D.; Faria, J. P.; Figueira, P.; Martins, J. H. C.; Micela,
G.; Pallé, E.; Sozzetti, A.; Tabernero, H. M.; Zapatero Osorio, M. R.;
Pepe, F.; Cristiani, S.; Rebolo, R.; Adibekyan, V.; Allende Prieto,
C.; Alibert, Y.; Bouchy, F.; Cabral, A.; Dekker, H.; Di Marcantonio,
P.; D'Odorico, V.; Dumusque, X.; González Hernández, J. I.; Lavie,
B.; Lo Curto, G.; Lovis, C.; Manescau, A.; Martins, C. J. A. P.;
Mégevand, D.; Mehner, A.; Molaro, P.; Nunes, N. J.; Poretti, E.;
Riva, M.; Sousa, S. G.; Suárez Mascareño, A.; Udry, S.
2020A&A...644A..51S Altcode: 2020arXiv201103746S
Context. The detection and characterization of exoplanet atmospheres
is currently one of the main drivers pushing the development of new
observing facilities. In this context, high-resolution spectrographs are
proving their potential and showing that high-resolution spectroscopy
will be paramount in this field. <BR /> Aims: We aim to make use
of ESPRESSO high-resolution spectra, which cover two transits of HD
209458b, to probe the broadband transmission optical spectrum of the
planet. <BR /> Methods: We applied the chromatic Rossiter-McLaughin
method to derive the transmission spectrum of HD 209458b. We compared
the results with previous HST observations and with synthetic
spectra. <BR /> Results: We recover a transmission spectrum of HD
209458b similar to the one obtained with HST data. The models suggest
that the observed signal can be explained by only Na, only TiO, or both
Na and TiO, even though none is fully capable of explaining our observed
transmission spectrum. Extra absorbers may be needed to explain the
full dataset, though modeling approximations and observational errors
can also be responsible for the observed mismatch. <BR /> Conclusions:
Using the chromatic Rossiter-McLaughlin technique, ESPRESSO is able to
provide broadband transmission spectra of exoplanets from the ground,
in conjunction with space-based facilities, opening good perspectives
for similar studies of other planets. <P />Based on Guaranteed Time
Observations collected at the European Southern Observatory under ESO
programme 1102.C-0744 by the ESPRESSO Consortium.
---------------------------------------------------------
Title: Chemical composition of the solar surface
Authors: Allende Prieto, Carlos
2020JApA...41...41A Altcode: 2021arXiv210610750A
The Sun provides a standard reference against which we compare the
chemical abundances found anywhere else in the Universe. Nevertheless,
there is not a unique `solar' composition, since the chemical abundances
found in the solar interior, the photosphere, the upper atmosphere, or
the solar wind, are not exactly the same. The composition of the solar
photosphere, usually preferred as a reference, changes with time due
to diffusion, convection, and probably accretion. In addition, we do
not know the solar photospheric abundances, inferred from the analysis
of the solar spectrum using model atmospheres, with high accuracy,
and uncertainties for many elements exceed 25%. This article gives an
overview of the methods and pitfalls of spectroscopic analysis, and
discusses the chemistry of the Sun in the context of the solar system.
---------------------------------------------------------
Title: WASP-127b: a misaligned planet with a partly cloudy atmosphere
and tenuous sodium signature seen by ESPRESSO
Authors: Allart, R.; Pino, L.; Lovis, C.; Sousa, S. G.;
Casasayas-Barris, N.; Zapatero Osorio, M. R.; Cretignier, M.; Palle,
E.; Pepe, F.; Cristiani, S.; Rebolo, R.; Santos, N. C.; Borsa, F.;
Bourrier, V.; Demangeon, O. D. S.; Ehrenreich, D.; Lavie, B.; Lendl,
M.; Lillo-Box, J.; Micela, G.; Oshagh, M.; Sozzetti, A.; Tabernero, H.;
Adibekyan, V.; Allende Prieto, C.; Alibert, Y.; Amate, M.; Benz, W.;
Bouchy, F.; Cabral, A.; Dekker, H.; D'Odorico, V.; Di Marcantonio, P.;
Dumusque, X.; Figueira, P.; Genova Santos, R.; González Hernández,
J. I.; Lo Curto, G.; Manescau, A.; Martins, C. J. A. P.; Mégevand,
D.; Mehner, A.; Molaro, P.; Nunes, N. J.; Poretti, E.; Riva, M.;
Suárez Mascareño, A.; Udry, S.; Zerbi, F.
2020A&A...644A.155A Altcode: 2020arXiv201015143A
Context. The study of exoplanet atmospheres is essential for
understanding the formation, evolution, and composition of
exoplanets. The transmission spectroscopy technique is playing a
significant role in this domain. In particular, the combination
of state-of-the-art spectrographs at low- and high-spectral
resolution is key to our understanding of atmospheric structure and
composition. <BR /> Aims: We observed two transits of the close-in
sub-Saturn-mass planet, WASP-127b, with ESPRESSO in the frame of
the Guaranteed Time Observations Consortium. We aim to use these
transit observations to study the system architecture and the
exoplanet atmosphere simultaneously. <BR /> Methods: We used the
Reloaded Rossiter-McLaughlin technique to measure the projected
obliquity λ and the projected rotational velocity v<SUB>eq</SUB>
ṡsin(i<SUB>*</SUB>). We extracted the high-resolution transmission
spectrum of the planet to study atomic lines. We also proposed a
new cross-correlation framework to search for molecular species and
we applied it to water vapor. <BR /> Results: The planet is orbiting
its slowly rotating host star (v<SUB>eq</SUB> ṡsin(i<SUB>*</SUB>) =
0.53<SUB>-0.05</SUB><SUP>+0.07</SUP> km s<SUP>-1</SUP>) on a retrograde
misaligned orbit (λ = -128.41<SUB>-5.46</SUB><SUP>+5.60</SUP> °). We
detected the sodium line core at the 9-σ confidence level with an
excess absorption of 0.34 ± 0.04%, a blueshift of 2.74 ± 0.79 km
s<SUP>-1</SUP>, and a full width at half maximum of 15.18 ± 1.75 km
s<SUP>-1</SUP>. However, we did not detect the presence of other atomic
species but set upper limits of only a few scale heights. Finally,
we put a 3-σ upper limit on the average depth of the 1600 strongest
water lines at equilibrium temperature in the visible band of 38
ppm. This constrains the cloud-deck pressure between 0.3 and 0.5 mbar
by combining our data with low-resolution data in the near-infrared
and models computed for this planet. <BR /> Conclusions: WASP-127b,
with an age of about 10 Gyr, is an unexpected exoplanet by its orbital
architecture but also by the small extension of its sodium atmosphere
(~7 scale heights). ESPRESSO allows us to take a step forward in the
detection of weak signals, thus bringing strong constraints on the
presence of clouds in exoplanet atmospheres. The framework proposed
in this work can be applied to search for molecular species and
study cloud-decks in other exoplanets. <P />Based on Guaranteed Time
Observations collected at the European Southern Observatory under ESO
programme 1102.C-0744 by the ESPRESSO Consortium.
---------------------------------------------------------
Title: Conceptual design of a high-resolution ultra-stable
spectrograph for GTC
Authors: Zhang, Kai; Shi, Jianrong; Zhu, Yongtian; Wang, Liang; Xiao,
Dong; Ye, Huiqi; Wang, Lei; Wu, Zhen; Liu, Chenchao; Hao, Zhibo;
Zhang, Huatao; Xin, Qiqige; Han, Jian; Tang, Zhen; Liu, Yujuan; Yan,
Hongliang; Li, Haining; Corradi, Romano L. M.; Allende Prieto, Carlos;
López, Javier Castro; González Hernández, Jonay I.
2020SPIE11447E..5IZ Altcode:
"A joint project has been proposed by the Chinese and Spanish astronomy
communities, to develop a high-resolution, ultra- stable spectrograph
for the Gran Telescopio Canarias (GTC) at La Palma. Being expected
to conduct precise radial velocity (PRV) measurement with extreme
precision of up to 10 cm s<SUP>-1</SUP>, the instrument would promote
the very high, present interest in the astronomical community to detect
and characterize exoplanets. The project successfully passed the
conceptual design review (CoDR) in 2019. The instrument is composed
of a near-UV band spectrograph (UVS) and a visible band spectrograph
(VIS). They provide a spectral resolving power of R ≥100,000 in the
visible band (420 nm - 780 nm), and R≥25,000 in the UV band (310
nm - 420 nm). The VIS subsystem will be enclosed in an ultra-stable
environment in the Coudé room for the stellar precise radial velocity
(PRV) measurements. T he UVS subsystem will be located near the Nasmyth
focus to improve the total throughput at the wavelength shorter than
400 nm, to ensure various additional science cases ranging from stellar
evolution to the measurement of fundamental constants. This paper gives
an overview of the project background, science cases, and technical
considerations during the conceptual design phase."
---------------------------------------------------------
Title: HORuS transmission spectroscopy of 55 Cnc e
Authors: Tabernero, H. M.; Allende Prieto, C.; Zapatero Osorio, M. R.;
González Hernández, J. I.; del Burgo, C.; García López, R.; Rebolo,
R.; Abril-Abril, M.; Barreto, R.; Calvo Tovar, J.; Díaz Torres, A.;
Fernández Izquierdo, P.; Gómez-Reñasco, M. F.; Gracia-Témich,
F.; Joven, E.; Peñate Castro, J.; Santana-Tschudi, S.; Tenegi, F.;
Viera Martín, H. D.
2020MNRAS.498.4222T Altcode: 2020MNRAS.tmp.2516T; 2020arXiv200910122T
The High Optical Resolution Spectrograph (HORuS) is a new
high-resolution echelle spectrograph available on the 10.4-m Gran
Telescopio Canarias (GTC). We report on the first HORuS observations
of a transit of the super-Earth planet 55 Cnc e. We investigate the
presence of Na I and Hα in its transmission spectrum and explore the
capabilities of HORuS for planetary transmission spectroscopy. Our
methodology leads to residuals in the difference spectrum between the
in-transit and out-of-transit spectra for the Na I doublet lines of (3.4
± 0.4) × 10<SUP>-4</SUP>, which sets an upper limit to the detection
of line absorption from the planetary atmosphere that is one order of
magnitude more stringent that those reported in the literature. We
demonstrate that we are able to reach the photon-noise limit in the
residual spectra using HORuS to a degree that we would be able to
easily detect giant planets with larger atmospheres. In addition,
we modelled the structure, chemistry, and transmission spectrum of 55
Cnc e using state-of-the-art open source tools.
---------------------------------------------------------
Title: VizieR Online Data Catalog: K2-111, an old system with two
planets (Mortier+, 2020)
Authors: Mortier, A.; Zapatero Osorio, M. R.; Malavolta, L.; Alibert,
Y.; Rice, K.; Lillo-Box, J.; Vanderburg, A.; Oshagh, M.; Buchhave,
L.; Adibekyan, V.; Delgado Mena, E.; Lopez-Morales, M.; Charbonneau,
D.; Sousa, S. G.; Lovis, C.; Affer, L.; Allende Prieto, C.; Barros,
S. C. C.; Benatti, S.; Bonomo, A. S.; Boschin, W.; Bouchy, F.; Cabral,
A.; Collier, Cameron A.; Cosentino, R.; Cristiani, S.; Demangeon,
O. D. S.; di Marcantonio, P.; D'Odorico, V.; Dumusque, X.; Ehrenreich,
D.; Figueira, P.; Fiorenzano, A.; Ghedina, A.; Gonzalez Hernandez,
J. I.; Haldemann, J.; Harutyunyan, A.; Haywood, R. D.; Latham,
D. W.; Lavie, B.; Lo Curto, G.; Maldonado, J.; Manescau, A.; Martins,
C. J. A. P.; Mayor, M.; Megevand, D.; Mehner, A.; Micela, G.; Molaro,
P.; Molinari, E.; Nunes, N. J.; Pepe, F. A.; Palle, E.; Phillips, D.;
Piotto, G.; Pinamonti, M.; Poretti, E.; Riva, M.; Rebolo, R.; Santos,
N. C.; Sasselov, D.; Sozzetti, A.; Suarez Mascareno, A.; Udry, S.;
West, R. G.; Watson, C. A.; Wilson, T. G.
2020yCat..74995004M Altcode:
tablerv.dat contains the radial velocities and activity indicators
from K2-111 obtained by HARPS-N and ESPRESSO. <P />tablep1.dat
contains the photometry for K2-111 from K-2, used for the transit
fit. <P />tablep2.dat contains the photometry for K2-111 from WASP,
and ASAS-SN, used to assess stellar variability. <P />(3 data files).
---------------------------------------------------------
Title: A precise architecture characterization of the π Mensae
planetary system
Authors: Damasso, M.; Sozzetti, A.; Lovis, C.; Barros, S. C. C.; Sousa,
S. G.; Demangeon, O. D. S.; Faria, J. P.; Lillo-Box, J.; Cristiani,
S.; Pepe, F.; Rebolo, R.; Santos, N. C.; Zapatero Osorio, M. R.;
González Hernández, J. I.; Amate, M.; Pasquini, L.; Zerbi, F. M.;
Adibekyan, V.; Abreu, M.; Affolter, M.; Alibert, Y.; Aliverti, M.;
Allart, R.; Allende Prieto, C.; Álvarez, D.; Alves, D.; Avila, G.;
Baldini, V.; Bandy, T.; Benz, W.; Bianco, A.; Borsa, F.; Bossini,
D.; Bourrier, V.; Bouchy, F.; Broeg, C.; Cabral, A.; Calderone,
G.; Cirami, R.; Coelho, J.; Conconi, P.; Coretti, I.; Cumani, C.;
Cupani, G.; D'Odorico, V.; Deiries, S.; Dekker, H.; Delabre, B.; Di
Marcantonio, P.; Dumusque, X.; Ehrenreich, D.; Figueira, P.; Fragoso,
A.; Genolet, L.; Genoni, M.; Génova Santos, R.; Hughes, I.; Iwert,
O.; Kerber, F.; Knudstrup, J.; Landoni, M.; Lavie, B.; Lizon, J. -L.;
Lo Curto, G.; Maire, C.; Martins, C. J. A. P.; Mégevand, D.; Mehner,
A.; Micela, G.; Modigliani, A.; Molaro, P.; Monteiro, M. A.; Monteiro,
M. J. P. F. G.; Moschetti, M.; Mueller, E.; Murphy, M. T.; Nunes,
N.; Oggioni, L.; Oliveira, A.; Oshagh, M.; Pallé, E.; Pariani, G.;
Poretti, E.; Rasilla, J. L.; Rebordão, J.; Redaelli, E. M.; Riva, M.;
Santana Tschudi, S.; Santin, P.; Santos, P.; Ségransan, D.; Schmidt,
T. M.; Segovia, A.; Sosnowska, D.; Spanò, P.; Suárez Mascareño,
A.; Tabernero, H.; Tenegi, F.; Udry, S.; Zanutta, A.
2020A&A...642A..31D Altcode: 2020arXiv200706410D
Context. The bright star π Men was chosen as the first target for a
radial velocity follow-up to test the performance of ESPRESSO, the new
high-resolution spectrograph at the European Southern Observatory's Very
Large Telescope. The star hosts a multi-planet system (a transiting
4 M<SUB>⊕</SUB> planet at ~0.07 au and a sub-stellar companion on
a ~2100-day eccentric orbit), which is particularly suitable for a
precise multi-technique characterization. <BR /> Aims: With the new
ESPRESSO observations, which cover a time span of 200 days, we aim
to improve the precision and accuracy of the planet parameters and
search for additional low-mass companions. We also take advantage of
the new photometric transits of π Men c observed by TESS over a time
span that overlaps with that of the ESPRESSO follow-up campaign. <BR
/> Methods: We analysed the enlarged spectroscopic and photometric
datasets and compared the results to those in the literature. We
further characterized the system by means of absolute astrometry with
HIPPARCOS and Gaia. We used the high-resolution spectra of ESPRESSO for
an independent determination of the stellar fundamental parameters. <BR
/> Results: We present a precise characterization of the planetary
system around π Men. The ESPRESSO radial velocities alone (37 nightly
binned data with typical uncertainty of 10 cm s<SUP>-1</SUP>) allow
for a precise retrieval of the Doppler signal induced by π Men c. The
residuals show a root mean square of 1.2 m s<SUP>-1</SUP>, which is half
that of the HARPS data; based on the residuals, we put limits on the
presence of additional low-mass planets (e.g. we can exclude companions
with a minimum mass less than ~2 M<SUB>⊕</SUB> within the orbit of
π Men c). We improve the ephemeris of π Men c using 18 additional
TESS transits, and, in combination with the astrometric measurements,
we determine the inclination of the orbital plane of π Men b with high
precision (i<SUB>b</SUB> =45.8<SUB>-1.1</SUB><SUP>+1.4</SUP> deg). This
leads to the precise measurement of its absolute mass m<SUB>b</SUB>
=14.1<SUB>-0.4</SUB><SUP>+0.5</SUP> M<SUB>Jup</SUB>, indicating that π
Men b can be classified as a brown dwarf. <BR /> Conclusions: The π
Men system represents a nice example of the extreme precision radial
velocities that can be obtained with ESPRESSO for bright targets. Our
determination of the 3D architecture of the π Men planetary system
and the high relative misalignment of the planetary orbital planes put
constraints on and challenge the theories of the formation and dynamical
evolution of planetary systems. The accurate measurement of the mass of
π Men b contributes to make the brown dwarf desert a bit greener. <P
/>Tables B.1 and B.2 are only available at the CDS via anonymous ftp to
<A href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/642/A31">http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/642/A31</A>
<P />Based (in part) on Guaranteed Time Observations collected at the
European Southern Observatory (ESO) under ESO programme(s) 1102.C-0744,
1102.C-0958, and 1104.C-0350 by the ESPRESSO Consortium.
---------------------------------------------------------
Title: Benchmark stars, benchmark spectrographs. Detailed
spectroscopic comparison of ESPRESSO, PEPSI, and HARPS data for Gaia
benchmark stars
Authors: Adibekyan, V.; Sousa, S. G.; Santos, N. C.; Figueira, P.;
Allende Prieto, C.; Delgado Mena, E.; González Hernández, J. I.;
de Laverny, P.; Recio-Blanco, A.; Campante, T. L.; Tsantaki, M.;
Hakobyan, A. A.; Oshagh, M.; Faria, J. P.; Bergemann, M.; Israelian,
G.; Boulet, T.
2020A&A...642A.182A Altcode: 2020arXiv200808371A
Context. Gaia benchmark stars are selected to be calibration stars for
different spectroscopic surveys. Very high-quality and homogeneous
spectroscopic data for these stars are therefore required. We
collected ultrahigh-resolution ESPRESSO spectra for 30 of the 34 Gaia
benchmark stars and made them public. <BR /> Aims: We quantify the
consistency of the results that are obtained with different high- (R ~
115 000), and ultrahigh- (R ~ 220 000) resolution spectrographs. We
also comprehensively studied the effect of using different spectral
reduction products of ESPRESSO on the final spectroscopic results. <BR
/> Methods: We used ultrahigh- and high-resolution spectra obtained
with the ESPRESSO, PEPSI, and HARPS spectrographs to measure spectral
line characteristics (line depth; line width; and equivalent width, EW)
and determined stellar parameters and abundances for a subset of 11 Gaia
benchmark stars. We used the ARES code for automatic measurements of
the spectral line parameters. <BR /> Results: Our measurements reveal
that the same individual spectral lines measured from adjacent 2D
(spectrum in the wavelength-order space) echelle orders of ESPRESSO
spectra differ slightly in line depth and line width. When a long list
of spectral lines is considered, the EW measurements based on the 2D and
1D (the final spectral product) ESPRESSO spectra agree very well. The
EW spectral line measurements based on the ESPRESSO, PEPSI, and HARPS
spectra also agree to within a few percent. However, we note that the
lines appear deeper in the ESPRESSO spectra than in PEPSI and HARPS. The
stellar parameters derived from each spectrograph by combining the
several available spectra agree well overall. <BR /> Conclusions: We
conclude that the ESPRESSO, PEPSI, and HARPS spectrographs can deliver
spectroscopic results that are sufficiently consistent for most of
the science cases in stellar spectroscopy. However, we found small but
important differences in the performance of the three spectrographs that
can be crucial for specific science cases. <P />Based on observations
collected at the Paranal Observatory, ESO (Chile) with the ESPRESSO
spectrograph at the VLT (ESO runs ID 0102.D-0185(A); 0103.D-0118(A);
0104.D-0362(A)).
---------------------------------------------------------
Title: Preliminary Target Selection for the DESI Milky Way Survey
(MWS)
Authors: Allende Prieto, Carlos; Cooper, Andrew P.; Dey, Arjun;
Gänsicke, Boris T.; Koposov, Sergey E.; Li, Ting; Manser, Christopher;
Nidever, David L.; Rockosi, Constance; Wang, Mei-Yu; Aguado, David
S.; Blum, Robert; Brooks, David; Eisenstein, Daniel J.; Duan, Yutong;
Eftekharzadeh, Sarah; Gaztañaga, Enrique; Kehoe, Robert; Landriau,
Martin; Lee, Chien-Hsiu; Levi, Michael E.; Meisner, Aaron M.; Myers,
Adam D.; Najita, Joan; Olsen, Knut; Palanque-Delabrouille, Nathalie;
Poppett, Claire; Prada, Francisco; Schlegel, David J.; Schubnell,
Michael; Tarlé, Gregory; Valluri, Monica; Wechsler, Risa H.; Yèche,
Christophe
2020RNAAS...4..188A Altcode: 2020arXiv201011284A
The DESI Milky Way Survey (MWS) will observe ≥8 million stars between
16 < r < 19 mag, supplemented by observations of brighter
targets under poor observing conditions. The survey will permit an
accurate determination of stellar kinematics and population gradients,
characterize diffuse substructure in the thick disk and stellar halo,
enable the discovery of extremely metal-poor stars and other rare
stellar types, and improve constraints on the Galaxy's 3D dark matter
distribution from halo star kinematics. MWS will also enable a detailed
characterization of the stellar populations within 100 pc of the Sun,
including a complete census of white dwarfs. The target catalog from
the preliminary selection described here is public (Available at
https://data.desi.lbl.gov/public/ets/target/catalogs/ and detailed
at https://desidatamodel.readthedocs.io).
---------------------------------------------------------
Title: APOGEE Data and Spectral Analysis from SDSS Data Release 16:
Seven Years of Observations Including First Results from APOGEE-South
Authors: Jönsson, Henrik; Holtzman, Jon A.; Allende Prieto,
Carlos; Cunha, Katia; García-Hernández, D. A.; Hasselquist, Sten;
Masseron, Thomas; Osorio, Yeisson; Shetrone, Matthew; Smith, Verne;
Stringfellow, Guy S.; Bizyaev, Dmitry; Edvardsson, Bengt; Majewski,
Steven R.; Mészáros, Szabolcs; Souto, Diogo; Zamora, Olga; Beaton,
Rachael L.; Bovy, Jo; Donor, John; Pinsonneault, Marc H.; Poovelil,
Vijith Jacob; Sobeck, Jennifer
2020AJ....160..120J Altcode: 2020arXiv200705537J
The spectral analysis and data products in Data Release 16 (DR16;
2019 December) from the high-resolution near-infrared Apache Point
Observatory Galactic Evolution Experiment (APOGEE)-2/Sloan Digital Sky
Survey (SDSS)-IV survey are described. Compared to the previous APOGEE
data release (DR14; 2017 July), APOGEE DR16 includes about 200,000
new stellar spectra, of which 100,000 are from a new southern APOGEE
instrument mounted on the 2.5 m du Pont telescope at Las Campanas
Observatory in Chile. DR16 includes all data taken up to 2018 August,
including data released in previous data releases. All of the data
have been re-reduced and re-analyzed using the latest pipelines,
resulting in a total of 473,307 spectra of 437,445 stars. Changes to
the analysis methods for this release include, but are not limited
to, the use of MARCS model atmospheres for calculation of the entire
main grid of synthetic spectra used in the analysis, a new method for
filling "holes" in the grids due to unconverged model atmospheres,
and a new scheme for continuum normalization. Abundances of the
neutron-capture element Ce are included for the first time. A new
scheme for estimating uncertainties of the derived quantities using
stars with multiple observations has been applied, and calibrated
values of surface gravities for dwarf stars are now supplied. Compared
to DR14, the radial velocities derived for this release more closely
match those in the Gaia DR2 database, and a clear improvement in
the spectral analysis of the coolest giants can be seen. The reduced
spectra as well as the result of the analysis can be downloaded using
links provided on the SDSS DR16 web page.
---------------------------------------------------------
Title: Characterization of the K2-38 planetary system. Unraveling
one of the densest planets known to date
Authors: Toledo-Padrón, B.; Lovis, C.; Suárez Mascareño, A.;
Barros, S. C. C.; González Hernández, J. I.; Sozzetti, A.; Bouchy,
F.; Zapatero Osorio, M. R.; Rebolo, R.; Cristiani, S.; Pepe, F. A.;
Santos, N. C.; Sousa, S. G.; Tabernero, H. M.; Lillo-Box, J.; Bossini,
D.; Adibekyan, V.; Allart, R.; Damasso, M.; D'Odorico, V.; Figueira,
P.; Lavie, B.; Lo Curto, G.; Mehner, A.; Micela, G.; Modigliani,
A.; Nunes, N. J.; Pallé, E.; Abreu, M.; Affolter, M.; Alibert, Y.;
Aliverti, M.; Allende Prieto, C.; Alves, D.; Amate, M.; Avila, G.;
Baldini, V.; Bandy, T.; Benatti, S.; Benz, W.; Bianco, A.; Broeg,
C.; Cabral, A.; Calderone, G.; Cirami, R.; Coelho, J.; Conconi,
P.; Coretti, I.; Cumani, C.; Cupani, G.; Deiries, S.; Dekker, H.;
Delabre, B.; Demangeon, O.; Di Marcantonio, P.; Ehrenreich, D.;
Fragoso, A.; Genolet, L.; Genoni, M.; Génova Santos, R.; Hughes,
I.; Iwert, O.; Knudstrup, J.; Landoni, M.; Lizon, J. L.; Maire,
C.; Manescau, A.; Martins, C. J. A. P.; Mégevand, D.; Molaro, P.;
Monteiro, M. J. P. F. G.; Monteiro, M. A.; Moschetti, M.; Mueller,
E.; Oggioni, L.; Oliveira, A.; Oshagh, M.; Pariani, G.; Pasquini, L.;
Poretti, E.; Rasilla, J. L.; Redaelli, E.; Riva, M.; Santana Tschudi,
S.; Santin, P.; Santos, P.; Segovia, A.; Sosnowska, D.; Spanò, P.;
Tenegi, F.; Udry, S.; Zanutta, A.; Zerbi, F.
2020A&A...641A..92T Altcode: 2020arXiv200701081T
Context. An accurate characterization of the known exoplanet population
is key to understanding the origin and evolution of planetary
systems. Determining true planetary masses through the radial velocity
(RV) method is expected to experience a great improvement thanks to
the availability of ultra-stable echelle spectrographs. <BR /> Aims: We
took advantage of the extreme precision of the new-generation echelle
spectrograph ESPRESSO to characterize the transiting planetary system
orbiting the G2V star K2-38 located at 194 pc from the Sun with V ~
11.4. This system is particularly interesting because it could contain
the densest planet detected to date. <BR /> Methods: We carried out
a photometric analysis of the available K2 photometric light curve of
this star to measure the radius of its two known planets, K2-38b and
K2-38c, with P<SUB>b</SUB> = 4.01593 ± 0.00050 d and P<SUB>c</SUB> =
10.56103 ± 0.00090 d, respectively. Using 43 ESPRESSO high-precision
RV measurements taken over the course of 8 months along with the 14
previously published HIRES RV measurements, we modeled the orbits
of the two planets through a Markov chain Monte Carlo analysis,
significantly improving their mass measurements. <BR /> Results: Using
ESPRESSO spectra, we derived the stellar parameters, T<SUB>eff</SUB>
= 5731 ± 66, log g = 4.38 ± 0.11 dex, and [Fe/H] = 0.26 ±
0.05 dex, and thus the mass and radius of K2-38, M<SUB>⋆</SUB> =
1.03<SUB>-0.02</SUB><SUP>+0.04</SUP> M<SUB>⊕</SUB> and R<SUB>⋆</SUB>
= 1.06<SUB>-0.06</SUB><SUP>+0.09</SUP> R<SUB>⊕</SUB>. We
determine new values for the planetary properties of both planets. We
characterize K2-38b as a super-Earth with R<SUB>P</SUB> = 1.54 ± 0.14
R<SUB>⊕</SUB> and M<SUB>p</SUB> = 7.3<SUB>-1.0</SUB><SUP>+1.1</SUP>
M<SUB>⊕</SUB>, and K2-38c as a sub-Neptune with
R<SUB>P</SUB> = 2.29 ± 0.26 R<SUB>⊕</SUB> and M<SUB>p</SUB> =
8.3<SUB>-1.3</SUB><SUP>+1.3</SUP> M<SUB>⊕</SUB>. Combining the radius
and mass measurements, we derived a mean density of ρ<SUB>p</SUB> =
11.0<SUB>-2.8</SUB><SUP>+4.1</SUP> g cm<SUP>-3</SUP> for K2-38b and
ρ<SUB>p</SUB> = 3.8<SUB>-1.1</SUB><SUP>+1.8</SUP> g cm<SUP>-3</SUP>
for K2-38c, confirming K2-38b as one of the densest planets known to
date. <BR /> Conclusions: The best description for the composition
of K2-38b comes from an iron-rich Mercury-like model, while K2-38c
is better described by a rocky-model with H2 envelope. The maximum
collision stripping boundary shows how giant impacts could be the cause
for the high density of K2-38b. The irradiation received by each planet
places them on opposite sides of the radius valley. We find evidence of
a long-period signal in the RV time-series whose origin could be linked
to a 0.25-3 M<SUB>J</SUB> planet or stellar activity. <P />The ESPRESSO
RVs used in this paper are only available at the CDS via anonymous ftp
to <A href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/641/A92">http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/641/A92</A>
<P />Based (in part) on Guaranteed Time Observations collected at
the European Southern Observatory under ESO programmes1102.C-0744,
112.C-0958, and 1104.C-0350 by the ESPRESSO Consortium.
---------------------------------------------------------
Title: Geometry of the Draco C1 Symbiotic Binary
Authors: Lewis, Hannah M.; Anguiano, Borja; Stassun, Keivan G.;
Majewski, Steven R.; Arras, Phil; Sarazin, Craig L.; Li, Zhi-Yun;
De Lee, Nathan; Troup, Nicholas W.; Allende Prieto, Carlos; Badenes,
Carles; Cunha, Katia; García-Hernández, D. A.; Nidever, David L.;
Palicio, Pedro A.; Simon, Joshua D.; Smith, Verne V.
2020ApJ...900L..43L Altcode: 2020arXiv200805962L
Draco C1 is a known symbiotic binary star system composed of a
carbon red giant and a hot, compact companion—likely a white
dwarf—belonging to the Draco dwarf spheroidal galaxy. From
near-infrared spectroscopic observations taken by the Apache Point
Observatory Galactic Evolution Experiment (APOGEE-2), part of Sloan
Digital Sky Survey IV, we provide updated stellar parameters for the
cool, giant component, and constrain the temperature and mass of the
hot, compact companion. Prior measurements of the periodicity of the
system, based on only a few epochs of radial velocity data or relatively
short baseline photometric observations, were sufficient only to place
lower limits on the orbital period (P > 300 days). For the first
time, we report precise orbital parameters for the binary system: with
43 radial velocity measurements from APOGEE spanning an observational
baseline of more than 3 yr, we definitively derive the period of the
system to be ${1220.0}_{-3.5}^{+3.7}$ days. Based on the newly derived
orbital period and separation of the system, together with estimates
of the radius of the red giant star, we find that the hot companion
must be accreting matter from the dense wind of its evolved companion.
---------------------------------------------------------
Title: VizieR Online Data Catalog: Sagittarius stream stars with
APOGEE obs. (Hasselquist+, 2019)
Authors: Hasselquist, S.; Carlin, J. L.; Holtzman, J. A.; Shetrone,
M.; Hayes, C. R.; Cunha, K.; Smith, V.; Beaton, R. L.; Sobeck,
J.; Allende Prieto, C.; Majewski, S. R.; Anguiano, B.; Bizyaev,
D.; Garcia-Hernandez, D. A.; Lane, R. R.; Pan, K.; Nidever, D. L.;
Fernandez-Trincado, J. G.; Wilson, J. C.; Zamora, O.
2020yCat..18720058H Altcode:
The APOGEE instrument is a high-resolution (R~22500) near-infrared
(1.51-1.70um) spectrograph. For the main survey the instrument was
connected to the Sloan 2.5m telescope. <P />To identify Sgr stream
stars in the APOGEE DR14 sample (Abolfathi+ 2018ApJS..235...42A), we
use the Sgr core sample from Hasselquist+ (2017ApJ...845..162H). <P
/>(2 data files).
---------------------------------------------------------
Title: White Dwarfs in Close Binaries: A Systematic Search for
Mass-transfer Systems and Supernova Ia Progenitors in the APOGEE
Survey
Authors: Anguiano, Borja; Lewis, Hannah M.; Corcoran, Kyle A.;
Washington, Jasmin; Majewski, Steven R.; Allende Prieto, Carlos;
Mazzola, Christine N.; Badenes, Carles; Stassun, Keivan; Blondin, John
2020RNAAS...4..127A Altcode:
We have created a new and unique database, the APOGEE-Galaxy Evolution
Explorer (GALEX)-Gaia catalog, to study white dwarfs in close binaries,
and, in particular, to: (1) create a minimally biased sample of white
dwarf-main sequence (WDMS) systems derived from the combination of
GALEX, Gaia, and the dual hemisphere, multi-epoch, high-resolution,
infrared APOGEE-1 and -2 spectroscopic surveys, and (2) exploit this
catalog to vastly increase the number of well-characterized WDMS
systems having derived dynamical parameters (e.g., masses, separation,
orbital periods, etc.) as well as precision multi-element chemical
compositions by exploiting the high resolution, multi-epoch data from
APOGEE. This catalog will significantly further our understanding of
compact binary evolution.
---------------------------------------------------------
Title: Strong chemical tagging with APOGEE: 21 candidate star clusters
that have dissolved across the Milky Way disc
Authors: Price-Jones, Natalie; Bovy, Jo; Webb, Jeremy J.; Allende
Prieto, Carlos; Beaton, Rachael; Brownstein, Joel R.; Cohen, Roger E.;
Cunha, Katia; Donor, John; Frinchaboy, Peter M.; García-Hernández,
D. A.; Lane, Richard R.; Majewski, Steven R.; Nidever, David L.;
Roman-Lopes, Alexandre
2020MNRAS.496.5101P Altcode: 2020arXiv200404263B; 2020arXiv200404263P; 2020MNRAS.tmp.2052P
Chemically tagging groups of stars born in the same birth cluster is
a major goal of spectroscopic surveys. To investigate the feasibility
of such strong chemical tagging, we perform a blind chemical tagging
experiment on abundances measured from APOGEE survey spectra. We
apply a density-based clustering algorithm to the 8D chemical space
defined by [Mg/Fe], [Al/Fe], [Si/Fe], [K/Fe], [Ti/Fe], [Mn/Fe],
[Fe/H], and [Ni/Fe], abundances ratios which together span multiple
nucleosynthetic channels. In a high-quality sample of 182 538 giant
stars, we detect 21 candidate clusters with more than 15 members. Our
candidate clusters are more chemically homogeneous than a population
of non-member stars with similar [Mg/Fe] and [Fe/H], even in abundances
not used for tagging. Group members are consistent with having the same
age and fall along a single stellar-population track in log g versus
T<SUB>eff</SUB> space. Each group's members are distributed over
multiple kpc, and the spread in their radial and azimuthal actions
increases with age. We qualitatively reproduce this increase using
N-body simulations of cluster dissolution in Galactic potentials
that include transient winding spiral arms. Observing our candidate
birth clusters with high-resolution spectroscopy in other wavebands
to investigate their chemical homogeneity in other nucleosynthetic
groups will be essential to confirming the efficacy of strong chemical
tagging. Our initially spatially compact but now widely dispersed
candidate clusters will provide novel limits on chemical evolution
and orbital diffusion in the Galactic disc, and constraints on star
formation in loosely bound groups.
---------------------------------------------------------
Title: The Pristine Inner Galaxy Survey (PIGS) II: Uncovering the
most metal-poor populations in the inner Milky Way
Authors: Arentsen, Anke; Starkenburg, Else; Martin, Nicolas F.;
Aguado, David S.; Zucker, Daniel B.; Allende Prieto, Carlos; Hill,
Vanessa; Venn, Kim A.; Carlberg, Raymond G.; González Hernández,
Jonay I.; Mashonkina, Lyudmila I.; Navarro, Julio F.; Sánchez-Janssen,
Rubén; Schultheis, Mathias; Thomas, Guillaume F.; Youakim, Kris;
Lewis, Geraint F.; Simpson, Jeffrey D.; Wan, Zhen; Cohen, Roger E.;
Geisler, Doug; O'Connell, Julia E.
2020MNRAS.496.4964A Altcode: 2020arXiv200608641A
Metal-poor stars are important tools for tracing the early history
of the Milky Way, and for learning about the first generations of
stars. Simulations suggest that the oldest metal-poor stars are to
be found in the inner Galaxy. Typical bulge surveys, however, lack
low metallicity ( $\rm {[Fe/H]} \lt -1.0$ ) stars because the inner
Galaxy is predominantly metal-rich. The aim of the Pristine Inner
Galaxy Survey (PIGS) is to study the metal-poor and very metal-poor
(VMP, $\rm {[Fe/H]} \lt -2.0$ ) stars in this region. In PIGS,
metal-poor targets for spectroscopic follow-up are selected from
metallicity-sensitive CaHK photometry from the CFHT. This work
presents the ∼250 deg<SUP>2</SUP> photometric survey as well as
intermediate-resolution spectroscopic follow-up observations for
∼8000 stars using AAOmega on the AAT. The spectra are analysed using
two independent tools: ULySS with an empirical spectral library, and
FERRE with a library of synthetic spectra. The comparison between the
two methods enables a robust determination of the stellar parameters
and their uncertainties. We present a sample of 1300 VMP stars - the
largest sample of VMP stars in the inner Galaxy to date. Additionally,
our spectroscopic data set includes ∼1700 horizontal branch stars,
which are useful metal-poor standard candles. We furthermore show that
PIGS photometry selects VMP stars with unprecedented efficiency: 86
per cent/80 per cent (lower/higher extinction) of the best candidates
satisfy $\rm {[Fe/H]} \lt -2.0$ , as do 80 per cent/63 per cent of a
larger, less strictly selected sample. We discuss future applications
of this unique data set that will further our understanding of the
chemical and dynamical evolution of the innermost regions of our Galaxy.
---------------------------------------------------------
Title: Helium Enhancement in the Metal-rich Red Giants of ω Centauri
Authors: Hema, B. P.; Pandey, Gajendra; Kurucz, R. L.; Allende
Prieto, C.
2020ApJ...897...32H Altcode: 2020arXiv200506807H
The helium-enriched (He-enriched) metal-rich red giants of ω
Centauri, discovered by Hema & Pandey using the low-resolution
spectra from the Vainu Bappu Telescope, and confirmed by the analyses
of the high-resolution spectra obtained from the HRS-South African
Large Telescope for LEID 34225 and LEID 39048, are reanalyzed here
to determine their degree of He enhancement/hydrogen deficiency (H
deficiency). The observed MgH band combined with model atmospheres with
differing He/H ratios are used for the analyses. The He/H ratios of
these two giants are determined by enforcing the fact that the derived
Mg abundances from the Mg I lines and from the subordinate lines of the
MgH band must be same for the adopted model atmosphere. The estimated
He/H ratios for LEID 34225 and LEID 39048 are 0.15 ± 0.04 and 0.20 ±
0.04, respectively, whereas the normal He/H ratio is 0.10. Following the
same criteria for the analyses of the other two comparison stars (LEID
61067 and LEID 32169), a normal He/H ratio of 0.10 is obtained. The
He/H ratio of 0.15-0.20 corresponds to a mass fraction of helium
(Z(He) = Y) of about 0.375-0.445. The range of helium enhancement
and the derived metallicity of the program stars are in line with
those determined for ω Cen's blue main-sequence stars. Hence, our
study provides the missing link for the evolutionary track of the
metal-rich helium-enhanced population of ω Centuari. This research
work is the very first spectroscopic determination of the amount of
He enhancement in the metal-rich red giants of ω Centauri using the
Mg I and MgH lines.
---------------------------------------------------------
Title: VizieR Online Data Catalog: pi Men radial velocity curves
(Damasso+, 2020)
Authors: Damasso, M.; Sozzetti, A.; Lovis, C.; Barros, S. C. C.; Sousa,
S. G.; Demangeon, O. D. S.; Faria, J. P.; Lillo-Box, J.; Cristiani,
S.; Pepe, F.; Rebolo, R.; Santos, N. C.; Zapatero Osorio, M. R.;
Gonzalez Hernandez, J. I.; Amate, M.; Pasquini, L.; Zerbi, F. M.;
Adibekyan, V.; Abreu, M.; Aolter, M.; Alibert, Y.; Aliverti, M.;
Allart, R.; Allende Prieto, C.; Alvarez, D.; Alves, D.; Avila, G.;
Baldini, V.; Bandy, T.; Benz, W.; Bianco, A.; Borsa, F.; Bossini,
D.; Bourrier, V.; Bouchy, F.; Broeg, C.; Cabral, A.; Calderone,
G.; Cirami, R.; Coelho, J.; Conconi, P.; Coretti, I.; Cumani, C.;
Cupani, G.; D'Odorico, V.; Deiries, S.; Dekker, H.; Delabre, B.; di
Marcantonio, P.; Dumusque, X.; Ehrenreich, D.; Figueira, P.; Fragoso,
A.; Genolet, L.; Genoni, M.; Genova Santos, R.; Hughes, I.; Iwert,
O.; F. Kerber; Knudstrup, J.; Landoni, M.; Lavie, B.; Lizon, J. -L.;
Lo Curto, G.; Maire, C.; J. A. P. Martins, C.; Megevand, D.; Mehner,
A.; Micela, G.; Modigliani, A.; Molaro, P.; Monteiro, M. A.; Monteiro,
M. J. P. F. G.; Moschetti, M.; Mueller, E.; Murphy, M. T.; Nunes,
N.; Oggioni, L.; Olive, Ira A.; Oshagh, M.; Palle, E.; Pariani, G.;
Poretti, E.; Rasilla, J. L.; Rebordao, J.; Redaelli, E. M.; Riva, M.;
Santana Tschudi, S.; Santin, P.; Santos, P.; Segransan, D.; Schmidt,
T. M.; Segovia, A.; Sosnowska, D.; Spano, P.; Suarez Mascareno, A.;
Tabernero, H.; Tenegi, F.; Udry, S.; Zanutta, A.
2020yCat..36420031D Altcode:
The observations of pi Men with ESPRESSO (using the instrument in single
Unit Telescope mode with a median resolving power R=138000 over the
378.2 and 788.7nm wavelength range) were carried out within one of the
sub-programmes of the Guaranteed Time Observations (GTOs), aimed at
using the very precise RVs to characterize (i.e. measure masses and
bulk densities) transiting planets discovered by TESS and Kepler's
second light K2 mission (see Pepe et al. 2020 (A&A, submitted)
for a detailed discussion of the ESPRESSO on-sky performance). The
pi Men system was observed starting from September 2018, right
before the end of the commissioning phase of the instrument, up to
March 2019. We collected 275 spectra over 37 nights (multiple and
consecutive exposures per night) during a total time span of 201
days. The spectra were acquired with a typical exposure time of 120s,
providing a median signal-to-noise ratio S/N=243 per extracted pixel
at λ=500nm. In this work we also use previously unreleased spectra
from CORALIE to extract additional RVs. The pi Men system was observed
with CORALIE from November 1998 to February 2020, during which time 60
spectra with typical exposure times of 300-600s (S/N=82-124 at 550nm)
were collected. <P />Radial velocities extracted from ESPRESSO and
CORALIE spectra, and spectroscopic stellar activity diagnostics from
ESPRESSO. <P />(2 data files).
---------------------------------------------------------
Title: The extreme enhancement in CNO of the iron-poor dwarf star
J0815+4729
Authors: González Hernández, J. I.; Aguado, D. S.; Allende Prieto,
C.; Burgasser, A. J.; Rebolo, R.
2020sea..confE.142G Altcode:
Low-mass extremely metal-poor (EMP) stars formed from a mixture of
material of the primordial nucleosynthesis and matter ejected from the
first supernovae. The chemical composition of EMP stars, especially
those still on the main sequence, holds crucial information on the
properties of the first stars, the first supernovae and the early
chemical enrichment of the Universe. We discovered the iron-poor dwarf
star SDSS J0815+4729 (Aguado et al. 2018a, ApJ Letters) using the OSIRIS
spectrograph at the 10.4m-GTC telescope in La Palma (Canary Islands,
Spain), revealing already the huge C enhancement in this primitive
star with a million times less iron than the Sun. We have recently
acquired high-resolution spectroscopy with HIRES at the 10m-KeckI
telescope, uncovering the unique abundance pattern of J0815+4729
(González Hernández et al. 2020, ApJ Letters). We derive [Fe/H] =
-5.5 and detect the near-IR OI triplet for the first time in an ultra
metal-poor star, confirming the extreme CNO abundances of J0815+4729
with ratios [X/Fe] > 4.
---------------------------------------------------------
Title: Revisiting Proxima with ESPRESSO
Authors: Suárez Mascareño, A.; Faria, J. P.; Figueira, P.; Lovis,
C.; Damasso, M.; González Hernández, J. I.; Rebolo, R.; Cristiani,
S.; Pepe, F.; Santos, N. C.; Zapatero Osorio, M. R.; Adibekyan, V.;
Hojjatpanah, S.; Sozzetti, A.; Murgas, F.; Abreu, M.; Affolter, M.;
Alibert, Y.; Aliverti, M.; Allart, R.; Allende Prieto, C.; Alves,
D.; Amate, M.; Avila, G.; Baldini, V.; Bandi, T.; Barros, S. C. C.;
Bianco, A.; Benz, W.; Bouchy, F.; Broeng, C.; Cabral, A.; Calderone,
G.; Cirami, R.; Coelho, J.; Conconi, P.; Coretti, I.; Cumani, C.;
Cupani, G.; D'Odorico, V.; Deiries, S.; Delabre, B.; Di Marcantonio,
P.; Dumusque, X.; Ehrenreich, D.; Fragoso, A.; Genolet, L.; Genoni,
M.; Génova Santos, R.; Hughes, I.; Iwert, O.; Kerber, F.; Knusdstrup,
J.; Landoni, M.; Lavie, B.; Lillo-Box, J.; Lizon, J.; Lo Curto, G.;
Maire, C.; Manescau, A.; Martins, C. J. A. P.; Mégevand, D.; Mehner,
A.; Micela, G.; Modigliani, A.; Molaro, P.; Monteiro, M. A.; Monteiro,
M. J. P. F. G.; Moschetti, M.; Mueller, E.; Nunes, N. J.; Oggioni,
L.; Oliveira, A.; Pallé, E.; Pariani, G.; Pasquini, L.; Poretti, E.;
Rasilla, J. L.; Redaelli, E.; Riva, M.; Santana Tschudi, S.; Santin,
P.; Santos, P.; Segovia, A.; Sosnowska, D.; Sousa, S.; Spanò, P.;
Tenegi, F.; Udry, S.; Zanutta, A.; Zerbi, F.
2020A&A...639A..77S Altcode: 2020arXiv200512114S
Context. The discovery of Proxima b marked one of the most important
milestones in exoplanetary science in recent years. Yet the limited
precision of the available radial velocity data and the difficulty
in modelling the stellar activity calls for a confirmation of the
Earth-mass planet. <BR /> Aims: We aim to confirm the presence
of Proxima b using independent measurements obtained with the new
ESPRESSO spectrograph, and refine the planetary parameters taking
advantage of its improved precision. <BR /> Methods: We analysed 63
spectroscopic ESPRESSO observations of Proxima (Gl 551) taken during
2019. We obtained radial velocity measurements with a typical radial
velocity photon noise of 26 cm s<SUP>-1</SUP>. We combined these data
with archival spectroscopic observations and newly obtained photometric
measurements to model the stellar activity signals and disentangle
them from planetary signals in the radial velocity (RV) data. We ran a
joint Markov chain Monte Carlo analysis on the time series of the RV and
full width half maximum of the cross-correlation function to model the
planetary and stellar signals present in the data, applying Gaussian
process regression to deal with the stellar activity signals. <BR />
Results: We confirm the presence of Proxima b independently in the
ESPRESSO data and in the combined ESPRESSO+ HARPS+UVES dataset. The
ESPRESSO data on its own shows Proxima b at a period of 11.218 ±
0.029 days, with a minimum mass of 1.29 ± 0.13 M<SUB>⊕</SUB>. In
the combined dataset we measure a period of 11.18427 ± 0.00070 days
with a minimum mass of 1.173 ± 0.086 M<SUB>⊕</SUB>. We get a clear
measurement of the stellar rotation period (87 ± 12 d) and its induced
RV signal, but no evidence of stellar activity as a potential cause
for the 11.2 days signal. We find some evidence for the presence
of a second short-period signal, at 5.15 days with a semi-amplitude
of only 40 cm s<SUP>-1</SUP>. If caused by a planetary companion, it
would correspond to a minimum mass of 0.29 ± 0.08 M<SUB>⊕</SUB>. We
find that forthe case of Proxima, the full width half maximum of the
cross-correlation function can be used as a proxy for the brightness
changes and that its gradient with time can be used to successfully
detrend the RV data from part of the influence of stellar activity. The
activity-induced RV signal in the ESPRESSO data shows a trend in
amplitude towards redder wavelengths. Velocities measured using the
red end of the spectrograph are less affected by activity, suggesting
that the stellar activity is spot dominated. This could be used to
create differential RVs that are activity dominated and can be used to
disentangle activity-induced and planetary-induced signals. The data
collected excludes the presence of extra companions with masses above
0.6 M<SUB>⊕</SUB> at periods shorter than 50 days. <P />The data used
in this paper are only available at the CDS via anonymous ftp to <A
href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/639/A77">http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/639/A77</A>
<P />Based [in part] on Guaranteed Time Observations collected at the
European Southern Observatory under ESO programme 1102.C-0744. by the
ESPRESSO Consortium. <P />This work makes use of observations from
the LCOGT network.
---------------------------------------------------------
Title: The Stellar Velocity Distribution Function in the Milky
Way Galaxy
Authors: Anguiano, Borja; Majewski, Steven R.; Hayes, Christian R.;
Allende Prieto, Carlos; Cheng, Xinlun; Bidin, Christian Moni; Beaton,
Rachael L.; Beers, Timothy C.; Minniti, Dante
2020AJ....160...43A Altcode: 2020arXiv200514534A
The stellar velocity distribution function in the solar vicinity is
reexamined using data from the Sloan Digital Sky Survey Apache Point
Observatory Galactic Evolution Experiment (APOGEE) survey's DR16 and
Gaia DR2. By exploiting APOGEE's ability to chemically discriminate
with great reliability the thin-disk, thick-disk, and (accreted) halo
populations, we can, for the first time, derive the three-dimensional
velocity distribution functions (DFs) for these chemically separated
populations. We employ this smaller but more data-rich APOGEE+Gaia
sample to build a data-driven model of the local stellar population
velocity DFs and use these as basis vectors for assessing the
relative density proportions of these populations over the 5 <
R < 12 kpc and -1.5 < z < 2.5 kpc range as derived from
the larger, more complete (i.e., all-sky, magnitude-limited) Gaia
database. We find that 81.9% ± 3.1% of the objects in the selected
Gaia data set are thin-disk stars, 16.6% ± 3.2% are thick-disk
stars, and 1.5% ± 0.1% belong to the Milky Way stellar halo. We
also find the local thick-to-thin-disk density normalization to be
ρ<SUB>T</SUB>(R<SUB>⊙</SUB>)/ρ<SUB>t</SUB>(R<SUB>⊙</SUB>) =
2.1% ± 0.2%, a result consistent with, but determined in a completely
different way from, typical star-count/density analyses. Using the same
methodology, the local halo-to-disk-density normalization is found to
be ρ<SUB>H</SUB>(R<SUB>⊙</SUB>)/(ρ<SUB>T</SUB>(R<SUB>⊙</SUB>) +
ρ<SUB>t</SUB>(R<SUB>⊙</SUB>)) = 1.2% ± 0.6%, a value that may be
inflated due to the chemical overlap of halo and metal-weak thick-disk
stars.
---------------------------------------------------------
Title: HORuS higher resolution for GTC
Authors: Allende Prieto, C.
2020sea..confE.210A Altcode:
The High Optical Resolution Spectrograph (HORus) has been available
on the 10-m GTC telescope since early 2019. Based largely on optical
elements reused from UES, in operation on the 4-m WHT in the 90s, HORuS
provides a resolving power of 25,000 with nearly complete coverage
in the range 380-700 nm. This instrument gives a signal-to-noise
ratio at 550 nm of 75 for a V=15 solar-like star in 1 hour, and
its particularly well-suited for stellar spectroscopy and exoplanet
transits. This seminar will describe the status of the instrument,
offer tips to prepare observations and analyze them with its dedicated
data reduction package, and touch on future plans.
---------------------------------------------------------
Title: The Stellar Velocity Distribution Function in the Milky
Way Galaxy
Authors: Anguiano, B.; Majewski, S.; Hayes, C.; Allende Prieto, C.;
Cheng, X.; Moni Bidin, C.; Beers, T.; Miniti, D.; Apogee Team
2020sea..confE.116A Altcode:
Motivation of this contribution: The velocity distribution function
(DF) of stars in the Galaxy -uncovering the relationships between
kinematics, metallicity and age for disk and halo stars- dynamical
history of stellar populations. Unbiased study of the Galactic velocity
DFs -derived from Gaia data- for the individual, chemically-separated
stellar populations, and to explore how these distributions change
for different Galactocentric radii and distances from the Galactic
mid-plane. Built a kinematical data-driven model, that we then apply to
the full Gaia database to ascertain the contribution of the different
Galactic structural components to the velocity-space DF as a function
of Galactic cylindrical coordinates, R and z.
---------------------------------------------------------
Title: VizieR Online Data Catalog: K2-38 ESPRESSO RVs (Toledo-Padron+,
2020)
Authors: Toledo-Padron B. . Lovis, C.; Suarez Mascareno, A.; Barros,
S. C. C.; Gonzalez Hernandez, J. I.; Sozzetti, A.; Bouchy, F.; Zapatero
Osorio, M. R.; Rebolo, R.; Cristiani, S.; Pepe, F. A.; Santos, N. C.;
Sousa, S. G.; Tabernero, H. M.; Lillo-Box, J.; Bossini, D.; Adibekyan,
V.; Allart, R.; Damasso, M.; D'Odorico, V.; Figueira, P.; Lavie, B.;
Lo Curto, G.; Mehner, A.; Micela, G.; Modigliani, A.; Nunes, N. J.;
Palle, E.; Abreu, M.; Affolter, M.; Alibert, Y.; Aliverti, M.; Allende
Prieto, C.; Alves, D.; Amate, M.; Avila, G.; Baldini, V.; Bandy, T.;
Benatti, S.; Benz, W.; Bianco, A.; Broeg, C.; Cabral, A.; Calderone,
G.; Cirami, R.; Coelho, J.; Conconi, P.; Coretti, I.; Cumani, C.;
Cupani, G.; Deiries, S.; Dekker, H.; Delabre, B.; Demangeon, O.; di
Marcantonio, P.; Ehrenreich, D.; Fragoso, A.; Genolet, L.; Genoni, M.;
Genova Santos, R.; Hughes, I.; Iwert, O.; Knudstrup, J.; Landoni, M.;
Lizon, J. L.; Maire, C.; Manescau, A.; Martins, C. J. A. P.; Megevand,
D.; Molaro, P.; Monteiro, M. J. P. F. G.; Monteiro, M. A.; Moschetti,
M.; Mueller, E.; Oggioni, L.; Oliveira, A.; O'Shagh, M.; Pariani, G.;
Pasquini, L.; Poretti, E.; Rasilla, J. L.; Redaelli, E.; Riva, M.;
Santana Tschudi, S.; Santin, P.; Santos, P.; Segovia, A.; Sosnowska,
D.; Spano, P.; Tenegi, F.; Udry, S.; Zanutta, A.; Zerbi, F.
2020yCat..36410092T Altcode:
We used the public version of the ESPRESSO pipeline
Data-Reduction-Software (DRS) to compute the RVs of K2-38. The pipeline
provides a crosscorrelation function (CCF) for each spectrum using a G2
mask that covers the entire wavelength range of the instrument (between
3800 and 7880Å). The CCFs were built using a RV step of 0.5km/s within
a range between -55 and -15km/s centered on the systemic velocity of
the star. This RV time-series presents a RV precision of 1.0m/s with a
RMS of 3.6m/s, an extremely good result for a relatively faint G2 star
(V=11.34) like K2-38. <P />(1 data file).
---------------------------------------------------------
Title: VizieR Online Data Catalog: Metallicities of Pristine stars
(Youakim+, 2017)
Authors: Youakim, K.; Starkenburg, E.; Aguado, D. S.; Martin,
N. F.; Fouesneau, M.; Gonzalez Hernandez, J. I.; Allende Prieto,
C.; Bonifacio, P.; Gentile, M.; Kielty, C.; Cote, P.; Jablonka, P.;
McConnachie, A.; Sanchez Janssen, R.; Tolstoy, E.; Venn, K.
2020yCat..74722963Y Altcode:
In conjunction with the photometric component of Pristine, a
spectroscopic follow-up programme has been observing the most promising,
bright (V<18) metal-poor candidates on 2-4m class telescopes with
medium- and high-resolution spectrographs. In this paper, we focus
on the homogeneous follow-up sample of 205 candidate stars observed
with the Intermediate Dispersion Spectrograph (IDS) on the 2.5m
Isaac Newton Telescope (INT) over the period of 2016 March 18-27,
May 15-23, July 20-24 and September 2-6, and with the Intermediate
dispersion Spectrograph and Imaging System (ISIS) on the 4.2m William
Herschel Telescope (WHT) over the period of 2016 May 1-2 and July 29-31
(Programs C71 and N5). Both telescopes are located at the Roque de Los
Muchachos Observatory in La Palma, Canary Islands. <P />(2 data files).
---------------------------------------------------------
Title: White Dwarfs in Close Binaries: A Systematic Search for Mass
Transfer Systems and Supernova Ia Progenitors
Authors: Anguiano, B.; Lewis, H.; Washington, J.; Corcoran, K.;
Majewski, S.; Allende-Prieto, C.; Badenes, C.; Stassun, K.; Blondin,
J.; Apogee Team
2020AAS...23610802A Altcode:
White dwarfs are the evolutionary end point of the vast majority of
stars (97 per cent),where a large fraction of systems, around 25 per
cent, are close enough to a binary companion that mass is transferred
from one star to the other, changing the structures of both stars
and their subsequent evolution. We present the APOGEE-GALEX-Gaia
catalog of white dwarfs in close binaries, a database that vastly
increases the number of white dwarf-main sequence systems that also
have characterization of key parameters (e.g., masses, separation,
derived orbital periods, etc.) coming from high resolution (APOGEE)
spectroscopy. Exploration of this catalog with additional follow-up
observations will improve our census of the range of white dwarf-main
sequence binary architectures, providing robust statistics for
furthering our understanding of compact binary evolution.
---------------------------------------------------------
Title: VizieR Online Data Catalog: 4 low-mass white-dwarf candidates
velocities (Kilic+, 2017)
Authors: Kilic, M.; Brown, W. R.; Gianninas, A.; Curd, B.; Bell,
K. J.; Allende Prieto, C.
2020yCat..74714218K Altcode:
We obtained follow-up optical spectroscopy of 34 (10) targets using the
8-m Gemini North (South) telescope equipped with the Gemini Multi-Object
Spectrograph (GMOS) as part of the programmes GN-2016A-Q-54,
GN-2016B-Q-45, GS-2015A-Q-10, GS-2016A-Q-58 and GS-2016B-Q-48. <P
/>Based on the initial velocity measurements from GMOS, we obtained
additional follow-up data for six targets (J1113+2712, J1237+4913,
J1323+3254, J1407+1241, J1633+3030 and J1716+2838) using the same
set-up as on Gemini North as part of the Fast Turnaround programme
GN-2016A-FT-34. <P />We used the 6.5-m MMT with the Blue Channel
spectrograph to obtain follow-up data on five targets (J0834+3049,
J1032+2147, J1235+1543, J1237+4913 and J2342+0811) between 2016 January
and 2017 March. <P />We also used the Kitt Peak National Observatory 4-m
telescope + KOSMOS in 2016 December and the Apache Point Observatory
3.5-m telescope with the Dual Imaging Spectrograph (DIS) in 2017
March to obtain additional follow-up spectroscopy of J1237+4913. <P
/>We obtained follow-up time-series photometry of one of our targets,
J1235+1543, using the McDonald Observatory 2.1-m Otto Struve telescope
with the ProEM camera and the BG40 filter. <P />(6 data files).
---------------------------------------------------------
Title: The Lazy Giants: APOGEE Abundances Reveal Low Star Formation
Efficiencies in the Magellanic Clouds
Authors: Nidever, David L.; Hasselquist, Sten; Hayes, Christian R.;
Hawkins, Keith; Povick, Joshua; Majewski, Steven R.; Smith, Verne V.;
Anguiano, Borja; Stringfellow, Guy S.; Sobeck, Jennifer S.; Cunha,
Katia; Beers, Timothy C.; Bestenlehner, Joachim M.; Cohen, Roger E.;
Garcia-Hernandez, D. A.; Jönsson, Henrik; Nitschelm, Christian;
Shetrone, Matthew; Lacerna, Ivan; Allende Prieto, Carlos; Beaton,
Rachael L.; Dell'Agli, Flavia; Fernández-Trincado, José G.; Feuillet,
Diane; Gallart, Carme; Hearty, Fred R.; Holtzman, Jon; Manchado,
Arturo; Muñoz, Ricardo R.; O'Connell, Robert; Rosado, Margarita
2020ApJ...895...88N Altcode: 2019arXiv190103448N
We report the first APOGEE metallicities and α-element abundances
measured for 3600 red giant stars spanning a large radial range of both
the Large (LMC) and Small Magellanic Clouds, the largest Milky Way (MW)
dwarf galaxies. Our sample is an order of magnitude larger than that
of previous studies and extends to much larger radial distances. These
are the first results presented that make use of the newly installed
southern APOGEE instrument on the du Pont telescope at Las Campanas
Observatory. Our unbiased sample of the LMC spans a large range
in metallicity, from [Fe/H] = -0.2 to very metal-poor stars with
[Fe/H] ≍ -2.5, the most metal-poor Magellanic Cloud (MC) stars
detected to date. The LMC [α/Fe]-[Fe/H] distribution is very flat
over a large metallicity range but rises by ∼0.1 dex at -1.0 <
[Fe/H] ≲ -0.5. We interpret this as a sign of the known recent
increase in MC star formation activity and are able to reproduce
the pattern with a chemical evolution model that includes a recent
"starburst." At the metal-poor end, we capture the increase of [α/Fe]
with decreasing [Fe/H] and constrain the "α-knee" to [Fe/H] ≲
-2.2 in both MCs, implying a low star formation efficiency of ∼0.01
Gyr<SUP>-1</SUP>. The MC knees are more metal-poor than those of less
massive MW dwarf galaxies such as Fornax, Sculptor, or Sagittarius. One
possible interpretation is that the MCs formed in a lower-density
environment than the MW, a hypothesis that is consistent with the
paradigm that the MCs fell into the MW's gravitational potential
only recently.
---------------------------------------------------------
Title: VizieR Online Data Catalog: APOGEE-2 data from DR16 (Majewski+,
2017)
Authors: Majewski, S. R.; Schiavon, R. P.; Frinchaboy, P. M.;
Allende Prieto, C.; Barkhouser, R.; Bizyaev, D.; Blank, B.; Brunner,
S.; Burton, A.; Carrera, R.; Chojnowski, S. D.; Cunha, K.; Epstein,
C.; Fitzgerald, G.; Garcia Perez, A. E.; Hearty, F. R.; Henderson,
C.; Holtzman, J. A.; Johnson, J. A.; Lam, C. R.; Lawler, J. E.;
Maseman, P.; Meszaros, S.; Nelson, M.; Nguyen, D. C.; Nidever, D. L.;
Pinsonneault, M.; Shetrone, M.; Smee, S.; Smith, V. V.; Stolberg, T.;
Skrutskie, M. F.; Walker, E.; Wilson, J. C.; Zasowski, G.; Anders,
F.; Basu, S.; Beland, S.; Blanton, M. R.; Bovy, J.; Brownstein, J. R.;
Carlberg, J.; Chaplin, W.; Chiappini, C.; Eisenstein, D. J.; Elsworth,
Y.; Feuillet, D.; Fleming, S. W.; Galbraith-Frew, J.; Garcia, R. A.;
Garcia-Hernandez, D. A.; Gillespie, B. A.; Girardi, L.; Gunn, J. E.;
Hasselquist, S.; Hayden, M. R.; Hekker, S.; Ivans, I.; Kinemuchi,
K.; Klaene, M.; Mahadevan, S.; Mathur, S.; Mosser, B.; Muna, D.;
Munn, J. A.; Nichol, R. C.; O'Connell, R. W.; Parejko, J. K.; Robin,
A. C.; Rocha-Pinto, H.; Schultheis, M.; Serenelli, A. M.; Shane, N.;
Silva Aguirre, E. V.; Sob Eck, J. S.; Thompson, B.; Troup, N. W.;
Weinberg, D. H.; Zamora, O.
2020yCat..51540094M Altcode:
The second generation of the Apache Point Observatory Galactic Evolution
Experiment (APOGEE-2) observes the "archaeological" record embedded
in hundreds of thousands of stars to explore the assembly history and
evolution of the Milky Way Galaxy. <P />APOGEE-2 maps the dynamical
and chemical patterns of Milky Way stars with data from the 1-meter
NMSU Telescope and the 2.5-meter Sloan Foundation Telescope at the
Apache Point Observatory in New Mexico (APOGEE-2N), and the 2.5-meter
du Pont Telescope at Las Campanas Observatory in Chile (APOGEE-2S). <P
/>(2 data files).
---------------------------------------------------------
Title: VizieR Online Data Catalog: Proxima Cen RV, FWHM and fluxes
(Suarez Mascareno+, 2020)
Authors: Suarez Mascareno, A.; Faria, J. P.; Figueira, P.; Lovis,
C.; Damasso, M.; Gonzalez Hernandez, J. I.; Rebolo, R.; Cristiano,
S.; Pepe, F.; Santos, N. C.; Zapatero Osorio, M. R.; Adibekyan, V.;
Hojjatpanah, S.; Sozzetti, A.; Murgas, F.; Abreu, M.; Affolter, M.;
Alibert, Y.; Aliverti, M.; Allart, R.; Allende Prieto, C.; Alves,
D.; Amate, M.; Avila, G.; Baldini, V.; Bandi, T.; Barros, S. C. C.;
Bianco, A.; Benz, W.; Bouchy, F.; Broeng, C.; Cabral, A.; Calderone,
G.; Cirami, R.; Coleho, J.; Conconi, P.; Coretti, I.; Cumani, C.;
Cupani, G.; D Odorico, V.; Deiries, S.; Delabre, B.; di Marcantonio,
P.; Dumusque, X.; Ehrenreich, D.; Fragoso, A.; Genolet, L.; Genoni,
M.; Genova Santos, R.; Hughes, I.; Iwert, O.; Kerber, F.; Knusdrtrup,
J.; Landoni, M.; Lavie, B.; Lillo-Box, J.; Lizon, J.; Lo Curto, G.;
Maire, C.; Manescau, A.; Martins, C. J. A. P.; Megevand, D.; Mehner,
A.; Micela, G.; Modigliani, A.; Molaro, P.; Monteiro, M. A.; Monteiro,
M. J. P. F. G.; Moschetti, M.; Mueller, E.; Nunes, N. J.; Oggioni,
L.; Oliveira, A.; Palle, E.; Pariani, G.; Pasquini, L.; Poretti E!,
.; Rasill, A. J. L.; Redaelli, E.; Riva, M.; Santana Tschudi, S.;
Santin, P.; Santos, P.; Segovia, A.; Sosnowska, D.; Sousa, S.; Snano,
P.; Tenegi, F.; Udry, S.; Zanutta, A.; Zerbi, F.
2020yCat..36390077S Altcode:
We obtained 67 individual spectra as part of the ESPRESSO GTO,
as part of programme ID 1102.C-744 (PI: F.Pepe). Measurements were
taken in ESPRESSO's 1UT high resolution (HR) mode with 15 minutes of
integration time. More information on the different observing modes
can be found on the ESO instrument page. ESPRESSO is equipped with its
own pipeline providing extracted and wavelength-calibrated spectra,
as well as RV measurements. The RV measurements are determined by a
Gaussian fit of the cross-correlation function (CCF) of the spectrum
with a binary mask computed from a stellar template. The mask was
created using an ESPRESSO spectrum of Proxima as a template. Lines were
identified through an automatic line-searching algorithm based on the
spectrum derivative. The pipeline, version 2.0.0, is fully available
to download from the ESO pipeline website. <P />In combination with
the ESPRESSO data we include the measurements taken between 2003 and
2017 with the High Accuracy Radial velocity Planet Searcher (HARPS)
spectrograph. These data where obtained by the Geneva/Grenoble survey
and the RedDots project, under programmes 072.C-0488, 082.C-0718,
183.C-0437, 191.C-0505, 096.C-0082, 099.C-0205, and 099.C-0880. This
dataset is comprised of 196 individual measurements that include
two high cadence campaigns in 2016 and 2017. The RVs were calculated
using the TERRA package and have been obtained from. In 2015 HARPS was
updated with new fibres, which improved its stability but also caused
an RV offset with respect to previous measurements. For this reason we
treat both HARPS datasets independently. The majority of the data were
obtained without simultaneous calibration, which limits the stability of
HARPS to a level of 1m/s. <P />Along with the previous data we include
the RVs taken with the Ultraviolet and Visual Echelle Spectrograph
(UVES) and analysed in Dmasso et al. 2020. This dataset consists of 77
nightly binned UVES RVs obtained between 2000 and 2007. The UVES data
were obtained in one of the early RV surveys for planets around M-dwarfs
under ESO programme IDs: 65.L-0428, 66.C-0446, 267.C-5700, 68.C-0415,
69.C-0722, 70.C-0044, 71.C-0498, 072.C-0495, 173.C-0606, and 078.C-0829
(PI: M. Kuerster). The data reduction and RV measurement is described in
Butler et al., 2019AJ....158..251B. Cat. J/AJ/158/251). The UVES data do
not include a measurement of the FWHM, as it is not easily available due
to calibration by the iodine gas absorption cell. <P />(3 data files).
---------------------------------------------------------
Title: The Open Cluster Chemical Abundances and Mapping
Survey. IV. Abundances for 128 Open Clusters Using SDSS/APOGEE DR16
Authors: Donor, John; Frinchaboy, Peter M.; Cunha, Katia; O'Connell,
Julia E.; Allende Prieto, Carlos; Almeida, Andrés; Anders, Friedrich;
Beaton, Rachael; Bizyaev, Dmitry; Brownstein, Joel R.; Carrera,
Ricardo; Chiappini, Cristina; Cohen, Roger; García-Hernández, D. A.;
Geisler, Doug; Hasselquist, Sten; Jönsson, Henrik; Lane, Richard
R.; Majewski, Steven R.; Minniti, Dante; Bidin, Christian Moni; Pan,
Kaike; Roman-Lopes, Alexandre; Sobeck, Jennifer S.; Zasowski, Gail
2020AJ....159..199D Altcode: 2020arXiv200208980D
The Open Cluster Chemical Abundances and Mapping (OCCAM) survey aims to
constrain key Galactic dynamical and chemical evolution parameters by
the construction of a large, comprehensive, uniform, infrared-based
spectroscopic data set of hundreds of open clusters. This fourth
contribution from the OCCAM survey presents analysis using Sloan
Digital Sky Survey/APOGEE DR16 of a sample of 128 open clusters, 71
of which we designate to be "high quality" based on the appearance of
their color-magnitude diagram. We find the APOGEE DR16 derived [Fe/H]
abundances to be in good agreement with previous high-resolution
spectroscopic open cluster abundance studies. Using the high-quality
sample, we measure Galactic abundance gradients in 16 elements, and find
evolution of some of the [X/Fe] gradients as a function of age. We find
an overall Galactic [Fe/H] versus R<SUB>GC</SUB> gradient of -0.068 ±
0.001 dex kpc<SUP>-1</SUP> over the range of 6 < R<SUB>GC</SUB> <
13.9 kpc; however, we note that this result is sensitive to the distance
catalog used, varying as much as 15%. We formally derive the location
of a break in the [Fe/H] abundance gradient as a free parameter in the
gradient fit for the first time. We also measure significant Galactic
gradients in O, Mg, S, Ca, Mn, Cr, Cu, Na, Al, and K, some of which
are measured for the first time. Our large sample allows us to examine
four well-populated age bins in order to explore the time evolution
of gradients for a large number of elements and comment on possible
implications for Galactic chemical evolution and radial migration.
---------------------------------------------------------
Title: NLTE for APOGEE: simultaneous multi-element NLTE radiative
transfer
Authors: Osorio, Y.; Allende Prieto, C.; Hubeny, I.; Mészáros, Sz.;
Shetrone, M.
2020A&A...637A..80O Altcode: 2020arXiv200313353O
Context. Relaxing the assumption of local thermodynamic equilibrium
(LTE) in modelling stellar spectra is a necessary step to determine
chemical abundances to better than about 10% in late-type stars. <BR />
Aims: We describe our multi-element (Na, Mg, K, and Ca) non-LTE (NLTE)
calculations, which can be applied to the APOGEE survey. <BR /> Methods:
The new version of TLUSTY allows for the calculation of restricted
NLTE in cool stars using pre-calculated opacity tables. We demonstrate
that TLUSTY gives consistent results with MULTI, a well-tested code
for NLTE in cool stars. We used TLUSTY to perform LTE and a series
of NLTE calculations that simultaneously used all combinations of
one, two, three and four of the elements in NLTE. <BR /> Results: We
take into account that departures from LTE in one element can affect
others through changes in the opacities of Na, Mg, K, and Ca. We
find that atomic Mg, which provides strong UV opacity and exhibits
significant departures from LTE in the low-energy states, can affect
the NLTE populations of Ca, leading to abundance corrections as large
as 0.07 dex. The differences in the derived abundances between the
single-element and the multi-element cases can exceed those between the
single-element NLTE determinations and an LTE analysis. We therefore
caution that this is not always a second-order effect. Based on
detailed tests for three stars with reliable atmospheric parameters
(Arcturus, Procyon, and the Sun), we conclude that our NLTE calculations
provide abundance corrections that can in the optical amount to 0.1,
0.2, and 0.7 dex for Ca, Na and K, but LTE is a good approximation
for Mg. In the H-band, NLTE corrections are much smaller and always
lower than 0.1 dex. The derived NLTE abundances in the optical and
in the IR are consistent. In all three stars, NLTE line profiles
fit the observations better than the LTE counterparts for all four
elements. <BR /> Conclusions: The atomic elements in ionisation stages
where over-ionisation is an important NLTE mechanism are likely affected
by departures from LTE in Mg. Particular care must be taken with the
collisions that are adopted for high-lying levels when NLTE profiles
of lines in the H-band are calculated. The derived NLTE corrections in
the optical and in the H-band differ, but the derived NLTE abundances
are consistent between the two spectral regions.
---------------------------------------------------------
Title: VizieR Online Data Catalog: APOGEE-2 data from DR16 (Johnsson+,
2020)
Authors: Jonsson, H.; Holtzman, J. A.; Allende Prieto, C.; Cunha, K.;
Garcia-Hernandez, D. A.; Hasselquist, S.; Masseron, T.; Osorio, Y.;
Shetrone, M.; Smith, V.; Stringfellow, G. S.; Bizyaev, D.; Edvardsson,
B.; Majewski, S. R.; Meszaros, S.; Souto, D.; Zamora, O.; Beaton,
R. L.; Bovy, Jo; Donor, J.; Pinsonneault, M. H.; Poovelil, V. J.;
Sobeck, J.
2020yCat.3284....0J Altcode:
The Apache Point Observatory Galactic Evolution Experiment (APOGEE;
Majewski+ 2017AJ....154...94M) was originally an infrared stellar
spectroscopic survey within Sloan Digital Sky Survey (SDSS)-III
(henceforth APOGEE-1; Eisenstein+ 2011AJ....142...72E), and APOGEE-2
is the continuation of the same program within SDSS-IV (Blanton+
2017AJ....154...28B). <P />APOGEE-2 DR16 (2019 December) maps the
dynamical and chemical patterns of Milky Way stars with data from the
1-meter NMSU Telescope and the 2.5-meter Sloan Foundation Telescope
at the Apache Point Observatory in New Mexico (APOGEE-2N), and the
2.5-meter du Pont Telescope at Las Campanas Observatory in Chile
(APOGEE-2S). <P />(4 data files).
---------------------------------------------------------
Title: VizieR Online Data Catalog: OCCAM. IV. Open cluster abundances
using APOGEE DR16 (Donor+, 2020)
Authors: Donor, J.; Frinchaboy, P. M.; Cunha, K.; O'Connell, J. E.;
Allende Prieto, C.; Almeida, A.; Anders, F.; Beaton, R.; Bizyaev,
D.; Brownstein, J. R.; Carrera, R.; Chiappini, C.; Cohen, R.;
Garcia-Hernandez, D. A.; Geisler, D.; Hasselquist, S.; Jonsson, H.;
Lane, R. R.; Majewski, S. R.; Minniti, D.; Bidin, C. M.; Pan, K.;
Roman-Lopes, A.; Sobeck, J. S.; Zasowski, G.
2020yCat..51590199D Altcode:
Our primary source of chemical abundance and radial velocity (RV)
data is the Sloan sky Digital Survey (SDSS) sixteenth data release
(DR16, H. Jonsson et al. 2020, in preparation) taken as part of the
second, dual-hemisphere phase of Apache Point Observatory Galactic
Evolution Experiment (APOGEE 2; Majewski+ 2017AJ....154...94M). APOGEE
is a high-resolution, near-infrared spectroscopic survey currently
operating in both hemispheres, at Apache Point Observatory (APO, New
Mexico) and Las Campanas Observatory (LCO; Chile). The APOGEE/DR16
data set includes about 430000 stars, collected between 2011 August
and 2018 August using the two 300-fiber APOGEE spectrographs. <P />Our
secondary source of data is Gaia DR2 (I/345); we use photometric and
astrometric data, radial velocity measurements, and parallax values
in common with APOGEE. <P />(2 data files).
---------------------------------------------------------
Title: VizieR Online Data Catalog: APOGEE-2 data from DR16 (Majewski+,
2017)
Authors: Majewski, S. R.; Schiavon, R. P.; Frinchaboy, P. M.;
Allende Prieto, C.; Barkhouser, R.; Bizyaev, D.; Blank, B.; Brunner,
S.; Burton, A.; Carrera, R.; Chojnowski, S. D.; Cunha, K.; Epstein,
C.; Fitzgerald, G.; Garcia Perez, A. E.; Hearty, F. R.; Henderson,
C.; Holtzman, J. A.; Johnson, J. A.; Lam, C. R.; Lawler, J. E.;
Maseman, P.; Meszaros, S.; Nelson, M.; Nguyen, D. C.; Nidever, D. L.;
Pinsonneault, M.; Shetrone, M.; Smee, S.; Smith, V. V.; Stolberg, T.;
Skrutskie, M. F.; Walker, E.; Wilson, J. C.; Zasowski, G.; Anders,
F.; Basu, S.; Beland, S.; Blanton, M. R.; Bovy, J.; Brownstein, J. R.;
Carlberg, J.; Chaplin, W.; Chiappini, C.; Eisenstein, D. J.; Elsworth,
Y.; Feuillet, D.; Fleming, S. W.; Galbraith-Frew, J.; Garcia, R. A.;
Garcia-Hernandez, D. A.; Gillespie, B. A.; Girardi, L.; Gunn, J. E.;
Hasselquist, S.; Hayden, M. R.; Hekker, S.; Ivans, I.; Kinemuchi,
K.; Klaene, M.; Mahadevan, S.; Mathur, S.; Mosser, B.; Muna, D.;
Munn, J. A.; Nichol, R. C.; O'Connell, R. W.; Parejko, J. K.; Robin,
A. C.; Rocha-Pinto, H.; Schultheis, M.; Serenelli, A. M.; Shane, N.;
Silva Aguirre, E. V.; Sob Eck, J. S.; Thompson, B.; Troup, N. W.;
Weinberg, D. H.; Zamora, O.
2020yCat.3284....0M Altcode:
The second generation of the Apache Point Observatory Galactic Evolution
Experiment (APOGEE-2) observes the "archaeological" record embedded
in hundreds of thousands of stars to explore the assembly history and
evolution of the Milky Way Galaxy. <P />APOGEE-2 maps the dynamical
and chemical patterns of Milky Way stars with data from the 1-meter
NMSU Telescope and the 2.5-meter Sloan Foundation Telescope at the
Apache Point Observatory in New Mexico (APOGEE-2N), and the 2.5-meter
du Pont Telescope at Las Campanas Observatory in Chile (APOGEE-2S). <P
/>(2 data files).
---------------------------------------------------------
Title: VizieR Online Data Catalog: Open cluster King 1 photometry
(Carrera+, 2017)
Authors: Carrera, R.; Rodriguez Espinosa, L.; Casamiquela, L.;
Balaguer Nunez, L.; Jordi, C.; Allende Prieto, C.; Stetson, P. B.
2020yCat..74704285C Altcode:
The observations were carried out the night of 2014 November 14 with
AutoFib2+WYFFOS (AF2) multi-object spectrograph installed at the
primary focus of the 4.2m William Herschel Telescope (WHT) at Roque
de los Muchachos Observatory (La Palma, Spain). <P />(1 data file).
---------------------------------------------------------
Title: Nightside condensation of iron in an ultrahot giant exoplanet
Authors: Ehrenreich, David; Lovis, Christophe; Allart, Romain;
Zapatero Osorio, María Rosa; Pepe, Francesco; Cristiani, Stefano;
Rebolo, Rafael; Santos, Nuno C.; Borsa, Francesco; Demangeon, Olivier;
Dumusque, Xavier; González Hernández, Jonay I.; Casasayas-Barris,
Núria; Ségransan, Damien; Sousa, Sérgio; Abreu, Manuel; Adibekyan,
Vardan; Affolter, Michael; Allende Prieto, Carlos; Alibert, Yann;
Aliverti, Matteo; Alves, David; Amate, Manuel; Avila, Gerardo; Baldini,
Veronica; Bandy, Timothy; Benz, Willy; Bianco, Andrea; Bolmont,
Émeline; Bouchy, François; Bourrier, Vincent; Broeg, Christopher;
Cabral, Alexandre; Calderone, Giorgio; Pallé, Enric; Cegla, H. M.;
Cirami, Roberto; Coelho, João M. P.; Conconi, Paolo; Coretti, Igor;
Cumani, Claudio; Cupani, Guido; Dekker, Hans; Delabre, Bernard;
Deiries, Sebastian; D'Odorico, Valentina; Di Marcantonio, Paolo;
Figueira, Pedro; Fragoso, Ana; Genolet, Ludovic; Genoni, Matteo;
Génova Santos, Ricardo; Hara, Nathan; Hughes, Ian; Iwert, Olaf;
Kerber, Florian; Knudstrup, Jens; Landoni, Marco; Lavie, Baptiste;
Lizon, Jean-Louis; Lendl, Monika; Lo Curto, Gaspare; Maire, Charles;
Manescau, Antonio; Martins, C. J. A. P.; Mégevand, Denis; Mehner,
Andrea; Micela, Giusi; Modigliani, Andrea; Molaro, Paolo; Monteiro,
Manuel; Monteiro, Mario; Moschetti, Manuele; Müller, Eric; Nunes,
Nelson; Oggioni, Luca; Oliveira, António; Pariani, Giorgio; Pasquini,
Luca; Poretti, Ennio; Rasilla, José Luis; Redaelli, Edoardo; Riva,
Marco; Santana Tschudi, Samuel; Santin, Paolo; Santos, Pedro; Segovia
Milla, Alex; Seidel, Julia V.; Sosnowska, Danuta; Sozzetti, Alessandro;
Spanò, Paolo; Suárez Mascareño, Alejandro; Tabernero, Hugo; Tenegi,
Fabio; Udry, Stéphane; Zanutta, Alessio; Zerbi, Filippo
2020Natur.580..597E Altcode: 2020arXiv200305528E
Ultrahot giant exoplanets receive thousands of times Earth's
insolation<SUP>1,2</SUP>. Their high-temperature atmospheres
(greater than 2,000 kelvin) are ideal laboratories for studying
extreme planetary climates and chemistry<SUP>3-5</SUP>. Daysides are
predicted to be cloud-free, dominated by atomic species<SUP>6</SUP>
and much hotter than nightsides<SUP>5,7,8</SUP>. Atoms are expected to
recombine into molecules over the nightside<SUP>9</SUP>, resulting in
different day and night chemistries. Although metallic elements and
a large temperature contrast have been observed<SUP>10-14</SUP>,
no chemical gradient has been measured across the surface of
such an exoplanet. Different atmospheric chemistry between the
day-to-night (`evening') and night-to-day (`morning') terminators
could, however, be revealed as an asymmetric absorption signature
during transit<SUP>4,7,15</SUP>. Here we report the detection of an
asymmetric atmospheric signature in the ultrahot exoplanet WASP-76b. We
spectrally and temporally resolve this signature using a combination of
high-dispersion spectroscopy with a large photon-collecting area. The
absorption signal, attributed to neutral iron, is blueshifted by
-11 ± 0.7 kilometres per second on the trailing limb, which can be
explained by a combination of planetary rotation and wind blowing from
the hot dayside<SUP>16</SUP>. In contrast, no signal arises from the
nightside close to the morning terminator, showing that atomic iron
is not absorbing starlight there. We conclude that iron must therefore
condense during its journey across the nightside.
---------------------------------------------------------
Title: The Pristine Survey - VIII. The metallicity distribution
function of the Milky Way halo down to the extremely metal-poor regime
Authors: Youakim, K.; Starkenburg, E.; Martin, N. F.; Matijevič,
G.; Aguado, D. S.; Allende Prieto, C.; Arentsen, A.; Bonifacio, P.;
Carlberg, R. G.; González Hernández, J. I.; Hill, V.; Kordopatis,
G.; Lardo, C.; Navarro, J. F.; Jablonka, P.; Sánchez Janssen, R.;
Sestito, F.; Thomas, G. F.; Venn, K.
2020MNRAS.492.4986Y Altcode: 2020arXiv200104988Y; 2020MNRAS.tmp..134Y
The Pristine survey uses narrow-band photometry to derive precise
metallicities down to the extremely metal-poor regime ( [Fe/H] <
-3), and currently consists of over 4 million FGK-type stars over a
sky area of ∼ 2500 deg^2. We focus our analysis on a subsample of
∼80 000 main-sequence turn-off stars with heliocentric distances
between 6 and 20 kpc, which we take to be a representative sample of
the inner halo. The resulting metallicity distribution function (MDF)
has a peak at [Fe/H] =-1.6, and a slope of Δ(LogN)/Δ [Fe/H] = 1.0
± 0.1 in the metallicity range of -3.4 < [Fe/H] < -2.5. This
agrees well with a simple closed-box chemical enrichment model in this
range, but is shallower than previous spectroscopic MDFs presented
in the literature, suggesting that there may be a larger proportion
of metal-poor stars in the inner halo than previously reported. We
identify the Monoceros/TriAnd/ACS/EBS/A13 structure in metallicity
space in a low-latitude field in the anticentre direction, and also
discuss the possibility that the inner halo is dominated by a single,
large merger event, but cannot strongly support or refute this idea
with the current data. Finally, based on the MDF of field stars, we
estimate the number of expected metal-poor globular clusters in the
Milky Way halo to be 5.4 for [Fe/H] < -2.5 and 1.5 for [Fe/H] <
-3, suggesting that the lack of low-metallicity globular clusters in
the Milky Way is not due simply to statistical undersampling.
---------------------------------------------------------
Title: Strategies for flux calibration in massive spectroscopic
surveys
Authors: Allende Prieto, Carlos
2020IAUGA..30..454A Altcode:
Optical large-scale medium-resolution spectroscopic surveys such as
SDSS, LAMOST, DESI, WEAVE or 4MOST are subject to constraints that
limit the choice of flux calibrators, and the attained precision. The
use of optical fibers, a large but limited field of view, the tiling
strategies and tight schedules, are all factors that call for a careful
evaluation of the flux calibration procedures. <P />The density of
stars with well-known spectral energy distributions is so low that
makes them unsuitable for flux calibration of large scale spectroscopic
surveys. The alternative is to use stars with relatively simple spectra,
which can be approximated well by synthetic spectra based on model
atmospheres. One example are white dwarfs (Bohlin 1996), but their
density is also too low for practical purposes: a few per square degree
down to 19th magnitude. An alternative choice, exploited by the SDSS,
are halo turn-off F-type stars (Stoughton et al.2002). A-type stars
offer another option, albeit with lower densities at high Galactic
latitudes (Allende Prieto del Burgo 2016). Ideally, one would use
stars of various spectral types. The most common type, halo turn-off
stars, can be used for the actual calibration, and the others for
quality assessment. <P />The spectral typing needs to be performed
before spectra are flux calibrated. Our group has explored various
strategies for continuum normalization (the removal of the instrument
response), finding good results using a running mean filter (Aguado
et al.2017; Allende Prieto et al.2014). Interpolation in the models
speeds up the model fitting process, but it is important to ensure that
interpolations are sufficiently accurate (see, e.g. Mészáros Allende
Prieto 2013). <P />Fiber-fed spectrographs are particularly challenging,
since errors in positioning fibers, guiding errors, or differential
atmospheric refraction, add up. In our tests with data from the Baryonic
Oscillations Spectroscopic Survey (BOSS; Dawson et al.2016), we conclude
that while the flux calibration is statistically accurate (<5%),
individual spectra can exhibit much larger excursions, in excess of 20%.
---------------------------------------------------------
Title: Erratum: The Pristine survey - VI. The first three years
of medium-resolution follow-up spectroscopy of Pristine EMP star
candidates
Authors: Aguado, David S.; Youakim, Kris; González Hernández,
Jonay I.; Allende Prieto, Carlos; Starkenburg, Else; Martin, Nicolas;
Bonifacio, Piercarlo; Arentsen, Anke; Caffau, Elisabetta; Peralta
de Arriba, Luis; Sestito, Federico; Garcia-Dias, Rafael; Fantin,
Nicholas; Hill, Vanessa; Jablonca, Pascale; Jahandar, Farbod; Kielty,
Collin; Longeard, Nicolas; Lucchesi, Romain; Sánchez-Janssen, Rubén;
Osorio, Yeisson; Palicio, Pedro A.; Tolstoy, Eline; Wilson, Thomas
G.; Côté, Patrick; Kordopatis, Georges; Lardo, Carmela; Navarro,
Julio F.; Thomas, Guillaume F.; Venn, Kim
2020MNRAS.491.5299A Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Stellar Characterization of M Dwarfs from the APOGEE Survey:
A Calibrator Sample for M-dwarf Metallicities
Authors: Souto, Diogo; Cunha, Katia; Smith, Verne V.; Allende Prieto,
C.; Burgasser, Adam; Covey, Kevin; García-Hernández, D. A.; Holtzman,
Jon A.; Johnson, Jennifer A.; Jönsson, Henrik; Mahadevan, Suvrath;
Majewski, Steven R.; Masseron, Thomas; Shetrone, Matthew; Rojas-Ayala,
Bárbara; Sobeck, Jennifer; Stassun, Keivan G.; Terrien, Ryan; Teske,
Johanna; Wanderley, Fábio; Zamora, Olga
2020ApJ...890..133S Altcode: 2020arXiv200105597S
We present spectroscopic determinations of the effective temperatures,
surface gravities, and metallicities for 21 M dwarfs observed at high
resolution (R ∼ 22,500) in the H band as part of the Sloan Digital Sky
Survey (SDSS)-IV Apache Point Observatory Galactic Evolution Experiment
(APOGEE) survey. The atmospheric parameters and metallicities are
derived from spectral syntheses with 1D LTE plane-parallel MARCS models
and the APOGEE atomic/molecular line list, together with up-to-date
H<SUB>2</SUB>O and FeH molecular line lists. Our sample range in
T<SUB>eff</SUB> from ∼3200 to 3800 K, where 11 stars are in binary
systems with a warmer (FGK) primary, while the other 10 M dwarfs have
interferometric radii in the literature. We define an ${M}_{{K}_{S}}$
M K S -radius calibration based on our M-dwarf radii derived from the
detailed analysis of APOGEE spectra and Gaia DR2 distances, as well
as a mass-radius relation using the spectroscopically derived surface
gravities. A comparison of the derived radii with interferometric
values from the literature finds that the spectroscopic radii are
slightly offset toward smaller values, with Δ = -0.01 ± 0.02
R⋆/R<SUB>⊙</SUB>. In addition, the derived M-dwarf masses based
upon the radii and surface gravities tend to be slightly smaller (by
∼5%-10%) than masses derived for M-dwarf members of eclipsing binary
systems for a given stellar radius. The metallicities derived for
the 11 M dwarfs in binary systems, compared to metallicities obtained
for their hotter FGK main-sequence primary stars from the literature,
show excellent agreement, with a mean difference of [Fe/H](M dwarf -
FGK primary) = +0.04 ± 0.18 dex, confirming the APOGEE metallicity
scale derived here for M dwarfs.
---------------------------------------------------------
Title: Signatures of the Galactic bar in high-order moments of proper
motions measured by Gaia
Authors: Alonso Palicio, Pedro; Martinez-Valpuesta, Inma; Allende
Prieto, Carlos; Dalla Vecchia, Claudio
2020arXiv200202847A Altcode:
Our location in the Milky Way provides an exceptional opportunity to
gain insight on the galactic evolution processes, and complement the
information inferred from observations of external galaxies. Since
the Milky Way is a barred galaxy, the study of motions of individual
stars in the bulge and disc is useful to understand the role of the
bar. The Gaia mission enables such study by providing the most precise
parallaxes and proper motions to date. In this theoretical work, we
explore the effects of the bar on the distribution of higher-order
moments --the skewness and kurtosis-- of the proper motions by
confronting two simulated galaxies, one with a bar and one nearly
axisymmetric, with observations from the latest Gaia data release
(GaiaDR2). We introduce the code ASGAIA to account for observational
errors of Gaia in the kinematical structures predicted by the numerical
models. As a result, we find clear imprints of the bar in the skewness
distribution of the longitudinal proper motion $\mu_\ell$ in GaiaDR2,
as well as other features predicted for the next Gaia data releases.
---------------------------------------------------------
Title: A detailed non-LTE analysis of LB-1: Revised parameters and
surface abundances
Authors: Simón-Díaz, S.; Maíz Apellániz, J.; Lennon, D. J.;
González Hernández, J. I.; Allende Prieto, C.; Castro, N.; de Burgos,
A.; Dufton, P. L.; Herrero, A.; Toledo-Padrón, B.; Smartt, S. J.
2020A&A...634L...7S Altcode: 2019arXiv191207255S
Context. It has recently been proposed that LB-1 is a binary system at
4 kpc consisting of a B-type star of 8 M<SUB>⊙</SUB> and a massive
stellar black hole (BH) of 70 M<SUB>⊙</SUB>. This finding challenges
our current theories of massive star evolution and formation of BHs at
solar metallicity. <BR /> Aims: Our objective is to derive the effective
temperature, surface gravity, and chemical composition of the B-type
component in order to determine its nature and evolutionary status
and, indirectly, to constrain the mass of the BH. <BR /> Methods:
We use the non-LTE stellar atmosphere code FASTWIND to analyze
new and archival high-resolution data. <BR /> Results: We determine
(T<SUB>eff</SUB>, log g) values of (14 000 ± 500 K, 3.50 ± 0.15 dex)
that, combined with the Gaia parallax, imply a spectroscopic mass,
from log g, of 3.2<SUP>+2.1</SUP><SUB>-1.9</SUB> M<SUB>⊙</SUB>
and an evolutionary mass, assuming single star evolution, of
5.2<SUP>+0.3</SUP><SUB>-0.6</SUB> M<SUB>⊙</SUB>. We determine
an upper limit of 8 km s<SUP>-1</SUP> for the projected rotational
velocity and derive the surface abundances; we find the star to have
a silicon abundance below solar, and to be significantly enhanced in
nitrogen and iron and depleted in carbon and magnesium. Complementary
evidence derived from a photometric extinction analysis and Gaia
yields similar results for T<SUB>eff</SUB> and log g and a consistent
distance around 2 kpc. <BR /> Conclusions: We propose that the B-type
star is a slightly evolved main sequence star of 3-5 M<SUB>⊙</SUB>
with surface abundances reminiscent of diffusion in late B/A chemically
peculiar stars with low rotational velocities. There is also evidence
for CN-processed material in its atmosphere. These conclusions rely
critically on the distance inferred from the Gaia parallax. The
goodness of fit of the Gaia astrometry also favors a high-inclination
orbit. If the orbit is edge-on and the B-type star has a mass of
3-5 M<SUB>⊙</SUB>, the mass of the dark companion would be 4-5
M<SUB>⊙</SUB>, which would be easier to explain with our current
stellar evolutionary models.
---------------------------------------------------------
Title: Signatures of the Galactic bar in high-order moments of proper
motions measured by Gaia
Authors: Palicio, Pedro A.; Martinez-Valpuesta, Inma; Allende Prieto,
Carlos; Dalla Vecchia, Claudio
2020A&A...634A..90P Altcode:
Our location in the Milky Way provides an exceptional opportunity to
gain insight on the galactic evolution processes, and complement the
information inferred from observations of external galaxies. Since the
Milky Way is a barred galaxy, the study of motions of individual stars
in the bulge and disc is useful to understand the role of the bar. The
Gaia mission enables such study by providing the most precise parallaxes
and proper motions to date. In this theoretical work, we explore
the effects of the bar on the distribution of higher-order moments -
the skewness and kurtosis - of the proper motions by confronting two
simulated galaxies, one with a bar and one nearly axisymmetric, with
observations from the latest Gaia data release (Gaia DR2). We introduce
the code ASGAIA to account for observational errors of Gaia in the
kinematical structures predicted by the numerical models. As a result,
we find clear imprints of the bar in the skewness distribution of the
longitudinal proper motion μ<SUB>ℓ</SUB> in Gaia DR2, as well as
other features predicted for the next Gaia data releases.
---------------------------------------------------------
Title: Does the binary system LB-1 host a Black Hole?
Authors: Lennon, Daniel J.; Allende-Prieto, Carlos; Bohlin, Ralph C.;
Casares, Jorges; Castro, Norberto; Deustua, Susana E.; Dufton, Philip;
Gonzalez-Hernandez, Jonay I.; Herrero, Artemio; Maiz Apellaniz,
Jesus; Munoz Darias, Teo; Simon-Diaz, Sergio; Smartt, Stephen J.;
de Burgos Sierra, Abel
2020hst..prop16079L Altcode:
It was recently proposed that the Galactic binary system LB-1 hosts an
~8+70 solar mass B-star+black hole (BH) wide binary that is X-ray quiet,
strongly challenging the current paradigm for the formation of stellar
mass black holes in metal rich environments. This claim was quickly
disputed in two ways: The Balmer emission lines originally thought to
arise from an accretion disk around the BH have been re-interpreted as
a stationary circumbinary disk, hence it is only possible to estimate a
minimum mass for the dark companion from the inferred mass of the B-type
star. Secondly, detailed non-LTE analyses of the optical spectrum and
spectral energy distribution of the B-type star now imply two scenarios
for a significantly lower mass of the B-type 'primary': It is found
to be either a main sequence B-type star of 3.2+/-2 solar masses or
a stripped helium star of 1.1+/-0.5 solar masses, consistent with a
'secondary' mass between approximately 2 and 5 solar masses. The dark
secondary could therefore still be a stellar mass BH, making it only
the second X-ray quiet star+BH system known, or possibly even a massive
neutron star. We propose obtaining an exquisite UV/optical/near-IR flux
calibrated spectrum of the system that will provide the pivotal means
of discriminating between these two scenarios by tightly constraining
the mass and helium abundance of the primary.
---------------------------------------------------------
Title: Homogeneous analysis of globular clusters from the APOGEE
survey with the BACCHUS code - II. The Southern clusters and overview
Authors: Mészáros, Szabolcs; Masseron, Thomas; García-Hernández,
D. A.; Allende Prieto, Carlos; Beers, Timothy C.; Bizyaev, Dmitry;
Chojnowski, Drew; Cohen, Roger E.; Cunha, Katia; Dell'Agli, Flavia;
Ebelke, Garrett; Fernández-Trincado, José G.; Frinchaboy, Peter;
Geisler, Doug; Hasselquist, Sten; Hearty, Fred; Holtzman, Jon;
Johnson, Jennifer; Lane, Richard R.; Lacerna, Ivan; Longa-Peña,
Penelopé; Majewski, Steven R.; Martell, Sarah L.; Minniti, Dante;
Nataf, David; Nidever, David L.; Pan, Kaike; Schiavon, Ricardo P.;
Shetrone, Matthew; Smith, Verne V.; Sobeck, Jennifer S.; Stringfellow,
Guy S.; Szigeti, László; Tang, Baitian; Wilson, John C.; Zamora, Olga
2020MNRAS.492.1641M Altcode: 2019MNRAS.492.1641M; 2019arXiv191204839M; 2019MNRAS.tmp.3134M
We investigate the Fe, C, N, O, Mg, Al, Si, K, Ca, Ce, and Nd abundances
of 2283 red giant stars in 31 globular clusters from high-resolution
spectra observed in both the Northern and Southern hemisphere by
the SDSS-IV APOGEE-2 survey. This unprecedented homogeneous data
set, largest to date, allows us to discuss the intrinsic Fe spread,
the shape, and statistics of Al-Mg and N-C anti-correlations as a
function of cluster mass, luminosity, age, and metallicity for all 31
clusters. We find that the Fe spread does not depend on these parameters
within our uncertainties including cluster metallicity, contradicting
earlier observations. We do not confirm the metallicity variations
previously observed in M22 and NGC 1851. Some clusters show a bimodal
Al distribution, while others exhibit a continuous distribution as has
been previously reported in the literature. We confirm more than two
populations in ω Cen and NGC 6752, and find new ones in M79. We discuss
the scatter of Al by implementing a correction to the standard chemical
evolution of Al in the Milky Way. After correction, its dependence on
cluster mass is increased suggesting that the extent of Al enrichment
as a function of mass was suppressed before the correction. We observe
a turnover in the Mg-Al anticorrelation at very low Mg in ω Cen,
similar to the pattern previously reported in M15 and M92. ω Cen may
also have a weak K-Mg anticorrelation, and if confirmed, it would be
only the third cluster known to show such a pattern.
---------------------------------------------------------
Title: ESPRESSO highlights the binary nature of the ultra-metal-poor
giant HE 0107-5240
Authors: Bonifacio, P.; Molaro, P.; Adibekyan, V.; Aguado, D.; Alibert,
Y.; Allende Prieto, C.; Caffau, E.; Cristiani, S.; Cupani, G.; Di
Marcantonio, P.; D'Odorico, V.; Ehrenreich, D.; Figueira, P.; Genova,
R.; González Hernández, J. I.; Lo Curto, G.; Lovis, C.; Martins,
C. J. A. P.; Mehner, A.; Micela, G.; Monaco, L.; Nunes, N. J.; Pepe,
F. A.; Poretti, E.; Rebolo, R.; Santos, N. C.; Saviane, I.; Sousa, S.;
Sozzetti, A.; Suarez-Mascareño, A.; Udry, S.; Zapatero-Osorio, M. R.
2020A&A...633A.129B Altcode:
Context. The vast majority of the known stars of ultra low metallicity
([Fe/H] < -4.5) are known to be enhanced in carbon, and belong to
the "low-carbon band" (A(C) = log(C/H)+12 ≤ 7.6). It is generally,
although not universally, accepted that this peculiar chemical
composition reflects the chemical composition of the gas cloud out
of which these stars were formed. The first ultra-metal-poor star
discovered, HE 0107-5240, is also enhanced in carbon and belongs to the
"low-carbon band". It has recently been claimed to be a long-period
binary, based on radial velocity measurements. It has also been claimed
that this binarity may explain its peculiar composition as being due
to mass transfer from a former AGB companion. Theoretically, low-mass
ratios in binary systems are much more favoured amongst Pop III stars
than they are amongst solar-metallicity stars. Any constraint on
the mass ratio of a system of such low metallicity would shed light
on the star formation mechanisms in this metallicity regime. <BR />
Aims: We acquired one high precision spectrum with ESPRESSO in order
to check the reality of the radial velocity variations. In addition we
analysed all the spectra of this star in the ESO archive obtained with
UVES to have a set of homogenously measured radial velocities. <BR />
Methods: The radial velocities were measured using cross correlation
against a synthetic spectrum template. Due to the weakness of metallic
lines in this star, the signal comes only from the CH molecular lines
of the G-band. <BR /> Results: The measurement obtained in 2018 from an
ESPRESSO spectrum demonstrates unambiguously that the radial velocity of
HE 0107-5240 has increased from 2001 to 2018. Closer inspection of the
measurements based on UVES spectra in the interval 2001-2006 show that
there is a 96% probability that the radial velocity correlates with
time, hence the radial velocity variations can already be suspected
from the UVES spectra alone. <BR /> Conclusions: We confirm the
earlier claims of radial velocity variations in HE 0107-5240. The
simplest explanation of such variations is that the star is indeed
in a binary system with a long period. The nature of the companion
is unconstrained and we consider it is equally probable that it is
an unevolved companion or a white dwarf. Continued monitoring of the
radial velocities of this star is strongly encouraged. <P />Tables
1 and 2 are also available at the CDS via anonymous ftp to <A
href="http://cdsarc.u-strasbg.fr/">http://cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/633/A129">http://cdsarc.</A><A
href="http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/633/A129">http://u-strasbg.fr/viz-bin/cat/J/A+A/633/A129</A>
---------------------------------------------------------
Title: The Extreme CNO-enhanced Composition of the Primitive Iron-poor
Dwarf Star J0815+4729
Authors: González Hernández, Jonay I.; Aguado, David S.; Allende
Prieto, Carlos; Burgasser, Adam J.; Rebolo, Rafael
2020ApJ...889L..13G Altcode: 2020arXiv200107257G
We present an analysis of high-resolution Keck/HIRES spectroscopic
observations of J0815+4729, an extremely carbon-enhanced, iron-poor
dwarf star. These high-quality data allow us to derive a metallicity
of [Fe/H] = -5.49 ± 0.14 from the three strongest Fe I lines and to
measure a high [Ca/Fe] = 0.75 ± 0.14. The large carbon abundance of
A(C) = 7.43 ± 0.17 (or [C/Fe] ∼ 4.49 ± 0.11) places this star in
the upper boundary of the low-carbon band in the A(C)-[Fe/H] diagram,
suggesting no contamination from a binary AGB companion. We detect the
oxygen triplet at 777 nm for the first time in an ultra-metal-poor star,
indicating a large oxygen-to-iron abundance ratio of [O/Fe] = 4.03 ±
0.12 (A(O) = 7.23 ± 0.14), significantly higher than the previously
most metal-poor dwarf J2209-0028 with an oxygen triplet detection with
[O/Fe] ∼ 2.2 dex at [Fe/H] ∼ -3.9. Nitrogen is also dramatically
enhanced with (A(N) = 6.75 ± 0.08) and an abundance ratio [N/Fe]
∼ 4.41 ± 0.08. We also detect Ca, Na, and Mg, while providing
upper limits for eight other elements. The abundance pattern of
J0815+4729 resembles that of HE 1327-2326, indicating that both are
second-generation stars contaminated by a ∼21-27 M<SUB>⊙</SUB>
single, zero-metallicity, low-energy supernova with very little
mixing and substantial fallback. The absence of lithium implies an
upper limit abundance A(Li) < 1.3 dex, about 0.7 dex below the
detected Li abundance in J0023+0307, which has a similar metallicity,
exacerbating the cosmological lithium problem.
---------------------------------------------------------
Title: Metallicity and α-Element Abundance Gradients along the
Sagittarius Stream as Seen by APOGEE
Authors: Hayes, Christian R.; Majewski, Steven R.; Hasselquist, Sten;
Anguiano, Borja; Shetrone, Matthew; Law, David R.; Schiavon, Ricardo
P.; Cunha, Katia; Smith, Verne V.; Beaton, Rachael L.; Price-Whelan,
Adrian M.; Allende Prieto, Carlos; Battaglia, Giuseppina; Bizyaev,
Dmitry; Brownstein, Joel R.; Cohen, Roger E.; Frinchaboy, Peter M.;
García-Hernández, D. A.; Lacerna, Ivan; Lane, Richard R.; Mészáros,
Szabolcs; Bidin, Christian Moni; Mũnoz, Ricardo R.; Nidever, David L.;
Oravetz, Audrey; Oravetz, Daniel; Pan, Kaike; Roman-Lopes, Alexandre;
Sobeck, Jennifer; Stringfellow, Guy
2020ApJ...889...63H Altcode: 2019arXiv191206707H
Using 3D positions and kinematics of stars relative to the Sagittarius
(Sgr) orbital plane and angular momentum, we identify 166 Sgr stream
members observed by the Apache Point Observatory Galactic Evolution
Experiment (APOGEE) that also have Gaia DR2 astrometry. This sample
of 63/103 stars in the Sgr trailing/leading arm is combined with an
APOGEE sample of 710 members of the Sgr dwarf spheroidal core (385
of them newly presented here) to establish differences of 0.6 dex
in median metallicity and 0.1 dex in [α/Fe] between our Sgr core
and dynamically older stream samples. Mild chemical gradients are
found internally along each arm, but these steepen when anchored by
core stars. With a model of Sgr tidal disruption providing estimated
dynamical ages (I.e., stripping times) for each stream star, we find
a mean metallicity gradient of 0.12 ± 0.03 dex Gyr<SUP>-1</SUP> for
stars stripped from Sgr over time. For the first time, an [α/Fe]
gradient is also measured within the stream, at 0.02 ± 0.01 dex
Gyr<SUP>-1</SUP> using magnesium abundances and at 0.04 ± 0.01 dex
Gyr<SUP>-1</SUP> using silicon, which imply that the Sgr progenitor
had significant radial abundance gradients. We discuss the magnitude
of those inferred gradients and their implication for the nature of
the Sgr progenitor within the context of the current family of Milky
Way satellite galaxies, and we suggest that more sophisticated Sgr
models are needed to properly interpret the growing chemodynamical
detail we have on the Sgr system.
---------------------------------------------------------
Title: VizieR Online Data Catalog: ESPRESSO radial velocities of
HE0107-5240 (Bonifacio+, 2020)
Authors: Bonifacio, P.; Molaro, P.; Adibekyan, V.; Aguado, D.; Alibert,
Y.; Allende Prieto, C.; Caffau, E.; Cristiani, S.; Cupani, G.; di
Marcantonio, P.; D'Odorico, V.; Ehrenreich, D.; Figueira, P.; Genova,
R.; Gonzalez Hernandez, J. I.; Lo Curto, G.; Lovis, C.; Martins,
C. J. A. P.; Mehner, A.; Micela, G.; Monaco, L.; Nunes, N. J.; Pepe,
F. A.; Poretti, E.; Rebolo, R.; Santos, N. C.; Saviane, I.; Sousa, S.;
Sozzetti, A.; Suarez-Mascareno, A.; Udry, S.; Zapatero-Osorio, M. R.
2020yCat..36330129B Altcode:
A new measurement of the radial velocity of the ultra-metal-poor star
HE 0107-5240 is derived using a high resolution spectrum obtained with
the Echelle SPectrograph for Rocky Exoplanets and Stable Spectroscopic
Observations (ESPRESSO). In the high resolution mode there are two
fibres with a core diameter of 140um that corresponds to 1.0" on the
sky. HE 0107-5240 was observed on September 3, 2018. The new measurement
is put into context with measurements derived using spectra taken in
the last 17 years and confirms the variation in radial velocity of
this star over this period. <P />(2 data files).
---------------------------------------------------------
Title: The BRITE-SONG of Aldebaran - stellar music in three voices
Authors: Beck, P. G.; Kuschnig, R.; Houdek, G.; Kallinger, T.;
Weiss, W. W.; Palle, P. L.; Grundahl, F.; Hatzes, A.; Parviainen, H.;
Allende Prieto, C.; Deeg, H. J.; Jiménez, A.; Mathur, S.; Garcia,
R. A.; White, T. R.; Bedding, T. R.; Grossmann, D. H.; Janisch, S.;
Zaqarashvili, T.; Hanslmeier, A.; Zwintz, K.
2020svos.conf...75B Altcode: 2020arXiv200104912B
Solar-like oscillations in red-giant stars are now commonly detected
in thousands of stars with space telescopes such as Kepler. Parallel
radial-velocity and photometric measurements would help us understand
better the physics governing the amplitudes of solar-like oscillators,
but most stars targetted for space photometry are too faint for
light-demanding ground-based spectroscopy. The BRITE-Constellation
provides a unique opportunity of monitoring in two colours the flux
variations of bright luminous red giants. Those stars are also bright
enough to be monitored with high-resolution spectrographs on small
telescopes, such as the SONG Network. This contribution provided a
first overview of our comprehensive, multi-year campaign to use both
BRITE and SONG to characterize Aldebaran (one of the brightest red
giants in the sky) seismically. Because luminous red giants can be
seen at large distances, when characterized well they will serve as
valuable benchmark stars for Galactic archeology.
---------------------------------------------------------
Title: The Pristine survey - VI. The first three years of
medium-resolution follow-up spectroscopy of Pristine EMP star
candidates
Authors: Aguado, David S.; Youakim, Kris; González Hernández,
Jonay I.; Allende Prieto, Carlos; Starkenburg, Else; Martin, Nicolas;
Bonifacio, Piercarlo; Arentsen, Anke; Caffau, Elisabetta; Peralta
de Arriba, Luis; Sestito, Federico; Garcia-Dias, Rafael; Fantin,
Nicholas; Hill, Vanessa; Jablonca, Pascale; Jahandar, Farbod; Kielty,
Collin; Longeard, Nicolas; Lucchesi, Romain; Sánchez-Janssen, Rubén;
Osorio, Yeisson; Palicio, Pedro A.; Tolstoy, Eline; Wilson, Thomas
G.; Côté, Patrick; Kordopatis, Georges; Lardo, Carmela; Navarro,
Julio F.; Thomas, Guillaume F.; Venn, Kim
2019MNRAS.490.2241A Altcode: 2019MNRAS.tmp.2271A; 2019arXiv190908138A
We present the results of a 3-yr long, medium-resolution spectroscopic
campaign aimed at identifying very metal-poor stars from candidates
selected with the CaHK, metallicity-sensitive Pristine survey. The
catalogue consists of a total of 1007 stars, and includes 146
rediscoveries of metal-poor stars already presented in previous
surveys, 707 new very metal-poor stars with [Fe/H] < -2.0, and
95 new extremely metal-poor stars with [Fe/H] < -3.0. We provide
a spectroscopic [Fe/H] for every star in the catalogue, and [C/Fe]
measurements for a subset of the stars (10 per cent with [Fe/H] <
-3 and 24 per cent with -3 < [Fe/H] < -2) for which a carbon
determination is possible, contingent mainly on the carbon abundance,
effective temperature and signal-to-noise ratio of the stellar
spectra. We find an average carbon enhancement fraction ([C/Fe] ≥
+0.7) of 41 ± 4 per cent for stars with -3 < [Fe/H] < -2 and
58 ± 14 per cent for stars with [Fe/H] < -3, and report updated
success rates for the Pristine survey of 56 per cent and 23 per cent to
recover stars with [Fe/H] < -2.5 and < -3, respectively. Finally,
we discuss the current status of the survey and its preparation for
providing targets to upcoming multi-object spectroscopic surveys such
as William Herschel Telescope Enhanced Area Velocity Explorer.
---------------------------------------------------------
Title: IMF radial gradients in most massive early-type galaxies
Authors: La Barbera, F.; Vazdekis, A.; Ferreras, I.; Pasquali, A.;
Allende Prieto, C.; Martín-Navarro, I.; Aguado, D. S.; de Carvalho,
R. R.; Rembold, S.; Falcón-Barroso, J.; van de Ven, G.
2019MNRAS.489.4090L Altcode: 2019MNRAS.tmp.2005L; 2019MNRAS.tmp.2186L; 2019arXiv190901382L
Using new long-slit spectroscopy obtained with X-Shooter at ESO-VLT,
we study, for the first time, radial gradients of optical and
near-infrared initial mass function (IMF)-sensitive features in a
representative sample of galaxies at the very high mass end of the
galaxy population. The sample consists of seven early-type galaxies
(ETGs) at z ∼ 0.05, with central velocity dispersion in the range
300 ≲ σ ≲ 350 km s<SUP>-1</SUP>. Using state-of-the-art stellar
population synthesis models, we fit a number of spectral indices, from
different chemical species (including TiO and Na indices), to constrain
the IMF slope (i.e. the fraction of low-mass stars), as a function of
galactocentric distance, over a radial range out to ∼4 kpc. ETGs in
our sample show a significant correlation of IMF slope and surface mass
density. The bottom-heavy population (i.e. an excess of low-mass stars
in the IMF) is confined to central galaxy regions with surface mass
density above ∼ 10^{10} M_⊙ kpc^{-2}, or, alternatively, within a
characteristic radius of ∼2 kpc. Radial distance, in physical units,
and surface mass density are the best correlators to IMF variations,
with respect to other dynamical (e.g. velocity dispersion) and stellar
population (e.g. metallicity) properties. Our results for the most
massive galaxies suggest that there is no single parameter that fully
explains variations in the stellar IMF, but IMF radial profiles at
z ∼ 0 rather result from the complex formation and mass accretion
history of galaxy inner and outer regions.
---------------------------------------------------------
Title: The Dark Energy Spectroscopic Instrument (DESI)
Authors: Levi, Michael; Allen, Lori E.; Raichoor, Anand; Baltay,
Charles; BenZvi, Segev; Beutler, Florian; Bolton, Adam; Castander,
Francisco J.; Chuang, Chia-Hsun; Cooper, Andrew; Cuby, Jean-Gabriel;
Dey, Arjun; Eisenstein, Daniel; Fan, Xiaohui; Flaugher, Brenna; Frenk,
Carlos; Gonzalez-Morales, Alma X.; Graur, Or; Guy, Julien; Habib,
Salman; Honscheid, Klaus; Juneau, Stephanie; Kneib, Jean-Paul; Lahav,
Ofer; Lang, Dustin; Leauthaud, Alexie; Lusso, Betta; de la Macorra,
Axel; Manera, Marc; Martini, Paul; Mao, Shude; Newman, Jeffrey A.;
Palanque-Delabrouille, Nathalie; Percival, Will J.; Allende Prieto,
Carlos; Rockosi, Constance M.; Ruhlmann-Kleider, Vanina; Schlegel,
David; Seo, Hee-Jong; Song, Yong-Seon; Tarle, Greg; Wechsler, Risa;
Weinberg, David; Yeche, Christophe; Zu, Ying
2019BAAS...51g..57L Altcode: 2019astro2020U..57L; 2019arXiv190710688L
We present the status of the Dark Energy Spectroscopic Instrument
(DESI) and its plans and opportunities for the coming decade. DESI is
an approved experiment of the U.S. Department of Energy. Beyond 2025,
we expect that DESI will remain one of the world's best facilities
for wide-field spectroscopy throughout the decade.
---------------------------------------------------------
Title: Machine learning in APOGEE. Identification of stellar
populations through chemical abundances
Authors: Garcia-Dias, Rafael; Allende Prieto, Carlos; Sánchez Almeida,
Jorge; Alonso Palicio, Pedro
2019A&A...629A..34G Altcode: 2019arXiv190712796G
Context. The vast volume of data generated by modern astronomical
surveys offers test beds for the application of machine-learning. In
these exploratory applications, it is important to evaluate potential
existing tools and determine those that are optimal for extracting
scientific knowledge from the available observations. <BR /> Aims: We
explore the possibility of using unsupervised clustering algorithms to
separate stellar populations with distinct chemical patterns. <BR />
Methods: Star clusters are likely the most chemically homogeneous
populations in the Galaxy, and therefore any practical approach
to identifying distinct stellar populations should at least be
able to separate clusters from each other. We have applied eight
clustering algorithms combined with four dimensionality reduction
strategies to automatically distinguish stellar clusters using
chemical abundances of 13 elements. Our test-bed sample includes
18 stellar clusters with a total of 453 stars. <BR /> Results: We
have applied statistical tests showing that some pairs of clusters
(e.g., NGC 2458-NGC 2420) are indistinguishable from each other
when chemical abundances from the Apache Point Galactic Evolution
Experiment (APOGEE) are used. However, for most clusters we are able
to automatically assign membership with metric scores similar to
previous works. The confusion level of the automatically selected
clusters is consistent with statistical tests that demonstrate the
impossibility of perfectly distinguishing all the clusters from each
other. These statistical tests and confusion levels establish a limit
for the prospect of blindly identifying stars born in the same cluster
based solely on chemical abundances. Conclusion. We find that some
of the algorithms we explored are capable of blindly identify stellar
populations with similar ages and chemical distributions in the APOGEE
data. Even though we are not able to fully separate the clusters
from each other, the main confusion arises from clusters with similar
ages. Because some stellar clusters are chemically indistinguishable,
our study supports the notion of extending weak chemical tagging that
involves families of clusters instead of individual clusters. <P />The
list of stars is only available at the CDS via anonymous ftp to <A
href="http://cdsarc.u-strasbg.fr/">http://cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/629/A34">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/629/A34</A>
---------------------------------------------------------
Title: VizieR Online Data Catalog: APOGEE stars members of 35 star
clusters (Garcia-Dias+, 2019)
Authors: Garcia-Dias, R.; Allende Prieto, C.; Sanchez Almeida, J.;
Alonso Palicio, P.
2019yCat..36290034G Altcode:
Initial list of stars used in the article. <P />(1 data file).
---------------------------------------------------------
Title: The Challenges of Observing, Calibrating, and Modeling Stellar
Spectral Energy Distributions
Authors: Allende Prieto, Carlos
2019ASPC..519....3A Altcode: 2019arXiv190306859A
While optical and quantum efficiency are on the rise, and spectrographs
becoming massively multiplexed, measuring spectral energy distributions
of astronomical sources with accuracy remains a challenge. In
addition to atmospheric refraction, extinction, variability, and
limited apertures of instrument entrance slits and optical fibers,
accurate calibration is hampered by issues such as a limited choice of
reliable standard stars. Modeling stellar spectral energy distributions
has seen good progress, but some weaknesses survive, especially for
late-type stars. This article provides an overview of these matters
and discusses observation, calibration, and modeling strategies for
future large spectroscopic surveys.
---------------------------------------------------------
Title: Stellar spectral models compared with empirical data
Authors: Knowles, Adam T.; Sansom, A. E.; Coelho, P. R. T.; Allende
Prieto, C.; Conroy, C.; Vazdekis, A.
2019MNRAS.486.1814K Altcode: 2019MNRAS.tmp..721K
The empirical MILES stellar library is used to test the accuracy
of three different, state-of-the-art, theoretical model libraries
of stellar spectra. These models are widely used in the literature
for stellar population analysis. A differential approach is used so
that responses to elemental abundance changes are tested rather than
absolute levels of the theoretical spectra. First we directly compare
model line strengths and spectra to empirical data to investigate
trends. Then we test how well line strengths match when element
response functions are used to account for changes in [α/Fe]
abundances. The aim is to find out where models best represent
real star spectra, in a differential way, and hence identify good
choices of models to use in stellar population analysis involving
abundance patterns. We find that most spectral line strengths are well
represented by these models, particularly iron- and sodium-sensitive
indices. Exceptions include the higher order Balmer lines (Hδ, Hγ),
in which the models show more variation than the data, particularly at
low temperatures. C<SUB>2</SUB>4668 is systematically underestimated by
the models compared to observations. We find that differences between
these models are generally less significant than the ways in which
models vary from the data. Corrections to C<SUB>2</SUB> line lists
for one set of models are identified, improving them for future use.
---------------------------------------------------------
Title: Mass Spectroscopy of the Milky Way
Authors: Dey, Arjun; Najita, Joan R.; Koposov, Sergey; Rockosi,
Connie; Li, Ting; Olsen, Knut; Allende Prieto, Carlos; Bonaca, Ana;
Besla, Gurtina; Garavito-Camargo, Nicolas; Allen, Lori; Gansicke,
Boris; Bolton, Adam; Bell, Eric F.; Johnson, Jennifer; Wang, Mei-Yu;
Valluri, Monica; Hattori, Kohei; Cooper, Andrew; Meisner, Aaron; Wyse,
Rosemary; Nidever, David; Ting, Yuan-Sen; Kollmeier, Juna; Cunha, Katia
2019BAAS...51c.489D Altcode: 2019astro2020T.489D
Massively multiplexed spectroscopic surveys of Milky Way stars will
revolutionize our understanding of our Galaxy's structural components,
revealing their past history and the small-scale structure of its
dark matter halo. A spectroscopic survey of 10<SUP>8</SUP> stars,
previously unimaginable, is now within reach of new instruments in
the coming decade.
---------------------------------------------------------
Title: VizieR Online Data Catalog: Pristine survey II. Bright stars
abundances (Caffau+, 2017)
Authors: Caffau, E.; Bonifacio, P.; Starkenburg, E.; Martin, N.;
Youakim, K.; Henden, A. A.; Gonzalez Hernandez, J. I.; Aguado, D. S.;
Allende Prieto, C.; Venn, K.; Jablonka, P.
2019yCat.113380686C Altcode:
Atmospheric parameters and radial velocities for 27 stars and detailed
abundances for 23 stars. <P />(2 data files).
---------------------------------------------------------
Title: Back to the Lithium Plateau with the [Fe/H] < -6 Star
J0023+0307
Authors: Aguado, David S.; González Hernández, Jonay I.; Allende
Prieto, Carlos; Rebolo, Rafael
2019ApJ...874L..21A Altcode: 2019arXiv190404892A
We present an analysis of the Ultraviolet and Visual Echelle
Spectrograph (UVES) high-resolution spectroscopic observations at the
8.2 m Very Large Telescope of J0023+0307, a main-sequence extremely
iron-poor dwarf star. We are unable to detect iron lines in the spectrum
but derive [Fe/H] < -6.1 from the Ca II resonance lines assuming
[Ca/Fe] ≥ 0.40. The chemical abundance pattern of J0023+0307,
with very low [Fe/Mg] and [Ca/Mg] abundance ratios but relatively
high absolute Mg and Si abundances, suggests J0023+0307 is a second
generation star formed from a molecular cloud polluted by only one
supernova in which the fallback mechanism played a role. We measure a
carbon abundance of A(C) = 6.2 that places J0023+0307 on the low band
in the A(C)-[Fe/H] diagram, suggesting no contamination from a binary
companion. This star is also unique having a lithium abundance A(Li) =
2.02 ± 0.08, close to the level of the lithium plateau, in contrast
with lower Li determinations or upper limits in all other extremely
iron-poor stars. The upper envelope of the lithium abundances in
unevolved stars spanning more than three orders of magnitude in
metallicity (-6 < [Fe/H] < -2.5) defines a nearly constant
value. We argue that it is unlikely that such uniformity is the result
of depletion processes in stars from a significantly higher initial
Li abundance, but suggests instead a lower primordial production,
pointing to new physics such as decaying massive particles, varying
fundamental constants, or nuclear resonances, that could have affected
the primordial <SUP>7</SUP>Li production. <P />Based on observations
made with Very Large Telescope (VLT) at Paranal Observatory, Chile.
---------------------------------------------------------
Title: Ca line formation in late-type stellar atmospheres. I. The
model atom
Authors: Osorio, Y.; Lind, K.; Barklem, P. S.; Allende Prieto, C.;
Zatsarinny, O.
2019A&A...623A.103O Altcode: 2019arXiv190111442O
Context. Departures from local thermodynamic equilibrium (LTE) distort
the calcium abundance derived from stellar spectra in various ways,
depending on the lines used and the stellar atmospheric parameters. The
collection of atomic data adopted in non-LTE (NLTE) calculations
must be sufficiently complete and accurate. <BR /> Aims: We derive
NLTE abundances from high-quality observations and reliable stellar
parameters using a model atom built afresh for this work, and check the
consistency of our results over a wide wavelength range with transitions
of atomic and singly ionised calcium. <BR /> Methods: We built and
tested Ca I and Ca II model atoms with state-of-the-art radiative
and collisional data, and tested their performance deriving the Ca
abundance in three benchmark stars: Procyon, the Sun, and Arcturus. We
have excellent-quality observations and accurate stellar parameters for
these stars. Two methods to derive the LTE/NLTE abundances were used
and compared. The LTE/NLTE centre-to-limb variation (CLV) of Ca lines
in the Sun was also investigated. <BR /> Results: The two methods used
give similar results in all three stars. Several discrepancies found
in LTE do not appear in our NLTE results; in particular the agreement
between abundances in the visual and infra-red (IR) and the Ca I and
Ca II ionisation balance is improved overall, although substantial
line-to-line scatter remains. The CLV of the calcium lines around 6165
Å can be partially reproduced. We suspect differences between our
modelling and CLV results are due to inhomogeneities in the atmosphere
that require 3D modelling.
---------------------------------------------------------
Title: Chemical Abundances of Main-sequence, Turnoff, Subgiant, and
Red Giant Stars from APOGEE Spectra. II. Atomic Diffusion in M67 Stars
Authors: Souto, Diogo; Allende Prieto, C.; Cunha, Katia; Pinsonneault,
Marc; Smith, Verne V.; Garcia-Dias, R.; Bovy, Jo; García-Hernández,
D. A.; Holtzman, Jon; Johnson, J. A.; Jönsson, Henrik; Majewski,
Steve R.; Shetrone, Matthew; Sobeck, Jennifer; Zamora, Olga; Pan,
Kaike; Nitschelm, Christian
2019ApJ...874...97S Altcode: 2019arXiv190210199S
Chemical abundances for 15 elements (C, N, O, Na, Mg, Al, Si, K, Ca,
Ti, V, Cr, Mn, Fe, and Ni) are presented for 83 stellar members of
the 4 Gyr old solar-metallicity open cluster M67. The sample contains
stars spanning a wide range of evolutionary phases, from G dwarfs to
red clump stars. The abundances were derived from near-IR (λ1.5-1.7
μm) high-resolution spectra (R = 22,500) from the SDSS-IV/Apache
Point Observatory Galactic Evolution Experiment (APOGEE) survey. A 1D
local thermodynamic equilibrium abundance analysis was carried out
using the APOGEE synthetic spectral libraries, via χ<SUP>2</SUP>
minimization of the synthetic and observed spectra with the qASPCAP
code. We found significant abundance differences (∼0.05-0.30 dex)
between the M67 member stars as a function of the stellar mass (or
position on the Hertzsprung-Russell diagram), where the abundance
patterns exhibit a general depletion (in [X/H]) in stars at the
main-sequence turnoff. The amount of the depletion is different for
different elements. We find that atomic diffusion models provide, in
general, good agreement with the abundance trends for most chemical
species, supporting recent studies indicating that measurable atomic
diffusion operates in M67 stars.
---------------------------------------------------------
Title: VizieR Online Data Catalog: Stellar parameters &
abund. from BACCHUS analysis (Jonsson+, 2018)
Authors: Jonsson, H.; Allende Prieto, C.; Holtzman, J. A.; Feuillet,
D. K.; Hawkins, K.; Cunha, K.; Meszaros, S.; Hasselquist, S.;
Fernandez-Trincado, J. G.; Garcia-Hernandez, D. A.; Bizyaev, D.;
Carrera, R.; Majewski, S. R.; Pinsonneault, M. H.; Shetrone, M.; Smith,
V.; Sobeck, J.; Souto, D.; Stringfellow, G. S.; Teske, J.; Zamora, O.
2019yCat..51560126J Altcode:
We have observed a sample of 100 stars using the optical spectrometer
ARCES (R~32000) on the Apache Point 3.5 m telescope. The stars
were chosen from the APOGEE catalog to have a spread in stellar
parameters, and include both dwarfs and giants with a wide range
of metallicities. The stars have 0.0<V<11.1 and the spectra
have an S/N that ranges from 50=<S/N=<300, with a median S/N
of 115 around 6000 Å. For determination of the stellar parameters
as well as the abundances of O, Na, Mg, Al, Si, S, K, Ca, Ti, V, Cr,
Mn, Co, Ni, Cu, Rb, and Y, we used the Brussels Automatic Code for
Characterizing High AccUracy Spectra (henceforth BACCHUS; Masseron
et al. 2016ascl.soft05004M). BACCHUS is a stellar parameter and
abundance analysis pipeline that uses Turbospectrum in combination
with MARCS spherical 1D LTE models. The model atmosphere grid is
alpha-enhanced for the lower metallicities according to the "standard"
MARCS scheme. The stellar parameters are determined in the classical
way, demanding excitation and ionization equilibrium using a set of Fe
I and Fe II lines. The analysis performed is similar to that described
in Hawkins et al. (2015MNRAS.447.2046H), with the exception of the
line list used: here we used the Gaia-ESO line list (v.5, U. Heiter et
al. 2015PhyS...90e4010H, 2018, in preparation), complemented with line
information from the VALD database (Kupka et al. 2000BaltA...9..590K;
Ryabchikova et al. 2015PhyS...90e4005R) for the non-covered wavelength
regimes in the Gaia-ESO list. <P />(3 data files).
---------------------------------------------------------
Title: Chemical Cartography with APOGEE: Multi-element Abundance
Ratios
Authors: Weinberg, David H.; Holtzman, Jon A.; Hasselquist, Sten;
Bird, Jonathan C.; Johnson, Jennifer A.; Shetrone, Matthew; Sobeck,
Jennifer; Allende Prieto, Carlos; Bizyaev, Dmitry; Carrera, Ricardo;
Cohen, Roger E.; Cunha, Katia; Ebelke, Garrett; Fernandez-Trincado,
J. G.; García-Hernández, D. A.; Hayes, Christian R.; Jönsson,
Henrik; Lane, Richard R.; Majewski, Steven R.; Malanushenko, Viktor;
Mészáros, Szabolcs; Nidever, David L.; Nitschelm, Christian; Pan,
Kaike; Rix, Hans-Walter; Rybizki, Jan; Schiavon, Ricardo P.; Schneider,
Donald P.; Wilson, John C.; Zamora, Olga
2019ApJ...874..102W Altcode: 2018arXiv181012325W
We map the trends of elemental abundance ratios across the Galactic
disk, spanning R=3{--}15 {kpc} and midplane distance | Z| =0{--}2 {kpc},
for 15 elements in a sample of 20,485 stars measured by the SDSS/APOGEE
survey (O, Na, Mg, Al, Si, P, S, K, Ca, V, Cr, Mn, Fe, Co, Ni). Adopting
Mg rather than Fe as our reference element, and separating stars into
two populations based on [Fe/Mg], we find that the median trends of
[X/Mg] versus [Mg/H] in each population are nearly independent of
location in the Galaxy. The full multi-element cartography can be
summarized by combining these nearly universal median sequences with
our measured metallicity distribution functions and the relative
proportions of the low-[Fe/Mg] (high-α) and high-[Fe/Mg] (low-α)
populations, which depend strongly on R and | Z| . We interpret the
median sequences with a semi-empirical “two-process” model that
describes both the ratio of core collapse and Type Ia supernova (SN Ia)
contributions to each element and the metallicity dependence of the
supernova yields. These observationally inferred trends can provide
strong tests of supernova nucleosynthesis calculations. Our results
lead to a relatively simple picture of abundance ratio variations in
the Milky Way, in which the trends at any location can be described
as the sum of two components with relative contributions that change
systematically and smoothly across the Galaxy. Deviations from this
picture and future extensions to other elements can provide further
insights into the physics of stellar nucleosynthesis and unusual events
in the Galaxy’s history.
---------------------------------------------------------
Title: Identifying Sagittarius Stream Stars by Their APOGEE Chemical
Abundance Signatures
Authors: Hasselquist, Sten; Carlin, Jeffrey L.; Holtzman, Jon A.;
Shetrone, Matthew; Hayes, Christian R.; Cunha, Katia; Smith, Verne;
Beaton, Rachael L.; Sobeck, Jennifer; Allende Prieto, Carlos; Majewski,
Steven R.; Anguiano, Borja; Bizyaev, Dmitry; García-Hernández, D. A.;
Lane, Richard R.; Pan, Kaike; Nidever, David L.; Fernández-Trincado,
José. G.; Wilson, John C.; Zamora, Olga
2019ApJ...872...58H Altcode: 2019arXiv190104559H
The SDSS-IV Apache Point Observatory Galactic Evolution Experiment
(APOGEE) survey provides precise chemical abundances of 18 chemical
elements for ∼176,000 red giant stars distributed over much of
the Milky Way Galaxy (MW), and includes observations of the core of
the Sagittarius dwarf spheroidal galaxy (Sgr). The APOGEE chemical
abundance patterns of Sgr have revealed that it is chemically distinct
from the MW in most chemical elements. We employ a k-means clustering
algorithm to six-dimensional chemical space defined by [(C+N)/Fe],
[O/Fe], [Mg/Fe], [Al/Fe], [Mn/Fe], and [Ni/Fe] to identify 62 MW stars
in the APOGEE sample that have Sgr-like chemical abundances. Of the
62 stars, 35 have Gaia kinematics and positions consistent with those
predicted by N-body simulations of the Sgr stream, and are likely
stars that have been stripped from Sgr during the last two pericenter
passages (<2 Gyr ago). Another 20 of the 62 stars exhibit chemical
abundances indistinguishable from the Sgr stream stars, but are on
highly eccentric orbits with median r <SUB>apo</SUB> ∼ 25 kpc. These
stars are likely the “accreted” halo population thought to be the
result of a separate merger with the MW 8-11 Gyr ago. We also find one
hypervelocity star candidate. We conclude that Sgr was enriched to
[Fe/H] ∼ -0.2 before its most recent pericenter passage. If the
“accreted halo” population is from one major accretion event,
then this progenitor galaxy was enriched to at least [Fe/H] ∼ -0.6,
and had a similar star formation history to Sgr before merging.
---------------------------------------------------------
Title: Homogeneous analysis of globular clusters from the APOGEE
survey with the BACCHUS code. I. The northern clusters
Authors: Masseron, T.; García-Hernández, D. A.; Mészáros, Sz.;
Zamora, O.; Dell'Agli, F.; Allende Prieto, C.; Edvardsson, B.;
Shetrone, M.; Plez, B.; Fernández-Trincado, J. G.; Cunha, K.;
Jönsson, H.; Geisler, D.; Beers, T. C.; Cohen, R. E.
2019A&A...622A.191M Altcode: 2018arXiv181208817M
<BR /> Aims: We seek to provide abundances of a large set of light
and neutron-capture elements homogeneously analyzed that cover a wide
range of metallicity to constrain globular cluster (GC) formation
and evolution models. <BR /> Methods: We analyzed a large sample of
885 GCs giants from the SDSS IV-Apache Point Observatory Galactic
Evolution Experiment (APOGEE) survey. We used the Cannon results to
separate the red giant branch and asymptotic giant branch stars, not
only allowing for a refinement of surface gravity from isochrones,
but also providing an independent H-band spectroscopic method to
distinguish stellar evolutionary status in clusters. We then used
the Brussels Automatic Code for Characterizing High accUracy Spectra
(BACCHUS) to derive metallicity, microturbulence, macroturbulence, many
light-element abundances, and the neutron-capture elements Nd and Ce for
the first time from the APOGEE GCs data. <BR /> Results: Our independent
analysis helped us to diagnose issues regarding the standard analysis
of the APOGEE DR14 for low-metallicity GC stars. Furthermore, while we
confirm most of the known correlations and anticorrelation trends (Na-O,
Mg-Al, C-N), we discover that some stars within our most metal-poor
clusters show an extreme Mg depletion and some Si enhancement. At the
same time, these stars show some relative Al depletion, displaying a
turnover in the Mg-Al diagram. These stars suggest that Al has been
partially depleted in their progenitors by very hot proton-capture
nucleosynthetic processes. Furthermore, we attempted to quantitatively
correlate the spread of Al abundances with the global properties of
GCs. We find an anticorrelation of the Al spread against clusters
metallicity and luminosity, but the data do not allow us to find clear
evidence of a dependence of N against metallicity in the more metal-poor
clusters. <BR /> Conclusions: Large and homogeneously analyzed samples
from ongoing spectroscopic surveys unveil unseen chemical details
for many clusters, including a turnover in the Mg-Al anticorrelation,
thus yielding new constrains for GCs formation/evolution models. <P
/>Full Table 2 is only available at the CDS via anonymous ftp to <A
href="http://cdsarc.u-strasbg.fr/">http://cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/622/A191">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/622/A191</A>
---------------------------------------------------------
Title: VizieR Online Data Catalog: 885 globular cluster giants
abundances (Masseron+, 2019)
Authors: Masseron, T.; Garcia-Hernandez, D. A.; Meszaros, S.; Zamora,
O.; Dell'Agli, F.; Allende Prieto, C.; Edvardsson, B.; Shetrone, M.;
Plez, B.; Fernandez-Trincado, J. G.; Cunha, K.; Jonsson, H.; Geisler,
D.; Beers, T. C.; Cohen, R. E.
2019yCat..36220191M Altcode:
We investigated the abundances of ten elements (C, N, O, Mg, Al, Si,
K, and Ca, Ce and Nd), for 885 stars in 10 globular clusters (NGC
7078, NGC 6341, NGC 5024, NGC 5466, NGC 6205, NGC 7089, NGC 5272, NGC
5904, NGC 6171, and NGC 6838) using Apache Point Observatory Galactic
Evolution Experiment (APOGEE; Majewski et al. 2015, Cat. J/AJ/149/7)
DR14 spectra. We make use of photometry and theoretical isochrones to
constrain the effective temperature (Teff) and surface gravity log(g)
and the stellar evolutionnary status (RGB, HB, or early AGB). The
abundances are derived by line fitting with the automatic code BACCHUS
(Masseron, Merle & Hawkins, 2016ascl.soft05004M), which uses
MARCS model atmospheres andf the APOGEE DR14 atomic and molecular
linelists. <P />(1 data file).
---------------------------------------------------------
Title: J-PLUS: The Javalambre Photometric Local Universe Survey
Authors: Cenarro, A. J.; Moles, M.; Cristóbal-Hornillos, D.;
Marín-Franch, A.; Ederoclite, A.; Varela, J.; López-Sanjuan,
C.; Hernández-Monteagudo, C.; Angulo, R. E.; Vázquez Ramió, H.;
Viironen, K.; Bonoli, S.; Orsi, A. A.; Hurier, G.; San Roman, I.;
Greisel, N.; Vilella-Rojo, G.; Díaz-García, L. A.; Logroño-García,
R.; Gurung-López, S.; Spinoso, D.; Izquierdo-Villalba, D.;
Aguerri, J. A. L.; Allende Prieto, C.; Bonatto, C.; Carvano, J. M.;
Chies-Santos, A. L.; Daflon, S.; Dupke, R. A.; Falcón-Barroso, J.;
Gonçalves, D. R.; Jiménez-Teja, Y.; Molino, A.; Placco, V. M.;
Solano, E.; Whitten, D. D.; Abril, J.; Antón, J. L.; Bello, R.;
Bielsa de Toledo, S.; Castillo-Ramírez, J.; Chueca, S.; Civera, T.;
Díaz-Martín, M. C.; Domínguez-Martínez, M.; Garzarán-Calderaro,
J.; Hernández-Fuertes, J.; Iglesias-Marzoa, R.; Iñiguez, C.;
Jiménez Ruiz, J. M.; Kruuse, K.; Lamadrid, J. L.; Lasso-Cabrera, N.;
López-Alegre, G.; López-Sainz, A.; Maícas, N.; Moreno-Signes, A.;
Muniesa, D. J.; Rodríguez-Llano, S.; Rueda-Teruel, F.; Rueda-Teruel,
S.; Soriano-Laguía, I.; Tilve, V.; Valdivielso, L.; Yanes-Díaz, A.;
Alcaniz, J. S.; Mendes de Oliveira, C.; Sodré, L.; Coelho, P.; Lopes
de Oliveira, R.; Tamm, A.; Xavier, H. S.; Abramo, L. R.; Akras, S.;
Alfaro, E. J.; Alvarez-Candal, A.; Ascaso, B.; Beasley, M. A.; Beers,
T. C.; Borges Fernandes, M.; Bruzual, G. R.; Buzzo, M. L.; Carrasco,
J. M.; Cepa, J.; Cortesi, A.; Costa-Duarte, M. V.; De Prá, M.; Favole,
G.; Galarza, A.; Galbany, L.; Garcia, K.; González Delgado, R. M.;
González-Serrano, J. I.; Gutiérrez-Soto, L. A.; Hernandez-Jimenez,
J. A.; Kanaan, A.; Kuncarayakti, H.; Landim, R. C. G.; Laur, J.;
Licandro, J.; Lima Neto, G. B.; Lyman, J. D.; Maíz Apellániz,
J.; Miralda-Escudé, J.; Morate, D.; Nogueira-Cavalcante, J. P.;
Novais, P. M.; Oncins, M.; Oteo, I.; Overzier, R. A.; Pereira,
C. B.; Rebassa-Mansergas, A.; Reis, R. R. R.; Roig, F.; Sako, M.;
Salvador-Rusiñol, N.; Sampedro, L.; Sánchez-Blázquez, P.; Santos,
W. A.; Schmidtobreick, L.; Siffert, B. B.; Telles, E.; Vilchez, J. M.
2019A&A...622A.176C Altcode: 2018arXiv180402667C
The Javalambre Photometric Local Universe Survey (J-PLUS ) is an
ongoing 12-band photometric optical survey, observing thousands
of square degrees of the Northern Hemisphere from the dedicated
JAST/T80 telescope at the Observatorio Astrofísico de Javalambre
(OAJ). The T80Cam is a camera with a field of view of 2 deg<SUP>2</SUP>
mounted on a telescope with a diameter of 83 cm, and is equipped
with a unique system of filters spanning the entire optical range
(3500-10 000 Å). This filter system is a combination of broad-,
medium-, and narrow-band filters, optimally designed to extract the
rest-frame spectral features (the 3700-4000 Å Balmer break region,
Hδ, Ca H+K, the G band, and the Mg b and Ca triplets) that are key
to characterizing stellar types and delivering a low-resolution
photospectrum for each pixel of the observed sky. With a typical
depth of AB ∼21.25 mag per band, this filter set thus allows for an
unbiased and accurate characterization of the stellar population in
our Galaxy, it provides an unprecedented 2D photospectral information
for all resolved galaxies in the local Universe, as well as accurate
photo-z estimates (at the δ z/(1 + z)∼0.005-0.03 precision level)
for moderately bright (up to r ∼ 20 mag) extragalactic sources. While
some narrow-band filters are designed for the study of particular
emission features ([O II]/λ3727, Hα/λ6563) up to z < 0.017, they
also provide well-defined windows for the analysis of other emission
lines at higher redshifts. As a result, J-PLUS has the potential to
contribute to a wide range of fields in Astrophysics, both in the
nearby Universe (Milky Way structure, globular clusters, 2D IFU-like
studies, stellar populations of nearby and moderate-redshift galaxies,
clusters of galaxies) and at high redshifts (emission-line galaxies
at z ≈ 0.77, 2.2, and 4.4, quasi-stellar objects, etc.). With this
paper, we release the first ∼1000 deg<SUP>2</SUP> of J-PLUS data,
containing about 4.3 million stars and 3.0 million galaxies at r <
21 mag. With a goal of 8500 deg<SUP>2</SUP> for the total J-PLUS
footprint, these numbers are expected to rise to about 35 million
stars and 24 million galaxies by the end of the survey.
---------------------------------------------------------
Title: Gaia Data Release 2. Properties and validation of the radial
velocities
Authors: Katz, D.; Sartoretti, P.; Cropper, M.; Panuzzo, P.;
Seabroke, G. M.; Viala, Y.; Benson, K.; Blomme, R.; Jasniewicz,
G.; Jean-Antoine, A.; Huckle, H.; Smith, M.; Baker, S.; Crifo,
F.; Damerdji, Y.; David, M.; Dolding, C.; Frémat, Y.; Gosset, E.;
Guerrier, A.; Guy, L. P.; Haigron, R.; Janßen, K.; Marchal, O.;
Plum, G.; Soubiran, C.; Thévenin, F.; Ajaj, M.; Allende Prieto, C.;
Babusiaux, C.; Boudreault, S.; Chemin, L.; Delle Luche, C.; Fabre, C.;
Gueguen, A.; Hambly, N. C.; Lasne, Y.; Meynadier, F.; Pailler, F.;
Panem, C.; Royer, F.; Tauran, G.; Zurbach, C.; Zwitter, T.; Arenou,
F.; Bossini, D.; Gerssen, J.; Gómez, A.; Lemaitre, V.; Leclerc, N.;
Morel, T.; Munari, U.; Turon, C.; Vallenari, A.; Žerjal, M.
2019A&A...622A.205K Altcode: 2018arXiv180409372K
Context. For Gaia DR2, 280 million spectra collected by the Radial
Velocity Spectrometer instrument on board Gaia were processed, and
median radial velocities were derived for 9.8 million sources brighter
than G<SUB>RVS</SUB> = 12 mag. <BR /> Aims: This paper describes the
validation and properties of the median radial velocities published
in Gaia DR2. <BR /> Methods: Quality tests and filters were applied to
select those of the 9.8 million radial velocities that have the quality
to be published in Gaia DR2. The accuracy of the selected sample was
assessed with respect to ground-based catalogues. Its precision was
estimated using both ground-based catalogues and the distribution of the
Gaia radial velocity uncertainties. <BR /> Results: Gaia DR2 contains
median radial velocities for 7 224 631 stars, with T<SUB>eff</SUB>
in the range [3550, 6900] K, which successfully passed the quality
tests. The published median radial velocities provide a full-sky
coverage and are complete with respect to the astrometric data to within
77.2% (for G ≤ 12.5 mag). The median radial velocity residuals with
respect to the ground-based surveys vary from one catalogue to another,
but do not exceed a few 100 m s<SUP>-1</SUP>. In addition, the Gaia
radial velocities show a positive trend as a function of magnitude,
which starts around G<SUB>RVS</SUB> 9 mag and reaches about + 500 m
s<SUP>-1</SUP> at G<SUB>RVS</SUB> = 11.75 mag. The origin of the trend
is under investigation, with the aim to correct for it in Gaia DR3. The
overall precision, estimated from the median of the Gaia radial velocity
uncertainties, is 1.05 km s<SUP>-1</SUP>. The radial velocity precision
is a function of many parameters, in particular, the magnitude and
effective temperature. For bright stars, G<SUB>RVS</SUB> ∈ [4, 8] mag,
the precision, estimated using the full dataset, is in the range 220-350
m s<SUP>-1</SUP>, which is about three to five times more precise than
the pre-launch specification of 1 km s<SUP>-1</SUP>. At the faint end,
G<SUB>RVS</SUB> = 11.75 mag, the precisions for T<SUB>eff</SUB> =
5000 and 6500 K are 1.4 and 3.7 km s<SUP>-1</SUP>, respectively.
---------------------------------------------------------
Title: Radial Velocities in the Outermost Disk toward the Anticenter
Authors: López-Corredoira, M.; Sylos Labini, F.; Kalberla, P. M. W.;
Allende Prieto, C.
2019AJ....157...26L Altcode: 2019arXiv190101300L
We measure the mean Galactocentric radial component of the velocity
of stars (v <SUB> R </SUB>) in the disk at 8 kpc < R < 28 kpc
in the direction of the anticenter. For this, we use the Apache Point
Galactic Evolution Experiment. Furthermore, we compare the result with
H I maps along the same line of sight. We find an increase in positive
(expansion) v <SUB> R </SUB> at R ≈ 9-13 kpc, reaching a maximum of
≈6 km s<SUP>-1</SUP>, and a decrease at large values of R, reaching a
negative (contraction) value of ≈-10 km s<SUP>-1</SUP> for R > 17
kpc. Negative velocities are also observed in 21 cm H I maps, possibly
dominated by local gas emission. Among the possible dynamical causes
for these non-zero v <SUB> R </SUB>, factors such as the effect of the
Galactic bar, streams, or mergers do not seem appropriate to explain
our observations. An explanation might be the gravitational attraction
of overdensities in a spiral arm. As a matter of fact, we see a change
of regime from positive to negative velocities around R ≈ 15 kpc, in
the position where we cross the Outer spiral arm in the anticenter. The
mass in spiral arms necessary to produce these velocities would be
about 3% of the mass of the disk, consistent with our knowledge of
the spiral arms. Another scenario that we explore is a simple class of
out-of-equilibrium systems in which radial motions are generally created
by the monolithic collapse of isolated self-gravitating overdensities.
---------------------------------------------------------
Title: The origin of accreted stellar halo populations in the Milky
Way using APOGEE, Gaia, and the EAGLE simulations
Authors: Mackereth, J. Ted; Schiavon, Ricardo P.; Pfeffer, Joel;
Hayes, Christian R.; Bovy, Jo; Anguiano, Borja; Allende Prieto,
Carlos; Hasselquist, Sten; Holtzman, Jon; Johnson, Jennifer A.;
Majewski, Steven R.; O'Connell, Robert; Shetrone, Matthew; Tissera,
Patricia B.; Fernández-Trincado, J. G.
2019MNRAS.482.3426M Altcode: 2018arXiv180800968M; 2018MNRAS.tmp.2814M
Recent work indicates that the nearby Galactic halo is dominated by
the debris from a major accretion event. We confirm that result from an
analysis of APOGEE-DR14 element abundances and Gaia-DR2 kinematics of
halo stars. We show that ∼2/3 of nearby halo stars have high orbital
eccentricities (e ≳ 0.8), and abundance patterns typical of massive
Milky Way dwarf galaxy satellites today, characterized by relatively low
[Fe/H], [Mg/Fe], [Al/Fe], and [Ni/Fe]. The trend followed by high-e
stars in the [Mg/Fe]-[Fe/H] plane shows a change of slope at [Fe/H]
∼ -1.3, which is also typical of stellar populations from relatively
massive dwarf galaxies. Low-e stars exhibit no such change of slope
within the observed [Fe/H] range and show slightly higher abundances
of Mg, Al, and Ni. Unlike their low-e counterparts, high-e stars
show slightly retrograde motion, make higher vertical excursions,
and reach larger apocentre radii. By comparing the position in
[Mg/Fe]-[Fe/H] space of high-e stars with those of accreted galaxies
from the EAGLE suite of cosmological simulations, we constrain the
mass of the accreted satellite to be in the range 10<SUP>8.5</SUP>
≲ M<SUB>*</SUB> ≲ 10<SUP>9</SUP> M<SUB>⊙</SUB>. We show that the
median orbital eccentricities of debris are largely unchanged since
merger time, implying that this accretion event likely happened at
z ≲ 1.5. The exact nature of the low-e population is unclear, but
we hypothesize that it is a combination of in situ star formation,
high-|z| disc stars, lower mass accretion events, and contamination
by the low-e tail of the high-e population. Finally, our results imply
that the accretion history of the Milky Way was quite unusual.
---------------------------------------------------------
Title: Comprehensive comparison between APOGEE and LAMOST. Radial
velocities and atmospheric stellar parameters
Authors: Anguiano, B.; Majewski, S. R.; Allende Prieto, C.;
Meszaros, S.; Jönsson, H.; García-Hernández, D. A.; Beaton, R. L.;
Stringfellow, G. S.; Cunha, K.; Smith, V. V.
2018A&A...620A..76A Altcode: 2018arXiv180707625A
Context. In the era of massive spectroscopy surveys, automated stellar
parameter pipelines and their validation are extremely important for
an efficient scientific exploitation of the spectra. <BR /> Aims:
We undertake a critical and comprehensive comparison of the radial
velocities and the main stellar atmosphere parameters for stars
in common between the latest data releases from the Apache Point
Observatory Galaxy Evolution Experiment (APOGEE) and the Large sky Area
Multi-Object Spectroscopic Telescope (LAMOST) surveys. <BR /> Methods:
APOGEE is a high-resolution (R = 22 500) spectroscopic survey with high
signal-to-noise ratio that is part of the Sloan Digital Sky Survey
(SDSS). The latest data release, SDSS DR14, comprises APOGEE spectra
for 263 444 stars, together with main stellar parameters and individual
abundances for up to 20 chemical species. LAMOST is a low-resolution (R
= 1800) optical spectroscopic survey also in the Northern Hemisphere,
where 4000 fibers can be allocated simultaneously. LAMOST DR3
contains 3 177 995 stars. <BR /> Results: A total of 42 420 dwarfs
and giants stars are in common between the APOGEE DR14 - LAMOST DR3
stellar catalogs. A comparison between APOGEE and LAMOST RVs shows
a clear offset of 4.54 ± 0.03 km s<SUP>-1</SUP>, with a dispersion
of 5.8 km s<SUP>-1</SUP>, in the sense that APOGEE radial velocities
are higher. We observe a small offset in the effective temperatures
of about 13 K, with a scatter of 155 K. A small offset in [Fe/H] of
about 0.06 dex together with a scatter of 0.13 dex is also observed. We
note that the largest offset between the surveys occurs in the surface
gravities. Using only surface gravities in calibrated red giants from
APOGEE DR14, with which there are 24 074 stars in common, a deviation
of 0.14 dex is found with substantial scatter (0.25 dex). There are
17 482 red giant stars in common between APOGEE DR14 and those in
LAMOST tied to APOGEE DR12 via the code called the Cannon. There is
generally good agreement between the two data-sets. However, we find
that the differences in the stellar parameters depend on effective
temperature. For metal-rich stars, a different trend for the [Fe/H]
discrepancies is found. Surprisingly, we see no correlation between the
internal APOGEE DR14 - DR12 differences in T<SUB>eff</SUB> and those
in DR14 - LAMOST tied to DR12, where a correlation should be expected
since LAMOST has been calibrated to APOGEE DR12. We find no correlation
either between the [Fe/H] discrepancies, suggesting that LAMOST/Cannon
is not well coupled to the APOGEE DR12 stellar parameter scale. An
[Fe/H] dependence between the stellar parameters in APOGEE DR12 and
those in DR14 is reported. We find a weak correlation in the differences
between APOGEE DR14 - DR12 and LAMOST on DR12 surface gravity for stars
hotter than 4800 K and in the log g range between 2.0 and 2.8 dex. We
do not observe an [Fe/H] dependency in the gravity discrepancies.
---------------------------------------------------------
Title: The Pristine survey IV: approaching the Galactic metallicity
floor with the discovery of an ultra-metal-poor star
Authors: Starkenburg, Else; Aguado, David S.; Bonifacio, Piercarlo;
Caffau, Elisabetta; Jablonka, Pascale; Lardo, Carmela; Martin,
Nicolas; Sánchez-Janssen, Rubén; Sestito, Federico; Venn, Kim A.;
Youakim, Kris; Allende Prieto, Carlos; Arentsen, Anke; Gentile, Marc;
González Hernández, Jonay I.; Kielty, Collin; Koppelman, Helmer H.;
Longeard, Nicolas; Tolstoy, Eline; Carlberg, Raymond G.; Côté,
Patrick; Fouesneau, Morgan; Hill, Vanessa; McConnachie, Alan W.;
Navarro, Julio F.
2018MNRAS.481.3838S Altcode: 2018arXiv180704292S; 2018MNRAS.tmp.2167S
The early Universe presented a star formation environment that
was almost devoid of heavy elements. The lowest metallicity stars
thus provide a unique window into the earliest Galactic stages,
but are exceedingly rare and difficult to find. Here, we present the
discovery of an ultra-metal-poor star, Pristine_221.8781+9.7844, using
narrow-band Ca H&K photometry from the Pristine survey. Follow-up
medium- and high-resolution spectroscopy confirms the ultra-metal-poor
nature of Pristine_221.8781+9.7844 ([Fe/H] = -4.66 ± 0.13 in 1D LTE)
with an enhancement of 0.3-0.4 dex in α-elements relative to Fe,
and an unusually low carbon abundance. We derive an upper limit of
A(C) = 5.6, well below typical A(C) values for such ultra-metal-poor
stars. This makes Pristine_221.8781+9.7844 one of the most metal-poor
stars; in fact, it is very similar to the most metal-poor star known
(SDSS J102915+172927). The existence of a class of ultra-metal-poor
stars with low(er) carbon abundances suggest that there must have
been several formation channels in the early Universe through which
long-lived, low-mass stars were formed.
---------------------------------------------------------
Title: The Origin of the 300 km s<SUP>-1</SUP> Stream near Segue 1
Authors: Fu, Sal Wanying; Simon, Joshua D.; Shetrone, Matthew; Bovy,
Jo; Beers, Timothy C.; Fernández-Trincado, J. G.; Placco, Vinicius
M.; Zamora, Olga; Allende Prieto, Carlos; García-Hernández, D. A.;
Harding, Paul; Ivans, Inese; Lane, Richard; Nitschelm, Christian;
Roman-Lopes, Alexandre; Sobeck, Jennifer
2018ApJ...866...42F Altcode: 2018arXiv180408622W; 2018arXiv180408622F
We present a search for new members of the 300 km s<SUP>-1</SUP> stream
(300S) near the dwarf galaxy Segue 1 using wide-field survey data. We
identify 11 previously unknown bright stream members in the APOGEE-2 and
SEGUE-1 and 2 spectroscopic surveys. Based on the spatial distribution
of the high-velocity stars, we confirm for the first time that this
kinematic structure is associated with a 24°-long stream seen in
SDSS and Pan-STARRS imaging data. The 300S stars display a metallicity
range of -2.17 < [Fe/H] < -1.24, with an intrinsic dispersion of
{0.21}<SUB>-0.09</SUB><SUP>+0.12</SUP> dex. They also have chemical
abundance patterns similar to those of Local Group dwarf galaxies,
as well as that of the Milky Way halo. Using the open-source code
galpy to model the orbit of the stream, we find that the progenitor
of the stream passed perigalacticon about 70 Myr ago, with a closest
approach to the Galactic center of about 4.1 kpc. Using Pan-STARRS DR1
data, we obtain an integrated stream luminosity of 4 × 10<SUP>3</SUP>
L <SUB>⊙</SUB>. We conclude that the progenitor of the stream was
a dwarf galaxy that is probably similar to the satellites that were
accreted to build the present-day Milky Way halo.
---------------------------------------------------------
Title: VizieR Online Data Catalog: Elemental abundances of KOIs in
APOGEE. I. (Wilson+, 2018)
Authors: Wilson, R. F.; Teske, J.; Majewski, S. R.; Cunha, K.; Smith,
V.; Souto, D.; Bender, C.; Mahadevan, S.; Troup, N.; Allende Prieto,
C.; Stassun, K. G.; Skrutskie, M. F.; Almeida, A.; Garcia-Hernandez,
D. A.; Zamora, O.; Brinkmann, J.
2018yCat..51550068W Altcode:
All the data in this work were collected as part of APOGEE in the
14th Data Release (DR14, Abolfathi et al. 2018ApJS..235...42A)
of the third and fourth Sloan Digital Sky Survey (Eisenstein et
al. 2011AJ....142...72E; Blanton et al. 2017AJ....154...28B). APOGEE
utilizes a multi-object spectrograph (Wilson et al. 2010SPIE.7735E..1CW,
2012AAS...21942802W) mounted on the Sloan 2.5 m telescope (Gunn et
al. 2006AJ....131.2332G) to sample up to 300 sources simultaneously
with high-resolution (R~22500), high signal-to-noise ratio
(S/N>100), H-band (1.5-1.7 μm) spectroscopy. All of the data
from APOGEE are processed through automated reduction and stellar
parameter pipelines (Holtzman et al. 2015AJ....150..148H; Nidever et
al. 2015AJ....150..173N), and the spectroscopic parameters used for the
stars in our sample are derived from the Automated Stellar Parameters
and Chemical Abundances Pipeline (ASPCAP). ASPCAP consists of two
principal components: a FORTRAN90 optimization code (FERRE; Allende
Prieto et al. 2006ApJ...636..804A) that compares the observed APOGEE
spectra to synthetic libraries, and a multifunctional IDL wrapper used
for bookkeeping and reading and preparing the input APOGEE spectra. <P
/>(3 data files).
---------------------------------------------------------
Title: A collection of model stellar spectra for spectral types B
to early-M
Authors: Allende Prieto, C.; Koesterke, L.; Hubeny, I.; Bautista,
M. A.; Barklem, P. S.; Nahar, S. N.
2018A&A...618A..25A Altcode: 2018arXiv180706049A
Context. Models of stellar spectra are necessary for interpreting light
from individual stars, planets, integrated stellar populations, nebulae,
and the interstellar medium. <BR /> Aims: We provide a comprehensive
and homogeneous collection of synthetic spectra for a wide range of
atmospheric parameters and chemical compositions. <BR /> Methods:
We compile atomic and molecular data from the literature. We adopt
the largest and most recent set of ATLAS9 model atmospheres, and use
the radiative code ASSɛT. <BR /> Results: The resulting collection
of spectra is made publicly available at medium and high-resolution
(R ≡ λ/δλ = 10 000, 100 000 and 300 000) spectral grids,
which include variations in effective temperature between 3500 K
and 30 000 K, surface gravity (0 ≤ log g ≤ 5), and metallicity
(-5 ≤ [Fe/H] ≤ +0:5), spanning the wavelength interval 120-6500
nm. A second set of denser grids with additional dimensions, [α/Fe]
and micro-turbulence, are also provided (covering 200-2500 nm). We
compare models with observations for a few representative cases. <P
/>Data files are only available at the CDS via anonymous ftp to <A
href="http://cdsarc.u-strasbg.fr/">http://cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/618/A25">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/618/A25</A>
---------------------------------------------------------
Title: Testing models of stellar structure and evolution -
I. Comparison with detached eclipsing binaries
Authors: del Burgo, C.; Allende Prieto, C.
2018MNRAS.479.1953D Altcode: 2021arXiv210610752D; 2018MNRAS.tmp.1332D
We present the results of an analysis aimed at testing the accuracy
and precision of the PARSEC v1.2S library of stellar evolution models,
combined with a Bayesian approach, to infer stellar parameters. We
mainly employ the online DEBCat catalogue by Southworth, a compilation
of detached eclipsing binary systems with published measurements of
masses and radii to ∼2 per cent precision. We select a sample of 318
binary components, with masses between 0.10 and 14.5 M<SUB>⊙</SUB>,
at distances between 1.3 pc and ∼8 kpc for Galactic objects and ∼
44-68 kpc for the extragalactic ones. The Bayesian analysis applied
takes as input effective temperature, radius, and [Fe/H], and their
uncertainties, returning theoretical predictions for other stellar
parameters. From the comparison with dynamical masses, we conclude that
the inferred masses are precisely derived for stars on the main-sequence
and in the core-helium-burning phase, with uncertainties of 4 per cent
and 7 per cent, respectively, on average. Masses for the subgiants
and red giants are predicted within 14 per cent, and those for early
asymptotic giant branch stars within 24 per cent. These results are
helpful to further improve the models, in particular for advanced
evolutionary stages for which our understanding is limited. We
obtain distances and ages for the binary systems and compare them,
whenever possible, with precise literature estimates, finding excellent
agreement. We discuss evolutionary effects and challenges for inferring
stellar ages from evolutionary models. We also provide useful polynomial
fittings to theoretical zero-age main-sequence relations.
---------------------------------------------------------
Title: APOGEE Data Releases 13 and 14: Data and Analysis
Authors: Holtzman, Jon A.; Hasselquist, Sten; Shetrone, Matthew; Cunha,
Katia; Allende Prieto, Carlos; Anguiano, Borja; Bizyaev, Dmitry; Bovy,
Jo; Casey, Andrew; Edvardsson, Bengt; Johnson, Jennifer A.; Jönsson,
Henrik; Meszaros, Szabolcs; Smith, Verne V.; Sobeck, Jennifer; Zamora,
Olga; Chojnowski, S. Drew; Fernandez-Trincado, Jose; Garcia-Hernandez,
D. A.; Majewski, Steven R.; Pinsonneault, Marc; Souto, Diogo;
Stringfellow, Guy S.; Tayar, Jamie; Troup, Nicholas; Zasowski, Gail
2018AJ....156..125H Altcode: 2018arXiv180709773H
The data and analysis methodology used for the SDSS/APOGEE Data
Releases 13 and 14 are described, highlighting differences from the
DR12 analysis presented in Holtzman et al. Some improvement in the
handling of telluric absorption and persistence is demonstrated. The
derivation and calibration of stellar parameters, chemical abundances,
and respective uncertainties are described, along with the ranges over
which calibration was performed. Some known issues with the public
data related to the calibration of the effective temperatures (DR13),
surface gravity (DR13 and DR14), and C and N abundances for dwarfs (DR13
and DR14) are highlighted. We discuss how results from a data-driven
technique, The Cannon, are included in DR14 and compare those with
results from the APOGEE Stellar Parameters and Chemical Abundances
Pipeline. We describe how using The Cannon in a mode that restricts
the abundance analysis of each element to regions of the spectrum with
known features from that element leads to Cannon abundances can lead
to significantly different results for some elements than when all
regions of the spectrum are used to derive abundances.
---------------------------------------------------------
Title: VizieR Online Data Catalog: Galactic halo with
APOGEE. II. Abundances. (Fernandez-Alvar+, 2018)
Authors: Fernandez-Alvar, E.; Carigi, L.; Schuster, W. J.; Hayes,
C. R.; Avila-Vergara, N.; Majewski, S. R.; Allende Prieto, C.; Beers,
T. C.; Sanchez, S. F.; Zamora, O.; Garcia-Hernandez, D. A.; Tang,
B.; Fernandez-Trincado, J. G.; Tissera, P.; Geisler, D.; Villanova, S.
2018yCat..18520050F Altcode:
The first APOGEE phase was in SDSS-III and collected data between
2011 and 2014 July, obtaining high-resolution (R~22500) spectra
with a typical signal-to-noise >=100 using a multiobject infrared
spectrograph coupled to the 2.5m SDSS telescope at the Apache Point
Observatory. The APOGEE Stellar Parameters and Abundances pipeline
(ASPCAP) was developed to obtain stellar atmospheric parameters
and chemical abundances from the H-band (1.5-1.7um), the spectral
range covered by the APOGEE spectrograph. The thirteenth data
release (DR13; Albareti+ 2017ApJS..233...25A) provides the final
products of a reanalysis, after including several improvements to
the pipeline. Chemical abundances of up to 26 chemical species are
available for some stars, including the α-elements: O, Mg, S, Si, Ca,
and Ti. From this database, we have selected 175 Galactic halo stars
(see Section 2 for further explanations). <P />(1 data file).
---------------------------------------------------------
Title: APOGEE Data Releases 13 and 14: Stellar Parameter and Abundance
Comparisons with Independent Analyses
Authors: Jönsson, Henrik; Allende Prieto, Carlos; Holtzman, Jon A.;
Feuillet, Diane K.; Hawkins, Keith; Cunha, Katia; Mészáros, Szabolcs;
Hasselquist, Sten; Fernández-Trincado, J. G.; García-Hernández,
D. A.; Bizyaev, Dmitry; Carrera, Ricardo; Majewski, Steven R.;
Pinsonneault, Marc H.; Shetrone, Matthew; Smith, Verne; Sobeck,
Jennifer; Souto, Diogo; Stringfellow, Guy S.; Teske, Johanna;
Zamora, Olga
2018AJ....156..126J Altcode: 2018arXiv180709784J
Data from the SDSS-IV/Apache Point Observatory Galactic Evolution
Experiment (APOGEE-2) have been released as part of SDSS Data
Releases 13 (DR13) and 14 (DR14). These include high-resolution
H-band spectra, radial velocities, and derived stellar parameters
and abundances. DR13, released in 2016 August, contained APOGEE
data for roughly 150,000 stars, and DR14, released in 2017 August,
added about 110,000 more. Stellar parameters and abundances have been
derived with an automated pipeline, the APOGEE Stellar Parameter and
Chemical Abundance Pipeline (ASPCAP). We evaluate the performance of
this pipeline by comparing the derived stellar parameters and abundances
to those inferred from optical spectra and analysis for several hundred
stars. For most elements—C, Na, Mg, Al, Si, S, Ca, Cr, Mn, Ni—the
DR14 ASPCAP analyses have systematic differences with the comparisons
samples of less than 0.05 dex (median), and random differences of
less than 0.15 dex (standard deviation). These differences are a
combination of the uncertainties in both the comparison samples as
well as the ASPCAP analysis. Compared to the references, magnesium is
the most accurate alpha-element derived by ASPCAP, and shows a very
clear thin/thick disk separation, while nickel is the most accurate
iron-peak element (besides iron itself).
---------------------------------------------------------
Title: Gaia Data Release 2. Processing the spectroscopic data
Authors: Sartoretti, P.; Katz, D.; Cropper, M.; Panuzzo, P.;
Seabroke, G. M.; Viala, Y.; Benson, K.; Blomme, R.; Jasniewicz,
G.; Jean-Antoine, A.; Huckle, H.; Smith, M.; Baker, S.; Crifo,
F.; Damerdji, Y.; David, M.; Dolding, C.; Frémat, Y.; Gosset, E.;
Guerrier, A.; Guy, L. P.; Haigron, R.; Janßen, K.; Marchal, O.;
Plum, G.; Soubiran, C.; Thévenin, F.; Ajaj, M.; Allende Prieto, C.;
Babusiaux, C.; Boudreault, S.; Chemin, L.; Delle Luche, C.; Fabre, C.;
Gueguen, A.; Hambly, N. C.; Lasne, Y.; Meynadier, F.; Pailler, F.;
Panem, C.; Riclet, F.; Royer, F.; Tauran, G.; Zurbach, C.; Zwitter,
T.; Arenou, F.; Gomez, A.; Lemaitre, V.; Leclerc, N.; Morel, T.;
Munari, U.; Turon, C.; Žerjal, M.
2018A&A...616A...6S Altcode: 2018arXiv180409371S
Context. The Gaia Data Release 2 (DR2) contains the first release
of radial velocities complementing the kinematic data of a sample
of about 7 million relatively bright, late-type stars. <BR /> Aims:
This paper provides a detailed description of the Gaia spectroscopic
data processing pipeline, and of the approach adopted to derive the
radial velocities presented in DR2. <BR /> Methods: The pipeline must
perform four main tasks: (i) clean and reduce the spectra observed
with the Radial Velocity Spectrometer (RVS); (ii) calibrate the RVS
instrument, including wavelength, straylight, line-spread function,
bias non-uniformity, and photometric zeropoint; (iii) extract the
radial velocities; and (iv) verify the accuracy and precision of the
results. The radial velocity of a star is obtained through a fit of the
RVS spectrum relative to an appropriate synthetic template spectrum. An
additional task of the spectroscopic pipeline was to provide first-order
estimates of the stellar atmospheric parameters required to select
such template spectra. We describe the pipeline features and present
the detailed calibration algorithms and software solutions we used to
produce the radial velocities published in DR2. <BR /> Results: The
spectroscopic processing pipeline produced median radial velocities
for Gaia stars with narrow-band near-IR magnitude G<SUB>RVS</SUB>
≤ 12 (i.e. brighter than V ~ 13). Stars identified as double-lined
spectroscopic binaries were removed from the pipeline, while variable
stars, single-lined, and non-detected double-lined spectroscopic
binaries were treated as single stars. The scatter in radial velocity
among different observations of a same star, also published in Gaia DR2,
provides information about radial velocity variability. For the hottest
(T<SUB>eff</SUB> ≥ 7000 K) and coolest (T<SUB>eff</SUB> ≤ 3500 K)
stars, the accuracy and precision of the stellar parameter estimates are
not sufficient to allow selection of appropriate templates. The radial
velocities obtained for these stars were removed from DR2. The pipeline
also provides a first-order estimate of the performance obtained. The
overall accuracy of radial velocity measurements is around ~200-300
m s<SUP>-1</SUP>, and the overall precision is ~1 km s<SUP>-1</SUP>;
it reaches ~200 m s<SUP>-1</SUP> for the brightest stars.
---------------------------------------------------------
Title: Gaia Data Release 2. Calibration and mitigation of electronic
offset effects in the data
Authors: Hambly, N. C.; Cropper, M.; Boudreault, S.; Crowley,
C.; Kohley, R.; de Bruijne, J. H. J.; Dolding, C.; Fabricius, C.;
Seabroke, G.; Davidson, M.; Rowell, N.; Collins, R.; Cross, N.;
Martín-Fleitas, J.; Baker, S.; Smith, M.; Sartoretti, P.; Marchal,
O.; Katz, D.; De Angeli, F.; Busso, G.; Riello, M.; Allende Prieto,
C.; Els, S.; Corcione, L.; Masana, E.; Luri, X.; Chassat, F.; Fusero,
F.; Pasquier, J. F.; Vétel, C.; Sarri, G.; Gare, P.
2018A&A...616A..15H Altcode: 2018arXiv180409830H
Context. The European Space Agency's Gaia satellite was launched
into orbit around L2 in December 2013. This ambitious mission has
strict requirements on residual systematic errors resulting from
instrumental corrections in order to meet a design goal of sub-10
microarcsecond astrometry. During the design and build phase of the
science instruments, various critical calibrations were studied in
detail to ensure that this goal could be met in orbit. In particular,
it was determined that the video-chain offsets on the analogue
side of the analogue-to-digital conversion electronics exhibited
instabilities that could not be mitigated fully by modifications to
the flight hardware. <BR /> Aims: We provide a detailed description
of the behaviour of the electronic offset levels on short (<1 ms)
timescales, identifying various systematic effects that are known
collectively as "offset non-uniformities". The effects manifest
themselves as transient perturbations on the gross zero-point
electronic offset level that is routinely monitored as part of the
overall calibration process. <BR /> Methods: Using in-orbit special
calibration sequences along with simple parametric models, we show how
the effects can be calibrated, and how these calibrations are applied
to the science data. While the calibration part of the process is
relatively straightforward, the application of the calibrations during
science data processing requires a detailed on-ground reconstruction of
the readout timing of each charge-coupled device (CCD) sample on each
device in order to predict correctly the highly time-dependent nature
of the corrections. <BR /> Results: We demonstrate the effectiveness
of our offset non-uniformity models in mitigating the effects in Gaia
data. <BR /> Conclusions: We demonstrate for all CCDs and operating
instrument/modes on board Gaia that the video-chain noise-limited
performance is recovered in the vast majority of science samples.
---------------------------------------------------------
Title: Gaia Data Release 2. Gaia Radial Velocity Spectrometer
Authors: Cropper, M.; Katz, D.; Sartoretti, P.; Prusti, T.; de Bruijne,
J. H. J.; Chassat, F.; Charvet, P.; Boyadjian, J.; Perryman, M.; Sarri,
G.; Gare, P.; Erdmann, M.; Munari, U.; Zwitter, T.; Wilkinson, M.;
Arenou, F.; Vallenari, A.; Gómez, A.; Panuzzo, P.; Seabroke, G.;
Allende Prieto, C.; Benson, K.; Marchal, O.; Huckle, H.; Smith, M.;
Dolding, C.; Janßen, K.; Viala, Y.; Blomme, R.; Baker, S.; Boudreault,
S.; Crifo, F.; Soubiran, C.; Frémat, Y.; Jasniewicz, G.; Guerrier,
A.; Guy, L. P.; Turon, C.; Jean-Antoine-Piccolo, A.; Thévenin, F.;
David, M.; Gosset, E.; Damerdji, Y.
2018A&A...616A...5C Altcode: 2018arXiv180409369C
This paper presents the specification, design, and development
of the Radial Velocity Spectrometer (RVS) on the European Space
Agency's Gaia mission. Starting with the rationale for the full six
dimensions of phase space in the dynamical modelling of the Galaxy,
the scientific goals and derived top-level instrument requirements
are discussed, leading to a brief description of the initial concepts
for the instrument. The main part of the paper is a description of
the flight RVS, considering the optical design, the focal plane,
the detection and acquisition chain, and the as-built performance
drivers and critical technical areas. After presenting the pre-launch
performance predictions, the paper concludes with the post-launch
developments and mitigation strategies, together with a summary of
the in-flight performance at the end of commissioning.
---------------------------------------------------------
Title: Construction progress of WEAVE: the next generation wide-field
spectroscopy facility for the William Herschel Telescope
Authors: Dalton, Gavin; Trager, Scott; Abrams, Don Carlos; Bonifacio,
Piercarlo; Aguerri, J. Alfonso L.; Vallenari, Antonella; Middleton,
Kevin; Benn, Chris; Dee, Kevin; Sayède, Frédéric; Lewis, Ian; Pragt,
Johannes; Picó, Sergio; Walton, Nicholas; Rey, Jeurg; Allende Prieto,
Carlos; Lhomé, Émilie; Terrett, David; Brock, Matthew; Gilbert,
James; Ridings, Andy; Verheijen, Marc; Tosh, Ian; Steele, Iain;
Stuik, Remko; Kroes, Gabby; Tromp, Neils; Kragt, Jan; Lesman, Dirk;
Mottram, Chris; Bates, Stuart; Gribbin, Frank; Burgal, José Alonso;
Herreros, Jose Miguel; Delgado, Jose Miguel; Martin, Carlos; Cano,
Diego; Navarro, Ramón; Irwin, Mike; Lewis, James; Gonzales Solares,
Eduardo; O'Mahony, Neil; Bianco, Andrea; Zurita, Christina; ter Horst,
Rik; Molinari, Emilio; Lodi, Marcello; Guerra, José; Baruffolo,
Andrea; Carrasco, Esperanza; Farkas, Szigfrid; Schallig, Ellen; Hill,
Vanessa; Smith, Dan; Drew, Janet; Poggianti, Bianca; Pieri, Mat; Jin,
Shoko; Dominquez Palmero, Lilian; Fariña, Cecilia; Martin, Adrian;
Worley, Clare; Murphy, David; Hidalgo, Andrea; Mignot, Shan; Bishop,
Georgia; Guest, Steve; Elswijk, Eddy; de Haan, Menno; Hanenburg,
Hiddo; Salasnich, Bernardo; Mayya, Divakara; Izazaga-Pérez, Rafael;
Peralta de Arriba, Luis
2018SPIE10702E..1BD Altcode:
We present an update on the overall construction progress of the WEAVE
next-generation spectroscopy facility for the William Herschel Telescope
(WHT), now that all the major fabrication contracts are in place. We
also present a summary of the current planning behind the 5-year
initial phase of survey operations, and some detailed end-to-end
science simulations that have been effected to evaluate the final
on-sky performance after data processing. WEAVE will provide optical
ground-based follow up of ground-based (LOFAR) and space-based (Gaia)
surveys. WEAVE is a multi-object and multi-IFU facility utilizing
a new 2-degree prime focus field of view at the WHT, with a buffered
pick-and-place positioner system hosting 1000 multi-object (MOS) fibres,
20 integral field units, or a single large IFU for each observation. The
fibres are fed to a single (dual-beam) spectrograph, with total of
16k spectral pixels, located within the WHT GHRIL enclosure on the
telescope Nasmyth platform, supporting observations at R 5000 over
the full 370-1000nm wavelength range in a single exposure, or a high
resolution mode with limited coverage in each arm at R 20000. The
project has experienced some delays in procurement and now has first
light expected for the middle of 2019.
---------------------------------------------------------
Title: Signatures of the Galactic bar on stellar kinematics unveiled
by APOGEE
Authors: Palicio, Pedro A.; Martinez-Valpuesta, Inma; Allende Prieto,
Carlos; Dalla Vecchia, Claudio; Zamora, Olga; Zasowski, Gail;
Fernandez-Trincado, J. G.; Masters, Karen L.; García-Hernández,
D. A.; Roman-Lopes, Alexandre
2018MNRAS.478.1231P Altcode: 2018MNRAS.tmp.1097P; 2018arXiv180504347A
Bars are common galactic structures in the local universe that play
an important role in the secular evolution of galaxies, including the
Milky Way. In particular, the velocity distribution of individual
stars in our galaxy is useful to shed light on stellar dynamics,
and provides information complementary to that inferred from the
integrated light of external galaxies. However, since a wide variety
of models reproduce the distribution of velocity and the velocity
dispersion observed in the Milky Way, we look for signatures of the
bar on higher order moments of the line-of-sight velocity (V_{los})
distribution. We use two different numerical simulations - one that has
developed a bar and one that remains nearly axisymmetric - to compare
them with observations in the latest Apache Point Observatory Galactic
Evolution Experiment data release (SDSS DR14). This comparison reveals
three interesting structures that support the notion that the Milky Way
is a barred galaxy. A high-skewness region found at positive longitudes
constrains the orientation angle of the bar, and is incompatible with
the orientation of the bar at ℓ = 0° proposed in previous studies. We
also analyse the V_{los} distributions in three regions, and introduce
the Hellinger distance to quantify the differences among them. Our
results show a strong non-Gaussian distribution both in the data and in
the barred model, confirming the qualitative conclusions drawn from the
velocity maps. In contrast to earlier work, we conclude it is possible
to infer the presence of the bar from the kurtosis distribution.
---------------------------------------------------------
Title: VizieR Online Data Catalog: Model stellar spectra for B to
early-M (Allende Prieto+, 2018)
Authors: Allende Prieto, C.; Koesterke, L.; Hubeny, I.; Bautista,
M.; Barklem, P. S.; Nahar, S. N.
2018yCat..36180025A Altcode:
The following text describes the data files available from
ftp://carlos:allende@ftp.ll.iac.es/collection <P />These are in ASCII
(but bzip2 compressed), and ready to be used with the FERRE code
(github.com/callendeprieto/ferre). The format includes a header
and as many rows as model spectra. See the FERRE manual for more
details (github.com/callendeprieto/ferre/docs/ferre.pdf). <P />There
are two main families of files. The 'coarse' (nsc) grids consider
three atmospheric parameters ([Fe/H], Teff and logg) and typically
include hundreds of models on a very coarse network, while the
'large' (ns) grids consider five (the previous three plus [alpha/Fe]
and microturbulence), and include tens to hundreds of thousands of
models. <P />The files are numbered 1-5 depending on the Teff range
they span. There are files (ns and nsc) smoothed with a Gaussian
kernal to R=10,000, while nsc files are provided for R=100,000
and 200,000 as well. The spectral range is 0.12-6.6um for the nsc
files and 0.2-2.5um for the ns files. <P />for the nsc files and
0.2-2.5um for the ns files. <P />nsc ('coarse' grids): [Fe/H], Teff,
logg <P />size filename Teff range R <P />158004765 f_nsc1.dat.bz2
3500<= Teff<=6000 10000 128868874 f_nsc2.dat.bz2 5750<=
Teff<=8000 102539424 f_nsc3.dat.bz2 7000<= Teff<=12000 77786534
f_nsc4.dat.bz2 10000<=Teff<=20000 26089034 f_nsc5.dat.bz2
20000<=Teff<=30000 <P />1430284037 f_hnsc1.dat.bz2 3500<=
Teff<=6000 100000 1159906320 f_hnsc2.dat.bz2 5750<= Teff<=8000
913976329 f_hnsc3.dat.bz2 7000<= Teff<=12000 695827559
f_hnsc4.dat.bz2 10000<=Teff<=20000 234598400 f_hnsc5.dat.bz2
20000<=Teff<=30000 <P />2596690648 f_uhnsc1.dat.bz2 3500<=
Teff<=6000 300000 2067630039 f_uhnsc2.dat.bz2 5750<= Teff<=8000
1605227763 f_uhnsc3.dat.bz2 7000<= Teff<=12000 1221970143
f_uhnsc4.dat.bz2 10000<=Teff<=20000 411096450 f_uhnsc5.dat.bz2
20000<=Teff<=30000 <P />ns ('large' grids): [Fe/H], [alpha/Fe],
log(micro), Teff, logg <P />30936708717 f_ns1.dat.bz2 3500<=
Teff<=6000 10000 22957349531 f_ns2.dat.bz2 5750<= Teff<=8000
19640724566 f_ns3.dat.bz2 7000<= Teff<=12000 14267448478
f_ns4.dat.bz2 10000<=Teff<=20000 8622793847 f_ns5.dat.bz2
20000<=Teff<=30000 <P />(2 data files).
---------------------------------------------------------
Title: ELT-HIRES, the high resolution spectrograph for the ELT:
results from the Phase A study
Authors: Marconi, A.; Allende Prieto, C.; Amado, P. J.; Amate, M.;
Augusto, S. R.; Becerril, S.; Bezawada, N.; Boisse, I.; Bouchy,
F.; Cabral, A.; Chazelas, B.; Cirami, R.; Coretti, I.; Cristiani,
S.; Cupani, G.; de Castro Leão, I.; de Medeiros, J. R.; de Souza,
M. A. F.; Di Marcantonio, P.; Di Varano, I.; D'Odorico, V.; Drass, H.;
Figueira, P.; Fragoso, A. B.; Fynbo, J. P. U.; Genoni, M.; González
Hernández, J. I.; Haehnelt, M.; Hughes, I.; Huke, P.; Kjeldsen,
H.; Korn, A. J.; Landoni, M.; Liske, J.; Lovis, C.; Maiolino, R.;
Marquart, T.; Martins, C. J. A. P.; Mason, E.; Monteiro, M. A.; Morris,
T.; Murray, G.; Niedzielski, A.; Oliva, E.; Origlia, L.; Pallé, E.;
Parr-Burman, P.; Parro, V. C.; Pepe, F.; Piskunov, N.; Rasilla, J. L.;
Rees, P.; Rebolo, R.; Riva, M.; Rousseau, S.; Sanna, N.; Santos, N. C.;
Shen, T. -C.; Sortino, F.; Sosnowska, D.; Sousa, S.; Stempels, E.;
Strassmeier, K.; Tenegi, F.; Tozzi, A.; Udry, S.; Valenziano, L.;
Vanzi, L.; Weber, M.; Woche, M.; Xompero, M.; Zackrisson, E.
2018SPIE10702E..1YM Altcode:
We present the results from the phase A study of ELT-HIRES, an
optical-infrared High Resolution Spectrograph for ELT, which has just
been completed by a consortium of 30 institutes from 12 countries
forming a team of about 200 scientists and engineers. The top science
cases of ELT-HIRES will be the detection of life signatures from
exoplanet atmospheres, tests on the stability of Nature's fundamental
couplings, the direct detection of the cosmic acceleration. However,
the science requirements of these science cases enable many other
groundbreaking science cases. The baseline design, which allows
to fulfil the top science cases, consists in a modular fiber- fed
cross-dispersed echelle spectrograph with two ultra-stable spectral
arms providing a simultaneous spectral range of 0.4-1.8 μm at a
spectral resolution of 100,000. The fiber-feeding allows ELT-HIRES to
have several, interchangeable observing modes including a SCAO module
and a small diffraction-limited IFU.
---------------------------------------------------------
Title: VizieR Online Data Catalog: APOGEE N-rich stars in inner Galaxy
(Schiavon+, 2017)
Authors: Schiavon, R. P.; Zamora, O.; Carrera, R.; Lucatello, S.;
Robin, A. C.; Ness, M.; Martell, S. L.; Smith, V. V.; Garcia-Hernandez,
D. A.; Manchado, A.; Schonrich, R.; Bastian, N.; Chiappini, C.;
Shetrone, M.; Mackereth, J. T.; Williams, R. A.; Meszaros, S.; Allende
Prieto, C.; Anders, F.; Bizyaev, D.; Beers, T. C.; Chojnowski, S. D.;
Cunha, K.; Epstein, C.; Frinchaboy, P. M.; Garcia Perez, A. E.; Hearty,
F. R.; Holtzman, J. A.; Johnson, J. A.; Kinemuchi, K.; Majewski, S. R.;
Muna, D.; Nidever, D. L.; Nguyen, D. C.; O'Connell, R. W.; Oravetz,
D.; Pan, K.; Pinsonneault, M.; Schneider, D. P.; Schultheis, M.;
Simmons, A.; Skrutskie, M. F.; Sobeck, J.; Wilson, J. C.; Zasowski, G.
2018yCat..74650501S Altcode:
The results reported in this paper are based on elemental abundances
for a large sample of Galactic stars from Data Release 12 (DR12;
Alam et al., 2015ApJS..219...12A, Cat. V/147) of the Apache Point
Observatory Galactic Evolution Experiment (APOGEE; Majewski et al.,
2017AJ....154...94M). <P />In this paper, we concern ourselves with
a subset of the APOGEE sample, namely stars located in the Galactic
bulge. Moreover, because we are interested in searching for stars with
chemical signatures typical of GC members, we focus on the abundances
of Fe, C, N, and Al. <P />(7 data files).
---------------------------------------------------------
Title: Machine learning in APOGEE. Unsupervised spectral
classification with K-means
Authors: Garcia-Dias, Rafael; Allende Prieto, Carlos; Sánchez Almeida,
Jorge; Ordovás-Pascual, Ignacio
2018A&A...612A..98G Altcode: 2018arXiv180107912G
Context. The volume of data generated by astronomical surveys is
growing rapidly. Traditional analysis techniques in spectroscopy
either demand intensive human interaction or are computationally
expensive. In this scenario, machine learning, and unsupervised
clustering algorithms in particular, offer interesting alternatives. The
Apache Point Observatory Galactic Evolution Experiment (APOGEE)
offers a vast data set of near-infrared stellar spectra, which is
perfect for testing such alternatives. <BR /> Aims: Our research
applies an unsupervised classification scheme based on K-means
to the massive APOGEE data set. We explore whether the data are
amenable to classification into discrete classes. <BR /> Methods:
We apply the K-means algorithm to 153 847 high resolution spectra
(R ≈ 22 500). We discuss the main virtues and weaknesses of the
algorithm, as well as our choice of parameters. <BR /> Results: We
show that a classification based on normalised spectra captures the
variations in stellar atmospheric parameters, chemical abundances,
and rotational velocity, among other factors. The algorithm is able
to separate the bulge and halo populations, and distinguish dwarfs,
sub-giants, RC, and RGB stars. However, a discrete classification in
flux space does not result in a neat organisation in the parameters'
space. Furthermore, the lack of obvious groups in flux space
causes the results to be fairly sensitive to the initialisation,
and disrupts the efficiency of commonly-used methods to select
the optimal number of clusters. Our classification is publicly
available, including extensive online material associated with the
APOGEE Data Release 12 (DR12). <BR /> Conclusions: Our description
of the APOGEE database can help greatly with the identification
of specific types of targets for various applications. We find a
lack of obvious groups in flux space, and identify limitations of
the K-means algorithm in dealing with this kind of data. <P />Full
Tables B.1-B.4 are only available at the CDS via anonymous ftp to
<A href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A>
(<A href="http://130.79.128.5">http://130.79.128.5</A>) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/612/A98">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/612/A98</A>
---------------------------------------------------------
Title: The Fourteenth Data Release of the Sloan Digital Sky Survey:
First Spectroscopic Data from the Extended Baryon Oscillation
Spectroscopic Survey and from the Second Phase of the Apache Point
Observatory Galactic Evolution Experiment
Authors: Abolfathi, Bela; Aguado, D. S.; Aguilar, Gabriela; Allende
Prieto, Carlos; Almeida, Andres; Ananna, Tonima Tasnim; Anders,
Friedrich; Anderson, Scott F.; Andrews, Brett H.; Anguiano, Borja;
Aragón-Salamanca, Alfonso; Argudo-Fernández, Maria; Armengaud,
Eric; Ata, Metin; Aubourg, Eric; Avila-Reese, Vladimir; Badenes,
Carles; Bailey, Stephen; Balland, Christophe; Barger, Kathleen A.;
Barrera-Ballesteros, Jorge; Bartosz, Curtis; Bastien, Fabienne;
Bates, Dominic; Baumgarten, Falk; Bautista, Julian; Beaton, Rachael;
Beers, Timothy C.; Belfiore, Francesco; Bender, Chad F.; Bernardi,
Mariangela; Bershady, Matthew A.; Beutler, Florian; Bird, Jonathan C.;
Bizyaev, Dmitry; Blanc, Guillermo A.; Blanton, Michael R.; Blomqvist,
Michael; Bolton, Adam S.; Boquien, Médéric; Borissova, Jura;
Bovy, Jo; Bradna Diaz, Christian Andres; Brandt, William Nielsen;
Brinkmann, Jonathan; Brownstein, Joel R.; Bundy, Kevin; Burgasser,
Adam J.; Burtin, Etienne; Busca, Nicolás G.; Cañas, Caleb I.;
Cano-Díaz, Mariana; Cappellari, Michele; Carrera, Ricardo; Casey,
Andrew R.; Cervantes Sodi, Bernardo; Chen, Yanping; Cherinka, Brian;
Chiappini, Cristina; Choi, Peter Doohyun; Chojnowski, Drew; Chuang,
Chia-Hsun; Chung, Haeun; Clerc, Nicolas; Cohen, Roger E.; Comerford,
Julia M.; Comparat, Johan; Correa do Nascimento, Janaina; da Costa,
Luiz; Cousinou, Marie-Claude; Covey, Kevin; Crane, Jeffrey D.;
Cruz-Gonzalez, Irene; Cunha, Katia; da Silva Ilha, Gabriele; Damke,
Guillermo J.; Darling, Jeremy; Davidson, James W., Jr.; Dawson, Kyle;
de Icaza Lizaola, Miguel Angel C.; de la Macorra, Axel; de la Torre,
Sylvain; De Lee, Nathan; de Sainte Agathe, Victoria; Deconto Machado,
Alice; Dell'Agli, Flavia; Delubac, Timothée; Diamond-Stanic,
Aleksandar M.; Donor, John; Downes, Juan José; Drory, Niv; du
Mas des Bourboux, Hélion; Duckworth, Christopher J.; Dwelly, Tom;
Dyer, Jamie; Ebelke, Garrett; Davis Eigenbrot, Arthur; Eisenstein,
Daniel J.; Elsworth, Yvonne P.; Emsellem, Eric; Eracleous, Michael;
Erfanianfar, Ghazaleh; Escoffier, Stephanie; Fan, Xiaohui; Fernández
Alvar, Emma; Fernandez-Trincado, J. G.; Fernando Cirolini, Rafael;
Feuillet, Diane; Finoguenov, Alexis; Fleming, Scott W.; Font-Ribera,
Andreu; Freischlad, Gordon; Frinchaboy, Peter; Fu, Hai; Gómez Maqueo
Chew, Yilen; Galbany, Lluís; García Pérez, Ana E.; Garcia-Dias,
R.; García-Hernández, D. A.; Garma Oehmichen, Luis Alberto; Gaulme,
Patrick; Gelfand, Joseph; Gil-Marín, Héctor; Gillespie, Bruce A.;
Goddard, Daniel; González Hernández, Jonay I.; Gonzalez-Perez,
Violeta; Grabowski, Kathleen; Green, Paul J.; Grier, Catherine J.;
Gueguen, Alain; Guo, Hong; Guy, Julien; Hagen, Alex; Hall, Patrick;
Harding, Paul; Hasselquist, Sten; Hawley, Suzanne; Hayes, Christian
R.; Hearty, Fred; Hekker, Saskia; Hernandez, Jesus; Hernandez Toledo,
Hector; Hogg, David W.; Holley-Bockelmann, Kelly; Holtzman, Jon A.;
Hou, Jiamin; Hsieh, Bau-Ching; Hunt, Jason A. S.; Hutchinson, Timothy
A.; Hwang, Ho Seong; Jimenez Angel, Camilo Eduardo; Johnson, Jennifer
A.; Jones, Amy; Jönsson, Henrik; Jullo, Eric; Khan, Fahim Sakil;
Kinemuchi, Karen; Kirkby, David; Kirkpatrick, Charles C., IV; Kitaura,
Francisco-Shu; Knapp, Gillian R.; Kneib, Jean-Paul; Kollmeier, Juna A.;
Lacerna, Ivan; Lane, Richard R.; Lang, Dustin; Law, David R.; Le Goff,
Jean-Marc; Lee, Young-Bae; Li, Hongyu; Li, Cheng; Lian, Jianhui;
Liang, Yu; Lima, Marcos; Lin, Lihwai; Long, Dan; Lucatello, Sara;
Lundgren, Britt; Mackereth, J. Ted; MacLeod, Chelsea L.; Mahadevan,
Suvrath; Maia, Marcio Antonio Geimba; Majewski, Steven; Manchado,
Arturo; Maraston, Claudia; Mariappan, Vivek; Marques-Chaves, Rui;
Masseron, Thomas; Masters, Karen L.; McDermid, Richard M.; McGreer,
Ian D.; Melendez, Matthew; Meneses-Goytia, Sofia; Merloni, Andrea;
Merrifield, Michael R.; Meszaros, Szabolcs; Meza, Andres; Minchev,
Ivan; Minniti, Dante; Mueller, Eva-Maria; Muller-Sanchez, Francisco;
Muna, Demitri; Muñoz, Ricardo R.; Myers, Adam D.; Nair, Preethi;
Nandra, Kirpal; Ness, Melissa; Newman, Jeffrey A.; Nichol, Robert
C.; Nidever, David L.; Nitschelm, Christian; Noterdaeme, Pasquier;
O'Connell, Julia; Oelkers, Ryan James; Oravetz, Audrey; Oravetz,
Daniel; Ortíz, Erik Aquino; Osorio, Yeisson; Pace, Zach; Padilla,
Nelson; Palanque-Delabrouille, Nathalie; Palicio, Pedro Alonso; Pan,
Hsi-An; Pan, Kaike; Parikh, Taniya; Pâris, Isabelle; Park, Changbom;
Peirani, Sebastien; Pellejero-Ibanez, Marcos; Penny, Samantha;
Percival, Will J.; Perez-Fournon, Ismael; Petitjean, Patrick; Pieri,
Matthew M.; Pinsonneault, Marc; Pisani, Alice; Prada, Francisco;
Prakash, Abhishek; Queiroz, Anna Bárbara de Andrade; Raddick,
M. Jordan; Raichoor, Anand; Barboza Rembold, Sandro; Richstein,
Hannah; Riffel, Rogemar A.; Riffel, Rogério; Rix, Hans-Walter; Robin,
Annie C.; Rodríguez Torres, Sergio; Román-Zúñiga, Carlos; Ross,
Ashley J.; Rossi, Graziano; Ruan, John; Ruggeri, Rossana; Ruiz, Jose;
Salvato, Mara; Sánchez, Ariel G.; Sánchez, Sebastián F.; Sanchez
Almeida, Jorge; Sánchez-Gallego, José R.; Santana Rojas, Felipe
Antonio; Santiago, Basílio Xavier; Schiavon, Ricardo P.; Schimoia,
Jaderson S.; Schlafly, Edward; Schlegel, David; Schneider, Donald P.;
Schuster, William J.; Schwope, Axel; Seo, Hee-Jong; Serenelli, Aldo;
Shen, Shiyin; Shen, Yue; Shetrone, Matthew; Shull, Michael; Silva
Aguirre, Víctor; Simon, Joshua D.; Skrutskie, Mike; Slosar, Anže;
Smethurst, Rebecca; Smith, Verne; Sobeck, Jennifer; Somers, Garrett;
Souter, Barbara J.; Souto, Diogo; Spindler, Ashley; Stark, David V.;
Stassun, Keivan; Steinmetz, Matthias; Stello, Dennis; Storchi-Bergmann,
Thaisa; Streblyanska, Alina; Stringfellow, Guy S.; Suárez, Genaro;
Sun, Jing; Szigeti, Laszlo; Taghizadeh-Popp, Manuchehr; Talbot,
Michael S.; Tang, Baitian; Tao, Charling; Tayar, Jamie; Tembe,
Mita; Teske, Johanna; Thakar, Aniruddha R.; Thomas, Daniel; Tissera,
Patricia; Tojeiro, Rita; Tremonti, Christy; Troup, Nicholas W.; Urry,
Meg; Valenzuela, O.; van den Bosch, Remco; Vargas-González, Jaime;
Vargas-Magaña, Mariana; Vazquez, Jose Alberto; Villanova, Sandro;
Vogt, Nicole; Wake, David; Wang, Yuting; Weaver, Benjamin Alan;
Weijmans, Anne-Marie; Weinberg, David H.; Westfall, Kyle B.; Whelan,
David G.; Wilcots, Eric; Wild, Vivienne; Williams, Rob A.; Wilson,
John; Wood-Vasey, W. M.; Wylezalek, Dominika; Xiao, Ting; Yan, Renbin;
Yang, Meng; Ybarra, Jason E.; Yèche, Christophe; Zakamska, Nadia;
Zamora, Olga; Zarrouk, Pauline; Zasowski, Gail; Zhang, Kai; Zhao,
Cheng; Zhao, Gong-Bo; Zheng, Zheng; Zheng, Zheng; Zhou, Zhi-Min; Zhu,
Guangtun; Zinn, Joel C.; Zou, Hu
2018ApJS..235...42A Altcode: 2017arXiv170709322A
The fourth generation of the Sloan Digital Sky Survey (SDSS-IV)
has been in operation since 2014 July. This paper describes the
second data release from this phase, and the 14th from SDSS overall
(making this Data Release Fourteen or DR14). This release makes the
data taken by SDSS-IV in its first two years of operation (2014-2016
July) public. Like all previous SDSS releases, DR14 is cumulative,
including the most recent reductions and calibrations of all data
taken by SDSS since the first phase began operations in 2000. New
in DR14 is the first public release of data from the extended Baryon
Oscillation Spectroscopic Survey; the first data from the second phase
of the Apache Point Observatory (APO) Galactic Evolution Experiment
(APOGEE-2), including stellar parameter estimates from an innovative
data-driven machine-learning algorithm known as “The Cannon”
and almost twice as many data cubes from the Mapping Nearby Galaxies
at APO (MaNGA) survey as were in the previous release (N = 2812 in
total). This paper describes the location and format of the publicly
available data from the SDSS-IV surveys. We provide references to the
important technical papers describing how these data have been taken
(both targeting and observation details) and processed for scientific
use. The SDSS web site (<A href="http://www.sdss.org">www.sdss.org</A>)
has been updated for this release and provides links to data downloads,
as well as tutorials and examples of data use. SDSS-IV is planning to
continue to collect astronomical data until 2020 and will be followed
by SDSS-V.
---------------------------------------------------------
Title: Chemical Abundances of Main-sequence, Turnoff, Subgiant, and
Red Giant Stars from APOGEE Spectra. I. Signatures of Diffusion in
the Open Cluster M67
Authors: Souto, Diogo; Cunha, Katia; Smith, Verne V.; Allende Prieto,
C.; García-Hernández, D. A.; Pinsonneault, Marc; Holzer, Parker;
Frinchaboy, Peter; Holtzman, Jon; Johnson, J. A.; Jönsson, Henrik;
Majewski, Steven R.; Shetrone, Matthew; Sobeck, Jennifer; Stringfellow,
Guy; Teske, Johanna; Zamora, Olga; Zasowski, Gail; Carrera, Ricardo;
Stassun, Keivan; Fernandez-Trincado, J. G.; Villanova, Sandro; Minniti,
Dante; Santana, Felipe
2018ApJ...857...14S Altcode: 2018arXiv180304461S
Detailed chemical abundance distributions for 14 elements are derived
for eight high-probability stellar members of the solar metallicity
old open cluster M67 with an age of ∼4 Gyr. The eight stars consist
of four pairs, with each pair occupying a distinct phase of stellar
evolution: two G dwarfs, two turnoff stars, two G subgiants, and two red
clump (RC) K giants. The abundance analysis uses near-IR high-resolution
spectra (λ1.5-1.7 μm) from the Apache Point Observatory Galactic
Evolution Experiment survey and derives abundances for C, N, O, Na, Mg,
Al, Si, K, Ca, Ti, V, Cr, Mn, and Fe. Our derived stellar parameters
and metallicity for 2M08510076+1153115 suggest that this star is a
solar twin, exhibiting abundance differences relative to the Sun of
≤0.04 dex for all elements. Chemical homogeneity is found within each
class of stars (∼0.02 dex), while significant abundance variations
(∼0.05-0.20 dex) are found across the different evolutionary
phases; the turnoff stars typically have the lowest abundances,
while the RCs tend to have the largest. Non-LTE corrections to the
LTE-derived abundances are unlikely to explain the differences. A
detailed comparison of the derived Fe, Mg, Si, and Ca abundances with
recently published surface abundances from stellar models that include
chemical diffusion provides a good match between the observed and
predicted abundances as a function of stellar mass. Such agreement
would indicate the detection of chemical diffusion processes in the
stellar members of M67.
---------------------------------------------------------
Title: Disk stars in the Milky Way detected beyond 25 kpc from
its center
Authors: López-Corredoira, M.; Allende Prieto, C.; Garzón, F.;
Wang, H.; Liu, C.; Deng, L.
2018A&A...612L...8L Altcode: 2018arXiv180403064L
Context. The maximum size of the Galactic stellar disk is not yet
known. Some studies have suggested an abrupt drop-off of the stellar
density of the disk at Galactocentric distances R ≳ 15 kpc, which
means that in practice no disk stars or only very few of them should
be found beyond this limit. However, stars in the Milky Way plane are
detected at larger distances. In addition to the halo component, star
counts have placed the end of the disk beyond 20 kpc, although this
has not been spectroscopically confirmed so far. <BR /> Aims: Here,
we aim to spectroscopically confirm the presence of the disk stars up
to much larger distances. <BR /> Methods: With data from the LAMOST
and SDSS-APOGEE spectroscopic surveys, we statistically derived the
maximum distance at which the metallicity distribution of stars in the
Galactic plane is distinct from that of the halo populations. <BR />
Results: Our analysis reveals the presence of disk stars at R >
26 kpc (99.7% C.L.) and even at R > 31 kpc (95.4% C.L.).
---------------------------------------------------------
Title: <SUP>12</SUP>C/<SUP>13</SUP>C isotopic ratios in red-giant
stars of the open cluster NGC 6791
Authors: Szigeti, László; Mészáros, Szabolcs; Smith,
Verne V.; Cunha, Katia; Lagarde, Nadège; Charbonnel, Corinne;
García-Hernández, D. A.; Shetrone, Matthew; Pinsonneault, Marc;
Allende Prieto, Carlos; Fernández-Trincado, J. G.; Kovács, József;
Villanova, Sandro
2018MNRAS.474.4810S Altcode: 2017arXiv171108183S
Carbon isotope ratios, along with carbon and nitrogen abundances,
are derived in a sample of 11 red-giant members of one of the most
metal-rich clusters in the Milky Way, NGC 6791. The selected red-giants
have a mean metallicity and standard deviation of [Fe/H] = +0.39
± 0.06 (Cunha et al. 2015). We used high-resolution H-band spectra
obtained by the SDSS-IV Apache Point Observatory Galactic Evolution
Experiment. The advantage of using high-resolution spectra in the H band
is that lines of CO are well represented and their line profiles are
sensitive to the variation of <SUP>12</SUP>C/<SUP>13</SUP>C. Values of
the <SUP>12</SUP>C/<SUP>13</SUP>C ratio were obtained from a spectrum
synthesis analysis. The derived <SUP>12</SUP>C/<SUP>13</SUP>C ratios
varied between 6.3 and 10.6 in NGC 6791, in agreement with the final
isotopic ratios from thermohaline-induced mixing models. The ratios
derived here are combined with those obtained for more metal poor
red-giants from the literature to examine the correlation between
<SUP>12</SUP>C/<SUP>13</SUP>C, mass, metallicity, and evolutionary
status.
---------------------------------------------------------
Title: VizieR Online Data Catalog: APOGEE full information on classes
(Garcia-Dias+, 2018)
Authors: Garcia-Dias, R.; Allende Prieto, C.; Sanchez Almeida, J.;
Ordovas-Pascual, I.
2018yCat..36120098G Altcode:
Data for the classes derived on the paper. The tables provide the star
labels, the mean spectra of the classes and the within class standard
deviation. <P />(3 data files).
---------------------------------------------------------
Title: Elemental Abundances of Kepler Objects of Interest in
APOGEE. I. Two Distinct Orbital Period Regimes Inferred from Host
Star Iron Abundances
Authors: Wilson, Robert F.; Teske, Johanna; Majewski, Steven R.;
Cunha, Katia; Smith, Verne; Souto, Diogo; Bender, Chad; Mahadevan,
Suvrath; Troup, Nicholas; Allende Prieto, Carlos; Stassun, Keivan G.;
Skrutskie, Michael F.; Almeida, Andrés; García-Hernández, D. A.;
Zamora, Olga; Brinkmann, Jonathan
2018AJ....155...68W Altcode: 2017arXiv171201198W
The Apache Point Observatory Galactic Evolution Experiment
(APOGEE) has observed ∼600 transiting exoplanets and exoplanet
candidates from Kepler (Kepler Objects of Interest, KOIs), most
with ≥18 epochs. The combined multi-epoch spectra are of high
signal-to-noise ratio (typically ≥100) and yield precise stellar
parameters and chemical abundances. We first confirm the ability of
the APOGEE abundance pipeline, ASPCAP, to derive reliable [Fe/H]
and effective temperatures for FGK dwarf stars—the primary
Kepler host stellar type—by comparing the ASPCAP-derived stellar
parameters with those from independent high-resolution spectroscopic
characterizations for 221 dwarf stars in the literature. With
a sample of 282 close-in (P< 100 days) KOIs observed in the
APOGEE KOI goal program, we find a correlation between orbital
period and host star [Fe/H] characterized by a critical period,
{P}<SUB>{crit</SUB>}={8.3}<SUB>-4.1</SUB><SUP>+0.1</SUP> days,
below which small exoplanets orbit statistically more metal-enriched
host stars. This effect may trace a metallicity dependence of the
protoplanetary disk inner radius at the time of planet formation or
may be a result of rocky planet ingestion driven by inward planetary
migration. We also consider that this may trace a metallicity dependence
of the dust sublimation radius, but we find no statistically significant
correlation with host {T}<SUB>{eff</SUB>} and orbital period to support
such a claim.
---------------------------------------------------------
Title: Stellar Multiplicity Meets Stellar Evolution and Metallicity:
The APOGEE View
Authors: Badenes, Carles; Mazzola, Christine; Thompson, Todd A.;
Covey, Kevin; Freeman, Peter E.; Walker, Matthew G.; Moe, Maxwell;
Troup, Nicholas; Nidever, David; Allende Prieto, Carlos; Andrews,
Brett; Barbá, Rodolfo H.; Beers, Timothy C.; Bovy, Jo; Carlberg,
Joleen K.; De Lee, Nathan; Johnson, Jennifer; Lewis, Hannah; Majewski,
Steven R.; Pinsonneault, Marc; Sobeck, Jennifer; Stassun, Keivan G.;
Stringfellow, Guy S.; Zasowski, Gail
2018ApJ...854..147B Altcode: 2017arXiv171100660B
We use the multi-epoch radial velocities acquired by the Apache Point
Observatory Galactic Evolution Experiment (APOGEE) survey to perform
a large-scale statistical study of stellar multiplicity for field
stars in the Milky Way, spanning the evolutionary phases between the
main sequence (MS) and the red clump. We show that the distribution of
maximum radial velocity shifts (ΔRV<SUB>max</SUB>) for APOGEE targets
is a strong function of log g, with MS stars showing ΔRV<SUB>max</SUB>
as high as ∼300 {km} {{{s}}}<SUP>-1</SUP>, and steadily dropping down
to ∼30 {km} {{{s}}}<SUP>-1</SUP> for log g ∼ 0, as stars climb up
the red giant branch (RGB). Red clump stars show a distribution of
ΔRV<SUB>max</SUB> values comparable to that of stars at the tip of
the RGB, implying they have similar multiplicity characteristics. The
observed attrition of high ΔRV<SUB>max</SUB> systems in the RGB
is consistent with a lognormal period distribution in the MS and a
multiplicity fraction of 0.35, which is truncated at an increasing
period as stars become physically larger and undergo mass transfer
after Roche Lobe overflow during H-shell burning. The ΔRV<SUB>max</SUB>
distributions also show that the multiplicity characteristics of field
stars are metallicity-dependent, with metal-poor ([Fe/H] ≲ -0.5)
stars having a multiplicity fraction a factor of 2-3 higher than
metal-rich ([Fe/H] ≳ 0.0) stars. This has profound implications for
the formation rates of interacting binaries observed by astronomical
transient surveys and gravitational wave detectors, as well as the
habitability of circumbinary planets.
---------------------------------------------------------
Title: J0023+0307: A Mega Metal-poor Dwarf Star from SDSS/BOSS
Authors: Aguado, David S.; Allende Prieto, Carlos; González
Hernández, Jonay I.; Rebolo, Rafael
2018ApJ...854L..34A Altcode: 2018arXiv180206240A
Only a handful of stars have been identified with an iron abundance
[Fe/H] < -5, and only one at [Fe/H] < -7. These stars have very
large carbon-to-iron ratios, with {\boldsymbol{A}}({\boldsymbol{C}})
∼ 7.0, most likely due to fallback in core-collapse supernovae,
which makes their total metallicity Z much higher than their iron
abundances. The failure to find population III stars, those with no
metals, has been interpreted, with support from theoretical modeling,
as the result of a top-heavy initial mass function. With zero or
very low metal abundance limiting radiative cooling, the formation of
low-mass stars could be inhibited. Currently, the star SDSS J1029+1729
sets the potential metallicity threshold for the formation of low-mass
stars at {log}Z/{Z}<SUB>⊙ </SUB>∼ -5. In our quest to push down the
metallicity threshold we have identified SDSS J0023+0307, a primitive
star with T <SUB>eff</SUB> = 6188 ± 84 K, and {log}g=4.9+/- 0.5, an
upper limit [Fe/H] < -6.6, and a carbon abundance A(C) < 6.3. We
find J0023+0307 to be one of the two most iron-poor stars known, and
it exhibits less carbon that most of the stars at [Fe/H] < -5. <P
/>Based on observations made with William Herschel Telescope (WHT) and
the Gran Telescopio de Canarias (GTC), at the Observatorio del Roque de
los Muchachos of the Instituto de Astrofísica de Canarias, in La Palma.
---------------------------------------------------------
Title: Characterizing the 300 km/s Stream Near Segue 1
Authors: Fu, Wanying; Simon, Joshua D.; Bovy, Jo; ALLENDE PRIETO,
CARLOS; Beers, Timothy; Harding, Paul; Ivans, Inese I.; Lane, Richard;
APOGEE-2
2018AAS...23125712F Altcode:
The characterization of stellar streams in the Milky Way halo can
provide important observational constraints on the ΛCDM cosmological
model, which posits that galaxies form via the accretion of smaller
satellites. One such stream, the 300 km/s stellar stream near the
dwarf galaxy Segue 1 (300S), was detected in narrow-field spectroscopic
surveys, but its photometric counterpart has not been identified. In
this study, we search for members of 300S in wide-field survey
data to map out the stream’s extent and further characterize its
progenitor. We add to the existing catalog of 300S members by finding
new members of 300S in SEGUE-1, SEGUE-2, and APOGEE-2 surveys,
and confirm the kinematic association of 300S with an elongated
substructure found in both SDSS and PanSTARRS photometric data. The
300S stars display a mean metallicity of [Fe/H] = -1.42 ± 0.26, and
have chemical abundance patterns similar to that of Local Group dwarf
galaxies, as well as that of the Milky Way halo. Using the open-source
code galpy to model a preliminary orbit of the stream, we suggest that
the progenitor of 300S experienced one major tidal disruption event on
its most recent pericentric passing. We conclude that the progenitor of
the stream is a dwarf galaxy that is probably similar to the satellites
that were accreted to build the present-day Milky Way halo.
---------------------------------------------------------
Title: VizieR Online Data Catalog: Properties of metal-poor stars
in APOGEE DR13 (Hayes+, 2018)
Authors: Hayes, C. R.; Majewski, S. R.; Shetrone, M.; Fernandez-Alvar,
E.; Allende Prieto, C.; Schuster, W. J.; Carigi, L.; Cunha, K.;
Smith, V. V.; Sobeck, J.; Almeida, A.; Beers, T. C.; Carrera, R.;
Fernandez-Trincado, J. G.; Garcia-Hernandez, D. A.; Geisler, D.;
Lane, R. R.; Lucatello, S.; Matthews, A. M.; Minniti, D.; Nitschelm,
C.; Tang, B.; Tissera, P. B.; Zamora, O.
2018yCat..18520049H Altcode:
Table 1 contains the properties, stellar parameters, and chemical
abundances of the metal-poor stars in reported by the Apache Point
Observatory Galactic Evolution Experiment (APOGEE) in the 13th data
release of the Sloan Digital Sky survey as presented in the paper. This
table also includes population assignments for these metal-poor stars
into to the two populations that have been identified. <P />(1 data
file).
---------------------------------------------------------
Title: J0815+4729: A Chemically Primitive Dwarf Star in the Galactic
Halo Observed with Gran Telescopio Canarias
Authors: Aguado, David S.; González Hernández, Jonay I.; Allende
Prieto, Carlos; Rebolo, Rafael
2018ApJ...852L..20A Altcode: 2017arXiv171206487A
We report the discovery of the carbon-rich hyper metal-poor unevolved
star J0815+4729. This dwarf star was selected from SDSS/BOSS as a
metal-poor candidate and follow-up spectroscopic observations at medium
resolution were obtained with the Intermediate dispersion Spectrograph
and Imaging System (ISIS) at William Herschel Telescope and the
Optical System for Imaging and low-intermediate-Resolution Integrated
Spectroscopy (OSIRIS) at Gran Telescopio de Canarias. We use the FERRE
code to derive the main stellar parameters, {T}<SUB>{eff</SUB>}=6215+/-
82 K, and {log}g=4.7+/- 0.5, an upper limit to the metallicity of
[Fe/H] ≤ -5.8, and a carbon abundance of [C/Fe] ≥ +5.0, while
[α /{Fe}]=0.4 is assumed. The metallicity upper limit is based on the
Ca II K line, which at the resolving power of the OSIRIS spectrograph
cannot be resolved from possible interstellar calcium. The star could
be the most iron-poor unevolved star known and also be among the ones
with the largest overabundances of carbon. High-resolution spectroscopy
of J0815+4729 will certainly help to derive other important elemental
abundances, possibly providing new fundamental constraints on the
early stages of the universe, the formation of the first stars, and
the properties of the first supernovae. <P />Based on observations
made with the Gran Telescopio Canarias (GTC), installed in the Spanish
Observatorio del Roque de los Muchachos of the Instituto de Astrofísica
de Canarias, on the island of La Palma. Program ID GTC90-15B and the
Discretionary Director Time GTC03-16ADDT and also based on observations
made with the William Herschel Telescope (WHT).
---------------------------------------------------------
Title: Disentangling the Galactic Halo with APOGEE. I. Chemical and
Kinematical Investigation of Distinct Metal-poor Populations
Authors: Hayes, Christian R.; Majewski, Steven R.; Shetrone,
Matthew; Fernández-Alvar, Emma; Allende Prieto, Carlos; Schuster,
William J.; Carigi, Leticia; Cunha, Katia; Smith, Verne V.; Sobeck,
Jennifer; Almeida, Andres; Beers, Timothy C.; Carrera, Ricardo;
Fernández-Trincado, J. G.; García-Hernández, D. A.; Geisler, Doug;
Lane, Richard R.; Lucatello, Sara; Matthews, Allison M.; Minniti,
Dante; Nitschelm, Christian; Tang, Baitian; Tissera, Patricia B.;
Zamora, Olga
2018ApJ...852...49H Altcode: 2017arXiv171105781H
We find two chemically distinct populations separated relatively
cleanly in the [Fe/H]-[Mg/Fe] plane, but also distinguished in other
chemical planes, among metal-poor stars (primarily with metallicities
[{Fe}/{{H}}]< -0.9) observed by the Apache Point Observatory
Galactic Evolution Experiment (APOGEE) and analyzed for Data Release 13
(DR13) of the Sloan Digital Sky Survey. These two stellar populations
show the most significant differences in their [X/Fe] ratios for the
α-elements, C+N, Al, and Ni. In addition to these populations having
differing chemistry, the low metallicity high-Mg population (which we
denote “the HMg population”) exhibits a significant net Galactic
rotation, whereas the low-Mg population (or “the LMg population”)
has halo-like kinematics with little to no net rotation. Based on its
properties, the origin of the LMg population is likely an accreted
population of stars. The HMg population shows chemistry (and to an
extent kinematics) similar to the thick disk, and is likely associated
with in situ formation. The distinction between the LMg and HMg
populations mimics the differences between the populations of low-
and high-α halo stars found in previous studies, suggesting that
these are samples of the same two populations.
---------------------------------------------------------
Title: Metallicity gradient of the thick disc progenitor at high
redshift
Authors: Kawata, Daisuke; Allende Prieto, Carlos; Brook, Chris B.;
Casagrande, Luca; Ciucă, Ioana; Gibson, Brad K.; Grand, Robert J. J.;
Hayden, Michael R.; Hunt, Jason A. S.
2018MNRAS.473..867K Altcode: 2017arXiv170601474K
We have developed a novel Markov Chain Monte Carlo chemical 'painting'
technique to explore possible radial and vertical metallicity gradients
for the thick disc progenitor. In our analysis, we match an N-body
simulation to the data from the Apache Point Observatory Galactic
Evolution Experiment survey. We assume that the thick disc has a
constant scaleheight and has completed its formation at an early epoch,
after which time radial mixing of its stars has taken place. Under these
assumptions, we find that the initial radial metallicity gradient of
the thick disc progenitor should not be negative, but either flat or
even positive, to explain the current negative vertical metallicity
gradient of the thick disc. Our study suggests that the thick disc
was built-up in an inside-out and upside-down fashion, and older,
smaller and thicker populations are more metal poor. In this case,
star-forming discs at different epochs of the thick disc formation
are allowed to have different radial metallicity gradients, including
a negative one, which helps to explain a variety of slopes observed
in high-redshift disc galaxies. This scenario helps to explain the
positive slope of the metallicity-rotation velocity relation observed
for the Galactic thick disc. On the other hand, radial mixing flattens
the slope of an existing gradient.
---------------------------------------------------------
Title: Disentangling the Galactic Halo with APOGEE. II. Chemical
and Star Formation Histories for the Two Distinct Populations
Authors: Fernández-Alvar, Emma; Carigi, Leticia; Schuster, William
J.; Hayes, Christian R.; Ávila-Vergara, Nancy; Majewski, Steve R.;
Allende Prieto, Carlos; Beers, Timothy C.; Sánchez, Sebastián F.;
Zamora, Olga; García-Hernández, Domingo Aníbal; Tang, Baitian;
Fernández-Trincado, José G.; Tissera, Patricia; Geisler, Douglas;
Villanova, Sandro
2018ApJ...852...50F Altcode: 2017arXiv171106225F
The formation processes that led to the current Galactic stellar
halo are still under debate. Previous studies have provided evidence
for different stellar populations in terms of elemental abundances
and kinematics, pointing to different chemical and star formation
histories (SFHs). In the present work, we explore, over a broader
range in metallicity (-2.2< [{Fe}/{{H}}]< +0.5), the two stellar
populations detected in the first paper of this series from metal-poor
stars in DR13 of the Apache Point Observatory Galactic Evolution
Experiment (APOGEE). We aim to infer signatures of the initial mass
function (IMF) and the SFH from the two α-to-iron versus iron abundance
chemical trends for the most APOGEE-reliable α-elements (O, Mg, Si,
and Ca). Using simple chemical-evolution models, we infer the upper mass
limit (M <SUB>up</SUB>) for the IMF and the star formation rate, and
its duration for each population. Compared with the low-α population,
we obtain a more intense and longer-lived SFH, and a top-heavier IMF
for the high-α population.
---------------------------------------------------------
Title: Probing Planet Formation with APOGEE: A Dichotomy in Planet
Orbital-Periods and Stellar Metallicities
Authors: Wilson, Robert Forrest; Teske, Johanna; Majewski, Steven R.;
Cunha, Katia; Smith, Verne; Souto, Diogo; Bender, Chad; Mahadevan,
Suvrath; Troup, Nicholas; ALLENDE PRIETO, CARLOS; Stassun, Keivan G.;
Skrutskie, Michael; ALMEIDA, ANDRES; Brinkmann, Jonathan; APOGEE
2018AAS...23121102W Altcode:
The Apache Point Observatory Galactic Evolution Experiment (APOGEE) is
a near-infrared (1.5-1.7 microns), high resolution (R~22,500), high S/N
(>100), spectroscopic survey as part of the Sloan Digital Sky Survey
(SDSS). Among the goals of this survey is multi-epoch monitoring of
exoplanetary systems discovered by the Kepler mission, resulting in
very high S/N (typically a few hundred) observations of Planet-hosting
stars. The combined visits and sensitivity of the Sloan 2.5-meter
telescope yield stellar parameters for a large number of planet-hosting
systems with higher precision (e.g., $\sigma_{[Fe/H]} < 0.05$ dex),
and deeper observations (H<14) than many other spectroscopic surveys
of similar scale. We have combined this rich dataset with orbital and
planetary properties from the Kepler mission to reveal a correlation
with stellar metallicity and planet orbital period in close-in
(P<100 days), small (R_p < 20 R_earth) exoplanetary systems. In
particular, we find that planets with orbital periods P ≤ 8.5 days
have statistically more metal-enriched hosts than planets with P >
8.5 days. This dichotomy implies that there may be different formation
histories between these two populations. For example, there may be a
protoplanetary disk inner-radius (such as the gas co-rotation radius or
the dust-sublimation radius) with a metallicity-dependence at the time
of planet formation that allows small, rocky planets to either form
or migrate closer in to their host star in metal-rich conditions. In
addition, based on previous work about the "Evaporation Valley",
there is theoretical support that this critical period of 8.5 days
may be tied to the bulk composition of the two exoplanet populations.
---------------------------------------------------------
Title: The Bulge Metallicity Distribution from the APOGEE Survey
Authors: García Pérez, Ana E.; Ness, Melissa; Robin, Annie C.;
Martinez-Valpuesta, Inma; Sobeck, Jennifer; Zasowski, Gail; Majewski,
Steven R.; Bovy, Jo; Allende Prieto, Carlos; Cunha, Katia; Girardi,
Léo; Mészáros, Szabolcs; Nidever, David; Schiavon, Ricardo P.;
Schultheis, Mathias; Shetrone, Matthew; Smith, Verne V.
2018ApJ...852...91G Altcode: 2017arXiv171201297G
The Apache Point Observatory Galactic Evolution Experiment (APOGEE)
provides spectroscopic information of regions of the inner Milky
Way, which are inaccessible to optical surveys. We present the
first large study of the metallicity distribution of the innermost
Galactic regions based on high-quality measurements for 7545 red
giant stars within 4.5 kpc of the Galactic center, with the goal to
shed light on the structure and origin of the Galactic bulge. Stellar
metallicities are found, through multiple Gaussian decompositions,
to be distributed in several components, which is indicative of the
presence of various stellar populations such as the bar or the thin
and the thick disks. Super-solar ([Fe/H] = +0.32) and solar ([Fe/H]
= +0.00) metallicity components, tentatively associated with the thin
disk and the Galactic bar, respectively, seem to be major contributors
near the midplane. A solar-metallicity component extends outwards in
the midplane but is not observed in the innermost regions. The central
regions (within 3 kpc of the Galactic center) reveal, on the other
hand, the presence of a significant metal-poor population ([Fe/H] =
-0.46), tentatively associated with the thick disk, which becomes
the dominant component far from the midplane (| Z| ≥slant +0.75
kpc). Varying contributions from these different components produce
a transition region at +0.5 kpc ≤slant | Z| ≤slant +1.0 {kpc},
characterized by a significant vertical metallicity gradient.
---------------------------------------------------------
Title: The Pristine survey - III. Spectroscopic confirmation of an
efficient search for extremely metal-poor stars
Authors: Youakim, K.; Starkenburg, E.; Aguado, D. S.; Martin, N. F.;
Fouesneau, M.; González Hernández, J. I.; Allende Prieto, C.;
Bonifacio, P.; Gentile, M.; Kielty, C.; Côté, P.; Jablonka, P.;
McConnachie, A.; Sánchez Janssen, R.; Tolstoy, E.; Venn, K.
2017MNRAS.472.2963Y Altcode: 2017arXiv170801264Y
The Pristine survey is a narrow-band, photometric survey focused around
the wavelength region of the Ca II H&K absorption lines, designed
to efficiently search for extremely metal-poor stars. In this work, we
use the first results of a medium-resolution spectroscopic follow-up
to refine the selection criteria for finding extremely metal-poor
stars ([Fe/H] ≤ -3.0) in the Pristine survey. We consider methods
by which stars can be selected from available broad-band and infrared
photometry plus the additional Pristine narrow-band photometry. The
sample consists of 205 stars in the magnitude range 14 < V <
18. Applying the photometric selection criteria cuts the sample down
to 149 stars, and from these we report a success rate of 70 per cent
for finding stars with [Fe/H] ≤ -2.5 and 22 per cent for finding
stars with [Fe/H] ≤ -3.0. These statistics compare favourably with
other surveys that search for extremely metal-poor stars, namely an
improvement by a factor of ∼4 - 5 for recovering stars with [Fe/H]
≤ -3.0. In addition, Pristine covers a fainter magnitude range than
its predecessors and can thus probe deeper into the Galactic halo.
---------------------------------------------------------
Title: The 13th Data Release of the Sloan Digital Sky Survey: First
Spectroscopic Data from the SDSS-IV Survey Mapping Nearby Galaxies
at Apache Point Observatory
Authors: Albareti, Franco D.; Allende Prieto, Carlos; Almeida,
Andres; Anders, Friedrich; Anderson, Scott; Andrews, Brett H.;
Aragón-Salamanca, Alfonso; Argudo-Fernández, Maria; Armengaud,
Eric; Aubourg, Eric; Avila-Reese, Vladimir; Badenes, Carles; Bailey,
Stephen; Barbuy, Beatriz; Barger, Kat; Barrera-Ballesteros, Jorge;
Bartosz, Curtis; Basu, Sarbani; Bates, Dominic; Battaglia, Giuseppina;
Baumgarten, Falk; Baur, Julien; Bautista, Julian; Beers, Timothy
C.; Belfiore, Francesco; Bershady, Matthew; Bertran de Lis, Sara;
Bird, Jonathan C.; Bizyaev, Dmitry; Blanc, Guillermo A.; Blanton,
Michael; Blomqvist, Michael; Bolton, Adam S.; Borissova, J.; Bovy,
Jo; Brandt, William Nielsen; Brinkmann, Jonathan; Brownstein,
Joel R.; Bundy, Kevin; Burtin, Etienne; Busca, Nicolás G.;
Camacho Chavez, Hugo Orlando; Cano Díaz, M.; Cappellari, Michele;
Carrera, Ricardo; Chen, Yanping; Cherinka, Brian; Cheung, Edmond;
Chiappini, Cristina; Chojnowski, Drew; Chuang, Chia-Hsun; Chung,
Haeun; Cirolini, Rafael Fernando; Clerc, Nicolas; Cohen, Roger E.;
Comerford, Julia M.; Comparat, Johan; Correa do Nascimento, Janaina;
Cousinou, Marie-Claude; Covey, Kevin; Crane, Jeffrey D.; Croft, Rupert;
Cunha, Katia; Darling, Jeremy; Davidson, James W., Jr.; Dawson, Kyle;
Da Costa, Luiz; Da Silva Ilha, Gabriele; Deconto Machado, Alice;
Delubac, Timothée; De Lee, Nathan; De la Macorra, Axel; De la Torre,
Sylvain; Diamond-Stanic, Aleksandar M.; Donor, John; Downes, Juan
Jose; Drory, Niv; Du, Cheng; Du Mas des Bourboux, Hélion; Dwelly,
Tom; Ebelke, Garrett; Eigenbrot, Arthur; Eisenstein, Daniel J.;
Elsworth, Yvonne P.; Emsellem, Eric; Eracleous, Michael; Escoffier,
Stephanie; Evans, Michael L.; Falcón-Barroso, Jesús; Fan, Xiaohui;
Favole, Ginevra; Fernandez-Alvar, Emma; Fernandez-Trincado, J. G.;
Feuillet, Diane; Fleming, Scott W.; Font-Ribera, Andreu; Freischlad,
Gordon; Frinchaboy, Peter; Fu, Hai; Gao, Yang; Garcia, Rafael A.;
Garcia-Dias, R.; Garcia-Hernández, D. A.; Garcia Pérez, Ana E.;
Gaulme, Patrick; Ge, Junqiang; Geisler, Douglas; Gillespie, Bruce;
Gil Marin, Hector; Girardi, Léo; Goddard, Daniel; Gomez Maqueo
Chew, Yilen; Gonzalez-Perez, Violeta; Grabowski, Kathleen; Green,
Paul; Grier, Catherine J.; Grier, Thomas; Guo, Hong; Guy, Julien;
Hagen, Alex; Hall, Matt; Harding, Paul; Harley, R. E.; Hasselquist,
Sten; Hawley, Suzanne; Hayes, Christian R.; Hearty, Fred; Hekker,
Saskia; Hernandez Toledo, Hector; Ho, Shirley; Hogg, David W.;
Holley-Bockelmann, Kelly; Holtzman, Jon A.; Holzer, Parker H.; Hu,
Jian; Huber, Daniel; Hutchinson, Timothy Alan; Hwang, Ho Seong;
Ibarra-Medel, Héctor J.; Ivans, Inese I.; Ivory, KeShawn; Jaehnig,
Kurt; Jensen, Trey W.; Johnson, Jennifer A.; Jones, Amy; Jullo, Eric;
Kallinger, T.; Kinemuchi, Karen; Kirkby, David; Klaene, Mark; Kneib,
Jean-Paul; Kollmeier, Juna A.; Lacerna, Ivan; Lane, Richard R.; Lang,
Dustin; Laurent, Pierre; Law, David R.; Leauthaud, Alexie; Le Goff,
Jean-Marc; Li, Chen; Li, Cheng; Li, Niu; Li, Ran; Liang, Fu-Heng;
Liang, Yu; Lima, Marcos; Lin, Lihwai; Lin, Lin; Lin, Yen-Ting; Liu,
Chao; Long, Dan; Lucatello, Sara; MacDonald, Nicholas; MacLeod,
Chelsea L.; Mackereth, J. Ted; Mahadevan, Suvrath; Maia, Marcio
Antonio Geimba; Maiolino, Roberto; Majewski, Steven R.; Malanushenko,
Olena; Malanushenko, Viktor; Mallmann, Nícolas Dullius; Manchado,
Arturo; Maraston, Claudia; Marques-Chaves, Rui; Martinez Valpuesta,
Inma; Masters, Karen L.; Mathur, Savita; McGreer, Ian D.; Merloni,
Andrea; Merrifield, Michael R.; Mészáros, Szabolcs; Meza, Andres;
Miglio, Andrea; Minchev, Ivan; Molaverdikhani, Karan; Montero-Dorta,
Antonio D.; Mosser, Benoit; Muna, Demitri; Myers, Adam; Nair,
Preethi; Nandra, Kirpal; Ness, Melissa; Newman, Jeffrey A.; Nichol,
Robert C.; Nidever, David L.; Nitschelm, Christian; O'Connell, Julia;
Oravetz, Audrey; Oravetz, Daniel J.; Pace, Zachary; Padilla, Nelson;
Palanque-Delabrouille, Nathalie; Pan, Kaike; Parejko, John; Paris,
Isabelle; Park, Changbom; Peacock, John A.; Peirani, Sebastien;
Pellejero-Ibanez, Marcos; Penny, Samantha; Percival, Will J.;
Percival, Jeffrey W.; Perez-Fournon, Ismael; Petitjean, Patrick;
Pieri, Matthew; Pinsonneault, Marc H.; Pisani, Alice; Prada, Francisco;
Prakash, Abhishek; Price-Jones, Natalie; Raddick, M. Jordan; Rahman,
Mubdi; Raichoor, Anand; Barboza Rembold, Sandro; Reyna, A. M.; Rich,
James; Richstein, Hannah; Ridl, Jethro; Riffel, Rogemar A.; Riffel,
Rogério; Rix, Hans-Walter; Robin, Annie C.; Rockosi, Constance M.;
Rodríguez-Torres, Sergio; Rodrigues, Thaíse S.; Roe, Natalie; Roman
Lopes, A.; Román-Zúñiga, Carlos; Ross, Ashley J.; Rossi, Graziano;
Ruan, John; Ruggeri, Rossana; Runnoe, Jessie C.; Salazar-Albornoz,
Salvador; Salvato, Mara; Sanchez, Sebastian F.; Sanchez, Ariel G.;
Sanchez-Gallego, José R.; Santiago, Basílio Xavier; Schiavon,
Ricardo; Schimoia, Jaderson S.; Schlafly, Eddie; Schlegel, David J.;
Schneider, Donald P.; Schönrich, Ralph; Schultheis, Mathias; Schwope,
Axel; Seo, Hee-Jong; Serenelli, Aldo; Sesar, Branimir; Shao, Zhengyi;
Shetrone, Matthew; Shull, Michael; Silva Aguirre, Victor; Skrutskie,
M. F.; Slosar, Anže; Smith, Michael; Smith, Verne V.; Sobeck,
Jennifer; Somers, Garrett; Souto, Diogo; Stark, David V.; Stassun,
Keivan G.; Steinmetz, Matthias; Stello, Dennis; Storchi Bergmann,
Thaisa; Strauss, Michael A.; Streblyanska, Alina; Stringfellow, Guy S.;
Suarez, Genaro; Sun, Jing; Taghizadeh-Popp, Manuchehr; Tang, Baitian;
Tao, Charling; Tayar, Jamie; Tembe, Mita; Thomas, Daniel; Tinker,
Jeremy; Tojeiro, Rita; Tremonti, Christy; Troup, Nicholas; Trump,
Jonathan R.; Unda-Sanzana, Eduardo; Valenzuela, O.; Van den Bosch,
Remco; Vargas-Magaña, Mariana; Vazquez, Jose Alberto; Villanova,
Sandro; Vivek, M.; Vogt, Nicole; Wake, David; Walterbos, Rene; Wang,
Yuting; Wang, Enci; Weaver, Benjamin Alan; Weijmans, Anne-Marie;
Weinberg, David H.; Westfall, Kyle B.; Whelan, David G.; Wilcots,
Eric; Wild, Vivienne; Williams, Rob A.; Wilson, John; Wood-Vasey,
W. M.; Wylezalek, Dominika; Xiao, Ting; Yan, Renbin; Yang, Meng;
Ybarra, Jason E.; Yeche, Christophe; Yuan, Fang-Ting; Zakamska,
Nadia; Zamora, Olga; Zasowski, Gail; Zhang, Kai; Zhao, Cheng; Zhao,
Gong-Bo; Zheng, Zheng; Zheng, Zheng; Zhou, Zhi-Min; Zhu, Guangtun;
Zinn, Joel C.; Zou, Hu
2017ApJS..233...25A Altcode: 2016arXiv160802013S
The fourth generation of the Sloan Digital Sky Survey (SDSS-IV)
began observations in 2014 July. It pursues three core programs: the
Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2),
Mapping Nearby Galaxies at APO (MaNGA), and the Extended Baryon
Oscillation Spectroscopic Survey (eBOSS). As well as its core program,
eBOSS contains two major subprograms: the Time Domain Spectroscopic
Survey (TDSS) and the SPectroscopic IDentification of ERosita Sources
(SPIDERS). This paper describes the first data release from SDSS-IV,
Data Release 13 (DR13). DR13 makes publicly available the first 1390
spatially resolved integral field unit observations of nearby galaxies
from MaNGA. It includes new observations from eBOSS, completing the
Sloan Extended QUasar, Emission-line galaxy, Luminous red galaxy
Survey (SEQUELS), which also targeted variability-selected objects
and X-ray-selected objects. DR13 includes new reductions of the
SDSS-III BOSS data, improving the spectrophotometric calibration
and redshift classification, and new reductions of the SDSS-III
APOGEE-1 data, improving stellar parameters for dwarf stars and
cooler stars. DR13 provides more robust and precise photometric
calibrations. Value-added target catalogs relevant for eBOSS, TDSS,
and SPIDERS and an updated red-clump catalog for APOGEE are also
available. This paper describes the location and format of the data
and provides references to important technical papers. The SDSS web
site, <A href="http://www.sdss.org">http://www.sdss.org</A>, provides
links to the data, tutorials, examples of data access, and extensive
documentation of the reduction and analysis procedures. DR13 is the
first of a scheduled set that will contain new data and analyses from
the planned ∼6 yr operations of SDSS-IV.
---------------------------------------------------------
Title: The Pristine survey - I. Mining the Galaxy for the most
metal-poor stars
Authors: Starkenburg, Else; Martin, Nicolas; Youakim, Kris; Aguado,
David S.; Allende Prieto, Carlos; Arentsen, Anke; Bernard, Edouard
J.; Bonifacio, Piercarlo; Caffau, Elisabetta; Carlberg, Raymond G.;
Côté, Patrick; Fouesneau, Morgan; François, Patrick; Franke,
Oliver; González Hernández, Jonay I.; Gwyn, Stephen D. J.; Hill,
Vanessa; Ibata, Rodrigo A.; Jablonka, Pascale; Longeard, Nicolas;
McConnachie, Alan W.; Navarro, Julio F.; Sánchez-Janssen, Rubén;
Tolstoy, Eline; Venn, Kim A.
2017MNRAS.471.2587S Altcode: 2017arXiv170501113S
We present the Pristine survey, a new narrow-band photometric survey
focused on the metallicity-sensitive Ca H&K lines and conducted
in the Northern hemisphere with the wide-field imager MegaCam on
the Canada-France-Hawaii Telescope. This paper reviews our overall
survey strategy and discusses the data processing and metallicity
calibration. Additionally we review the application of these data to
the main aims of the survey, which are to gather a large sample of
the most metal-poor stars in the Galaxy, to further characterize the
faintest Milky Way satellites, and to map the (metal-poor) substructure
in the Galactic halo. The current Pristine footprint comprises over
1000 deg<SUP>2</SUP> in the Galactic halo ranging from b ∼ 30° to
∼78° and covers many known stellar substructures. We demonstrate
that, for Sloan Digital Sky Survey (SDSS) stellar objects, we can
calibrate the photometry at the 0.02-mag level. The comparison with
existing spectroscopic metallicities from SDSS/Sloan Extension for
Galactic Understanding and Exploration (SEGUE) and Large Sky Area
Multi-Object Fiber Spectroscopic Telescope shows that, when combined
with SDSS broad-band g and I photometry, we can use the CaHK photometry
to infer photometric metallicities with an accuracy of ∼0.2 dex from
[Fe/H] = -0.5 down to the extremely metal-poor regime ([Fe/H] <
-3.0). After the removal of various contaminants, we can efficiently
select metal-poor stars and build a very complete sample with high
purity. The success rate of uncovering [Fe/H]<SUB>SEGUE</SUB> <
-3.0 stars among [Fe/H]<SUB>Pristine</SUB> < -3.0 selected stars
is 24 per cent, and 85 per cent of the remaining candidates are still
very metal poor ([Fe/H]<-2.0). We further demonstrate that Pristine
is well suited to identify the very rare and pristine Galactic stars
with [Fe/H] < -4.0, which can teach us valuable lessons about the
early Universe.
---------------------------------------------------------
Title: A Gemini snapshot survey for double degenerates
Authors: Kilic, Mukremin; Brown, Warren R.; Gianninas, A.; Curd,
Brandon; Bell, Keaton J.; Allende Prieto, Carlos
2017MNRAS.471.4218K Altcode: 2017arXiv170708948K
We present the results from a Gemini snapshot radial-velocity survey of
44 low-mass white-dwarf candidates selected from the Sloan Digital Sky
Survey (SDSS) spectroscopy. To find sub-hour orbital period binary
systems, our time-series spectroscopy had cadences of 2-8 min over
a period of 20-30 min. Through follow-up observations at Gemini and
the MMT, we identify four double-degenerate binary systems with
periods ranging from 53 min to 7 h. The shortest period system,
SDSS J123549.88+154319.3, was recently identified as a sub-hour
period detached binary by Breedt and collaborators. Here, we refine
the orbital and physical parameters of this system. High-speed and
time-domain survey photometry observations do not reveal eclipses or
other photometric effects in any of our targets. We compare the period
distribution of these four systems with the orbital period distribution
of known double white dwarfs; the median period decreases from 0.64 to
0.24 d for M = 0.3-0.5 M<SUB>⊙</SUB> to M < 0.3 M<SUB>⊙</SUB>
white dwarfs. However, we do not find a statistically significant
correlation between the orbital period and white-dwarf mass.
---------------------------------------------------------
Title: The puzzling interpretation of NIR indices: The case of NaI2.21
Authors: Röck, B.; Vazdekis, A.; La Barbera, F.; Peletier, R. F.;
Knapen, J. H.; Allende-Prieto, C.; Aguado, D. S.
2017MNRAS.472..361R Altcode: 2017arXiv170804638R
We present a detailed study of the Na I line strength index centred in
the K band at 22 100 Å (NaI2.21 hereafter) relying on different samples
of early-type galaxies. Consistent with previous studies, we find that
the observed line strength indices cannot be fit by state-of-the-art
scaled-solar stellar population models, even using our newly developed
models in the near infrared (NIR). The models clearly underestimate the
large NaI2.21 values measured for most early-type galaxies. However, we
develop an Na-enhanced version of our newly developed models in the NIR,
which - together with the effect of a bottom-heavy initial mass function
- yield NaI2.21 indices in the range of the observations. Therefore, we
suggest a scenario in which the combined effect of [Na/Fe] enhancement
and a bottom-heavy initial mass function are mainly responsible for
the large NaI2.21 indices observed for most early-type galaxies. To a
smaller extent, also [C/Fe] enhancement might contribute to the large
observed NaI2.21 values.
---------------------------------------------------------
Title: The Pristine Survey
Authors: Allende Prieto, Carlos
2017edrs.confE..12A Altcode:
In this talk I will describe the PRISTINE project to identify extremely
metal-poor stars. I will also set the bases for expanding the search
using J-PLUS data and show some preliminary results based on the EDR
data set.
---------------------------------------------------------
Title: The open cluster King 1 in the second quadrant
Authors: Carrera, Ricardo; Rodríguez Espinosa, Loreto; Casamiquela,
Laia; Balaguer Nuñez, Lola; Jordi, Carme; Allende Prieto, Carlos;
Stetson, Peter B.
2017MNRAS.470.4285C Altcode: 2017arXiv170604863C
We analyse the poorly studied open cluster King 1 in the second
Galactic quadrant. From wide-field photometry, we have studied the
spatial distribution of this cluster. We determined that the centre of
King 1 is located at α<SUB>2000</SUB> = 00<SUP>h</SUP>22<SUP>m</SUP>
and δ<SUB>2000</SUB> = +64°23<SUP>΄</SUP>. By parameterizing
the stellar density with a King profile, we have obtained a central
density of ρ<SUB>0</SUB> = 6.5 ± 0.2 star arcmin<SUP>-2</SUP> and
a core radius of r<SUB>core</SUB> = 1.9 ± 0.2 arcmin. By comparing
the observed colour-magnitude diagram of King 1 with those of similar
open clusters and with different sets of isochrones, we have estimated
an age of 2.8 ± 0.3 Gyr, a distance modulus of (m - M)<SUB>o</SUB>
= 10.6 ± 0.1 mag and a reddening of E(B - V) = 0.80 ± 0.05 mag. To
complete our analysis, we acquired medium resolution spectra for 189
stars in the area of King 1. From their derived radial velocities, we
determined an average velocity <V<SUB>r</SUB>> = -53.1 ± 3.1
km s<SUP>-1</SUP>. From the strength of the infrared Ca II lines in
red giants we have determined an average metallicity of <[M/H]>
= +0.07 ± 0.08 dex. From spectral synthesis, we have also estimated
an α-elements abundance of <[α/M]> = -0.10 ± 0.08 dex.
---------------------------------------------------------
Title: WHT follow-up observations of extremely metal-poor stars
identified from SDSS and LAMOST
Authors: Aguado, D. S.; González Hernández, J. I.; Allende Prieto,
C.; Rebolo, R.
2017A&A...605A..40A Altcode: 2017arXiv170509233A
<BR /> Aims: We have identified several tens of extremely metal-poor
star candidates from SDSS and LAMOST, which we follow up with
the 4.2 m William Herschel Telescope (WHT) telescope to confirm
their metallicity. <BR /> Methods: We followed a robust two-step
methodology. We first analyzed the SDSS and LAMOST spectra. A
first set of stellar parameters was derived from these spectra
with the FERRE code, taking advantage of the continuum shape to
determine the atmospheric parameters, in particular, the effective
temperature. Second, we selected interesting targets for follow-up
observations, some of them with very low-quality SDSS or LAMOST data. We
then obtained and analyzed higher-quality medium-resolution spectra
obtained with the Intermediate dispersion Spectrograph and Imaging
System (ISIS) on the WHT to arrive at a second more reliable set of
atmospheric parameters. This allowed us to derive the metallicity
with accuracy, and we confirm the extremely metal-poor nature in
most cases. In this second step we also employed FERRE, but we took a
running mean to normalize both the observed and the synthetic spectra,
and therefore the final parameters do not rely on having an accurate
flux calibration or continuum placement. We have analyzed with the
same tools and following the same procedure six well-known metal-poor
stars, five of them at [Fe/H] <-4 to verify our results. This
showed that our methodology is able to derive accurate metallicity
determinations down to [Fe/H] <-5.0. <BR /> Results: The results
for these six reference stars give us confidence on the metallicity
scale for the rest of the sample. In addition, we present 12 new
extremely metal-poor candidates: 2 stars at [Fe/H] ≃-4, 6 more
in the range -4 < [Fe / H] < -3.5, and 4 more at -3.5 <
[Fe / H] < -3.0. <BR /> Conclusions: We conclude that we can
reliably determine metallicities for extremely metal-poor stars with
a precision of 0.2 dex from medium-resolution spectroscopy with our
improved methodology. This provides a highly effective way of verifying
candidates from lower quality data. Our model spectra and the details of
the fitting algorithm are made public to facilitate the standardization
of the analysis of spectra from the same or similar instruments. <P
/>The model spectra are only available at the CDS via anonymous ftp to
<A href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A>
(<A href="http://130.79.128.5">http://130.79.128.5</A>) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/605/A40">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/605/A40</A>
---------------------------------------------------------
Title: Gaia Data Release 1. Testing parallaxes with local Cepheids
and RR Lyrae stars
Authors: Gaia Collaboration; Clementini, G.; Eyer, L.; Ripepi, V.;
Marconi, M.; Muraveva, T.; Garofalo, A.; Sarro, L. M.; Palmer, M.;
Luri, X.; Molinaro, R.; Rimoldini, L.; Szabados, L.; Musella, I.;
Anderson, R. I.; Prusti, T.; de Bruijne, J. H. J.; Brown, A. G. A.;
Vallenari, A.; Babusiaux, C.; Bailer-Jones, C. A. L.; Bastian, U.;
Biermann, M.; Evans, D. W.; Jansen, F.; Jordi, C.; Klioner, S. A.;
Lammers, U.; Lindegren, L.; Mignard, F.; Panem, C.; Pourbaix,
D.; Randich, S.; Sartoretti, P.; Siddiqui, H. I.; Soubiran, C.;
Valette, V.; van Leeuwen, F.; Walton, N. A.; Aerts, C.; Arenou,
F.; Cropper, M.; Drimmel, R.; Høg, E.; Katz, D.; Lattanzi, M. G.;
O'Mullane, W.; Grebel, E. K.; Holland, A. D.; Huc, C.; Passot,
X.; Perryman, M.; Bramante, L.; Cacciari, C.; Castañeda, J.;
Chaoul, L.; Cheek, N.; De Angeli, F.; Fabricius, C.; Guerra, R.;
Hernández, J.; Jean-Antoine-Piccolo, A.; Masana, E.; Messineo,
R.; Mowlavi, N.; Nienartowicz, K.; Ordóñez-Blanco, D.; Panuzzo,
P.; Portell, J.; Richards, P. J.; Riello, M.; Seabroke, G. M.;
Tanga, P.; Thévenin, F.; Torra, J.; Els, S. G.; Gracia-Abril, G.;
Comoretto, G.; Garcia-Reinaldos, M.; Lock, T.; Mercier, E.; Altmann,
M.; Andrae, R.; Astraatmadja, T. L.; Bellas-Velidis, I.; Benson,
K.; Berthier, J.; Blomme, R.; Busso, G.; Carry, B.; Cellino, A.;
Cowell, S.; Creevey, O.; Cuypers, J.; Davidson, M.; De Ridder, J.;
de Torres, A.; Delchambre, L.; Dell'Oro, A.; Ducourant, C.; Frémat,
Y.; García-Torres, M.; Gosset, E.; Halbwachs, J. -L.; Hambly, N. C.;
Harrison, D. L.; Hauser, M.; Hestroffer, D.; Hodgkin, S. T.; Huckle,
H. E.; Hutton, A.; Jasniewicz, G.; Jordan, S.; Kontizas, M.; Korn,
A. J.; Lanzafame, A. C.; Manteiga, M.; Moitinho, A.; Muinonen, K.;
Osinde, J.; Pancino, E.; Pauwels, T.; Petit, J. -M.; Recio-Blanco,
A.; Robin, A. C.; Siopis, C.; Smith, M.; Smith, K. W.; Sozzetti, A.;
Thuillot, W.; van Reeven, W.; Viala, Y.; Abbas, U.; Abreu Aramburu,
A.; Accart, S.; Aguado, J. J.; Allan, P. M.; Allasia, W.; Altavilla,
G.; Álvarez, M. A.; Alves, J.; Andrei, A. H.; Anglada Varela, E.;
Antiche, E.; Antoja, T.; Antón, S.; Arcay, B.; Bach, N.; Baker,
S. G.; Balaguer-Núñez, L.; Barache, C.; Barata, C.; Barbier, A.;
Barblan, F.; Barrado y Navascués, D.; Barros, M.; Barstow, M. A.;
Becciani, U.; Bellazzini, M.; Bello García, A.; Belokurov, V.;
Bendjoya, P.; Berihuete, A.; Bianchi, L.; Bienaymé, O.; Billebaud,
F.; Blagorodnova, N.; Blanco-Cuaresma, S.; Boch, T.; Bombrun, A.;
Borrachero, R.; Bouquillon, S.; Bourda, G.; Bragaglia, A.; Breddels,
M. A.; Brouillet, N.; Brüsemeister, T.; Bucciarelli, B.; Burgess,
P.; Burgon, R.; Burlacu, A.; Busonero, D.; Buzzi, R.; Caffau,
E.; Cambras, J.; Campbell, H.; Cancelliere, R.; Cantat-Gaudin, T.;
Carlucci, T.; Carrasco, J. M.; Castellani, M.; Charlot, P.; Charnas,
J.; Chiavassa, A.; Clotet, M.; Cocozza, G.; Collins, R. S.; Costigan,
G.; Crifo, F.; Cross, N. J. G.; Crosta, M.; Crowley, C.; Dafonte,
C.; Damerdji, Y.; Dapergolas, A.; David, P.; David, M.; De Cat, P.;
de Felice, F.; de Laverny, P.; De Luise, F.; De March, R.; de Souza,
R.; Debosscher, J.; del Pozo, E.; Delbo, M.; Delgado, A.; Delgado,
H. E.; Di Matteo, P.; Diakite, S.; Distefano, E.; Dolding, C.; Dos
Anjos, S.; Drazinos, P.; Durán, J.; Dzigan, Y.; Edvardsson, B.;
Enke, H.; Evans, N. W.; Eynard Bontemps, G.; Fabre, C.; Fabrizio,
M.; Falcão, A. J.; Farràs Casas, M.; Federici, L.; Fedorets,
G.; Fernández-Hernández, J.; Fernique, P.; Fienga, A.; Figueras,
F.; Filippi, F.; Findeisen, K.; Fonti, A.; Fouesneau, M.; Fraile,
E.; Fraser, M.; Fuchs, J.; Gai, M.; Galleti, S.; Galluccio, L.;
Garabato, D.; García-Sedano, F.; Garralda, N.; Gavras, P.; Gerssen,
J.; Geyer, R.; Gilmore, G.; Girona, S.; Giuffrida, G.; Gomes, M.;
González-Marcos, A.; González-Núñez, J.; González-Vidal, J. J.;
Granvik, M.; Guerrier, A.; Guillout, P.; Guiraud, J.; Gúrpide, A.;
Gutiérrez-Sánchez, R.; Guy, L. P.; Haigron, R.; Hatzidimitriou, D.;
Haywood, M.; Heiter, U.; Helmi, A.; Hobbs, D.; Hofmann, W.; Holl, B.;
Holland, G.; Hunt, J. A. S.; Hypki, A.; Icardi, V.; Irwin, M.; Jevardat
de Fombelle, G.; Jofré, P.; Jonker, P. G.; Jorissen, A.; Julbe, F.;
Karampelas, A.; Kochoska, A.; Kohley, R.; Kolenberg, K.; Kontizas,
E.; Koposov, S. E.; Kordopatis, G.; Koubsky, P.; Krone-Martins, A.;
Kudryashova, M.; Bachchan, R. K.; Lacoste-Seris, F.; Lanza, A. F.;
Lavigne, J. -B.; Le Poncin-Lafitte, C.; Lebreton, Y.; Lebzelter, T.;
Leccia, S.; Leclerc, N.; Lecoeur-Taibi, I.; Lemaitre, V.; Lenhardt,
H.; Leroux, F.; Liao, S.; Licata, E.; Lindstrøm, H. E. P.; Lister,
T. A.; Livanou, E.; Lobel, A.; Löffler, W.; López, M.; Lorenz, D.;
MacDonald, I.; Magalhães Fernandes, T.; Managau, S.; Mann, R. G.;
Mantelet, G.; Marchal, O.; Marchant, J. M.; Marinoni, S.; Marrese,
P. M.; Marschalkó, G.; Marshall, D. J.; Martín-Fleitas, J. M.;
Martino, M.; Mary, N.; Matijevič, G.; McMillan, P. J.; Messina,
S.; Michalik, D.; Millar, N. R.; Miranda, B. M. H.; Molina, D.;
Molinaro, M.; Molnár, L.; Moniez, M.; Montegriffo, P.; Mor, R.;
Mora, A.; Morbidelli, R.; Morel, T.; Morgenthaler, S.; Morris, D.;
Mulone, A. F.; Narbonne, J.; Nelemans, G.; Nicastro, L.; Noval, L.;
Ordénovic, C.; Ordieres-Meré, J.; Osborne, P.; Pagani, C.; Pagano,
I.; Pailler, F.; Palacin, H.; Palaversa, L.; Parsons, P.; Pecoraro,
M.; Pedrosa, R.; Pentikäinen, H.; Pichon, B.; Piersimoni, A. M.;
Pineau, F. -X.; Plachy, E.; Plum, G.; Poujoulet, E.; Prša, A.;
Pulone, L.; Ragaini, S.; Rago, S.; Rambaux, N.; Ramos-Lerate, M.;
Ranalli, P.; Rauw, G.; Read, A.; Regibo, S.; Reylé, C.; Ribeiro,
R. A.; Riva, A.; Rixon, G.; Roelens, M.; Romero-Gómez, M.; Rowell,
N.; Royer, F.; Ruiz-Dern, L.; Sadowski, G.; Sagristà Sellés, T.;
Sahlmann, J.; Salgado, J.; Salguero, E.; Sarasso, M.; Savietto, H.;
Schultheis, M.; Sciacca, E.; Segol, M.; Segovia, J. C.; Segransan,
D.; Shih, I. -C.; Smareglia, R.; Smart, R. L.; Solano, E.; Solitro,
F.; Sordo, R.; Soria Nieto, S.; Souchay, J.; Spagna, A.; Spoto, F.;
Stampa, U.; Steele, I. A.; Steidelmüller, H.; Stephenson, C. A.;
Stoev, H.; Suess, F. F.; Süveges, M.; Surdej, J.; Szegedi-Elek, E.;
Tapiador, D.; Taris, F.; Tauran, G.; Taylor, M. B.; Teixeira, R.;
Terrett, D.; Tingley, B.; Trager, S. C.; Turon, C.; Ulla, A.; Utrilla,
E.; Valentini, G.; van Elteren, A.; Van Hemelryck, E.; van Leeuwen, M.;
Varadi, M.; Vecchiato, A.; Veljanoski, J.; Via, T.; Vicente, D.; Vogt,
S.; Voss, H.; Votruba, V.; Voutsinas, S.; Walmsley, G.; Weiler, M.;
Weingrill, K.; Wevers, T.; Wyrzykowski, Ł.; Yoldas, A.; Žerjal, M.;
Zucker, S.; Zurbach, C.; Zwitter, T.; Alecu, A.; Allen, M.; Allende
Prieto, C.; Amorim, A.; Anglada-Escudé, G.; Arsenijevic, V.; Azaz,
S.; Balm, P.; Beck, M.; Bernstein, H. -H.; Bigot, L.; Bijaoui, A.;
Blasco, C.; Bonfigli, M.; Bono, G.; Boudreault, S.; Bressan, A.;
Brown, S.; Brunet, P. -M.; Bunclark, P.; Buonanno, R.; Butkevich,
A. G.; Carret, C.; Carrion, C.; Chemin, L.; Chéreau, F.; Corcione,
L.; Darmigny, E.; de Boer, K. S.; de Teodoro, P.; de Zeeuw, P. T.;
Delle Luche, C.; Domingues, C. D.; Dubath, P.; Fodor, F.; Frézouls,
B.; Fries, A.; Fustes, D.; Fyfe, D.; Gallardo, E.; Gallegos, J.;
Gardiol, D.; Gebran, M.; Gomboc, A.; Gómez, A.; Grux, E.; Gueguen,
A.; Heyrovsky, A.; Hoar, J.; Iannicola, G.; Isasi Parache, Y.;
Janotto, A. -M.; Joliet, E.; Jonckheere, A.; Keil, R.; Kim, D. -W.;
Klagyivik, P.; Klar, J.; Knude, J.; Kochukhov, O.; Kolka, I.; Kos,
J.; Kutka, A.; Lainey, V.; LeBouquin, D.; Liu, C.; Loreggia, D.;
Makarov, V. V.; Marseille, M. G.; Martayan, C.; Martinez-Rubi, O.;
Massart, B.; Meynadier, F.; Mignot, S.; Munari, U.; Nguyen, A. -T.;
Nordlander, T.; O'Flaherty, K. S.; Ocvirk, P.; Olias Sanz, A.; Ortiz,
P.; Osorio, J.; Oszkiewicz, D.; Ouzounis, A.; Park, P.; Pasquato, E.;
Peltzer, C.; Peralta, J.; Péturaud, F.; Pieniluoma, T.; Pigozzi, E.;
Poels, J.; Prat, G.; Prod'homme, T.; Raison, F.; Rebordao, J. M.;
Risquez, D.; Rocca-Volmerange, B.; Rosen, S.; Ruiz-Fuertes, M. I.;
Russo, F.; Serraller Vizcaino, I.; Short, A.; Siebert, A.; Silva, H.;
Sinachopoulos, D.; Slezak, E.; Soffel, M.; Sosnowska, D.; Straižys,
V.; ter Linden, M.; Terrell, D.; Theil, S.; Tiede, C.; Troisi, L.;
Tsalmantza, P.; Tur, D.; Vaccari, M.; Vachier, F.; Valles, P.; Van
Hamme, W.; Veltz, L.; Virtanen, J.; Wallut, J. -M.; Wichmann, R.;
Wilkinson, M. I.; Ziaeepour, H.; Zschocke, S.
2017A&A...605A..79G Altcode: 2017arXiv170500688G; 2017A&A...605A..79.
Context. Parallaxes for 331 classical Cepheids, 31 Type II Cepheids,
and 364 RR Lyrae stars in common between Gaia and the HIPPARCOS and
Tycho-2 catalogues are published in Gaia Data Release 1 (DR1) as part
of the Tycho-Gaia Astrometric Solution (TGAS). <BR /> Aims: In order to
test these first parallax measurements of the primary standard candles
of the cosmological distance ladder, which involve astrometry collected
by Gaia during the initial 14 months of science operation, we compared
them with literature estimates and derived new period-luminosity (PL),
period-Wesenheit (PW) relations for classical and Type II Cepheids and
infrared PL, PL-metallicity (PLZ), and optical luminosity-metallicity
(M<SUB>V</SUB>-[Fe/H]) relations for the RR Lyrae stars, with zero
points based on TGAS. <BR /> Methods: Classical Cepheids were carefully
selected in order to discard known or suspected binary systems. The
final sample comprises 102 fundamental mode pulsators with periods
ranging from 1.68 to 51.66 days (of which 33 with σ<SUB>ϖ</SUB>/ϖ<
0.5). The Type II Cepheids include a total of 26 W Virginis and BL
Herculis stars spanning the period range from 1.16 to 30.00 days
(of which only 7 with σ<SUB>ϖ</SUB>/ϖ< 0.5). The RR Lyrae stars
include 200 sources with pulsation period ranging from 0.27 to 0.80
days (of which 112 with σ<SUB>ϖ</SUB>/ϖ< 0.5). The new relations
were computed using multi-band (V,I,J,K<SUB>s</SUB>) photometry
and spectroscopic metal abundances available in the literature, and
by applying three alternative approaches: (i) linear least-squares
fitting of the absolute magnitudes inferred from direct transformation
of the TGAS parallaxes; (ii) adopting astrometry-based luminosities;
and (iii) using a Bayesian fitting approach. The last two methods work
in parallax space where parallaxes are used directly, thus maintaining
symmetrical errors and allowing negative parallaxes to be used. The
TGAS-based PL,PW,PLZ, and M<SUB>V</SUB>- [Fe/H] relations are discussed
by comparing the distance to the Large Magellanic Cloud provided by
different types of pulsating stars and alternative fitting methods. <BR
/> Results: Good agreement is found from direct comparison of the
parallaxes of RR Lyrae stars for which both TGAS and HST measurements
are available. Similarly, very good agreement is found between the
TGAS values and the parallaxes inferred from the absolute magnitudes
of Cepheids and RR Lyrae stars analysed with the Baade-Wesselink
method. TGAS values also compare favourably with the parallaxes inferred
by theoretical model fitting of the multi-band light curves for two
of the three classical Cepheids and one RR Lyrae star, which were
analysed with this technique in our samples. The K-band PL relations
show the significant improvement of the TGAS parallaxes for Cepheids
and RR Lyrae stars with respect to the HIPPARCOS measurements. This
is particularly true for the RR Lyrae stars for which improvement
in quality and statistics is impressive. <BR /> Conclusions: TGAS
parallaxes bring a significant added value to the previous HIPPARCOS
estimates. The relations presented in this paper represent the first
Gaia-calibrated relations and form a work-in-progress milestone report
in the wait for Gaia-only parallaxes of which a first solution will
become available with Gaia Data Release 2 (DR2) in 2018. <P />Full
Tables A.1-A.3 are only available at the CDS via anonymous ftp to
<A href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A>
(<A href="http://130.79.128.5">http://130.79.128.5</A>) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/605/A79">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/605/A79</A>
---------------------------------------------------------
Title: Atypical Mg-poor Milky Way Field Stars with Globular Cluster
Second-generation-like Chemical Patterns
Authors: Fernández-Trincado, J. G.; Zamora, O.; García-Hernández,
D. A.; Souto, Diogo; Dell'Agli, F.; Schiavon, R. P.; Geisler, D.;
Tang, B.; Villanova, S.; Hasselquist, Sten; Mennickent, R. E.; Cunha,
Katia; Shetrone, M.; Allende Prieto, Carlos; Vieira, K.; Zasowski,
G.; Sobeck, J.; Hayes, C. R.; Majewski, S. R.; Placco, V. M.; Beers,
T. C.; Schleicher, D. R. G.; Robin, A. C.; Mészáros, Sz.; Masseron,
T.; García Pérez, Ana E.; Anders, F.; Meza, A.; Alves-Brito, A.;
Carrera, R.; Minniti, D.; Lane, R. R.; Fernández-Alvar, E.; Moreno,
E.; Pichardo, B.; Pérez-Villegas, A.; Schultheis, M.; Roman-Lopes,
A.; Fuentes, C. E.; Nitschelm, C.; Harding, P.; Bizyaev, D.; Pan,
K.; Oravetz, D.; Simmons, A.; Ivans, Inese I.; Blanco-Cuaresma, S.;
Hernández, J.; Alonso-García, J.; Valenzuela, O.; Chanamé, J.
2017ApJ...846L...2F Altcode: 2017arXiv170703108F
We report the peculiar chemical abundance patterns of 11 atypical
Milky Way (MW) field red giant stars observed by the Apache Point
Observatory Galactic Evolution Experiment (APOGEE). These atypical
giants exhibit strong Al and N enhancements accompanied by C and Mg
depletions, strikingly similar to those observed in the so-called
second-generation (SG) stars of globular clusters (GCs). Remarkably,
we find low Mg abundances ([Mg/Fe] < 0.0) together with strong Al
and N overabundances in the majority (5/7) of the metal-rich ([Fe/H]
≳ -1.0) sample stars, which is at odds with actual observations
of SG stars in Galactic GCs of similar metallicities. This chemical
pattern is unique and unprecedented among MW stars, posing urgent
questions about its origin. These atypical stars could be former SG
stars of dissolved GCs formed with intrinsically lower abundances of
Mg and enriched Al (subsequently self-polluted by massive AGB stars)
or the result of exotic binary systems. We speculate that the stars
Mg-deficiency as well as the orbital properties suggest that they
could have an extragalactic origin. This discovery should guide future
dedicated spectroscopic searches of atypical stellar chemical patterns
in our Galaxy, a fundamental step forward to understanding the Galactic
formation and evolution.
---------------------------------------------------------
Title: The Apache Point Observatory Galactic Evolution Experiment
(APOGEE)
Authors: Majewski, Steven R.; Schiavon, Ricardo P.; Frinchaboy, Peter
M.; Allende Prieto, Carlos; Barkhouser, Robert; Bizyaev, Dmitry;
Blank, Basil; Brunner, Sophia; Burton, Adam; Carrera, Ricardo;
Chojnowski, S. Drew; Cunha, Kátia; Epstein, Courtney; Fitzgerald,
Greg; García Pérez, Ana E.; Hearty, Fred R.; Henderson, Chuck;
Holtzman, Jon A.; Johnson, Jennifer A.; Lam, Charles R.; Lawler,
James E.; Maseman, Paul; Mészáros, Szabolcs; Nelson, Matthew;
Nguyen, Duy Coung; Nidever, David L.; Pinsonneault, Marc; Shetrone,
Matthew; Smee, Stephen; Smith, Verne V.; Stolberg, Todd; Skrutskie,
Michael F.; Walker, Eric; Wilson, John C.; Zasowski, Gail; Anders,
Friedrich; Basu, Sarbani; Beland, Stephane; Blanton, Michael R.;
Bovy, Jo; Brownstein, Joel R.; Carlberg, Joleen; Chaplin, William;
Chiappini, Cristina; Eisenstein, Daniel J.; Elsworth, Yvonne; Feuillet,
Diane; Fleming, Scott W.; Galbraith-Frew, Jessica; García, Rafael A.;
García-Hernández, D. Aníbal; Gillespie, Bruce A.; Girardi, Léo;
Gunn, James E.; Hasselquist, Sten; Hayden, Michael R.; Hekker, Saskia;
Ivans, Inese; Kinemuchi, Karen; Klaene, Mark; Mahadevan, Suvrath;
Mathur, Savita; Mosser, Benoît; Muna, Demitri; Munn, Jeffrey A.;
Nichol, Robert C.; O'Connell, Robert W.; Parejko, John K.; Robin,
A. C.; Rocha-Pinto, Helio; Schultheis, Matthias; Serenelli, Aldo M.;
Shane, Neville; Silva Aguirre, Victor; Sobeck, Jennifer S.; Thompson,
Benjamin; Troup, Nicholas W.; Weinberg, David H.; Zamora, Olga
2017AJ....154...94M Altcode: 2015arXiv150905420M
The Apache Point Observatory Galactic Evolution Experiment (APOGEE),
one of the programs in the Sloan Digital Sky Survey III (SDSS-III),
has now completed its systematic, homogeneous spectroscopic survey
sampling all major populations of the Milky Way. After a three-year
observing campaign on the Sloan 2.5 m Telescope, APOGEE has collected a
half million high-resolution (R ∼ 22,500), high signal-to-noise ratio
(>100), infrared (1.51-1.70 μm) spectra for 146,000 stars, with
time series information via repeat visits to most of these stars. This
paper describes the motivations for the survey and its overall
design—hardware, field placement, target selection, operations—and
gives an overview of these aspects as well as the data reduction,
analysis, and products. An index is also given to the complement of
technical papers that describe various critical survey components
in detail. Finally, we discuss the achieved survey performance and
illustrate the variety of potential uses of the data products by way
of a number of science demonstrations, which span from time series
analysis of stellar spectral variations and radial velocity variations
from stellar companions, to spatial maps of kinematics, metallicity,
and abundance patterns across the Galaxy and as a function of age, to
new views of the interstellar medium, the chemistry of star clusters,
and the discovery of rare stellar species. As part of SDSS-III Data
Release 12 and later releases, all of the APOGEE data products are
publicly available.
---------------------------------------------------------
Title: APOGEE Chemical Abundances of the Sagittarius Dwarf Galaxy
Authors: Hasselquist, Sten; Shetrone, Matthew; Smith, Verne; Holtzman,
Jon; McWilliam, Andrew; Fernández-Trincado, J. G.; Beers, Timothy
C.; Majewski, Steven R.; Nidever, David L.; Tang, Baitian; Tissera,
Patricia B.; Fernández Alvar, Emma; Allende Prieto, Carlos; Almeida,
Andres; Anguiano, Borja; Battaglia, Giuseppina; Carigi, Leticia;
Delgado Inglada, Gloria; Frinchaboy, Peter; García-Hernández,
D. A.; Geisler, Doug; Minniti, Dante; Placco, Vinicius M.; Schultheis,
Mathias; Sobeck, Jennifer; Villanova, Sandro
2017ApJ...845..162H Altcode: 2017arXiv170703456H
The Apache Point Observatory Galactic Evolution Experiment provides
the opportunity of measuring elemental abundances for C, N, O, Na,
Mg, Al, Si, P, K, Ca, V, Cr, Mn, Fe, Co, and Ni in vast numbers of
stars. We analyze thechemical-abundance patterns of these elements
for 158 red giant stars belonging to the Sagittarius dwarf galaxy
(Sgr). This is the largest sample of Sgr stars with detailed chemical
abundances, and it is the first time that C, N, P, K, V, Cr, Co, and
Ni have been studied at high resolution in this galaxy. We find that
the Sgr stars with [Fe/H] ≳ -0.8 are deficient in all elemental
abundance ratios (expressed as [X/Fe]) relative to the Milky Way,
suggesting that the Sgr stars observed today were formed from gas
that was less enriched by Type II SNe than stars formed in the Milky
Way. By examining the relative deficiencies of the hydrostatic (O, Na,
Mg, and Al) and explosive (Si, P, K, and Mn) elements, our analysis
supports the argument that previous generations of Sgr stars were
formed with a top-light initial mass function, one lacking the most
massive stars that would normally pollute the interstellar medium with
the hydrostatic elements. We use a simple chemical-evolution model,
flexCE, to further support our claim and conclude that recent stellar
generations of Fornax and the Large Magellanic Cloud could also have
formed according to a top-light initial mass function.
---------------------------------------------------------
Title: Adding the s-Process Element Cerium to the APOGEE Survey:
Identification and Characterization of Ce II Lines in the H-band
Spectral Window
Authors: Cunha, Katia; Smith, Verne V.; Hasselquist, Sten; Souto,
Diogo; Shetrone, Matthew D.; Allende Prieto, Carlos; Bizyaev,
Dmitry; Frinchaboy, Peter; García-Hernández, D. Anibal; Holtzman,
Jon; Johnson, Jennifer A.; Jőnsson, Henrik; Majewski, Steven R.;
Mészáros, Szabolcs; Nidever, David; Pinsonneault, Mark; Schiavon,
Ricardo P.; Sobeck, Jennifer; Skrutskie, Michael F.; Zamora, Olga;
Zasowski, Gail; Fernández-Trincado, J. G.
2017ApJ...844..145C Altcode:
Nine Ce II lines have been identified and characterized within
the spectral window observed by the Apache Point Observatory
Galactic Evolution Experiment (APOGEE) survey (between λ1.51 and
1.69 μm). At solar metallicities, cerium is an element that is
produced predominantly as a result of the slow capture of neutrons
(the s-process) during asymptotic giant branch stellar evolution. The
Ce II lines were identified using a combination of a high-resolution
(R=λ /δ λ ={{100,000}}) Fourier Transform Spectrometer (FTS)
spectrum of α Boo and an APOGEE spectrum (R = 22,400) of a metal-poor,
but s-process enriched, red giant (2M16011638-1201525). Laboratory
oscillator strengths are not available for these lines. Astrophysical
gf-values were derived using α Boo as a standard star, with the
absolute cerium abundance in α Boo set by using optical Ce II lines
that have precise published laboratory gf-values. The near-infrared
Ce II lines identified here are also analyzed, as consistency checks,
in a small number of bright red giants using archival FTS spectra,
as well as a small sample of APOGEE red giants, including two members
of the open cluster NGC 6819, two field stars, and seven metal-poor
N- and Al-rich stars. The conclusion is that this set of Ce II lines
can be detected and analyzed in a large fraction of the APOGEE red
giant sample and will be useful for probing chemical evolution of the
s-process products in various populations of the Milky Way.
---------------------------------------------------------
Title: STools: IDL Tools for Spectroscopic Analysis
Authors: Allende Prieto, Carlos
2017ascl.soft08005A Altcode:
STools contains a variety of simple tools for spectroscopy, such
as reading an IRAF-formatted (multispec) echelle spectrum in FITS,
measuring the wavelength of the center of a line, Gaussian convolution,
deriving synthetic photometry from an input spectrum, and extracting
and interpolating a MARCS model atmosphere (standard composition).
---------------------------------------------------------
Title: New ultra metal-poor stars from SDSS: follow-up GTC
medium-resolution spectroscopy
Authors: Aguado, D. S.; Allende Prieto, C.; González Hernández,
J. I.; Rebolo, R.; Caffau, E.
2017A&A...604A...9A Altcode: 2017arXiv170604179A
Context. The first generation of stars formed in the Galaxy left behind
the chemical signatures of their nucleosynthesis in the interstellar
medium, visible today in the atmospheres of low-mass stars that formed
afterwards. Sampling the chemistry of those low-mass provides insight
into the first stars. <BR /> Aims: We aim to increase the samples
of stars with extremely low metal abundances, identifying ultra
metal-poor stars from spectra with modest spectral resolution and
signal-to-noise ratio (S/N). Achieving this goal involves deriving
reliable metallicities and carbon abundances from such spectra. <BR
/> Methods: We carry out follow-up observations of faint, V > 19,
metal-poor candidates selected from SDSS spectroscopy and observed
with the Optical System for Imaging and low-Intermediate-Resolution
Integrated Spectroscopy (OSIRIS) at GTC. The SDSS and follow-up
OSIRIS spectra were analyzed using the FERRE code to derive effective
temperatures, surface gravities, metallicities and carbon abundances. In
addition, a well-known extremely metal-poor star has been included in
our sample to calibrate the analysis methodology. <BR /> Results: We
observed and analyzed five metal-poor candidates from modest-quality
SDSS spectra. All stars in our sample have been confirmed as extremely
metal-poor stars, in the [Fe/H] < -3.3 regime. We report the
recognition of J173403+644632, a carbon-enhanced ultra metal-poor dwarf
star with [Fe/H] = -4.3 and [C/Fe] = + 3.1. <P />Based on observations
made with the Gran Telescopio Canarias (GTC), installed in the Spanish
Observatorio del Roque de los Muchachos of the Instituto de Astrofísica
de Canarias, on the island of La Palma. Programme ID GTC2E-16A and
ID GTC65-16B.
---------------------------------------------------------
Title: The Pristine survey II: A sample of bright stars observed
with FEROS
Authors: Caffau, E.; Bonifacio, P.; Starkenburg, E.; Martin, N.;
Youakim, K.; Henden, A. A.; González Hernández, J. I.; Aguado,
D. S.; Allende Prieto, C.; Venn, K.; Jablonka, P.
2017AN....338..686C Altcode: 2017arXiv170510280C
Extremely metal-poor (EMP) stars are old objects formed in the first Gyr
of the Universe. They are rare and, to select them the most successful
strategy has been to build on large and low-resolution spectroscopic
surveys. The combination of narrow- and broad-band photometry provides
a powerful and cheaper alternative to select metal-poor stars. The
ongoing Pristine Survey is adopting this strategy, conducting photometry
with the Canada France Hawaii Telescope MegaCam wide-field imager
and a narrow-band filter centered at 395.2 nm on the Ca II-H and -K
lines. In this paper, we present the results of the spectroscopic
follow-up conducted on a sample of 26 stars at the bright end of the
magnitude range of the Survey (g⩽15), using FEROS at the MPG/ESO
2.2-m telescope (manufactured by Zeiss, Oberkochen, Germany). From our
chemical investigation on the sample, we conclude that this magnitude
range is too bright to use the Sloan Digital Sky Survey (SDSS) gri
bands, which are typically saturated. Instead, the Pristine photometry
can be usefully combined with the AAVSO Photometric All Sky Survey
(APASS) griphotometry to provide reliable metallicity estimates. Data
from FEROS.Funding Information Robert Martin Ayers Sciences Fund,
PICS, Emmy Noether program, NSF, AST-1412587. Spanish Ministry of
Economy and Competitiveness (MINECO);, MINECO RYC-2013-14875, MINECO
AYA2014-56359-P.
---------------------------------------------------------
Title: Sloan Digital Sky Survey IV: Mapping the Milky Way, Nearby
Galaxies, and the Distant Universe
Authors: Blanton, Michael R.; Bershady, Matthew A.; Abolfathi,
Bela; Albareti, Franco D.; Allende Prieto, Carlos; Almeida,
Andres; Alonso-García, Javier; Anders, Friedrich; Anderson,
Scott F.; Andrews, Brett; Aquino-Ortíz, Erik; Aragón-Salamanca,
Alfonso; Argudo-Fernández, Maria; Armengaud, Eric; Aubourg, Eric;
Avila-Reese, Vladimir; Badenes, Carles; Bailey, Stephen; Barger,
Kathleen A.; Barrera-Ballesteros, Jorge; Bartosz, Curtis; Bates,
Dominic; Baumgarten, Falk; Bautista, Julian; Beaton, Rachael; Beers,
Timothy C.; Belfiore, Francesco; Bender, Chad F.; Berlind, Andreas A.;
Bernardi, Mariangela; Beutler, Florian; Bird, Jonathan C.; Bizyaev,
Dmitry; Blanc, Guillermo A.; Blomqvist, Michael; Bolton, Adam S.;
Boquien, Médéric; Borissova, Jura; van den Bosch, Remco; Bovy,
Jo; Brandt, William N.; Brinkmann, Jonathan; Brownstein, Joel R.;
Bundy, Kevin; Burgasser, Adam J.; Burtin, Etienne; Busca, Nicolás G.;
Cappellari, Michele; Delgado Carigi, Maria Leticia; Carlberg, Joleen
K.; Carnero Rosell, Aurelio; Carrera, Ricardo; Chanover, Nancy J.;
Cherinka, Brian; Cheung, Edmond; Gómez Maqueo Chew, Yilen; Chiappini,
Cristina; Choi, Peter Doohyun; Chojnowski, Drew; Chuang, Chia-Hsun;
Chung, Haeun; Cirolini, Rafael Fernando; Clerc, Nicolas; Cohen, Roger
E.; Comparat, Johan; da Costa, Luiz; Cousinou, Marie-Claude; Covey,
Kevin; Crane, Jeffrey D.; Croft, Rupert A. C.; Cruz-Gonzalez, Irene;
Garrido Cuadra, Daniel; Cunha, Katia; Damke, Guillermo J.; Darling,
Jeremy; Davies, Roger; Dawson, Kyle; de la Macorra, Axel; Dell'Agli,
Flavia; De Lee, Nathan; Delubac, Timothée; Di Mille, Francesco;
Diamond-Stanic, Aleks; Cano-Díaz, Mariana; Donor, John; Downes, Juan
José; Drory, Niv; du Mas des Bourboux, Hélion; Duckworth, Christopher
J.; Dwelly, Tom; Dyer, Jamie; Ebelke, Garrett; Eigenbrot, Arthur D.;
Eisenstein, Daniel J.; Emsellem, Eric; Eracleous, Mike; Escoffier,
Stephanie; Evans, Michael L.; Fan, Xiaohui; Fernández-Alvar, Emma;
Fernandez-Trincado, J. G.; Feuillet, Diane K.; Finoguenov, Alexis;
Fleming, Scott W.; Font-Ribera, Andreu; Fredrickson, Alexander;
Freischlad, Gordon; Frinchaboy, Peter M.; Fuentes, Carla E.;
Galbany, Lluís; Garcia-Dias, R.; García-Hernández, D. A.; Gaulme,
Patrick; Geisler, Doug; Gelfand, Joseph D.; Gil-Marín, Héctor;
Gillespie, Bruce A.; Goddard, Daniel; Gonzalez-Perez, Violeta;
Grabowski, Kathleen; Green, Paul J.; Grier, Catherine J.; Gunn,
James E.; Guo, Hong; Guy, Julien; Hagen, Alex; Hahn, ChangHoon;
Hall, Matthew; Harding, Paul; Hasselquist, Sten; Hawley, Suzanne
L.; Hearty, Fred; Gonzalez Hernández, Jonay I.; Ho, Shirley; Hogg,
David W.; Holley-Bockelmann, Kelly; Holtzman, Jon A.; Holzer, Parker
H.; Huehnerhoff, Joseph; Hutchinson, Timothy A.; Hwang, Ho Seong;
Ibarra-Medel, Héctor J.; da Silva Ilha, Gabriele; Ivans, Inese I.;
Ivory, KeShawn; Jackson, Kelly; Jensen, Trey W.; Johnson, Jennifer A.;
Jones, Amy; Jönsson, Henrik; Jullo, Eric; Kamble, Vikrant; Kinemuchi,
Karen; Kirkby, David; Kitaura, Francisco-Shu; Klaene, Mark; Knapp,
Gillian R.; Kneib, Jean-Paul; Kollmeier, Juna A.; Lacerna, Ivan;
Lane, Richard R.; Lang, Dustin; Law, David R.; Lazarz, Daniel; Lee,
Youngbae; Le Goff, Jean-Marc; Liang, Fu-Heng; Li, Cheng; Li, Hongyu;
Lian, Jianhui; Lima, Marcos; Lin, Lihwai; Lin, Yen-Ting; Bertran de
Lis, Sara; Liu, Chao; de Icaza Lizaola, Miguel Angel C.; Long, Dan;
Lucatello, Sara; Lundgren, Britt; MacDonald, Nicholas K.; Deconto
Machado, Alice; MacLeod, Chelsea L.; Mahadevan, Suvrath; Geimba Maia,
Marcio Antonio; Maiolino, Roberto; Majewski, Steven R.; Malanushenko,
Elena; Malanushenko, Viktor; Manchado, Arturo; Mao, Shude; Maraston,
Claudia; Marques-Chaves, Rui; Masseron, Thomas; Masters, Karen L.;
McBride, Cameron K.; McDermid, Richard M.; McGrath, Brianne; McGreer,
Ian D.; Medina Peña, Nicolás; Melendez, Matthew; Merloni, Andrea;
Merrifield, Michael R.; Meszaros, Szabolcs; Meza, Andres; Minchev,
Ivan; Minniti, Dante; Miyaji, Takamitsu; More, Surhud; Mulchaey, John;
Müller-Sánchez, Francisco; Muna, Demitri; Munoz, Ricardo R.; Myers,
Adam D.; Nair, Preethi; Nandra, Kirpal; Correa do Nascimento, Janaina;
Negrete, Alenka; Ness, Melissa; Newman, Jeffrey A.; Nichol, Robert C.;
Nidever, David L.; Nitschelm, Christian; Ntelis, Pierros; O'Connell,
Julia E.; Oelkers, Ryan J.; Oravetz, Audrey; Oravetz, Daniel; Pace,
Zach; Padilla, Nelson; Palanque-Delabrouille, Nathalie; Alonso Palicio,
Pedro; Pan, Kaike; Parejko, John K.; Parikh, Taniya; Pâris, Isabelle;
Park, Changbom; Patten, Alim Y.; Peirani, Sebastien; Pellejero-Ibanez,
Marcos; Penny, Samantha; Percival, Will J.; Perez-Fournon, Ismael;
Petitjean, Patrick; Pieri, Matthew M.; Pinsonneault, Marc; Pisani,
Alice; Poleski, Radosław; Prada, Francisco; Prakash, Abhishek;
Queiroz, Anna Bárbara de Andrade; Raddick, M. Jordan; Raichoor,
Anand; Barboza Rembold, Sandro; Richstein, Hannah; Riffel, Rogemar A.;
Riffel, Rogério; Rix, Hans-Walter; Robin, Annie C.; Rockosi, Constance
M.; Rodríguez-Torres, Sergio; Roman-Lopes, A.; Román-Zúñiga,
Carlos; Rosado, Margarita; Ross, Ashley J.; Rossi, Graziano; Ruan,
John; Ruggeri, Rossana; Rykoff, Eli S.; Salazar-Albornoz, Salvador;
Salvato, Mara; Sánchez, Ariel G.; Aguado, D. S.; Sánchez-Gallego,
José R.; Santana, Felipe A.; Santiago, Basílio Xavier; Sayres, Conor;
Schiavon, Ricardo P.; da Silva Schimoia, Jaderson; Schlafly, Edward
F.; Schlegel, David J.; Schneider, Donald P.; Schultheis, Mathias;
Schuster, William J.; Schwope, Axel; Seo, Hee-Jong; Shao, Zhengyi;
Shen, Shiyin; Shetrone, Matthew; Shull, Michael; Simon, Joshua D.;
Skinner, Danielle; Skrutskie, M. F.; Slosar, Anže; Smith, Verne V.;
Sobeck, Jennifer S.; Sobreira, Flavia; Somers, Garrett; Souto, Diogo;
Stark, David V.; Stassun, Keivan; Stauffer, Fritz; Steinmetz,
Matthias; Storchi-Bergmann, Thaisa; Streblyanska, Alina; Stringfellow,
Guy S.; Suárez, Genaro; Sun, Jing; Suzuki, Nao; Szigeti, Laszlo;
Taghizadeh-Popp, Manuchehr; Tang, Baitian; Tao, Charling; Tayar,
Jamie; Tembe, Mita; Teske, Johanna; Thakar, Aniruddha R.; Thomas,
Daniel; Thompson, Benjamin A.; Tinker, Jeremy L.; Tissera, Patricia;
Tojeiro, Rita; Hernandez Toledo, Hector; de la Torre, Sylvain;
Tremonti, Christy; Troup, Nicholas W.; Valenzuela, Octavio; Martinez
Valpuesta, Inma; Vargas-González, Jaime; Vargas-Magaña, Mariana;
Vazquez, Jose Alberto; Villanova, Sandro; Vivek, M.; Vogt, Nicole;
Wake, David; Walterbos, Rene; Wang, Yuting; Weaver, Benjamin Alan;
Weijmans, Anne-Marie; Weinberg, David H.; Westfall, Kyle B.; Whelan,
David G.; Wild, Vivienne; Wilson, John; Wood-Vasey, W. M.; Wylezalek,
Dominika; Xiao, Ting; Yan, Renbin; Yang, Meng; Ybarra, Jason E.;
Yèche, Christophe; Zakamska, Nadia; Zamora, Olga; Zarrouk, Pauline;
Zasowski, Gail; Zhang, Kai; Zhao, Gong-Bo; Zheng, Zheng; Zheng, Zheng;
Zhou, Xu; Zhou, Zhi-Min; Zhu, Guangtun B.; Zoccali, Manuela; Zou, Hu
2017AJ....154...28B Altcode: 2017arXiv170300052B
We describe the Sloan Digital Sky Survey IV (SDSS-IV), a project
encompassing three major spectroscopic programs. The Apache Point
Observatory Galactic Evolution Experiment 2 (APOGEE-2) is observing
hundreds of thousands of Milky Way stars at high resolution and high
signal-to-noise ratios in the near-infrared. The Mapping Nearby Galaxies
at Apache Point Observatory (MaNGA) survey is obtaining spatially
resolved spectroscopy for thousands of nearby galaxies (median z∼
0.03). The extended Baryon Oscillation Spectroscopic Survey (eBOSS) is
mapping the galaxy, quasar, and neutral gas distributions between z∼
0.6 and 3.5 to constrain cosmology using baryon acoustic oscillations,
redshift space distortions, and the shape of the power spectrum. Within
eBOSS, we are conducting two major subprograms: the SPectroscopic
IDentification of eROSITA Sources (SPIDERS), investigating X-ray AGNs
and galaxies in X-ray clusters, and the Time Domain Spectroscopic Survey
(TDSS), obtaining spectra of variable sources. All programs use the
2.5 m Sloan Foundation Telescope at the Apache Point Observatory;
observations there began in Summer 2014. APOGEE-2 also operates a
second near-infrared spectrograph at the 2.5 m du Pont Telescope
at Las Campanas Observatory, with observations beginning in early
2017. Observations at both facilities are scheduled to continue through
2020. In keeping with previous SDSS policy, SDSS-IV provides regularly
scheduled public data releases; the first one, Data Release 13, was
made available in 2016 July.
---------------------------------------------------------
Title: Four new massive pulsating white dwarfs including an
ultramassive DAV
Authors: Curd, Brandon; Gianninas, A.; Bell, Keaton J.; Kilic,
Mukremin; Romero, A. D.; Allende Prieto, Carlos; Winget, D. E.;
Winget, K. I.
2017MNRAS.468..239C Altcode: 2017arXiv170203343C
We report the discovery of four massive (M > 0.8 M<SUB>⊙</SUB>)
ZZ Ceti white dwarfs, including an ultramassive 1.16 M<SUB>⊙</SUB>
star. We obtained ground-based, time series photometry for 13 white
dwarfs from the Sloan Digital Sky Survey Data Release 7 and Data
Release 10 whose atmospheric parameters place them within the ZZ Ceti
instability strip. We detect monoperiodic pulsations in three of our
targets (J1015, J1554 and J2038) and identify three periods of pulsation
in J0840 (173, 327 and 797 s). Fourier analysis of the remaining
nine objects does not indicate variability above the 4<A>
detection threshold. Our preliminary asteroseismic analysis of J0840
yields a stellar mass M = 1.14 ± 0.01 M<SUB>⊙</SUB>, hydrogen and
helium envelope masses of M<SUB>H</SUB> = 5.8 × 10<SUP>-7</SUP>
M<SUB>⊙</SUB> and M<SUB>He</SUB> = 4.5 × 10<SUP>-4</SUP>
M<SUB>⊙</SUB> and an expected core crystallized mass ratio of 50-70
per cent. J1015, J1554 and J2038 have masses in the range 0.84-0.91
M<SUB>⊙</SUB> and are expected to have a CO core; however, the core of
J0840 could consist of highly crystallized CO or ONeMg given its high
mass. These newly discovered massive pulsators represent a significant
increase in the number of known ZZ Ceti white dwarfs with mass M >
0.85 M<SUB>⊙</SUB>, and detailed asteroseismic modelling of J0840
will allow for significant tests of crystallization theory in CO and
ONeMg core white dwarfs.
---------------------------------------------------------
Title: The Gaia-ESO Survey: Low-α element stars in the Galactic bulge
Authors: Recio-Blanco, A.; Rojas-Arriagada, A.; de Laverny, P.;
Mikolaitis, S.; Hill, V.; Zoccali, M.; Fernández-Trincado, J. G.;
Robin, A. C.; Babusiaux, C.; Gilmore, G.; Randich, S.; Alfaro, E.;
Allende Prieto, C.; Bragaglia, A.; Carraro, G.; Jofré, P.; Lardo,
C.; Monaco, L.; Morbidelli, L.; Zaggia, S.
2017A&A...602L..14R Altcode: 2017arXiv170204500R
We take advantage of the Gaia-ESO Survey iDR4 bulge data to search
for abundance anomalies that could shed light on the composite
nature of the Milky Way bulge. The α-element (Mg, Si, and whenever
available, Ca) abundances, and their trends with Fe abundances have
been analysed for a total of 776 bulge stars. In addition, the aluminum
abundances and their ratio to Fe and Mg have also been examined. Our
analysis reveals the existence of low-α element abundance stars with
respect to the standard bulge sequence in the [α/ Fe] versus [Fe/H]
plane. Eighteen objects present deviations in [α/ Fe] ranging from 2.1
to 5.3σ with respect to the median standard value. Those stars do not
show Mg-Al anti-correlation patterns. Incidentally, this sign of the
existence of multiple stellar populations is reported firmly for the
first time for the bulge globular cluster NGC 6522. The identified
low-α abundance stars have chemical patterns that are compatible
with those of the thin disc. Their link with massive dwarf galaxies
accretion seems unlikely, as larger deviations in α abundance and
Al would be expected. The vision of a bulge composite nature and a
complex formation process is reinforced by our results. The approach
used, which is a multi-method and model-driven analysis of high
resolution data, seems crucial to reveal this complexity. <P />Based
on data products from observations made with ESO Telescopes at the La
Silla Paranal Observatory under programme ID 188.B-3002. These data
products have been processed by the Cambridge Astronomy Survey Unit
(CASU) at the Institute of Astronomy, University of Cambridge, and
by the FLAMES/UVES reduction team at INAF/Osservatorio Astrofisico di
Arcetri. These data have been obtained from the Gaia-ESO Survey Data
Archive, and prepared and hosted by the Wide Field Astronomy Unit,
Institute for Astronomy, University of Edinburgh, which is funded by
the UK Science and Technology Facilities Council.
---------------------------------------------------------
Title: Follow up observationes of extremely metal-poor stars
identified from SDSS and LAMOST
Authors: Aguado, David; Allende Prieto, Carlos; González Hernández,
Jonay I.; Rebolo, Rafael
2017AAS...23031516A Altcode:
The most metal-poor stars in the Milky Way witnessed the early phases
of formation of the Galaxy, and have chemical compositions close to
the pristine mixture from Big Bang nucleosynthesis, polluted by one
or very few supernovae. Here we present a program to search for and
characterize new ultra metal-poor stars in the Galactic halo. These
stars are extremely rare; despite significant efforts, only a
handful of stars have been identified with a metallicity [Fe/H]<
-5. We select candidates from SDSS and LAMOST. Dozens of them have
already been observed with the ISIS spectrograph on the 4.2 m William
Herschel Telescope. The most interesting objects have been confirmed
with OSIRIS on the 10.4m-GTC and HRS on the 9.2 m HET. Our analysis is
highly automated, and based on the FERRE code. We report the discovery
of a new carbon-rich ultra metal-poor (CRUMP) dwarf star at [Fe/H]~
-5.8 with an extreme carbon over-abundance [C/Fe]~ +5.0.
---------------------------------------------------------
Title: Timing the Evolution of the Galactic Disk with NGC 6791:
An Open Cluster with Peculiar High-α Chemistry as Seen by APOGEE
Authors: Linden, Sean T.; Pryal, Matthew; Hayes, Christian R.; Troup,
Nicholas W.; Majewski, Steven R.; Andrews, Brett H.; Beers, Timothy C.;
Carrera, Ricardo; Cunha, Katia; Fernández-Trincado, J. G.; Frinchaboy,
Peter; Geisler, Doug; Lane, Richard R.; Nitschelm, Christian; Pan,
Kaike; Allende Prieto, Carlos; Roman-Lopes, Alexandre; Smith, Verne
V.; Sobeck, Jennifer; Tang, Baitian; Villanova, Sandro; Zasowski, Gail
2017ApJ...842...49L Altcode: 2017arXiv170407305L
We utilize elemental-abundance information for Galactic red giant
stars in five open clusters (NGC 7789, NGC 6819, M67, NGC 188,
and NGC 6791) from the Apache Point Observatory Galactic Evolution
Experiment (APOGEE) DR13 data set to age-date the chemical evolution
of the high- and low-α element sequences of the Milky Way (MW). Key
to this time-stamping is the cluster NGC 6791, whose stellar members
have mean abundances that place it in the high-α, high-[Fe/H] region
of the [α/Fe]-[Fe/H] plane. Based on the cluster’s age (∼8 Gyr),
Galactocentric radius, and height above the Galactic plane, as well as
comparable chemistry reported for APOGEE stars in Baade’s Window,
we suggest that the two most likely origins for NGC 6791 are as an
original part of the thick disk, or as a former member of the Galactic
bulge. Moreover, because NGC 6791 lies at the high-metallicity end
([Fe/H] ∼ 0.4) of the high-α sequence, the age of NGC 6791 places
a limit on the youngest age of stars in the high-metallicity, high-α
sequence for the cluster’s parent population (I.e., either the bulge
or the disk). In a similar way, we can also use the age and chemistry
of NGC 188 to set a limit of ∼7 Gyr on the oldest age of the low-α
sequence of the MW. Therefore, NGC 6791 and NGC 188 are potentially
a pair of star clusters that bracket both the timing and the duration
of an important transition point in the chemical history of the MW.
---------------------------------------------------------
Title: VizieR Online Data Catalog: Example of FERRE code spectra
(Aguado+, 2017)
Authors: Aguado, D. S.; Gonzalez Hernandez, J. I.; Allende Prieto,
C.; Rebolo, R.
2017yCat..36050040A Altcode:
FERRE matches physical models to observed data. It was created to deal
with the common problem of having numerical models that are costly
to evaluate, and need to be used to interpret large data sets. <P
/>ferre.pdf file contains the FERRE uses's guide. <P />The code can
be obtained from http://hebe.as.utexas.edu/ferre <P />Example : <P
/>f_crump3h.dat is a tool usable with FERRE with the parameters shown in
its header: Resolving Power:10.000 3600 <= λ <= 9000Å, -6 <=
[Fe/H] <=-2, -1 <= [C/Fe] <= 5, 4750 <= Tefff <= 7000,
1.0 <= logg <= 5.0, <P />It is the grid used for the paper. <P
/>(2 data files).
---------------------------------------------------------
Title: The Correlation between Mixing Length and Metallicity on the
Giant Branch: Implications for Ages in the Gaia Era
Authors: Tayar, Jamie; Somers, Garrett; Pinsonneault, Marc H.;
Stello, Dennis; Mints, Alexey; Johnson, Jennifer A.; Zamora, O.;
García-Hernández, D. A.; Maraston, Claudia; Serenelli, Aldo; Allende
Prieto, Carlos; Bastien, Fabienne A.; Basu, Sarbani; Bird, J. C.;
Cohen, R. E.; Cunha, Katia; Elsworth, Yvonne; García, Rafael A.;
Girardi, Leo; Hekker, Saskia; Holtzman, Jon; Huber, Daniel; Mathur,
Savita; Mészáros, Szabolcs; Mosser, B.; Shetrone, Matthew; Silva
Aguirre, Victor; Stassun, Keivan; Stringfellow, Guy S.; Zasowski,
Gail; Roman-Lopes, A.
2017ApJ...840...17T Altcode: 2017arXiv170401164T
In the updated APOGEE-Kepler catalog, we have asteroseismic and
spectroscopic data for over 3000 first ascent red giants. Given the
size and accuracy of this sample, these data offer an unprecedented
test of the accuracy of stellar models on the post-main-sequence. When
we compare these data to theoretical predictions, we find a metallicity
dependent temperature offset with a slope of around 100 K per dex in
metallicity. We find that this effect is present in all model grids
tested, and that theoretical uncertainties in the models, correlated
spectroscopic errors, and shifts in the asteroseismic mass scale are
insufficient to explain this effect. Stellar models can be brought
into agreement with the data if a metallicity-dependent convective
mixing length is used, with Δα <SUB>ML,YREC</SUB> ∼ 0.2 per
dex in metallicity, a trend inconsistent with the predictions of
three-dimensional stellar convection simulations. If this effect is not
taken into account, isochrone ages for red giants from the Gaia data
will be off by as much as a factor of two even at modest deviations
from solar metallicity ([Fe/H] = -0.5).
---------------------------------------------------------
Title: Gaia Data Release 1. Open cluster astrometry: performance,
limitations, and future prospects
Authors: Gaia Collaboration; van Leeuwen, F.; Vallenari, A.; Jordi,
C.; Lindegren, L.; Bastian, U.; Prusti, T.; de Bruijne, J. H. J.;
Brown, A. G. A.; Babusiaux, C.; Bailer-Jones, C. A. L.; Biermann,
M.; Evans, D. W.; Eyer, L.; Jansen, F.; Klioner, S. A.; Lammers,
U.; Luri, X.; Mignard, F.; Panem, C.; Pourbaix, D.; Randich, S.;
Sartoretti, P.; Siddiqui, H. I.; Soubiran, C.; Valette, V.; Walton,
N. A.; Aerts, C.; Arenou, F.; Cropper, M.; Drimmel, R.; Høg, E.; Katz,
D.; Lattanzi, M. G.; O'Mullane, W.; Grebel, E. K.; Holland, A. D.; Huc,
C.; Passot, X.; Perryman, M.; Bramante, L.; Cacciari, C.; Castañeda,
J.; Chaoul, L.; Cheek, N.; De Angeli, F.; Fabricius, C.; Guerra, R.;
Hernández, J.; Jean-Antoine-Piccolo, A.; Masana, E.; Messineo, R.;
Mowlavi, N.; Nienartowicz, K.; Ordóñez-Blanco, D.; Panuzzo, P.;
Portell, J.; Richards, P. J.; Riello, M.; Seabroke, G. M.; Tanga, P.;
Thévenin, F.; Torra, J.; Els, S. G.; Gracia-Abril, G.; Comoretto,
G.; Garcia-Reinaldos, M.; Lock, T.; Mercier, E.; Altmann, M.; Andrae,
R.; Astraatmadja, T. L.; Bellas-Velidis, I.; Benson, K.; Berthier,
J.; Blomme, R.; Busso, G.; Carry, B.; Cellino, A.; Clementini, G.;
Cowell, S.; Creevey, O.; Cuypers, J.; Davidson, M.; De Ridder, J.;
de Torres, A.; Delchambre, L.; Dell'Oro, A.; Ducourant, C.; Frémat,
Y.; García-Torres, M.; Gosset, E.; Halbwachs, J. -L.; Hambly, N. C.;
Harrison, D. L.; Hauser, M.; Hestroffer, D.; Hodgkin, S. T.; Huckle,
H. E.; Hutton, A.; Jasniewicz, G.; Jordan, S.; Kontizas, M.; Korn,
A. J.; Lanzafame, A. C.; Manteiga, M.; Moitinho, A.; Muinonen, K.;
Osinde, J.; Pancino, E.; Pauwels, T.; Petit, J. -M.; Recio-Blanco,
A.; Robin, A. C.; Sarro, L. M.; Siopis, C.; Smith, M.; Smith, K. W.;
Sozzetti, A.; Thuillot, W.; van Reeven, W.; Viala, Y.; Abbas, U.;
Abreu Aramburu, A.; Accart, S.; Aguado, J. J.; Allan, P. M.; Allasia,
W.; Altavilla, G.; Álvarez, M. A.; Alves, J.; Anderson, R. I.; Andrei,
A. H.; Anglada Varela, E.; Antiche, E.; Antoja, T.; Antón, S.; Arcay,
B.; Bach, N.; Baker, S. G.; Balaguer-Núñez, L.; Barache, C.; Barata,
C.; Barbier, A.; Barblan, F.; Barrado y Navascués, D.; Barros, M.;
Barstow, M. A.; Becciani, U.; Bellazzini, M.; Bello García, A.;
Belokurov, V.; Bendjoya, P.; Berihuete, A.; Bianchi, L.; Bienaymé,
O.; Billebaud, F.; Blagorodnova, N.; Blanco-Cuaresma, S.; Boch, T.;
Bombrun, A.; Borrachero, R.; Bouquillon, S.; Bourda, G.; Bouy, H.;
Bragaglia, A.; Breddels, M. A.; Brouillet, N.; Brüsemeister, T.;
Bucciarelli, B.; Burgess, P.; Burgon, R.; Burlacu, A.; Busonero, D.;
Buzzi, R.; Caffau, E.; Cambras, J.; Campbell, H.; Cancelliere, R.;
Cantat-Gaudin, T.; Carlucci, T.; Carrasco, J. M.; Castellani, M.;
Charlot, P.; Charnas, J.; Chiavassa, A.; Clotet, M.; Cocozza, G.;
Collins, R. S.; Costigan, G.; Crifo, F.; Cross, N. J. G.; Crosta, M.;
Crowley, C.; Dafonte, C.; Damerdji, Y.; Dapergolas, A.; David, P.;
David, M.; De Cat, P.; de Felice, F.; de Laverny, P.; De Luise, F.;
De March, R.; de Martino, D.; de Souza, R.; Debosscher, J.; del Pozo,
E.; Delbo, M.; Delgado, A.; Delgado, H. E.; Di Matteo, P.; Diakite, S.;
Distefano, E.; Dolding, C.; Dos Anjos, S.; Drazinos, P.; Durán, J.;
Dzigan, Y.; Edvardsson, B.; Enke, H.; Evans, N. W.; Eynard Bontemps,
G.; Fabre, C.; Fabrizio, M.; Faigler, S.; Falcão, A. J.; Farràs
Casas, M.; Federici, L.; Fedorets, G.; Fernández-Hernández, J.;
Fernique, P.; Fienga, A.; Figueras, F.; Filippi, F.; Findeisen, K.;
Fonti, A.; Fouesneau, M.; Fraile, E.; Fraser, M.; Fuchs, J.; Gai, M.;
Galleti, S.; Galluccio, L.; Garabato, D.; García-Sedano, F.; Garofalo,
A.; Garralda, N.; Gavras, P.; Gerssen, J.; Geyer, R.; Gilmore,
G.; Girona, S.; Giuffrida, G.; Gomes, M.; González-Marcos, A.;
González-Núñez, J.; González-Vidal, J. J.; Granvik, M.; Guerrier,
A.; Guillout, P.; Guiraud, J.; Gúrpide, A.; Gutiérrez-Sánchez,
R.; Guy, L. P.; Haigron, R.; Hatzidimitriou, D.; Haywood, M.; Heiter,
U.; Helmi, A.; Hobbs, D.; Hofmann, W.; Holl, B.; Holland, G.; Hunt,
J. A. S.; Hypki, A.; Icardi, V.; Irwin, M.; Jevardat de Fombelle,
G.; Jofré, P.; Jonker, P. G.; Jorissen, A.; Julbe, F.; Karampelas,
A.; Kochoska, A.; Kohley, R.; Kolenberg, K.; Kontizas, E.; Koposov,
S. E.; Kordopatis, G.; Koubsky, P.; Krone-Martins, A.; Kudryashova, M.;
Kull, I.; Bachchan, R. K.; Lacoste-Seris, F.; Lanza, A. F.; Lavigne,
J. -B.; Le Poncin-Lafitte, C.; Lebreton, Y.; Lebzelter, T.; Leccia, S.;
Leclerc, N.; Lecoeur-Taibi, I.; Lemaitre, V.; Lenhardt, H.; Leroux, F.;
Liao, S.; Licata, E.; Lindstrøm, H. E. P.; Lister, T. A.; Livanou,
E.; Lobel, A.; Löffler, W.; López, M.; Lorenz, D.; MacDonald, I.;
Magalhães Fernandes, T.; Managau, S.; Mann, R. G.; Mantelet, G.;
Marchal, O.; Marchant, J. M.; Marconi, M.; Marinoni, S.; Marrese,
P. M.; Marschalkó, G.; Marshall, D. J.; Martín-Fleitas, J. M.;
Martino, M.; Mary, N.; Matijevič, G.; Mazeh, T.; McMillan, P. J.;
Messina, S.; Michalik, D.; Millar, N. R.; Miranda, B. M. H.; Molina,
D.; Molinaro, R.; Molinaro, M.; Molnár, L.; Moniez, M.; Montegriffo,
P.; Mor, R.; Mora, A.; Morbidelli, R.; Morel, T.; Morgenthaler, S.;
Morris, D.; Mulone, A. F.; Muraveva, T.; Musella, I.; Narbonne, J.;
Nelemans, G.; Nicastro, L.; Noval, L.; Ordénovic, C.; Ordieres-Meré,
J.; Osborne, P.; Pagani, C.; Pagano, I.; Pailler, F.; Palacin, H.;
Palaversa, L.; Parsons, P.; Pecoraro, M.; Pedrosa, R.; Pentikäinen,
H.; Pichon, B.; Piersimoni, A. M.; Pineau, F. -X.; Plachy, E.;
Plum, G.; Poujoulet, E.; Prša, A.; Pulone, L.; Ragaini, S.; Rago,
S.; Rambaux, N.; Ramos-Lerate, M.; Ranalli, P.; Rauw, G.; Read, A.;
Regibo, S.; Reylé, C.; Ribeiro, R. A.; Rimoldini, L.; Ripepi, V.;
Riva, A.; Rixon, G.; Roelens, M.; Romero-Gómez, M.; Rowell, N.; Royer,
F.; Ruiz-Dern, L.; Sadowski, G.; Sagristà Sellés, T.; Sahlmann, J.;
Salgado, J.; Salguero, E.; Sarasso, M.; Savietto, H.; Schultheis, M.;
Sciacca, E.; Segol, M.; Segovia, J. C.; Segransan, D.; Shih, I. -C.;
Smareglia, R.; Smart, R. L.; Solano, E.; Solitro, F.; Sordo, R.;
Soria Nieto, S.; Souchay, J.; Spagna, A.; Spoto, F.; Stampa, U.;
Steele, I. A.; Steidelmüller, H.; Stephenson, C. A.; Stoev, H.;
Suess, F. F.; Süveges, M.; Surdej, J.; Szabados, L.; Szegedi-Elek,
E.; Tapiador, D.; Taris, F.; Tauran, G.; Taylor, M. B.; Teixeira, R.;
Terrett, D.; Tingley, B.; Trager, S. C.; Turon, C.; Ulla, A.; Utrilla,
E.; Valentini, G.; van Elteren, A.; Van Hemelryck, E.; vanLeeuwen,
M.; Varadi, M.; Vecchiato, A.; Veljanoski, J.; Via, T.; Vicente, D.;
Vogt, S.; Voss, H.; Votruba, V.; Voutsinas, S.; Walmsley, G.; Weiler,
M.; Weingrill, K.; Wevers, T.; Wyrzykowski, Ł.; Yoldas, A.; Žerjal,
M.; Zucker, S.; Zurbach, C.; Zwitter, T.; Alecu, A.; Allen, M.; Allende
Prieto, C.; Amorim, A.; Anglada-Escudé, G.; Arsenijevic, V.; Azaz, S.;
Balm, P.; Beck, M.; Bernstein, H. -H.; Bigot, L.; Bijaoui, A.; Blasco,
C.; Bonfigli, M.; Bono, G.; Boudreault, S.; Bressan, A.; Brown, S.;
Brunet, P. -M.; Bunclark, P.; Buonanno, R.; Butkevich, A. G.; Carret,
C.; Carrion, C.; Chemin, L.; Chéreau, F.; Corcione, L.; Darmigny,
E.; de Boer, K. S.; de Teodoro, P.; de Zeeuw, P. T.; Delle Luche,
C.; Domingues, C. D.; Dubath, P.; Fodor, F.; Frézouls, B.; Fries,
A.; Fustes, D.; Fyfe, D.; Gallardo, E.; Gallegos, J.; Gardiol, D.;
Gebran, M.; Gomboc, A.; Gómez, A.; Grux, E.; Gueguen, A.; Heyrovsky,
A.; Hoar, J.; Iannicola, G.; Isasi Parache, Y.; Janotto, A. -M.;
Joliet, E.; Jonckheere, A.; Keil, R.; Kim, D. -W.; Klagyivik, P.;
Klar, J.; Knude, J.; Kochukhov, O.; Kolka, I.; Kos, J.; Kutka, A.;
Lainey, V.; LeBouquin, D.; Liu, C.; Loreggia, D.; Makarov, V. V.;
Marseille, M. G.; Martayan, C.; Martinez-Rubi, O.; Massart, B.;
Meynadier, F.; Mignot, S.; Munari, U.; Nguyen, A. -T.; Nordlander,
T.; O'Flaherty, K. S.; Ocvirk, P.; Olias Sanz, A.; Ortiz, P.; Osorio,
J.; Oszkiewicz, D.; Ouzounis, A.; Palmer, M.; Park, P.; Pasquato, E.;
Peltzer, C.; Peralta, J.; Péturaud, F.; Pieniluoma, T.; Pigozzi, E.;
Poels, J.; Prat, G.; Prod'homme, T.; Raison, F.; Rebordao, J. M.;
Risquez, D.; Rocca-Volmerange, B.; Rosen, S.; Ruiz-Fuertes, M. I.;
Russo, F.; Sembay, S.; Serraller Vizcaino, I.; Short, A.; Siebert,
A.; Silva, H.; Sinachopoulos, D.; Slezak, E.; Soffel, M.; Sosnowska,
D.; Straižys, V.; ter Linden, M.; Terrell, D.; Theil, S.; Tiede,
C.; Troisi, L.; Tsalmantza, P.; Tur, D.; Vaccari, M.; Vachier, F.;
Valles, P.; Van Hamme, W.; Veltz, L.; Virtanen, J.; Wallut, J. -M.;
Wichmann, R.; Wilkinson, M. I.; Ziaeepour, H.; Zschocke, S.
2017A&A...601A..19G Altcode: 2017arXiv170301131G
Context. The first Gaia Data Release contains the Tycho-Gaia Astrometric
Solution (TGAS). This is a subset of about 2 million stars for which,
besides the position and photometry, the proper motion and parallax are
calculated using HIPPARCOS and Tycho-2 positions in 1991.25 as prior
information. <BR /> Aims: We investigate the scientific potential
and limitations of the TGAS component by means of the astrometric
data for open clusters. <BR /> Methods: Mean cluster parallax and
proper motion values are derived taking into account the error
correlations within the astrometric solutions for individual stars,
an estimate of the internal velocity dispersion in the cluster, and,
where relevant, the effects of the depth of the cluster along the line
of sight. Internal consistency of the TGAS data is assessed. <BR />
Results: Values given for standard uncertainties are still inaccurate
and may lead to unrealistic unit-weight standard deviations of least
squares solutions for cluster parameters. Reconstructed mean cluster
parallax and proper motion values are generally in very good agreement
with earlier HIPPARCOS-based determination, although the Gaia mean
parallax for the Pleiades is a significant exception. We have no current
explanation for that discrepancy. Most clusters are observed to extend
to nearly 15 pc from the cluster centre, and it will be up to future
Gaia releases to establish whether those potential cluster-member stars
are still dynamically bound to the clusters. <BR /> Conclusions: The
Gaia DR1 provides the means to examine open clusters far beyond their
more easily visible cores, and can provide membership assessments
based on proper motions and parallaxes. A combined HR diagram shows
the same features as observed before using the HIPPARCOS data, with
clearly increased luminosities for older A and F dwarfs. <P />Tables
D.1 to D.19 are also available at the CDS via anonymous ftp to <A
href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A>
(<A href="http://130.79.128.5">http://130.79.128.5</A>) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/601/A19">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/601/A19</A>
---------------------------------------------------------
Title: Baade's window and APOGEE. Metallicities, ages, and chemical
abundances
Authors: Schultheis, M.; Rojas-Arriagada, A.; García Pérez, A. E.;
Jönsson, H.; Hayden, M.; Nandakumar, G.; Cunha, K.; Allende Prieto,
C.; Holtzman, J. A.; Beers, T. C.; Bizyaev, D.; Brinkmann, J.; Carrera,
R.; Cohen, R. E.; Geisler, D.; Hearty, F. R.; Fernandez-Tricado, J. G.;
Maraston, C.; Minnitti, D.; Nitschelm, C.; Roman-Lopes, A.; Schneider,
D. P.; Tang, B.; Villanova, S.; Zasowski, G.; Majewski, S. R.
2017A&A...600A..14S Altcode: 2017arXiv170201547S
Context. Baade's window (BW) is one of the most observed Galactic bulge
fields in terms of chemical abundances. Owing to its low and homogeneous
interstellar absorption it is considered the perfect calibration
field for Galactic bulge studies. <BR /> Aims: In the era of large
spectroscopic surveys, calibration fields such as BW are necessary for
cross calibrating the stellar parameters and individual abundances of
the APOGEE survey. <BR /> Methods: We use the APOGEE BW stars to derive
the metallicity distribution function (MDF) and individual abundances
for α- and iron-peak elements of the APOGEE ASPCAP pipeline (DR13),
as well as the age distribution for stars in BW. <BR /> Results:
We determine the MDF of APOGEE stars in BW and find a remarkable
agreement with that of the Gaia-ESO survey (GES). Both exhibit a clear
bimodal distribution. We also find that the Mg-metallicity planes of
the two surveys agree well, except for the metal-rich part ([Fe/H]
> 0.1), where APOGEE finds systematically higher Mg abundances
with respect to the GES. The ages based on the [C/N] ratio reveal a
bimodal age distribution, with a major old population at ~ 10 Gyr,
with a decreasing tail towards younger stars. A comparison of stellar
parameters determined by APOGEE and those determined by other sources
reveals detectable systematic offsets, in particular for spectroscopic
surface gravity estimates. In general, we find a good agreement between
individual abundances of O, Na, Mg, Al, Si, K, Ca, Cr, Mn, Co, and
Ni from APOGEE with that of literature values. <BR /> Conclusions: We
have shown that in general APOGEE data show a good agreement in terms
of MDF and individual chemical abundances with respect to literature
works. Using the [C/N] ratio we found a significant fraction of young
stars in BW.
---------------------------------------------------------
Title: APOGEE chemical abundances of globular cluster giants in the
inner Galaxy
Authors: Schiavon, Ricardo P.; Johnson, Jennifer A.; Frinchaboy, Peter
M.; Zasowski, Gail; Mészáros, Szabolcs; García-Hernández, D. A.;
Cohen, Roger E.; Tang, Baitian; Villanova, Sandro; Geisler, Douglas;
Beers, Timothy C.; Fernández-Trincado, J. G.; García Pérez, Ana E.;
Lucatello, Sara; Majewski, Steven R.; Martell, Sarah L.; O'Connell,
Robert W.; Allende Prieto, Carlos; Bizyaev, Dmitry; Carrera, Ricardo;
Lane, Richard R.; Malanushenko, Elena; Malanushenko, Viktor; Muñoz,
Ricardo R.; Nitschelm, Christian; Oravetz, Daniel; Pan, Kaike;
Roman-Lopes, Alexandre; Schultheis, Matthias; Simmons, Audrey
2017MNRAS.466.1010S Altcode: 2016arXiv161103086S
We report chemical abundances obtained by Sloan Digital Sky Survey
(SDSS)-III/Apache Point Observatory Galactic Evolution Experiment
for giant stars in five globular clusters located within 2.2 kpc
of the Galactic Centre. We detect the presence of multiple stellar
populations in four of those clusters (NGC 6553, NGC 6528, Terzan 5 and
Palomar 6) and find strong evidence for their presence in NGC 6522. All
clusters with a large enough sample present a significant spread in
the abundances of N, C, Na and Al, with the usual correlations and
anticorrelations between various abundances seen in other globular
clusters. Our results provide important quantitative constraints
on theoretical models for self-enrichment of globular clusters, by
testing their predictions for the dependence of yields of elements
such as Na, N, C and Al on metallicity. They also confirm that, under
the assumption that field N-rich stars originate from globular cluster
destruction, they can be used as tracers of their parental systems in
the high-metallicity regime.
---------------------------------------------------------
Title: VizieR Online Data Catalog: Gaia DR1 open cluster members
(Gaia Collaboration+, 2017)
Authors: Gaia Collaboration; van Leeuwen F.; Vallenari, A.; Jordi,
C.; Lindegren, L.; Bastian, U.; Prusti, T.; de Bruijne, J. H. J.;
Brown, A. G. A.; Babusiaux, C.; Bailer-Jones, C. A. L.; Biermann,
M.; Evans, D. W.; Eyer, L.; Jansen, F.; Klioner, S. A.; Lammers,
U.; Luri, X.; Mignard, F.; Panem, C.; Pourbaix, D.; Randich, S.;
Sartoretti, P.; Siddiqui, H. I.; Soubiran, C.; Valette, V.; Walton,
N. A.; Aerts, C.; Arenou, F.; Cropper, M.; Drimmel, R.; Hog, E.; Katz,
D.; Lattanzi, M. G.; O'Mullane, W.; Grebel, E. K.; Holland, A. D.; Huc,
C.; Passot, X.; Perryman, M.; Bramante, L.; Cacciari, C.; Castaneda,
J.; Chaoul, L.; Cheek, N.; de Angeli, F.; Fabricius, C.; Guerra,
R.; Hernandez, J.; Jean-Antoine-Piccolo, A.; Masana, E.; Messineo,
R.; Mowlavi, N.; Nienartowicz, K.; Ordonez-Blanco, D.; Panuzzo, P.;
Portell, J.; Richards, P. J.; Riello, M.; Seabroke, G. M.; Tanga, P.;
Thevenin, F.; Torra, J.; Els, S. G.; Gracia-Abril, G.; Comoretto, G.;
Garcia-Reinaldos, M.; Lock, T.; Mercier, E.; Altmann, M.; Andrae,
R.; Astraatmadja, T. L.; Bellas-Velidis, I.; Benson, K.; Berthier,
J.; Blomme, R.; Busso, G.; Carry, B.; Cellino, A.; Clementini, G.;
Cowell, S.; Creevey, O.; Cuypers, J.; Davidson, M.; De Ridder, J.;
de Torres, A.; Delchambre, L.; Dell'Oro, A.; Ducourant, C.; Fremat,
Y.; Garcia-Torres, M.; Gosset, E.; Halbwachs, J. -L.; Hambly, N. C.;
Harrison, D. L.; Hauser, M.; Hestroffer, D.; Hodgkin, S. T.; Huckle,
H. E.; Hutton, A.; Jasniewicz, G.; Jordan, S.; Kontizas, M.; Korn,
A. J.; Lanzafame, A. C.; Manteiga, M.; Moitinho, A.; Muinonen, K.;
Osinde, J.; Pancino, E.; Pauwels, T.; Petit, J. -M.; Recio-Blanco,
A.; Robin, A. C.; Sarro, L. M.; Siopis, C.; Smith, M.; Smith, K. W.;
Sozzetti, A.; Thuillot, W.; van Reeven, W.; Viala, Y.; Abbas, U.;
Abreu Aramburu, A.; Accart, S.; Aguado, J. J.; Allan, P. M.; Allasia,
W.; Altavilla, G.; Alvarez, M. A.; Alves, J.; Anderson, R. I.; Andrei,
A. H.; Anglada Varela, E.; Antiche, E.; Antoja, T.; Anton, S.; Arcay,
B.; Bach, N.; Baker, S. G.; Balaguer-Nunez, L.; Barache, C.; Barata,
C.; Barbier, A.; Barblan, F.; Barrado, Y. Navascues D.; Barros,
M.; Barstow, M. A.; Becciani, U.; Bellazzini, M.; Bello Garcia, A.;
Belokuro, V. V.; Ben Djoya, P.; Berihuete, A.; Bianchi, L.; Bienayme,
O.; Billebaud, F.; Blagorodnova, N.; Blanco-Cuaresma, S.; Boch, T.;
Bombrun, A.; Borrachero, R.; Bouquillon, S.; Bourda, G.; Bouy, H.;
Bragaglia, A.; Breddels, M. A.; Brouillet, N.; Bruesemeister, T.;
Bucciarelli, B.; Burgess, P.; Burgon, R.; Burlacu, A.; Busonero, D.;
Buzzi, R.; Caffau, E.; Cambras, J.; Campbell, H.; Cancelliere, R.;
Cantat-Gaudin, T.; Carlucci, T.; Carrasco, J. M.; Castellani, M.;
Charlot, P.; Charnas, J.; Chiavassa, A.; Clotet, M.; Cocozza, G.;
Collins, R. S.; Costigan, G.; Crifo, F.; Cross, N. J. G.; Crosta,
M.; Crowley, C.; Dafonte, C.; Damerdji, Y.; Dapergolas, A.; David,
P.; David, M.; De Cat, P.; de Felice, F.; de Laverny, P.; de Luise,
F.; de March, R.; de Martino, D.; de Souza, R.; Debosscher, J.;
Del Pozo, E.; Delbo, M.; Delgado, A.; Delgado, H. E.; Di Matteo, P.;
Diakite, S.; Distefano, E.; Dolding, C.; Dos Anjos, S.; Drazinos, P.;
Duran, J.; Dzigan, Y.; Edvardsson, B.; Enke, H.; Evans, N. W.; Eynard
Bontemps, G.; Fabre, C.; Fabrizio, M.; Faigler, S.; Falcao, A. J.;
Farras Casas, M.; Federici, L.; Fedorets, G.; Fernandez-Hernandez,
J.; Fernique, P.; Fienga, A.; Figueras, F.; Filippi, F.; Findeisen,
K.; Fonti, A.; Fouesneau, M.; Fraile, E.; Fraser, M.; Fuchs, J.;
Gai, M.; Galleti, S.; Galluccio, L.; Garabato, D.; Garcia-Sedano,
F.; Garofalo, A.; Garralda, N.; Gavras, P.; Gerssen, J.; Geyer, R.;
Gilmore, G.; Girona, S.; Giuffrida, G.; Gomes, M.; Gonzalez-Marcos,
A.; Gonzalez-Nunez, J.; Gonzalez-Vidal, J. J.; Granvik, M.; Guerrier,
A.; Guillout, P.; Guiraud, J.; Gurpide, A.; Gutierrez-Sanchez, R.;
Guy, L. P.; Haigron, R.; Hatzidimitriou, D.; Haywood, M.; Heiter,
U.; Helmi, A.; Hobbs, D.; Hofmann, W.; Holl, B.; Holland, G.; Hunt,
J. A. S.; Hypki, A.; Icardi, V.; Irwin, M.; Jevardat de Fombelle,
G.; Jofre, P.; Jonker, P. G.; Jorissen, A.; Julbe, F.; Karampelas,
A.; Kochoska, A.; Kohley, R.; Kolenberg, K.; Kontizas, E.; Koposov,
S. E.; Kordopatis, G.; Koubsky, P.; Krone-Martins, A.; Kudryashova, M.;
Kull, I.; Bachchan, R. K.; Lacoste-Seris, F.; Lanza, A. F.; Lavigne,
J. -B.; Le Poncin-Lafitte, C.; Lebreton, Y.; Lebzelter, T.; Leccia, S.;
Lecler, C. N.; Lecoeur-Taibi, I.; Lemaitre, V.; Lenhardt, H.; Leroux,
F.; Liao, S.; Licata, E.; Lindstrom, H. E. P.; Lister, T. A.; Livanou,
E.; Lobel, A.; Loeffler, W.; Lopez, M.; Lorenz, D.; MacDonald, I.;
Magalhaes Fernandes, T.; Managau, S.; Mann, R. G.; Mantelet, G.;
Marchal, O.; Marchant, J. M.; Marconi, M.; Marinoni, S.; Marrese,
P. M.; Marschalko, G.; Marshall, D. J.; Martin-Fleitas, J. M.; Martino,
M.; Mary, N.; Matijevic, G.; Mazeh, T.; McMillan, P. J.; Messina, S.;
Michalik, D.; Millar, N. R.; Miranda, B. M. H.; Molina, D.; Molinaro,
R.; Molinaro, M.; Molnar, L.; Moniez, M.; Montegriffo, P.; Mor, R.;
Mora, A.; Morbidelli, R.; Morel, T.; Morgenthaler, S.; Morris, D.;
Mulone, A. F.; Muraveva, T.; Musella, I.; Narbonne, J.; Nelemans, G.;
Nicastro, L.; Noval, L.; Ordenovic, C.; Ordieres-Mere, J.; Osborne,
P.; Pagani, C.; Pagano, I.; Pailler, F.; Palacin, H.; Palaversa, L.;
Parsons, P.; Pecoraro, M.; Pedrosa, R.; Pentikaeinen, H.; Pichon, B.;
Piersimoni, A. M.; Pineau, F. -X.; Plachy, E.; Plum, G.; Poujoulet, E.;
Prsa, A.; Pulone, L.; Ragaini, S.; Rago, S.; Rambaux, N.; Ramos-Lerate,
M.; Ranalli, P.; Rauw, G.; Read, A.; Regibo, S.; Reyle, C.; Ribeiro,
R. A.; Rimoldini, L.; Ripepi, V.; Riva, A.; Rixon, G.; Roelens, M.;
Romero-Gomez, M.; Rowell, N.; Royer, F.; Ruiz-Dern, L.; Sadowski,
G.; Sagrista Selles, T.; Sahlmann, J.; Salgado, J.; Salguero, E.;
Sarasso, M.; Savietto, H.; Schultheis, M.; Sciacca, E.; Segol, M.;
Segovia, J. C.; Segransan, D.; Shih, I. -C.; Smareglia, R.; Smart,
R. L.; Solano, E.; Solitro, F.; Sordo, R.; Soria Nieto, S.; Souchay,
J.; Spagna, A.; Spoto, F.; Stampa, U.; Steele, I. A.; Steidelmueller,
H.; Stephenson, C. A.; Stoev, H.; Suess, F. F.; Sueveges, M.; Surdej,
J.; Szabados, L.; Szegedi-Elek, E.; Tapiador, D.; Taris, F.; Tauran,
G.; Taylor, M. B.; Teixeira, R.; Terrett, D.; Tingley, B.; Trager,
S. C.; Turon, C.; Ulla, A.; Utrilla, E.; Valentini, G.; van Elteren,
A.; van Hemelryck, E.; Vanleeuwen, M.; Varadi, M.; Vecchiato, A.;
Veljanoski, J.; Via, T.; Vicente, D.; Vogt, S.; Voss, H.; Votruba,
V.; Voutsinas, S.; Walmsley, G.; Weiler, M.; Weingrill, K.; Wevers,
T.; Wyrzykowski, L.; Yoldas, A.; Zerjal, M.; Zucker, S.; Zurbach,
C.; Zwitter, T.; Alecu, A.; Allen, M.; Allende Prieto, C.; Amorim,
A.; Anglada-Escude, G.; Arsenijevic, V.; Azaz, S.; Balm, P.; Beck,
M.; Bernstein, H. -H.; Bigot, L.; Bijaoui, A.; Blasco, C.; Bonfigli,
M.; Bono, G.; Boudreault, S.; Bressan, A.; Brown, S.; Brunet, P. -M.;
Bunclark, P.; Buonanno, R.; Butkevich, A. G.; Carret, C.; Carrion, C.;
Chemin, L.; Chereau, F.; Corcione, L.; Darmigny, E.; de Boer, K. S.;
de Teodoro, P.; de Zeeuw, P. T.; Delle Luche, C.; Domingues, C. D.;
Dubath, P.; Fodor, F.; Frezouls, B.; Fries, A.; Fustes, D.; Fyfe,
D.; Gallardo, E.; Gallegos, J.; Gardiol, D.; Gebran, M.; Gomboc, A.;
Gomez, A.; Grux, E.; Gueguen, A.; Heyrovsky, A.; Hoar, J.; Iannicola,
G.; Isasi Parache, Y.; Janotto, A. -M.; Joliet, E.; Jonckheere, A.;
Keil, R.; Kim, D. -W.; Klagyivik, P.; Klar, J.; Knude, J.; Kochukhov,
O.; Kolka, I.; Kos, J.; Kutka, A.; Lainey, V.; Lebouquin, D.; Liu,
C.; Loreggia, D.; Makarov, V. V.; Marseille, M. G.; Martayan, C.;
Martinez-Rubi, O.; Massart, B.; Meynadier, F.; Mignot, S.; Munari,
U.; Nguyen, A. -T.; Nordlander, T.; O'Flaherty, K. S.; Ocvirk, P.;
Olias Sanz, A.; Ortiz, P.; Osorio, J.; Oszkiewicz, D.; Ouzounis, A.;
Palmer, M.; Park, P.; Pasquato, E.; Peltzer, C.; Peralta, J.; Peturaud,
F.; Pieniluoma, T.; Pigozzi, E.; Poels, J.; Prat, G.; Prod'homme, T.;
Raison, F.; Rebordao, J. M.; Risquez, D.; Rocca-Volmerange, B.; Rosen,
S.; Ruiz-Fuertes, M. I.; Russo, F.; Sembay, S.; Serraller Vizcaino,
I.; Short, A.; Siebert, A.; Silva, H.; Sinachopoulos, D.; Slezak, E.;
Soffel, M.; Sosnowska, D.; Straizys, V.; Ter Linden, M.; Terrell, D.;
Theil, S.; Tiede, C.; Troisi, L.; Tsalmantza, P.; Tur, D.; Vaccari,
M.; Vachier, F.; Valles, P.; van Hamme, W.; Veltz, L.; Virtanen,
J.; Wallut, J. -M.; Wichmann, R.; Wilkinson, M. I.; Ziaeepour, H.;
Zschocke, S.
2017yCat..36010019G Altcode:
We have determined and examined the astrometric data for 19 open
clusters, ranging from the Hyades at just under 47pc to NGC 2422
at nearly 440pc. The clusters are : the Hyades, Coma Berenices, the
Pleiades, Praesepe, alpha Per, IC 2391, IC 2602, Blanco 1, NGC 2451,
NGC 6475, NGC 7092, NGC 2516, NGC 2232, IC 4665, NGC 6633, Collinder
140, NGC 2422, NGC 3532 and NGC 2547. <P />(2 data files).
---------------------------------------------------------
Title: Chemical trends in the Galactic halo from APOGEE data
Authors: Fernández-Alvar, E.; Carigi, L.; Allende Prieto, C.; Hayden,
M. R.; Beers, T. C.; Fernández-Trincado, J. G.; Meza, A.; Schultheis,
M.; Santiago, B. X.; Queiroz, A. B.; Anders, F.; da Costa, L. N.;
Chiappini, C.
2017MNRAS.465.1586F Altcode: 2016arXiv161101249F
The galaxy formation process in the Λ cold dark matter scenario can
be constrained from the analysis of stars in the Milky Way's halo
system. We examine the variation of chemical abundances in distant
halo stars observed by the Apache Point Observatory Galactic Evolution
Experiment (APOGEE), as a function of distance from the Galactic Centre
(r) and iron abundance ([M/H]), in the range 5 ≲ r ≲ 30 kpc and -2.5
< [M/H] < 0.0. We perform a statistical analysis of the abundance
ratios derived by the APOGEE pipeline (ASPCAP) and distances calculated
by several approaches. Our analysis reveals signatures of a different
chemical enrichment between the inner and outer regions of the halo,
with a transition at about 15 kpc. The derived metallicity distribution
function exhibits two peaks, at [M/H] ∼ -1.5 and ∼-2.1, consistent
with previously reported halo metallicity distributions. We obtain a
difference of ∼0.1 dex for α-element-to-iron ratios for stars at r
> 15 kpc and [M/H] > -1.1 (larger in the case of O, Mg, and S)
with respect to the nearest halo stars. This result confirms previous
claims for low-α stars found at larger distances. Chemical differences
in elements with other nucleosynthetic origins (Ni, K, Na, and Al)
are also detected. C and N do not provide reliable information about
the interstellar medium from which stars formed because our sample
comprises red giant branch and asymptotic giant branch stars and can
experience mixing of material to their surfaces.
---------------------------------------------------------
Title: The Gaia-ESO Survey: Calibration strategy
Authors: Pancino, E.; Lardo, C.; Altavilla, G.; Marinoni, S.; Ragaini,
S.; Cocozza, G.; Bellazzini, M.; Sabbi, E.; Zoccali, M.; Donati, P.;
Heiter, U.; Koposov, S. E.; Blomme, R.; Morel, T.; Símon-Díaz, S.;
Lobel, A.; Soubiran, C.; Montalban, J.; Valentini, M.; Casey, A. R.;
Blanco-Cuaresma, S.; Jofré, P.; Worley, C. C.; Magrini, L.; Hourihane,
A.; François, P.; Feltzing, S.; Gilmore, G.; Randich, S.; Asplund, M.;
Bonifacio, P.; Drew, J. E.; Jeffries, R. D.; Micela, G.; Vallenari,
A.; Alfaro, E. J.; Allende Prieto, C.; Babusiaux, C.; Bensby, T.;
Bragaglia, A.; Flaccomio, E.; Hambly, N.; Korn, A. J.; Lanzafame,
A. C.; Smiljanic, R.; Van Eck, S.; Walton, N. A.; Bayo, A.; Carraro,
G.; Costado, M. T.; Damiani, F.; Edvardsson, B.; Franciosini, E.;
Frasca, A.; Lewis, J.; Monaco, L.; Morbidelli, L.; Prisinzano, L.;
Sacco, G. G.; Sbordone, L.; Sousa, S. G.; Zaggia, S.; Koch, A.
2017A&A...598A...5P Altcode: 2016arXiv161006480P
The Gaia-ESO survey (GES) is now in its fifth and last year of
observations and has produced tens of thousands of high-quality spectra
of stars in all Milky Way components. This paper presents the strategy
behind the selection of astrophysical calibration targets, ensuring
that all GES results on radial velocities, atmospheric parameters,
and chemical abundance ratios will be both internally consistent and
easily comparable with other literature results, especially from
other large spectroscopic surveys and from Gaia. The calibration
of GES is particularly delicate because of (I) the large space of
parameters covered by its targets, ranging from dwarfs to giants,
from O to M stars; these targets have a large wide of metallicities
and also include fast rotators, emission line objects, and stars
affected by veiling; (II) the variety of observing setups, with
different wavelength ranges and resolution; and (III) the choice of
analyzing the data with many different state-of-the-art methods, each
stronger in a different region of the parameter space, which ensures
a better understanding of systematic uncertainties. An overview
of the GES calibration and homogenization strategy is also given,
along with some examples of the usage and results of calibrators in
GES iDR4, which is the fourth internal GES data release and will form
the basis of the next GES public data release. The agreement between
GES iDR4 recommended values and reference values for the calibrating
objects are very satisfactory. The average offsets and spreads are
generally compatible with the GES measurement errors, which in iDR4 data
already meet the requirements set by the main GES scientific goals. <P
/>Based on data products from observations made with ESO Telescopes
at the La Silla Paranal Observatory under programme IDs 188.B-3002 and
193.B-0936.Full Table 2 is only available at the CDS via anonymous ftp
to <A href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A>
(<A href="http://130.79.128.5">http://130.79.128.5</A>) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/598/A5">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/598/A5</A>
---------------------------------------------------------
Title: Chemical tagging with APOGEE: discovery of a large population
of N-rich stars in the inner Galaxy
Authors: Schiavon, Ricardo P.; Zamora, Olga; Carrera, Ricardo;
Lucatello, Sara; Robin, A. C.; Ness, Melissa; Martell, Sarah L.; Smith,
Verne V.; García-Hernández, D. A.; Manchado, Arturo; Schönrich,
Ralph; Bastian, Nate; Chiappini, Cristina; Shetrone, Matthew;
Mackereth, J. Ted; Williams, Rob A.; Mészáros, Szabolcs; Allende
Prieto, Carlos; Anders, Friedrich; Bizyaev, Dmitry; Beers, Timothy
C.; Chojnowski, S. Drew; Cunha, Katia; Epstein, Courtney; Frinchaboy,
Peter M.; García Pérez, Ana E.; Hearty, Fred R.; Holtzman, Jon A.;
Johnson, Jennifer A.; Kinemuchi, Karen; Majewski, Steven R.; Muna,
Demitri; Nidever, David L.; Nguyen, Duy Cuong; O'Connell, Robert W.;
Oravetz, Daniel; Pan, Kaike; Pinsonneault, Marc; Schneider, Donald P.;
Schultheis, Matthias; Simmons, Audrey; Skrutskie, Michael F.; Sobeck,
Jennifer; Wilson, John C.; Zasowski, Gail
2017MNRAS.465..501S Altcode: 2016arXiv160605651S; 2016MNRAS.tmp.1288S
Formation of globular clusters (GCs), the Galactic bulge, or galaxy
bulges in general is an important unsolved problem in Galactic
astronomy. Homogeneous infrared observations of large samples of
stars belonging to GCs and the Galactic bulge field are one of
the best ways to study these problems. We report the discovery by
APOGEE (Apache Point Observatory Galactic Evolution Experiment)
of a population of field stars in the inner Galaxy with abundances
of N, C, and Al that are typically found in GC stars. The newly
discovered stars have high [N/Fe], which is correlated with [Al/Fe]
and anticorrelated with [C/Fe]. They are homogeneously distributed
across, and kinematically indistinguishable from, other field stars
within the same volume. Their metallicity distribution is seemingly
unimodal, peaking at [Fe/H] ∼ -1, thus being in disagreement with
that of the Galactic GC system. Our results can be understood in
terms of different scenarios. N-rich stars could be former members of
dissolved GCs, in which case the mass in destroyed GCs exceeds that
of the surviving GC system by a factor of ∼8. In that scenario, the
total mass contained in so-called `first-generation' stars cannot be
larger than that in `second-generation' stars by more than a factor
of ∼9 and was certainly smaller. Conversely, our results may imply
the absence of a mandatory genetic link between `second-generation'
stars and GCs. Last, but not least, N-rich stars could be the oldest
stars in the Galaxy, the by-products of chemical enrichment by the
first stellar generations formed in the heart of the Galaxy.
---------------------------------------------------------
Title: Chemical Abundances of M-dwarfs from the APOGEE Survey. I. The
Exoplanet Hosting Stars Kepler-138 and Kepler-186
Authors: Souto, D.; Cunha, K.; García-Hernández, D. A.; Zamora, O.;
Allende Prieto, C.; Smith, V. V.; Mahadevan, S.; Blake, C.; Johnson,
J. A.; Jönsson, H.; Pinsonneault, M.; Holtzman, J.; Majewski,
S. R.; Shetrone, M.; Teske, J.; Nidever, D.; Schiavon, R.; Sobeck,
J.; García Pérez, A. E.; Gómez Maqueo Chew, Y.; Stassun, K.
2017ApJ...835..239S Altcode: 2016arXiv161201598S
We report the first detailed chemical abundance analysis of the
exoplanet-hosting M-dwarf stars Kepler-138 and Kepler-186 from the
analysis of high-resolution (R ∼ 22,500) H-band spectra from the
SDSS-IV-APOGEE survey. Chemical abundances of 13 elements—C,
O, Na, Mg, Al, Si, K, Ca, Ti, V, Cr, Mn, and Fe—are extracted
from the APOGEE spectra of these early M-dwarfs via spectrum
syntheses computed with an improved line list that takes into
account H<SUB>2</SUB>O and FeH lines. This paper demonstrates
that APOGEE spectra can be analyzed to determine detailed chemical
compositions of M-dwarfs. Both exoplanet-hosting M-dwarfs display
modest sub-solar metallicities: [Fe/H]<SUB>Kepler-138</SUB> = -0.09
± 0.09 dex and [Fe/H]<SUB>Kepler-186</SUB> = -0.08 ± 0.10 dex. The
measured metallicities resulting from this high-resolution analysis
are found to be higher by ∼0.1-0.2 dex than previous estimates
from lower-resolution spectra. The C/O ratios obtained for the two
planet-hosting stars are near-solar, with values of 0.55 ± 0.10 for
Kepler-138 and 0.52 ± 0.12 for Kepler-186. Kepler-186 exhibits a
marginally enhanced [Si/Fe] ratio.
---------------------------------------------------------
Title: Calibration of (B-V)_{0} for MILES stars
Authors: de C. Milone, A.; Sánchez-Blázquez, P.; Vazdekis, A.;
Allende Prieto, C.; Sansom, A.
2017ASInC..14...57D Altcode:
The integrated spectral properties of a stellar system bring information
from the mixture of stellar populations within the system. The (B-V)
colour is one of the observational properties that can help determine
the age and metallicity of stellar populations in a star cluster or
even in galaxies. We have derived a series of empirical calibrations of
the intrinsic colour, (B-V)_{0}, as a function of T_{eff}, [Fe/H] and
[α/Fe]. The stellar parameters of MILES stars have been redetermined
homogeneously. The calibrations were obtained individually for distinct
spectral types (O-B, A, F-G-K and M), which were then further subdivided
into as many as five ranges in [Fe/H]. For the M types only, the stars
were divided into dwarfs and giants. (B-V)_{0} was measured directly
using the MILES fully calibrated stellar spectra (typical error =
0.025 mag). Here, we present just the (B-V)_{0} calibrations for F-G-K
types that are split into five [Fe/H] ranges. We find that the error in
(B-V)_{0} varies from 0.014-0.022 mag. The next main goal is to compute
(B-V)_{0} self-consistently for semi-empirical simple stellar population
models based on MILES.
---------------------------------------------------------
Title: APOGEE Chemical Abundances of the Sagittarius Dwarf Galaxy
Authors: Hasselquist, Sten; Shetrone, Matthew D.; Smith, Verne V.;
Cunha, Katia M. L.; McWilliam, Andrew; Holtzman, Jon A.; Majewski,
Steven R.; Sobeck, Jennifer; Frinchaboy, Peter M.; Roman-Lopes,
Alexandre; Ivans, Inese I.; Allende-Prieto, Carlos; Placco, Vinicius
M.; Lane, Richard; Zasowski, Gail; APOGEE
2017AAS...22912304H Altcode:
The Apache Point Observatory Galactic Evolution Experiment (APOGEE)
provides elemental abundances for C, N, O, Na, Mg, Al, Si, P, S, K,
Ca, Ti, V, Cr, Mn, Fe, Co, and Ni. We analyze the chemical abundance
patterns of these elements for ~ 350 stars belonging to the Sagittarius
Dwarf Galaxy (Sgr). This is the largest sample of Sgr stars with
detailed chemical abundances and the first time C, N, P, K, V, Cr,
Co, and Ni have been studied in the dwarf galaxy. For Sgr stars with
[Fe/H] > -0.9, we find that Sgr is deficient in all elemental
abundance ratios (expressed as [X/Fe]) relative to the Milky Way,
which suggests that Sgr stars observed today were formed from gas that
was less enriched by both Type II and Type Ia SNe. By examining the
relative deficiencies of the hydrostatic (O, Mg, and Al) and explosive
(Si, K, and Mn) elements , we find support that previous generations
of Sgr stars were formed with a top-light IMF, lacking the most massive
stars that would normally pollute the ISM with the hydrostatic elements.
---------------------------------------------------------
Title: Galactic archaeology with asteroseismology and spectroscopy:
Red giants observed by CoRoT and APOGEE
Authors: Anders, F.; Chiappini, C.; Rodrigues, T. S.; Miglio, A.;
Montalbán, J.; Mosser, B.; Girardi, L.; Valentini, M.; Noels,
A.; Morel, T.; Johnson, J. A.; Schultheis, M.; Baudin, F.; de Assis
Peralta, R.; Hekker, S.; Themeßl, N.; Kallinger, T.; García, R. A.;
Mathur, S.; Baglin, A.; Santiago, B. X.; Martig, M.; Minchev, I.;
Steinmetz, M.; da Costa, L. N.; Maia, M. A. G.; Allende Prieto,
C.; Cunha, K.; Beers, T. C.; Epstein, C.; García Pérez, A. E.;
García-Hernández, D. A.; Harding, P.; Holtzman, J.; Majewski, S. R.;
Mészáros, Sz.; Nidever, D.; Pan, K.; Pinsonneault, M.; Schiavon,
R. P.; Schneider, D. P.; Shetrone, M. D.; Stassun, K.; Zamora, O.;
Zasowski, G.
2017A&A...597A..30A Altcode: 2016arXiv160407763A; 2016A&A...597A..30A
With the advent of the space missions CoRoT and Kepler, it has recently
become feasible to determine precise asteroseismic masses and relative
ages for large samples of red giant stars. We present the CoRoGEE
dataset, obtained from CoRoT light curves for 606 red giants in two
fields of the Galactic disc that have been co-observed by the Apache
Point Observatory Galactic Evolution Experiment (APOGEE). We used
the Bayesian parameter estimation code PARAM to calculate distances,
extinctions, masses, and ages for these stars in a homogeneous analysis,
resulting in relative statistical uncertainties of ≲2% in distance, 4%
in radius, 9% in mass and 25% in age. We also assessed systematic age
uncertainties stemming from different input physics and mass loss. We
discuss the correlation between ages and chemical abundance patterns
of field stars over a broad radial range of the Milky Way disc (5 kpc
<R<SUB>Gal</SUB>< 14 kpc), focussing on the [α/Fe]-[Fe/H]-age
plane in five radial bins of the Galactic disc. We find an overall
agreement with the expectations of pure chemical-evolution models
computed before the present data were available, especially
for the outer regions. However, our data also indicate that a
significant fraction of stars now observed near and beyond the solar
neighbourhood migrated from inner regions. Mock CoRoGEE observations
of a chemodynamical Milky Way disc model indicate that the number of
high-metallicity stars in the outer disc is too high to be accounted
for even by the strong radial mixing present in the model. The mock
observations also show that the age distribution of the [α/Fe]-enhanced
sequence in the CoRoGEE inner-disc field is much broader than expected
from a combination of radial mixing and observational errors. We suggest
that a thick-disc/bulge component that formed stars for more than 3 Gyr
may account for these discrepancies. Our results are subject to future
improvements due to (a) the still low statistics, because our sample
had to be sliced into bins of Galactocentric distances and ages; (b)
large uncertainties in proper motions (and therefore guiding radii);
and (c) corrections to the asteroseismic mass-scaling relation. The
situation will improve not only upon the upcoming Gaia data releases,
but also with the foreseen increase in the number of stars with
both seismic and spectroscopic information. <P />The data described
in Table B.1 are only available at the CDS via anonymous ftp to <A
href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A>
(<A href="http://130.79.128.5">http://130.79.128.5</A>) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/597/A30">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/597/A30</A>
---------------------------------------------------------
Title: IMF and [Na/Fe] abundance ratios from optical and NIR spectral
features in early-type galaxies
Authors: La Barbera, F.; Vazdekis, A.; Ferreras, I.; Pasquali, A.;
Allende Prieto, C.; Röck, B.; Aguado, D. S.; Peletier, R. F.
2017MNRAS.464.3597L Altcode: 2016arXiv161003853L
We present a joint analysis of the four most prominent sodium-sensitive
features (Na D, Na I λ8190Å, Na I λ1.14 μm, and Na I λ2.21 μm),
in the optical and near-infrared spectral ranges, of two nearby,
massive (σ ∼ 300 km s<SUP>-1</SUP>), early-type galaxies (named XSG1
and XSG2). Our analysis relies on deep Very Large Telescope/X-Shooter
long-slit spectra, along with newly developed stellar population models,
allowing for [Na/Fe] variations, up to ∼1.2 dex, over a wide range of
age, total metallicity, and initial mass function (IMF) slope. The new
models show that the response of the Na-dependent spectral indices to
[Na/Fe] is stronger when the IMF is bottom heavier. For the first
time, we are able to match all four Na features in the central
regions of massive early-type galaxies finding an overabundance of
[Na/Fe] in the range 0.5-0.7 dex and a bottom-heavy IMF. Therefore,
individual abundance variations cannot be fully responsible for the
trends of gravity-sensitive indices, strengthening the case towards a
non-universal IMF. Given current limitations of theoretical atmosphere
models, our [Na/Fe] estimates should be taken as upper limits. For
XSG1, where line strengths are measured out to ∼0.8 R<SUB>e</SUB>,
the radial trend of [Na/Fe] is similar to [α/Fe] and [C/Fe], being
constant out to ∼0.5 R<SUB>e</SUB>, and decreasing by ∼0.2-0.3
dex at ∼0.8 R<SUB>e</SUB>, without any clear correlation with local
metallicity. Such a result seems to be in contrast to the predicted
increase of Na nucleosynthetic yields from asymptotic giant branch
stars and Type II supernovae. For XSG1, the Na-inferred IMF radial
profile is consistent, within the errors, with that derived from TiO
features and the Wing-Ford band presented in a recent paper.
---------------------------------------------------------
Title: The Open Cluster Chemical Abundances and Mapping (OCCAM)
Survey: Galactic Gradients using SDSS-IV/DR13 and Gaia
Authors: Frinchaboy, Peter M.; Donor, John; O'Connell, Julia; Cunha,
Katia M. L.; Thompson, Benjamin A.; Melendez, Matthew; Shetrone,
Matthew D.; Majewski, Steven R.; Zasowski, Gail; Allende-Prieto,
Carlos; Carrera, Ricardo; García Pérez, Ana; Hayden, Michael R.;
Hearty, Fred R.; Holtzman, Jon A.; Johnson, Jennifer; Meszaros,
Szabolcs; Nidever, David L.; Pinsonneault, Marc H.; Roman-Lopes,
Alexandre; Schiavon, Ricardo P.; Schultheis, Mathias; Smith, Verne V.;
Sobeck, Jennifer; Stassun, Keivan G.; APOGEE Team
2017AAS...22934302F Altcode:
The Open Cluster Chemical Analysis and Mapping (OCCAM) survey aims to
produce a comprehensive, uniform, infrared-based data set forhundreds
of open clusters, and constrain key Galactic dynamical and chemical
parameters using the SDSS/APOGEE survey. We report on multi-element
radial abundance gradients obtained from a sample of over 30 disk open
clusters. The chemical abundances were derived automatically by the
ASPCAP pipeline and these are part of the SDSS IV Data Release 13. The
open cluster sample studied spans a significant range in age allowing
exploration of the evolution of the Galactic abundance gradient.This
work is supported by an NSF AAG grant AST-1311835.
---------------------------------------------------------
Title: The Open Cluster Chemical Abundances and Mapping (OCCAM)
Survey: Overview and Membership Methods
Authors: Donor, John; Frinchaboy, Peter M.; O'Connell, Julia; Cunha,
Katia M. L.; Thompson, Benjamin A.; Melendez, Matthew; Shetrone,
Matthew D.; Majewski, Steven R.; Zasowski, Gail; Allende-Prieto,
Carlos; Pinsonneault, Marc H.; Roman-Lopes, Alexandre; Schultheis,
Mathias; Stassun, Keivan G.; Apogee Team
2017AAS...22934301D Altcode:
The Open Cluster Chemical Analysis and Mapping (OCCAM) survey aims
to produce a comprehensive, uniform, infrared-based data set for
hundreds of open clusters, and constrain key Galactic dynamical and
chemical parameters using the SDSS/APOGEE survey. We present the sample
and methods being used by the survey to determine membership for the
few-star sampling for most clusters as observed by the SDSS/APOGEE. We
present verification of the membership method using the DR13 sample,
and show an extension of the method by incorporation of proper motion
and parallax data from the ESA Gaia mission.This work is supported by
an NSF AAG grant AST-1311835.
---------------------------------------------------------
Title: NLTE Analysis of High-resolution H-band Spectra. II. Neutral
Magnesium
Authors: Zhang, Junbo; Shi, Jianrong; Pan, Kaike; Allende Prieto,
Carlos; Liu, Chao
2017ApJ...835...90Z Altcode: 2016arXiv161005893Z
Aiming at testing the validity of our magnesium atomic model and
investigating the effects of non-local thermodynamical equilibrium
(NLTE) on the formation of the H-band neutral magnesium lines, we derive
the differential Mg abundances from selected transitions for 13 stars
either adopting or relaxing the assumption of local thermodynamical
equilibrium (LTE). Our analysis is based on high-resolution and
high signal-to-noise ratio H-band spectra from the Apache Point
Observatory Galactic Evolution Experiment (APOGEE) and optical spectra
from several instruments. The absolute differences between the Mg
abundances derived from the two wavelength bands are always less than
0.1 dex in the NLTE analysis, while they are slightly larger for the
LTE case. This suggests that our Mg atomic model is appropriate for
investigating the NLTE formation of the H-band Mg lines. The NLTE
corrections for the Mg I H-band lines are sensitive to the surface
gravity, becoming larger for smaller log g values, and strong lines
are more susceptible to departures from LTE. For cool giants, NLTE
corrections tend to be negative, and for the strong line at 15765 Å
they reach -0.14 dex in our sample, and up to -0.22 dex for other
APOGEE stars. Our results suggest that it is important to include
NLTE corrections in determining Mg abundances from the H-band Mg I
transitions, especially when strong lines are used. <P />Based on
observations collected on the 2.16 m telescope at Xinglong station,
National Astronomical Observatories, Chinese Academy of Sciences, the
2.2 m telescope at the Calar Alto Observatory, the 1.88 m reflector
on the Okayama Astrophysical Observatory, the Kitt Peak coudé feed
telescope, and the McMath-Pierce solar telescope and the coudé focus
of the Mayall 4 m reflector at Kitt Peak.
---------------------------------------------------------
Title: NLTE Analysis of High-Resolution H-band Spectra. I. Neutral
Silicon
Authors: Zhang, Junbo; Shi, Jianrong; Pan, Kaike; Allende Prieto,
Carlos; Liu, Chao
2016ApJ...833..137Z Altcode:
We investigated the reliability of our silicon atomic model and
the influence of non-local thermodynamical equilibrium (NLTE) on
the formation of neutral silicon (Si I) lines in the near-infrared
(near-IR) H-band. We derived the differential Si abundances for 13
sample stars with high-resolution H-band spectra from the Apache Point
Observatory Galactic Evolution Experiment (APOGEE), as well as from
optical spectra, both under local thermodynamical equilibrium (LTE) and
NLTE conditions. We found that the differences between the Si abundances
derived from the H-band and from optical lines for the same stars are
less than 0.1 dex when the NLTE effects are included, and that NLTE
reduces the line-to-line scatter in the H-band spectra for most sample
stars. These results suggest that our Si atomic model is appropriate
for studying the formation of H-band Si lines. Our calculations show
that the NLTE corrections of the Si I H-band lines are negative, I.e.,
the final Si abundances will be overestimated in LTE. The corrections
for strong lines depend on surface gravity, and tend to be larger for
giants, reaching ∼-0.2 dex in our sample, and up to ∼-0.4 dex
in extreme cases of APOGEE targets. Thus, the NLTE effects should
be included in deriving silicon abundances from H-band Si I lines,
especially for the cases where only strong lines are available. <P
/>Based on observations collected with the 2.16 m telescope at Xinglong
station, National Astronomical Observatories, Chinese Academy of
Sciences, the 2.2 m telescope at the Calar Alto Observatory, the 1.88
m reflector at the Okayama Astrophysical Observatory, the Kitt Peak
coudé feed telescope, and the McMath-Pierce solar telescope and the
coudé focus of the Mayall 4 m reflector at Kitt Peak.
---------------------------------------------------------
Title: Identification of Neodymium in the Apogee H-Band Spectra
Authors: Hasselquist, Sten; Shetrone, Matthew; Cunha, Katia; Smith,
Verne V.; Holtzman, Jon; Lawler, J. E.; Allende Prieto, Carlos;
Beers, Timothy C.; Chojnowski, Drew; Fernández-Trincado, J. G.;
García-Hernández, D. A.; Hearty, Fred R.; Majewski, Steven R.;
Pereira, C. B.; Placco, Vinicius M.; Villanova, Sandro; Zamora, Olga
2016ApJ...833...81H Altcode:
We present the detection of 10 lines of singly ionized neodymium
(Nd II, Z = 60) in H-band spectra using observations from the
SDSS-III Apache Point Observatory Galactic Evolution Experiment
(APOGEE) survey. These lines were detected in a metal-poor ([Fe/H]
∼ -1.5), neutron-capture element-enhanced star recently discovered
in the APOGEE sample. Using an optical high-resolution spectrum, we
derive a Nd abundance for this star using Nd II lines with precise,
laboratory-derived gf values. This optical abundance is used to derive
log(gf) values for the H-band lines. We use these lines to rederive Nd
II abundances for two more metal-rich, s-process enhanced stars observed
by APOGEE and find that these lines yield consistent Nd II abundances,
confirming the Nd enhancement of these stars. We explore the region of
parameter space in the APOGEE sample over which these lines can be used
to measure Nd II abundances. We find that Nd abundances can be reliably
derived for ∼18% of the red giants observed by APOGEE. This will
result in ∼50,000 Milky Way stars with Nd II abundances following
the conclusion of APOGEE-2, allowing for studies of neutron-capture
element abundance distributions across the entire Milky Way.
---------------------------------------------------------
Title: Accurate parameters for HD 209458 and its planet from HST
spectrophotometry
Authors: del Burgo, C.; Allende Prieto, C.
2016MNRAS.463.1400D Altcode: 2017arXiv170301449D; 2016MNRAS.tmp.1126D
We present updated parameters for the star HD 209458 and its transiting
giant planet. The stellar angular diameter θ = 0.2254 ± 0.0017 mas
is obtained from the average ratio between the absolute flux observed
with the Hubble Space Telescope and that of the best-fitting Kurucz
model atmosphere. This angular diameter represents an improvement in
precision of more than four times compared to available interferometric
determinations. The stellar radius R<SUB>⋆</SUB> = 1.20 ± 0.05
R<SUB>⊙</SUB> is ascertained by combining the angular diameter with
the Hipparcos trigonometric parallax, which is the main contributor
to its uncertainty, and therefore the radius accuracy should be
significantly improved with Gaia's measurements. The radius of the
exoplanet R<SUB>p</SUB> = 1.41 ± 0.06 R<SUB>J</SUB> is derived from
the corresponding transit depth in the light curve and our stellar
radius. From the model fitting, we accurately determine the effective
temperature, T<SUB>eff</SUB> = 6071 ± 20 K, which is in perfect
agreement with the value of 6070 ± 24 K calculated from the angular
diameter and the integrated spectral energy distribution. We also find
precise values from recent Padova isochrones, such as R<SUB>⋆</SUB>
= 1.20 ± 0.06 R<SUB>⊙</SUB> and T<SUB>eff</SUB> = 6099 ± 41 K. We
arrive at a consistent picture from these methods and compare the
results with those from the literature.
---------------------------------------------------------
Title: Redshift Measurement and Spectral Classification for eBOSS
Galaxies with the redmonster Software
Authors: Hutchinson, Timothy A.; Bolton, Adam S.; Dawson, Kyle
S.; Allende Prieto, Carlos; Bailey, Stephen; Bautista, Julian E.;
Brownstein, Joel R.; Conroy, Charlie; Guy, Julien; Myers, Adam D.;
Newman, Jeffrey A.; Prakash, Abhishek; Carnero-Rosell, Aurelio; Seo,
Hee-Jong; Tojeiro, Rita; Vivek, M.; Ben Zhu, Guangtun
2016AJ....152..205H Altcode: 2016arXiv160702432H
We describe the redmonster automated redshift measurement and spectral
classification software designed for the extended Baryon Oscillation
Spectroscopic Survey (eBOSS) of the Sloan Digital Sky Survey IV
(SDSS-IV). We describe the algorithms, the template standard and
requirements, and the newly developed galaxy templates to be used
on eBOSS spectra. We present results from testing on early data
from eBOSS, where we have found a 90.5% automated redshift and
spectral classification success rate for the luminous red galaxy
sample (redshifts 0.6 ≲ z ≲ 1.0). The redmonster performance
meets the eBOSS cosmology requirements for redshift classification
and catastrophic failures and represents a significant improvement
over the previous pipeline. We describe the empirical processes
used to determine the optimum number of additive polynomial terms
in our models and an acceptable {{Δ }}{χ }<SUB>r</SUB><SUP>2</SUP>
threshold for declaring statistical confidence. Statistical errors on
redshift measurement due to photon shot noise are assessed, and we find
typical values of a few tens of km s<SUP>-1</SUP>. An investigation of
redshift differences in repeat observations scaled by error estimates
yields a distribution with a Gaussian mean and standard deviation of
μ ∼ 0.01 and σ ∼ 0.65, respectively, suggesting the reported
statistical redshift uncertainties are over-estimated by ∼54%. We
assess the effects of object magnitude, signal-to-noise ratio, fiber
number, and fiber head location on the pipeline’s redshift success
rate. Finally, we describe directions of ongoing development.
---------------------------------------------------------
Title: The rotation-metallicity relation for the Galactic disk as
measured in the Gaia DR1 TGAS and APOGEE data
Authors: Allende Prieto, Carlos; Kawata, Daisuke; Cropper, Mark
2016A&A...596A..98A Altcode: 2016arXiv160907821A
<BR /> Aims: Previous studies have found that the Galactic rotation
velocity-metallicity (V-[Fe/H]) relations for the thin and thick disk
populations show negative and positive slopes, respectively. The
first Gaia data release includes the Tycho-Gaia Astrometric
Solution (TGAS) information, which we use to analyze the V-[Fe/H]
relation for a strictly selected sample with high enough astrometric
accuracy. We aim to present an explanation for the slopes of the
V-[Fe/H] relationship. <BR /> Methods: We have identified a sample
of stars with accurate Gaia TGAS data and SDSS APOGEE [α/Fe] and
[Fe/H] measurements. We measured the V-[Fe/H] relation for thin
and thick disk stars classified on the basis of their [α/Fe] and
[Fe/H] abundances. <BR /> Results: We find dV/ d [Fe/H] = -18 ± 2 km
s<SUP>-1</SUP> dex<SUP>-1</SUP> for stars in the thin disk and dV/ d
[Fe/H] = +23 ± 10 km s<SUP>-1</SUP> dex<SUP>-1</SUP> for thick disk
stars, and thus we confirm the different signs for the slopes. The
negative value of dV/d[Fe/H] for thin disk stars is consistent with
previous work, but the combination of TGAS and APOGEE data provides
higher precision, even though systematic errors could exceed ±5 km
s<SUP>-1</SUP> dex<SUP>-1</SUP>. Our average measurement of dV/d[Fe/H]
for local thick disk stars shows a somewhat flatter slope than in
previous studies, but we confirm a significant spread and a dependence
of the slope on the [α/Fe] ratio of the stars. Using a simple N-body
model, we demonstrate that the observed trends for the thick and thin
disk can be explained by the measured radial metallicity gradients
and the correlation between orbital eccentricity and metallicity in
the thick disk. <BR /> Conclusions: We conclude that the V-[Fe/H]
relation for thin disk stars is well determined from our TGAS-APOGEE
sample, and a direct consequence of the radial metallicity gradient
and the correlation between Galactic rotation and mean Galactocentric
distance. Stars formed farther away from the solar circle tend to
be near their orbital pericenter, showing larger velocities and on
average lower metallicities, while those closer to the Galactic center
are usually closer to their orbital apocenter, therefore moving slower
and with higher metallicities. The positive dV/d[Fe/H] for the thick
disk sample is likely connected to the correlation between orbital
eccentricity and metallicity for that population.
---------------------------------------------------------
Title: VizieR Online Data Catalog: H-band spectroscopic analysis of
25 bright M31 GCs (Sakari+, 2016)
Authors: Sakari, C. M.; Shetrone, M. D.; Schiavon, R. P.; Bizyaev, D.;
Allende Prieto, C.; Beers, T. C.; Caldwell, N.; Garcia-Hernandez,
D. A.; Lucatello, S.; Majewski, S.; O'Connell, R. W.; Pan, K.;
Strader, J.
2016yCat..18290116S Altcode:
H-band spectra (1.51-1.69um) of the target clusters were obtained with
the moderately high resolution (R=22500) APOGEE spectrograph on the 2.5m
Telescope at Apache Point Observatory in 2011 and 2013. The details
of the observations can be found in Majewski+ (2015arXiv150905420M)
and Zasowski+ (2013AJ....146...81Z), including descriptions of
the plates and fibers that were utilized for the observations. <P
/>The high-resolution optical abundances from Colucci et al. (2009,
J/ApJ/704/385 and 2014ApJ...797..116C) are supplemented with new
results for five globular clusters (GCs). The new optical spectra
were obtained in 2009 and 2010 with the High Resolution Spectrograph
on the Hobby-Eberly Telescope at McDonald Observatory in Fort Davis,
TX (R=30000; spectral coverage over ~5320-6290 and ~6360-7340Å in
the blue and the red, respectively). <P />(5 data files).
---------------------------------------------------------
Title: VizieR Online Data Catalog: Gaia-ESO Survey iDR4 calibrators
(Pancino+, 2017)
Authors: Pancino, E.; Lardo, C.; Altavilla, G.; Marinoni, S.; Ragaini,
S.; Cocozza, G.; Bellazzini, M.; Sabbi, E.; Zoccali, M.; Donati,
P.; Heiter, U.; Koposov, S. E.; Blomme, R.; Morel, T.; Simon-Diaz,
S.; Lobel, A.; Soubiran, C.; Montalban, J.; Valentini, M.; Casey,
A. R.; Blanco-Cuaresma, S.; Jofre, P.; Worley, C. C.; Magrini, L.;
Hourihane, A.; Francois, P.; Feltzing, S.; Gilmore, G.; Randich, S.;
Asplund, M.; Bonifacio, P.; Drew, J. E.; Jeffries, R. D.; Micela,
G.; Vallenari, A.; Alfaro, E. J.; Allende Prieto, C.; Babusiaux,
C.; Bensby, T.; Bragaglia, A.; Flaccomio, E.; Hambly, N.; Korn,
A. J.; Lanzafame, A. C.; Smiljanic, R.; van Eck, S.; Walton, N. A.;
Bayo, A.; Carraro, G.; Costado, M. T.; Damiani, F.; Edvardsson, B.;
Franciosini, E.; Frasca, A.; Lewis, J.; Monaco, L.; Morbidelli, L.;
Prisinzano, L.; Sacco, G. G.; Sbordone, L.; Sousa, S. G.; Zaggia,
S.; Koch, A.; Gaia-ESO Collaboration
2016yCat..35980005P Altcode:
List of GES iDR4 calibrators. It can be used to select the iDR4
calibrators from the upcoming ESO Phase 3 public release. The columns
contain: the GES unique identifier of each star (the CName), based on
the object sexagesimal coordinates; the calibration type, which can
be GC or OC for clusters, RV for radial velocity standards, BM for
benchmark stars, or CR for CoRoT targets; the field name; and the
2MASS J and K magnitudes, when available. <P />(1 data file).
---------------------------------------------------------
Title: Learning about stars from their colors
Authors: Allende Prieto, C.
2016A&A...595A.129A Altcode: 2016arXiv160908557A
<BR /> Aims: We pose the question of how much information on the
atmospheric parameters of late-type stars can be retrieved purely
from color information using standard photometric systems. <BR />
Methods: We carried out numerical experiments using stellar fluxes from
model atmospheres, injecting random noise before analyzing them. We
examined the presence of degeneracies among atmospheric parameters,
and evaluated how well the parameters are extracted depending on
the number and wavelength span of the photometric filters available,
from the UV GALEX to the mid-IR WISE passbands. We also considered
spectrophotometry from the Gaia mission. <BR /> Results: We find
that stellar effective temperatures can be determined accurately
(σ 0.01 dex or about 150 K) when reddening is negligible or known,
based merely on optical photometry, and the accuracy can be improved
twofold by including IR data. On the other hand, stellar metallicities
and surface gravities are fairly unconstrained from optical or IR
photometry: 1 dex for both parameters at low metallicity, and 0.5
dex for [Fe/H] and 1 dex for log g at high metallicity. However,
our ability to retrieve these parameters can improve significantly by
adding UV photometry. When reddening is considered a free parameter,
assuming it can be modeled perfectly, our experiments suggest that it
can be disentangled from the rest of the parameters. <BR /> Conclusions:
This theoretical study indicates that combining broad-band photometry
from the UV to the mid-IR allows atmospheric parameters and interstellar
extinction to be determined with fair accuracy, and that the results
are moderately robust to the presence of systematic imperfections in
our models of stellar spectral energy distributions (SEDs). The use
of UV passbands helps substantially to derive metallicities (down to
[Fe/H] -3) and surface gravities, as well as to break the degeneracy
between effective temperature and reddening. The Gaia BP/RP data can
disentangle all the parameters, provided the stellar SEDs are modeled
reasonably well.
---------------------------------------------------------
Title: Probing Seismic Solar Analogues Through Observations With The
NASA Kepler Space Telescope and Hermes High-Resolution Spectrograph
Authors: Beck, P. G.; Salabert, D.; Garcia, R. A.; do Nascimento, J.,
Jr.; Duarte, T. S. S.; Mathis, S.; Regulo, C.; Ballot, J.; Egeland,
R.; Castro, M.; Pérez-Herńandez, F.,; Creevey, O.; Tkachenko, A.;
van Reeth, T.; Bigot, L.; Corsaro, E.; Metcalfe, T.; Mathur, S.; Palle,
P. L.; Allende Prieto, C.; Montes, D.; Johnston, C.; Andersen, M. F.;
van Winckel, H.
2016csss.confE..42B Altcode: 2016arXiv161104329B
Stars similar to the Sun, known as solar analogues, provide an excellent
opportunity to study the preceding and following evolutionary phases of
our host star. The unprecedented quality of photometric data collected
by the Kepler NASA mission allows us to characterise solar-like stars
through asteroseismology and study diagnostics of stellar evolution,
such as variation of magnetic activity, rotation and the surface
lithium abundance. In this project, presented in a series of papers
by Salabert et al (2016ab) and Beck et al. (2016ab), we investigate
the link between stellar activity, rotation, lithium abundance and
oscillations in a group of 18 solar-analogue stars through space
photometry, obtained with the NASA Kepler space telescope and from
currently 50+ hours of ground-based, high-resolution spectroscopy
with the Hermes instrument. In these proceedings, we first discuss the
selection of the stars in the sample, observations and calibrations and
then summarise the main results of the project.<BR /> By investigating
the chromospheric and photospheric activity of the solar analogues in
this sample, it was shown that for a large fraction of these stars the
measured activity levels are compatible to levels of the 11-year solar
activity cycle 23. A clear correlation between the lithium abundance
and surface rotation was found for rotation periods shorter than the
solar value. Comparing the lithium abundance measured in the solar
analogues to evolutionary models with the Toulouse-Geneva Evolutionary
Code (TGEC), we found that the solar models calibrated to the Sun also
correctly describe the set of solar/stellar analogs showing that they
share the same internal mixing physics. Finally, the star KIC3241581
and KIC10644353 are discussed in more detail.
---------------------------------------------------------
Title: The Gaia mission
Authors: Gaia Collaboration; Prusti, T.; de Bruijne, J. H. J.; Brown,
A. G. A.; Vallenari, A.; Babusiaux, C.; Bailer-Jones, C. A. L.;
Bastian, U.; Biermann, M.; Evans, D. W.; Eyer, L.; Jansen, F.; Jordi,
C.; Klioner, S. A.; Lammers, U.; Lindegren, L.; Luri, X.; Mignard, F.;
Milligan, D. J.; Panem, C.; Poinsignon, V.; Pourbaix, D.; Randich, S.;
Sarri, G.; Sartoretti, P.; Siddiqui, H. I.; Soubiran, C.; Valette,
V.; van Leeuwen, F.; Walton, N. A.; Aerts, C.; Arenou, F.; Cropper,
M.; Drimmel, R.; Høg, E.; Katz, D.; Lattanzi, M. G.; O'Mullane, W.;
Grebel, E. K.; Holland, A. D.; Huc, C.; Passot, X.; Bramante, L.;
Cacciari, C.; Castañeda, J.; Chaoul, L.; Cheek, N.; De Angeli, F.;
Fabricius, C.; Guerra, R.; Hernández, J.; Jean-Antoine-Piccolo,
A.; Masana, E.; Messineo, R.; Mowlavi, N.; Nienartowicz, K.;
Ordóñez-Blanco, D.; Panuzzo, P.; Portell, J.; Richards, P. J.;
Riello, M.; Seabroke, G. M.; Tanga, P.; Thévenin, F.; Torra, J.;
Els, S. G.; Gracia-Abril, G.; Comoretto, G.; Garcia-Reinaldos, M.;
Lock, T.; Mercier, E.; Altmann, M.; Andrae, R.; Astraatmadja, T. L.;
Bellas-Velidis, I.; Benson, K.; Berthier, J.; Blomme, R.; Busso,
G.; Carry, B.; Cellino, A.; Clementini, G.; Cowell, S.; Creevey, O.;
Cuypers, J.; Davidson, M.; De Ridder, J.; de Torres, A.; Delchambre,
L.; Dell'Oro, A.; Ducourant, C.; Frémat, Y.; García-Torres, M.;
Gosset, E.; Halbwachs, J. -L.; Hambly, N. C.; Harrison, D. L.;
Hauser, M.; Hestroffer, D.; Hodgkin, S. T.; Huckle, H. E.; Hutton,
A.; Jasniewicz, G.; Jordan, S.; Kontizas, M.; Korn, A. J.; Lanzafame,
A. C.; Manteiga, M.; Moitinho, A.; Muinonen, K.; Osinde, J.; Pancino,
E.; Pauwels, T.; Petit, J. -M.; Recio-Blanco, A.; Robin, A. C.; Sarro,
L. M.; Siopis, C.; Smith, M.; Smith, K. W.; Sozzetti, A.; Thuillot,
W.; van Reeven, W.; Viala, Y.; Abbas, U.; Abreu Aramburu, A.; Accart,
S.; Aguado, J. J.; Allan, P. M.; Allasia, W.; Altavilla, G.; Álvarez,
M. A.; Alves, J.; Anderson, R. I.; Andrei, A. H.; Anglada Varela, E.;
Antiche, E.; Antoja, T.; Antón, S.; Arcay, B.; Atzei, A.; Ayache, L.;
Bach, N.; Baker, S. G.; Balaguer-Núñez, L.; Barache, C.; Barata,
C.; Barbier, A.; Barblan, F.; Baroni, M.; Barrado y Navascués, D.;
Barros, M.; Barstow, M. A.; Becciani, U.; Bellazzini, M.; Bellei, G.;
Bello García, A.; Belokurov, V.; Bendjoya, P.; Berihuete, A.; Bianchi,
L.; Bienaymé, O.; Billebaud, F.; Blagorodnova, N.; Blanco-Cuaresma,
S.; Boch, T.; Bombrun, A.; Borrachero, R.; Bouquillon, S.; Bourda, G.;
Bouy, H.; Bragaglia, A.; Breddels, M. A.; Brouillet, N.; Brüsemeister,
T.; Bucciarelli, B.; Budnik, F.; Burgess, P.; Burgon, R.; Burlacu,
A.; Busonero, D.; Buzzi, R.; Caffau, E.; Cambras, J.; Campbell, H.;
Cancelliere, R.; Cantat-Gaudin, T.; Carlucci, T.; Carrasco, J. M.;
Castellani, M.; Charlot, P.; Charnas, J.; Charvet, P.; Chassat, F.;
Chiavassa, A.; Clotet, M.; Cocozza, G.; Collins, R. S.; Collins, P.;
Costigan, G.; Crifo, F.; Cross, N. J. G.; Crosta, M.; Crowley, C.;
Dafonte, C.; Damerdji, Y.; Dapergolas, A.; David, P.; David, M.; De
Cat, P.; de Felice, F.; de Laverny, P.; De Luise, F.; De March, R.;
de Martino, D.; de Souza, R.; Debosscher, J.; del Pozo, E.; Delbo, M.;
Delgado, A.; Delgado, H. E.; di Marco, F.; Di Matteo, P.; Diakite, S.;
Distefano, E.; Dolding, C.; Dos Anjos, S.; Drazinos, P.; Durán, J.;
Dzigan, Y.; Ecale, E.; Edvardsson, B.; Enke, H.; Erdmann, M.; Escolar,
D.; Espina, M.; Evans, N. W.; Eynard Bontemps, G.; Fabre, C.; Fabrizio,
M.; Faigler, S.; Falcão, A. J.; Farràs Casas, M.; Faye, F.; Federici,
L.; Fedorets, G.; Fernández-Hernández, J.; Fernique, P.; Fienga, A.;
Figueras, F.; Filippi, F.; Findeisen, K.; Fonti, A.; Fouesneau, M.;
Fraile, E.; Fraser, M.; Fuchs, J.; Furnell, R.; Gai, M.; Galleti, S.;
Galluccio, L.; Garabato, D.; García-Sedano, F.; Garé, P.; Garofalo,
A.; Garralda, N.; Gavras, P.; Gerssen, J.; Geyer, R.; Gilmore,
G.; Girona, S.; Giuffrida, G.; Gomes, M.; González-Marcos, A.;
González-Núñez, J.; González-Vidal, J. J.; Granvik, M.; Guerrier,
A.; Guillout, P.; Guiraud, J.; Gúrpide, A.; Gutiérrez-Sánchez,
R.; Guy, L. P.; Haigron, R.; Hatzidimitriou, D.; Haywood, M.; Heiter,
U.; Helmi, A.; Hobbs, D.; Hofmann, W.; Holl, B.; Holland, G.; Hunt,
J. A. S.; Hypki, A.; Icardi, V.; Irwin, M.; Jevardat de Fombelle,
G.; Jofré, P.; Jonker, P. G.; Jorissen, A.; Julbe, F.; Karampelas,
A.; Kochoska, A.; Kohley, R.; Kolenberg, K.; Kontizas, E.; Koposov,
S. E.; Kordopatis, G.; Koubsky, P.; Kowalczyk, A.; Krone-Martins, A.;
Kudryashova, M.; Kull, I.; Bachchan, R. K.; Lacoste-Seris, F.; Lanza,
A. F.; Lavigne, J. -B.; Le Poncin-Lafitte, C.; Lebreton, Y.; Lebzelter,
T.; Leccia, S.; Leclerc, N.; Lecoeur-Taibi, I.; Lemaitre, V.; Lenhardt,
H.; Leroux, F.; Liao, S.; Licata, E.; Lindstrøm, H. E. P.; Lister,
T. A.; Livanou, E.; Lobel, A.; Löffler, W.; López, M.; Lopez-Lozano,
A.; Lorenz, D.; Loureiro, T.; MacDonald, I.; Magalhães Fernandes, T.;
Managau, S.; Mann, R. G.; Mantelet, G.; Marchal, O.; Marchant, J. M.;
Marconi, M.; Marie, J.; Marinoni, S.; Marrese, P. M.; Marschalkó,
G.; Marshall, D. J.; Martín-Fleitas, J. M.; Martino, M.; Mary, N.;
Matijevič, G.; Mazeh, T.; McMillan, P. J.; Messina, S.; Mestre, A.;
Michalik, D.; Millar, N. R.; Miranda, B. M. H.; Molina, D.; Molinaro,
R.; Molinaro, M.; Molnár, L.; Moniez, M.; Montegriffo, P.; Monteiro,
D.; Mor, R.; Mora, A.; Morbidelli, R.; Morel, T.; Morgenthaler, S.;
Morley, T.; Morris, D.; Mulone, A. F.; Muraveva, T.; Musella, I.;
Narbonne, J.; Nelemans, G.; Nicastro, L.; Noval, L.; Ordénovic, C.;
Ordieres-Meré, J.; Osborne, P.; Pagani, C.; Pagano, I.; Pailler, F.;
Palacin, H.; Palaversa, L.; Parsons, P.; Paulsen, T.; Pecoraro, M.;
Pedrosa, R.; Pentikäinen, H.; Pereira, J.; Pichon, B.; Piersimoni,
A. M.; Pineau, F. -X.; Plachy, E.; Plum, G.; Poujoulet, E.; Prša,
A.; Pulone, L.; Ragaini, S.; Rago, S.; Rambaux, N.; Ramos-Lerate,
M.; Ranalli, P.; Rauw, G.; Read, A.; Regibo, S.; Renk, F.; Reylé,
C.; Ribeiro, R. A.; Rimoldini, L.; Ripepi, V.; Riva, A.; Rixon, G.;
Roelens, M.; Romero-Gómez, M.; Rowell, N.; Royer, F.; Rudolph, A.;
Ruiz-Dern, L.; Sadowski, G.; Sagristà Sellés, T.; Sahlmann, J.;
Salgado, J.; Salguero, E.; Sarasso, M.; Savietto, H.; Schnorhk, A.;
Schultheis, M.; Sciacca, E.; Segol, M.; Segovia, J. C.; Segransan,
D.; Serpell, E.; Shih, I. -C.; Smareglia, R.; Smart, R. L.; Smith,
C.; Solano, E.; Solitro, F.; Sordo, R.; Soria Nieto, S.; Souchay, J.;
Spagna, A.; Spoto, F.; Stampa, U.; Steele, I. A.; Steidelmüller, H.;
Stephenson, C. A.; Stoev, H.; Suess, F. F.; Süveges, M.; Surdej, J.;
Szabados, L.; Szegedi-Elek, E.; Tapiador, D.; Taris, F.; Tauran, G.;
Taylor, M. B.; Teixeira, R.; Terrett, D.; Tingley, B.; Trager, S. C.;
Turon, C.; Ulla, A.; Utrilla, E.; Valentini, G.; van Elteren, A.; Van
Hemelryck, E.; van Leeuwen, M.; Varadi, M.; Vecchiato, A.; Veljanoski,
J.; Via, T.; Vicente, D.; Vogt, S.; Voss, H.; Votruba, V.; Voutsinas,
S.; Walmsley, G.; Weiler, M.; Weingrill, K.; Werner, D.; Wevers, T.;
Whitehead, G.; Wyrzykowski, Ł.; Yoldas, A.; Žerjal, M.; Zucker, S.;
Zurbach, C.; Zwitter, T.; Alecu, A.; Allen, M.; Allende Prieto, C.;
Amorim, A.; Anglada-Escudé, G.; Arsenijevic, V.; Azaz, S.; Balm,
P.; Beck, M.; Bernstein, H. -H.; Bigot, L.; Bijaoui, A.; Blasco,
C.; Bonfigli, M.; Bono, G.; Boudreault, S.; Bressan, A.; Brown, S.;
Brunet, P. -M.; Bunclark, P.; Buonanno, R.; Butkevich, A. G.; Carret,
C.; Carrion, C.; Chemin, L.; Chéreau, F.; Corcione, L.; Darmigny,
E.; de Boer, K. S.; de Teodoro, P.; de Zeeuw, P. T.; Delle Luche,
C.; Domingues, C. D.; Dubath, P.; Fodor, F.; Frézouls, B.; Fries,
A.; Fustes, D.; Fyfe, D.; Gallardo, E.; Gallegos, J.; Gardiol, D.;
Gebran, M.; Gomboc, A.; Gómez, A.; Grux, E.; Gueguen, A.; Heyrovsky,
A.; Hoar, J.; Iannicola, G.; Isasi Parache, Y.; Janotto, A. -M.;
Joliet, E.; Jonckheere, A.; Keil, R.; Kim, D. -W.; Klagyivik, P.;
Klar, J.; Knude, J.; Kochukhov, O.; Kolka, I.; Kos, J.; Kutka, A.;
Lainey, V.; LeBouquin, D.; Liu, C.; Loreggia, D.; Makarov, V. V.;
Marseille, M. G.; Martayan, C.; Martinez-Rubi, O.; Massart, B.;
Meynadier, F.; Mignot, S.; Munari, U.; Nguyen, A. -T.; Nordlander,
T.; Ocvirk, P.; O'Flaherty, K. S.; Olias Sanz, A.; Ortiz, P.; Osorio,
J.; Oszkiewicz, D.; Ouzounis, A.; Palmer, M.; Park, P.; Pasquato, E.;
Peltzer, C.; Peralta, J.; Péturaud, F.; Pieniluoma, T.; Pigozzi, E.;
Poels, J.; Prat, G.; Prod'homme, T.; Raison, F.; Rebordao, J. M.;
Risquez, D.; Rocca-Volmerange, B.; Rosen, S.; Ruiz-Fuertes, M. I.;
Russo, F.; Sembay, S.; Serraller Vizcaino, I.; Short, A.; Siebert,
A.; Silva, H.; Sinachopoulos, D.; Slezak, E.; Soffel, M.; Sosnowska,
D.; Straižys, V.; ter Linden, M.; Terrell, D.; Theil, S.; Tiede,
C.; Troisi, L.; Tsalmantza, P.; Tur, D.; Vaccari, M.; Vachier, F.;
Valles, P.; Van Hamme, W.; Veltz, L.; Virtanen, J.; Wallut, J. -M.;
Wichmann, R.; Wilkinson, M. I.; Ziaeepour, H.; Zschocke, S.
2016A&A...595A...1G Altcode: 2016arXiv160904153G
Gaia is a cornerstone mission in the science programme of the
EuropeanSpace Agency (ESA). The spacecraft construction was approved
in 2006, following a study in which the original interferometric
concept was changed to a direct-imaging approach. Both the spacecraft
and the payload were built by European industry. The involvement
of the scientific community focusses on data processing for which
the international Gaia Data Processing and Analysis Consortium
(DPAC) was selected in 2007. Gaia was launched on 19 December 2013
and arrived at its operating point, the second Lagrange point of
the Sun-Earth-Moon system, a few weeks later. The commissioning
of the spacecraft and payload was completed on 19 July 2014. The
nominal five-year mission started with four weeks of special,
ecliptic-pole scanning and subsequently transferred into full-sky
scanning mode. We recall the scientific goals of Gaia and give a
description of the as-built spacecraft that is currently (mid-2016)
being operated to achieve these goals. We pay special attention to
the payload module, the performance of which is closely related to
the scientific performance of the mission. We provide a summary of
the commissioning activities and findings, followed by a description
of the routine operational mode. We summarise scientific performance
estimates on the basis of in-orbit operations. Several intermediate
Gaia data releases are planned and the data can be retrieved from the
Gaia Archive, which is available through the Gaia home page. <P /><A
href="http://www.cosmos.esa.int/gaia">http://www.cosmos.esa.int/gaia</A>
---------------------------------------------------------
Title: Gaia Data Release 1. Summary of the astrometric, photometric,
and survey properties
Authors: Gaia Collaboration; Brown, A. G. A.; Vallenari, A.; Prusti,
T.; de Bruijne, J. H. J.; Mignard, F.; Drimmel, R.; Babusiaux, C.;
Bailer-Jones, C. A. L.; Bastian, U.; Biermann, M.; Evans, D. W.;
Eyer, L.; Jansen, F.; Jordi, C.; Katz, D.; Klioner, S. A.; Lammers,
U.; Lindegren, L.; Luri, X.; O'Mullane, W.; Panem, C.; Pourbaix, D.;
Randich, S.; Sartoretti, P.; Siddiqui, H. I.; Soubiran, C.; Valette,
V.; van Leeuwen, F.; Walton, N. A.; Aerts, C.; Arenou, F.; Cropper,
M.; Høg, E.; Lattanzi, M. G.; Grebel, E. K.; Holland, A. D.; Huc,
C.; Passot, X.; Perryman, M.; Bramante, L.; Cacciari, C.; Castañeda,
J.; Chaoul, L.; Cheek, N.; De Angeli, F.; Fabricius, C.; Guerra, R.;
Hernández, J.; Jean-Antoine-Piccolo, A.; Masana, E.; Messineo, R.;
Mowlavi, N.; Nienartowicz, K.; Ordóñez-Blanco, D.; Panuzzo, P.;
Portell, J.; Richards, P. J.; Riello, M.; Seabroke, G. M.; Tanga, P.;
Thévenin, F.; Torra, J.; Els, S. G.; Gracia-Abril, G.; Comoretto,
G.; Garcia-Reinaldos, M.; Lock, T.; Mercier, E.; Altmann, M.; Andrae,
R.; Astraatmadja, T. L.; Bellas-Velidis, I.; Benson, K.; Berthier,
J.; Blomme, R.; Busso, G.; Carry, B.; Cellino, A.; Clementini, G.;
Cowell, S.; Creevey, O.; Cuypers, J.; Davidson, M.; De Ridder, J.;
de Torres, A.; Delchambre, L.; Dell'Oro, A.; Ducourant, C.; Frémat,
Y.; García-Torres, M.; Gosset, E.; Halbwachs, J. -L.; Hambly, N. C.;
Harrison, D. L.; Hauser, M.; Hestroffer, D.; Hodgkin, S. T.; Huckle,
H. E.; Hutton, A.; Jasniewicz, G.; Jordan, S.; Kontizas, M.; Korn,
A. J.; Lanzafame, A. C.; Manteiga, M.; Moitinho, A.; Muinonen, K.;
Osinde, J.; Pancino, E.; Pauwels, T.; Petit, J. -M.; Recio-Blanco,
A.; Robin, A. C.; Sarro, L. M.; Siopis, C.; Smith, M.; Smith, K. W.;
Sozzetti, A.; Thuillot, W.; van Reeven, W.; Viala, Y.; Abbas, U.;
Abreu Aramburu, A.; Accart, S.; Aguado, J. J.; Allan, P. M.; Allasia,
W.; Altavilla, G.; Álvarez, M. A.; Alves, J.; Anderson, R. I.; Andrei,
A. H.; Anglada Varela, E.; Antiche, E.; Antoja, T.; Antón, S.; Arcay,
B.; Bach, N.; Baker, S. G.; Balaguer-Núñez, L.; Barache, C.; Barata,
C.; Barbier, A.; Barblan, F.; Barrado y Navascués, D.; Barros, M.;
Barstow, M. A.; Becciani, U.; Bellazzini, M.; Bello García, A.;
Belokurov, V.; Bendjoya, P.; Berihuete, A.; Bianchi, L.; Bienaymé,
O.; Billebaud, F.; Blagorodnova, N.; Blanco-Cuaresma, S.; Boch, T.;
Bombrun, A.; Borrachero, R.; Bouquillon, S.; Bourda, G.; Bouy, H.;
Bragaglia, A.; Breddels, M. A.; Brouillet, N.; Brüsemeister, T.;
Bucciarelli, B.; Burgess, P.; Burgon, R.; Burlacu, A.; Busonero, D.;
Buzzi, R.; Caffau, E.; Cambras, J.; Campbell, H.; Cancelliere, R.;
Cantat-Gaudin, T.; Carlucci, T.; Carrasco, J. M.; Castellani, M.;
Charlot, P.; Charnas, J.; Chiavassa, A.; Clotet, M.; Cocozza, G.;
Collins, R. S.; Costigan, G.; Crifo, F.; Cross, N. J. G.; Crosta, M.;
Crowley, C.; Dafonte, C.; Damerdji, Y.; Dapergolas, A.; David, P.;
David, M.; De Cat, P.; de Felice, F.; de Laverny, P.; De Luise, F.;
De March, R.; de Martino, D.; de Souza, R.; Debosscher, J.; del Pozo,
E.; Delbo, M.; Delgado, A.; Delgado, H. E.; Di Matteo, P.; Diakite, S.;
Distefano, E.; Dolding, C.; Dos Anjos, S.; Drazinos, P.; Duran, J.;
Dzigan, Y.; Edvardsson, B.; Enke, H.; Evans, N. W.; Eynard Bontemps,
G.; Fabre, C.; Fabrizio, M.; Faigler, S.; Falcão, A. J.; Farràs
Casas, M.; Federici, L.; Fedorets, G.; Fernández-Hernández, J.;
Fernique, P.; Fienga, A.; Figueras, F.; Filippi, F.; Findeisen, K.;
Fonti, A.; Fouesneau, M.; Fraile, E.; Fraser, M.; Fuchs, J.; Gai, M.;
Galleti, S.; Galluccio, L.; Garabato, D.; García-Sedano, F.; Garofalo,
A.; Garralda, N.; Gavras, P.; Gerssen, J.; Geyer, R.; Gilmore,
G.; Girona, S.; Giuffrida, G.; Gomes, M.; González-Marcos, A.;
González-Núñez, J.; González-Vidal, J. J.; Granvik, M.; Guerrier,
A.; Guillout, P.; Guiraud, J.; Gúrpide, A.; Gutiérrez-Sánchez,
R.; Guy, L. P.; Haigron, R.; Hatzidimitriou, D.; Haywood, M.; Heiter,
U.; Helmi, A.; Hobbs, D.; Hofmann, W.; Holl, B.; Holland, G.; Hunt,
J. A. S.; Hypki, A.; Icardi, V.; Irwin, M.; Jevardat de Fombelle,
G.; Jofré, P.; Jonker, P. G.; Jorissen, A.; Julbe, F.; Karampelas,
A.; Kochoska, A.; Kohley, R.; Kolenberg, K.; Kontizas, E.; Koposov,
S. E.; Kordopatis, G.; Koubsky, P.; Krone-Martins, A.; Kudryashova, M.;
Kull, I.; Bachchan, R. K.; Lacoste-Seris, F.; Lanza, A. F.; Lavigne,
J. -B.; Le Poncin-Lafitte, C.; Lebreton, Y.; Lebzelter, T.; Leccia, S.;
Leclerc, N.; Lecoeur-Taibi, I.; Lemaitre, V.; Lenhardt, H.; Leroux, F.;
Liao, S.; Licata, E.; Lindstrøm, H. E. P.; Lister, T. A.; Livanou,
E.; Lobel, A.; Löffler, W.; López, M.; Lorenz, D.; MacDonald, I.;
Magalhães Fernandes, T.; Managau, S.; Mann, R. G.; Mantelet, G.;
Marchal, O.; Marchant, J. M.; Marconi, M.; Marinoni, S.; Marrese,
P. M.; Marschalkó, G.; Marshall, D. J.; Martín-Fleitas, J. M.;
Martino, M.; Mary, N.; Matijevič, G.; Mazeh, T.; McMillan, P. J.;
Messina, S.; Michalik, D.; Millar, N. R.; Miranda, B. M. H.; Molina,
D.; Molinaro, R.; Molinaro, M.; Molnár, L.; Moniez, M.; Montegriffo,
P.; Mor, R.; Mora, A.; Morbidelli, R.; Morel, T.; Morgenthaler, S.;
Morris, D.; Mulone, A. F.; Muraveva, T.; Musella, I.; Narbonne, J.;
Nelemans, G.; Nicastro, L.; Noval, L.; Ordénovic, C.; Ordieres-Meré,
J.; Osborne, P.; Pagani, C.; Pagano, I.; Pailler, F.; Palacin, H.;
Palaversa, L.; Parsons, P.; Pecoraro, M.; Pedrosa, R.; Pentikäinen,
H.; Pichon, B.; Piersimoni, A. M.; Pineau, F. -X.; Plachy, E.;
Plum, G.; Poujoulet, E.; Prša, A.; Pulone, L.; Ragaini, S.; Rago,
S.; Rambaux, N.; Ramos-Lerate, M.; Ranalli, P.; Rauw, G.; Read, A.;
Regibo, S.; Reylé, C.; Ribeiro, R. A.; Rimoldini, L.; Ripepi, V.;
Riva, A.; Rixon, G.; Roelens, M.; Romero-Gómez, M.; Rowell, N.; Royer,
F.; Ruiz-Dern, L.; Sadowski, G.; Sagristà Sellés, T.; Sahlmann, J.;
Salgado, J.; Salguero, E.; Sarasso, M.; Savietto, H.; Schultheis, M.;
Sciacca, E.; Segol, M.; Segovia, J. C.; Segransan, D.; Shih, I. -C.;
Smareglia, R.; Smart, R. L.; Solano, E.; Solitro, F.; Sordo, R.;
Soria Nieto, S.; Souchay, J.; Spagna, A.; Spoto, F.; Stampa, U.;
Steele, I. A.; Steidelmüller, H.; Stephenson, C. A.; Stoev, H.;
Suess, F. F.; Süveges, M.; Surdej, J.; Szabados, L.; Szegedi-Elek,
E.; Tapiador, D.; Taris, F.; Tauran, G.; Taylor, M. B.; Teixeira, R.;
Terrett, D.; Tingley, B.; Trager, S. C.; Turon, C.; Ulla, A.; Utrilla,
E.; Valentini, G.; van Elteren, A.; Van Hemelryck, E.; van Leeuwen,
M.; Varadi, M.; Vecchiato, A.; Veljanoski, J.; Via, T.; Vicente, D.;
Vogt, S.; Voss, H.; Votruba, V.; Voutsinas, S.; Walmsley, G.; Weiler,
M.; Weingrill, K.; Wevers, T.; Wyrzykowski, Ł.; Yoldas, A.; Žerjal,
M.; Zucker, S.; Zurbach, C.; Zwitter, T.; Alecu, A.; Allen, M.; Allende
Prieto, C.; Amorim, A.; Anglada-Escudé, G.; Arsenijevic, V.; Azaz, S.;
Balm, P.; Beck, M.; Bernstein, H. -H.; Bigot, L.; Bijaoui, A.; Blasco,
C.; Bonfigli, M.; Bono, G.; Boudreault, S.; Bressan, A.; Brown, S.;
Brunet, P. -M.; Bunclark, P.; Buonanno, R.; Butkevich, A. G.; Carret,
C.; Carrion, C.; Chemin, L.; Chéreau, F.; Corcione, L.; Darmigny,
E.; de Boer, K. S.; de Teodoro, P.; de Zeeuw, P. T.; Delle Luche,
C.; Domingues, C. D.; Dubath, P.; Fodor, F.; Frézouls, B.; Fries,
A.; Fustes, D.; Fyfe, D.; Gallardo, E.; Gallegos, J.; Gardiol, D.;
Gebran, M.; Gomboc, A.; Gómez, A.; Grux, E.; Gueguen, A.; Heyrovsky,
A.; Hoar, J.; Iannicola, G.; Isasi Parache, Y.; Janotto, A. -M.;
Joliet, E.; Jonckheere, A.; Keil, R.; Kim, D. -W.; Klagyivik, P.;
Klar, J.; Knude, J.; Kochukhov, O.; Kolka, I.; Kos, J.; Kutka, A.;
Lainey, V.; LeBouquin, D.; Liu, C.; Loreggia, D.; Makarov, V. V.;
Marseille, M. G.; Martayan, C.; Martinez-Rubi, O.; Massart, B.;
Meynadier, F.; Mignot, S.; Munari, U.; Nguyen, A. -T.; Nordlander,
T.; Ocvirk, P.; O'Flaherty, K. S.; Olias Sanz, A.; Ortiz, P.; Osorio,
J.; Oszkiewicz, D.; Ouzounis, A.; Palmer, M.; Park, P.; Pasquato, E.;
Peltzer, C.; Peralta, J.; Péturaud, F.; Pieniluoma, T.; Pigozzi, E.;
Poels, J.; Prat, G.; Prod'homme, T.; Raison, F.; Rebordao, J. M.;
Risquez, D.; Rocca-Volmerange, B.; Rosen, S.; Ruiz-Fuertes, M. I.;
Russo, F.; Sembay, S.; Serraller Vizcaino, I.; Short, A.; Siebert,
A.; Silva, H.; Sinachopoulos, D.; Slezak, E.; Soffel, M.; Sosnowska,
D.; Straižys, V.; ter Linden, M.; Terrell, D.; Theil, S.; Tiede,
C.; Troisi, L.; Tsalmantza, P.; Tur, D.; Vaccari, M.; Vachier, F.;
Valles, P.; Van Hamme, W.; Veltz, L.; Virtanen, J.; Wallut, J. -M.;
Wichmann, R.; Wilkinson, M. I.; Ziaeepour, H.; Zschocke, S.
2016A&A...595A...2G Altcode: 2016arXiv160904172G
Context. At about 1000 days after the launch of Gaia we present
the first Gaia data release, Gaia DR1, consisting of astrometry and
photometry for over 1 billion sources brighter than magnitude 20.7. <BR
/> Aims: A summary of Gaia DR1 is presented along with illustrations
of the scientific quality of the data, followed by a discussion of
the limitations due to the preliminary nature of this release. <BR />
Methods: The raw data collected by Gaia during the first 14 months of
the mission have been processed by the Gaia Data Processing and Analysis
Consortium (DPAC) and turned into an astrometric and photometric
catalogue. <BR /> Results: Gaia DR1 consists of three components: a
primary astrometric data set which contains the positions, parallaxes,
and mean proper motions for about 2 million of the brightest stars
in common with the Hipparcos and Tycho-2 catalogues - a realisation
of the Tycho-Gaia Astrometric Solution (TGAS) - and a secondary
astrometric data set containing the positions for an additional 1.1
billion sources. The second component is the photometric data set,
consisting of mean G-band magnitudes for all sources. The G-band light
curves and the characteristics of 3000 Cepheid and RR Lyrae stars,
observed at high cadence around the south ecliptic pole, form the third
component. For the primary astrometric data set the typical uncertainty
is about 0.3 mas for the positions and parallaxes, and about 1 mas
yr<SUP>-1</SUP> for the proper motions. A systematic component of 0.3
mas should be added to the parallax uncertainties. For the subset of
94 000 Hipparcos stars in the primary data set, the proper motions are
much more precise at about 0.06 mas yr<SUP>-1</SUP>. For the secondary
astrometric data set, the typical uncertainty of the positions is 10
mas. The median uncertainties on the mean G-band magnitudes range from
the mmag level to 0.03 mag over the magnitude range 5 to 20.7. <BR />
Conclusions: Gaia DR1 is an important milestone ahead of the next Gaia
data release, which will feature five-parameter astrometry for all
sources. Extensive validation shows that Gaia DR1 represents a major
advance in the mapping of the heavens and the availability of basic
stellar data that underpin observational astrophysics. Nevertheless,
the very preliminary nature of this first Gaia data release does lead
to a number of important limitations to the data quality which should
be carefully considered before drawing conclusions from the data.
---------------------------------------------------------
Title: The Open Cluster Chemical Abundances from Spanish Observatories
Survey (OCCASO)
Authors: Carrera, R.; Casamiquela, L.; Balaguer-Núñez, L.;
Jordi, C.; Pancino, E.; Allende-Prieto, C.; Blanco-Cuaresma, S.;
Martínez-Vázquez, C. E.; Murabito, S.; del Pino, A.; Aparicio, A.;
Gallart, C.; Recio-Blanco, A.
2016ASPC..507..171C Altcode:
We present the motivation, design and current status of the Open Cluster
Chemical Abundances from Spanish Observatories survey (OCCASO). Using
the high resolution spectroscopic facilities available at Spanish
observatories, OCCASO will derive chemical abundances in a sample of
20 to 25 OCs older than 0.5 Gyr. This sample will be used to study
in detail the formation and evolution of the Galactic disk using OCs
as tracers.
---------------------------------------------------------
Title: Infrared High-resolution Integrated Light Spectral Analyses
of M31 Globular Clusters from APOGEE
Authors: Sakari, Charli M.; Shetrone, Matthew D.; Schiavon, Ricardo P.;
Bizyaev, Dmitry; Allende Prieto, Carlos; Beers, Timothy C.; Caldwell,
Nelson; García-Hernández, D. A.; Lucatello, Sara; Majewski, Steven;
O'Connell, Robert W.; Pan, Kaike; Strader, Jay
2016ApJ...829..116S Altcode: 2016arXiv160706811S
Chemical abundances are presented for 25 M31 globular clusters (GCs),
based on moderately high resolution (R = 22,500) H-band integrated light
(IL) spectra from the Apache Point Observatory Galactic Evolution
Experiment (APOGEE). Infrared (IR) spectra offer lines from new
elements, lines of different strengths, and lines at higher excitation
potentials compared to the optical. Integrated abundances of C, N,
and O are derived from CO, CN, and OH molecular features, while Fe,
Na, Mg, Al, Si, K, Ca, and Ti abundances are derived from atomic
features. These abundances are compared to previous results from the
optical, demonstrating the validity and value of IR IL analyses. The
CNO abundances are consistent with typical tip of the red giant branch
stellar abundances but are systematically offset from optical Lick
index abundances. With a few exceptions, the other abundances agree
between the optical and the IR within the 1σ uncertainties. The first
integrated K abundances are also presented and demonstrate that K
tracks the α elements. The combination of IR and optical abundances
allows better determinations of GC properties and enables probes
of the multiple populations in extragalactic GCs. In particular,
the integrated effects of the Na/O anticorrelation can be directly
examined for the first time.
---------------------------------------------------------
Title: On the estimation of stellar parameters with uncertainty
prediction from Generative Artificial Neural Networks: application
to Gaia RVS simulated spectra
Authors: Dafonte, C.; Fustes, D.; Manteiga, M.; Garabato, D.; Álvarez,
M. A.; Ulla, A.; Allende Prieto, C.
2016A&A...594A..68D Altcode: 2016arXiv160705954D
<BR /> Aims: We present an innovative artificial neural network (ANN)
architecture, called Generative ANN (GANN), that computes the forward
model, that is it learns the function that relates the unknown outputs
(stellar atmospheric parameters, in this case) to the given inputs
(spectra). Such a model can be integrated in a Bayesian framework to
estimate the posterior distribution of the outputs. <BR /> Methods:
The architecture of the GANN follows the same scheme as a normal ANN,
but with the inputs and outputs inverted. We train the network with
the set of atmospheric parameters (T<SUB>eff</SUB>, log g, [Fe/H]
and [α/ Fe]), obtaining the stellar spectra for such inputs. The
residuals between the spectra in the grid and the estimated spectra
are minimized using a validation dataset to keep solutions as general
as possible. <BR /> Results: The performance of both conventional
ANNs and GANNs to estimate the stellar parameters as a function of
the star brightness is presented and compared for different Galactic
populations. GANNs provide significantly improved parameterizations
for early and intermediate spectral types with rich and intermediate
metallicities. The behaviour of both algorithms is very similar for
our sample of late-type stars, obtaining residuals in the derivation
of [Fe/H] and [α/ Fe] below 0.1 dex for stars with Gaia magnitude
G<SUB>rvs</SUB> < 12, which accounts for a number in the order of
four million stars to be observed by the Radial Velocity Spectrograph
of the Gaia satellite. <BR /> Conclusions: Uncertainty estimation of
computed astrophysical parameters is crucial for the validation of the
parameterization itself and for the subsequent exploitation by the
astronomical community. GANNs produce not only the parameters for a
given spectrum, but a goodness-of-fit between the observed spectrum and
the predicted one for a given set of parameters. Moreover, they allow
us to obtain the full posterior distribution over the astrophysical
parameters space once a noise model is assumed. This can be used for
novelty detection and quality assessment.
---------------------------------------------------------
Title: Chemical Abundances in a Sample of Red Giants in the Open
Cluster NGC 2420 from APOGEE
Authors: Souto, Diogo; Cunha, K.; Smith, V.; Allende Prieto, C.;
Pinsonneault, M.; Zamora, O.; García-Hernández, D. A.; Mészáros,
Sz.; Bovy, J.; García Pérez, A. E.; Anders, F.; Bizyaev, D.; Carrera,
R.; Frinchaboy, P. M.; Holtzman, J.; Ivans, I.; Majewski, S. R.;
Shetrone, M.; Sobeck, J.; Pan, K.; Tang, B.; Villanova, S.; Geisler, D.
2016ApJ...830...35S Altcode: 2016arXiv160706102S
NGC 2420 is a ∼2 Gyr old well-populated open cluster that lies
about 2 kpc beyond the solar circle, in the general direction of
the Galactic anti-center. Most previous abundance studies have found
this cluster to be mildly metal-poor, but with a large scatter in the
obtained metallicities. Detailed chemical abundance distributions are
derived for 12 red-giant members of NGC 2420 via a manual abundance
analysis of high-resolution (R = 22,500) near-infrared (λ1.5-1.7 μm)
spectra obtained from the Apache Point Observatory Galactic Evolution
Experiment (APOGEE) survey. The sample analyzed contains six stars
that are identified as members of the first-ascent red giant branch
(RGB), as well as six members of the red clump (RC). We find small
scatter in the star-to-star abundances in NGC 2420, with a mean
cluster abundance of [Fe/H] = -0.16 ± 0.04 for the 12 red giants. The
internal abundance dispersion for all elements (C, N, O, Na, Mg, Al,
Si, K, Ca, Ti, V, Cr, Mn, Co and Ni) is also very small (∼0.03-0.06
dex), indicating a uniform cluster abundance distribution within the
uncertainties. NGC 2420 is one of the clusters used to calibrate the
APOGEE Stellar Parameter and Chemical Abundance Pipeline (ASPCAP). The
results from this manual analysis compare well with ASPCAP abundances
for most of the elements studied, although for Na, Al, and V there
are more significant offsets. No evidence of extra-mixing at the RGB
luminosity bump is found in the <SUP>12</SUP>C and <SUP>14</SUP>N
abundances from the pre-luminosity-bump RGB stars in comparison to
the post-He core-flash RC stars.
---------------------------------------------------------
Title: NLTE Analysis of High Resolution H-band Spectra. I. Neutral
Silicon
Authors: Zhang, Junbo; Shi, Jianrong; Pan, Kaike; Allende Prieto,
Carlos; Liu, Chao
2016arXiv161005888Z Altcode:
We investigated the reliability of our silicon atomic model and
the influence of non-local thermodynamical equilibrium (NLTE) on
the formation of neutral silicon (Si I) lines in the near-infrared
(near-IR) H-band. We derived the differential Si abundances for 13
sample stars with high-resolution H-band spectra from the Apache
Point Observatory Galactic Evolution Experiment (APOGEE), as well as
from optical spectra, both under local thermodynamical equilibrium
(LTE) and NLTE conditions. We found that the differences between the
Si abundances derived from the H-band and from optical lines for the
same stars are less than 0.1 dex when the NLTE effects included, and
that NLTE reduces the line-to-line scatter in the H-band spectra for
most sample stars. These results suggest that our Si atomic model
is appropriate for studying the formation of H-band Si lines. Our
calculations show that the NLTE corrections of the Si I H-band lines
are negative, i.e. the final Si abundances will be overestimated
in LTE. The corrections for strong lines depend on surface gravity,
and tend to be larger for giants, reaching ~ -0.2 dex in our sample,
and up to ~ -0.4 dex in extreme cases of APOGEE targets. Thus, the NLTE
effects should be included in deriving silicon abundances from H-band Si
I lines, especially for the cases where only strong lines are available.
---------------------------------------------------------
Title: VizieR Online Data Catalog: Companions to APOGEE
stars. I. (Troup+, 2016)
Authors: Troup, N. W.; Nidever, D. L.; de, Lee N.; Carlberg, J.;
Majewski, S. R.; Fernandez, M.; Covey, K.; Chojnowski, S. D.; Pepper,
J.; Nguyen, D. T.; Stassun, K.; Nguyen, D. C.; Wisniewski, J. P.;
Fleming, S. W.; Bizyaev, D.; Frinchaboy, P. M.; Garcia-Hernandez,
D. A.; Ge, J.; Hearty, F.; Meszaros, S.; Pan, K.; Allende Prieto,
C.; Schneider, D. P.; Shetrone, M. D.; Skrutskie, M. F.; Wilson, J.;
Zamora, O.
2016yCat..51510085T Altcode:
All APOGEE-1 observations were taken using fibers connected to either
the Sloan 2.5 m telescope (Gunn et al. 2006AJ....131.2332G) or the
NMSU 1 m telescope at Apache Point Observatory (APO; Majewski et
al. 2017AJ....154...94M). In normal use on the Sloan 2.5 m telescope,
APOGEE employs a massively multiplexed, fiber-fed spectrograph capable
of recording 300 spectra at a time. Of the 146000 stars observed in
APOGEE-1, 14840 had at least eight visits; these stars were selected
for analysis here. APOGEE first light observations were obtained in
2011 May and APOGEE-1 observations concluded at the end of SDSS-III
in 2014 July, providing a maximum temporal baseline of slightly more
than three years (~1000 days). Using refined criteria, 382 stars (55%
of the statistically significant RV variable sample) were selected
to be a part of the "gold sample," which represent the best-quality
companion candidates detected by APOGEE. <P />(1 data file).
---------------------------------------------------------
Title: The DESI Experiment Part I: Science,Targeting, and Survey
Design
Authors: DESI Collaboration; Aghamousa, Amir; Aguilar, Jessica; Ahlen,
Steve; Alam, Shadab; Allen, Lori E.; Allende Prieto, Carlos; Annis,
James; Bailey, Stephen; Balland, Christophe; Ballester, Otger;
Baltay, Charles; Beaufore, Lucas; Bebek, Chris; Beers, Timothy
C.; Bell, Eric F.; Bernal, José Luis; Besuner, Robert; Beutler,
Florian; Blake, Chris; Bleuler, Hannes; Blomqvist, Michael; Blum,
Robert; Bolton, Adam S.; Briceno, Cesar; Brooks, David; Brownstein,
Joel R.; Buckley-Geer, Elizabeth; Burden, Angela; Burtin, Etienne;
Busca, Nicolas G.; Cahn, Robert N.; Cai, Yan-Chuan; Cardiel-Sas, Laia;
Carlberg, Raymond G.; Carton, Pierre-Henri; Casas, Ricard; Castander,
Francisco J.; Cervantes-Cota, Jorge L.; Claybaugh, Todd M.; Close,
Madeline; Coker, Carl T.; Cole, Shaun; Comparat, Johan; Cooper, Andrew
P.; Cousinou, M. -C.; Crocce, Martin; Cuby, Jean-Gabriel; Cunningham,
Daniel P.; Davis, Tamara M.; Dawson, Kyle S.; de la Macorra, Axel;
De Vicente, Juan; Delubac, Timothée; Derwent, Mark; Dey, Arjun;
Dhungana, Govinda; Ding, Zhejie; Doel, Peter; Duan, Yutong T.; Ealet,
Anne; Edelstein, Jerry; Eftekharzadeh, Sarah; Eisenstein, Daniel J.;
Elliott, Ann; Escoffier, Stéphanie; Evatt, Matthew; Fagrelius,
Parker; Fan, Xiaohui; Fanning, Kevin; Farahi, Arya; Farihi, Jay;
Favole, Ginevra; Feng, Yu; Fernandez, Enrique; Findlay, Joseph R.;
Finkbeiner, Douglas P.; Fitzpatrick, Michael J.; Flaugher, Brenna;
Flender, Samuel; Font-Ribera, Andreu; Forero-Romero, Jaime E.;
Fosalba, Pablo; Frenk, Carlos S.; Fumagalli, Michele; Gaensicke,
Boris T.; Gallo, Giuseppe; Garcia-Bellido, Juan; Gaztanaga, Enrique;
Pietro Gentile Fusillo, Nicola; Gerard, Terry; Gershkovich, Irena;
Giannantonio, Tommaso; Gillet, Denis; Gonzalez-de-Rivera, Guillermo;
Gonzalez-Perez, Violeta; Gott, Shelby; Graur, Or; Gutierrez, Gaston;
Guy, Julien; Habib, Salman; Heetderks, Henry; Heetderks, Ian; Heitmann,
Katrin; Hellwing, Wojciech A.; Herrera, David A.; Ho, Shirley; Holland,
Stephen; Honscheid, Klaus; Huff, Eric; Hutchinson, Timothy A.; Huterer,
Dragan; Hwang, Ho Seong; Illa Laguna, Joseph Maria; Ishikawa, Yuzo;
Jacobs, Dianna; Jeffrey, Niall; Jelinsky, Patrick; Jennings, Elise;
Jiang, Linhua; Jimenez, Jorge; Johnson, Jennifer; Joyce, Richard;
Jullo, Eric; Juneau, Stéphanie; Kama, Sami; Karcher, Armin; Karkar,
Sonia; Kehoe, Robert; Kennamer, Noble; Kent, Stephen; Kilbinger,
Martin; Kim, Alex G.; Kirkby, David; Kisner, Theodore; Kitanidis,
Ellie; Kneib, Jean-Paul; Koposov, Sergey; Kovacs, Eve; Koyama, Kazuya;
Kremin, Anthony; Kron, Richard; Kronig, Luzius; Kueter-Young, Andrea;
Lacey, Cedric G.; Lafever, Robin; Lahav, Ofer; Lambert, Andrew;
Lampton, Michael; Landriau, Martin; Lang, Dustin; Lauer, Tod R.;
Le Goff, Jean-Marc; Le Guillou, Laurent; Le Van Suu, Auguste; Lee,
Jae Hyeon; Lee, Su-Jeong; Leitner, Daniela; Lesser, Michael; Levi,
Michael E.; L'Huillier, Benjamin; Li, Baojiu; Liang, Ming; Lin, Huan;
Linder, Eric; Loebman, Sarah R.; Lukić, Zarija; Ma, Jun; MacCrann,
Niall; Magneville, Christophe; Makarem, Laleh; Manera, Marc; Manser,
Christopher J.; Marshall, Robert; Martini, Paul; Massey, Richard;
Matheson, Thomas; McCauley, Jeremy; McDonald, Patrick; McGreer, Ian D.;
Meisner, Aaron; Metcalfe, Nigel; Miller, Timothy N.; Miquel, Ramon;
Moustakas, John; Myers, Adam; Naik, Milind; Newman, Jeffrey A.; Nichol,
Robert C.; Nicola, Andrina; Nicolati da Costa, Luiz; Nie, Jundan; Niz,
Gustavo; Norberg, Peder; Nord, Brian; Norman, Dara; Nugent, Peter;
O'Brien, Thomas; Oh, Minji; Olsen, Knut A. G.; Padilla, Cristobal;
Padmanabhan, Hamsa; Padmanabhan, Nikhil; Palanque-Delabrouille,
Nathalie; Palmese, Antonella; Pappalardo, Daniel; Pâris, Isabelle;
Park, Changbom; Patej, Anna; Peacock, John A.; Peiris, Hiranya
V.; Peng, Xiyan; Percival, Will J.; Perruchot, Sandrine; Pieri,
Matthew M.; Pogge, Richard; Pollack, Jennifer E.; Poppett, Claire;
Prada, Francisco; Prakash, Abhishek; Probst, Ronald G.; Rabinowitz,
David; Raichoor, Anand; Ree, Chang Hee; Refregier, Alexandre; Regal,
Xavier; Reid, Beth; Reil, Kevin; Rezaie, Mehdi; Rockosi, Constance
M.; Roe, Natalie; Ronayette, Samuel; Roodman, Aaron; Ross, Ashley J.;
Ross, Nicholas P.; Rossi, Graziano; Rozo, Eduardo; Ruhlmann-Kleider,
Vanina; Rykoff, Eli S.; Sabiu, Cristiano; Samushia, Lado; Sanchez,
Eusebio; Sanchez, Javier; Schlegel, David J.; Schneider, Michael;
Schubnell, Michael; Secroun, Aurélia; Seljak, Uros; Seo, Hee-Jong;
Serrano, Santiago; Shafieloo, Arman; Shan, Huanyuan; Sharples, Ray;
Sholl, Michael J.; Shourt, William V.; Silber, Joseph H.; Silva,
David R.; Sirk, Martin M.; Slosar, Anze; Smith, Alex; Smoot, George
F.; Som, Debopam; Song, Yong-Seon; Sprayberry, David; Staten, Ryan;
Stefanik, Andy; Tarle, Gregory; Sien Tie, Suk; Tinker, Jeremy L.;
Tojeiro, Rita; Valdes, Francisco; Valenzuela, Octavio; Valluri,
Monica; Vargas-Magana, Mariana; Verde, Licia; Walker, Alistair R.;
Wang, Jiali; Wang, Yuting; Weaver, Benjamin A.; Weaverdyck, Curtis;
Wechsler, Risa H.; Weinberg, David H.; White, Martin; Yang, Qian;
Yeche, Christophe; Zhang, Tianmeng; Zhao, Gong-Bo; Zheng, Yi; Zhou,
Xu; Zhou, Zhimin; Zhu, Yaling; Zou, Hu; Zu, Ying
2016arXiv161100036D Altcode:
DESI (Dark Energy Spectroscopic Instrument) is a Stage IV ground-based
dark energy experiment that will study baryon acoustic oscillations
(BAO) and the growth of structure through redshift-space distortions
with a wide-area galaxy and quasar redshift survey. To trace the
underlying dark matter distribution, spectroscopic targets will be
selected in four classes from imaging data. We will measure luminous
red galaxies up to $z=1.0$. To probe the Universe out to even higher
redshift, DESI will target bright [O II] emission line galaxies up
to $z=1.7$. Quasars will be targeted both as direct tracers of the
underlying dark matter distribution and, at higher redshifts ($ 2.1
< z < 3.5$), for the Ly-$\alpha$ forest absorption features in
their spectra, which will be used to trace the distribution of neutral
hydrogen. When moonlight prevents efficient observations of the faint
targets of the baseline survey, DESI will conduct a magnitude-limited
Bright Galaxy Survey comprising approximately 10 million galaxies with a
median $z\approx 0.2$. In total, more than 30 million galaxy and quasar
redshifts will be obtained to measure the BAO feature and determine
the matter power spectrum, including redshift space distortions.
---------------------------------------------------------
Title: The DESI Experiment Part II: Instrument Design
Authors: DESI Collaboration; Aghamousa, Amir; Aguilar, Jessica; Ahlen,
Steve; Alam, Shadab; Allen, Lori E.; Allende Prieto, Carlos; Annis,
James; Bailey, Stephen; Balland, Christophe; Ballester, Otger;
Baltay, Charles; Beaufore, Lucas; Bebek, Chris; Beers, Timothy
C.; Bell, Eric F.; Bernal, José Luis; Besuner, Robert; Beutler,
Florian; Blake, Chris; Bleuler, Hannes; Blomqvist, Michael; Blum,
Robert; Bolton, Adam S.; Briceno, Cesar; Brooks, David; Brownstein,
Joel R.; Buckley-Geer, Elizabeth; Burden, Angela; Burtin, Etienne;
Busca, Nicolas G.; Cahn, Robert N.; Cai, Yan-Chuan; Cardiel-Sas, Laia;
Carlberg, Raymond G.; Carton, Pierre-Henri; Casas, Ricard; Castander,
Francisco J.; Cervantes-Cota, Jorge L.; Claybaugh, Todd M.; Close,
Madeline; Coker, Carl T.; Cole, Shaun; Comparat, Johan; Cooper, Andrew
P.; Cousinou, M. -C.; Crocce, Martin; Cuby, Jean-Gabriel; Cunningham,
Daniel P.; Davis, Tamara M.; Dawson, Kyle S.; de la Macorra, Axel;
De Vicente, Juan; Delubac, Timothée; Derwent, Mark; Dey, Arjun;
Dhungana, Govinda; Ding, Zhejie; Doel, Peter; Duan, Yutong T.; Ealet,
Anne; Edelstein, Jerry; Eftekharzadeh, Sarah; Eisenstein, Daniel J.;
Elliott, Ann; Escoffier, Stéphanie; Evatt, Matthew; Fagrelius,
Parker; Fan, Xiaohui; Fanning, Kevin; Farahi, Arya; Farihi, Jay;
Favole, Ginevra; Feng, Yu; Fernandez, Enrique; Findlay, Joseph R.;
Finkbeiner, Douglas P.; Fitzpatrick, Michael J.; Flaugher, Brenna;
Flender, Samuel; Font-Ribera, Andreu; Forero-Romero, Jaime E.;
Fosalba, Pablo; Frenk, Carlos S.; Fumagalli, Michele; Gaensicke,
Boris T.; Gallo, Giuseppe; Garcia-Bellido, Juan; Gaztanaga, Enrique;
Pietro Gentile Fusillo, Nicola; Gerard, Terry; Gershkovich, Irena;
Giannantonio, Tommaso; Gillet, Denis; Gonzalez-de-Rivera, Guillermo;
Gonzalez-Perez, Violeta; Gott, Shelby; Graur, Or; Gutierrez, Gaston;
Guy, Julien; Habib, Salman; Heetderks, Henry; Heetderks, Ian; Heitmann,
Katrin; Hellwing, Wojciech A.; Herrera, David A.; Ho, Shirley; Holland,
Stephen; Honscheid, Klaus; Huff, Eric; Hutchinson, Timothy A.; Huterer,
Dragan; Hwang, Ho Seong; Illa Laguna, Joseph Maria; Ishikawa, Yuzo;
Jacobs, Dianna; Jeffrey, Niall; Jelinsky, Patrick; Jennings, Elise;
Jiang, Linhua; Jimenez, Jorge; Johnson, Jennifer; Joyce, Richard;
Jullo, Eric; Juneau, Stéphanie; Kama, Sami; Karcher, Armin; Karkar,
Sonia; Kehoe, Robert; Kennamer, Noble; Kent, Stephen; Kilbinger,
Martin; Kim, Alex G.; Kirkby, David; Kisner, Theodore; Kitanidis,
Ellie; Kneib, Jean-Paul; Koposov, Sergey; Kovacs, Eve; Koyama, Kazuya;
Kremin, Anthony; Kron, Richard; Kronig, Luzius; Kueter-Young, Andrea;
Lacey, Cedric G.; Lafever, Robin; Lahav, Ofer; Lambert, Andrew;
Lampton, Michael; Landriau, Martin; Lang, Dustin; Lauer, Tod R.;
Le Goff, Jean-Marc; Le Guillou, Laurent; Le Van Suu, Auguste; Lee,
Jae Hyeon; Lee, Su-Jeong; Leitner, Daniela; Lesser, Michael; Levi,
Michael E.; L'Huillier, Benjamin; Li, Baojiu; Liang, Ming; Lin, Huan;
Linder, Eric; Loebman, Sarah R.; Lukić, Zarija; Ma, Jun; MacCrann,
Niall; Magneville, Christophe; Makarem, Laleh; Manera, Marc; Manser,
Christopher J.; Marshall, Robert; Martini, Paul; Massey, Richard;
Matheson, Thomas; McCauley, Jeremy; McDonald, Patrick; McGreer, Ian D.;
Meisner, Aaron; Metcalfe, Nigel; Miller, Timothy N.; Miquel, Ramon;
Moustakas, John; Myers, Adam; Naik, Milind; Newman, Jeffrey A.; Nichol,
Robert C.; Nicola, Andrina; Nicolati da Costa, Luiz; Nie, Jundan; Niz,
Gustavo; Norberg, Peder; Nord, Brian; Norman, Dara; Nugent, Peter;
O'Brien, Thomas; Oh, Minji; Olsen, Knut A. G.; Padilla, Cristobal;
Padmanabhan, Hamsa; Padmanabhan, Nikhil; Palanque-Delabrouille,
Nathalie; Palmese, Antonella; Pappalardo, Daniel; Pâris, Isabelle;
Park, Changbom; Patej, Anna; Peacock, John A.; Peiris, Hiranya
V.; Peng, Xiyan; Percival, Will J.; Perruchot, Sandrine; Pieri,
Matthew M.; Pogge, Richard; Pollack, Jennifer E.; Poppett, Claire;
Prada, Francisco; Prakash, Abhishek; Probst, Ronald G.; Rabinowitz,
David; Raichoor, Anand; Ree, Chang Hee; Refregier, Alexandre; Regal,
Xavier; Reid, Beth; Reil, Kevin; Rezaie, Mehdi; Rockosi, Constance
M.; Roe, Natalie; Ronayette, Samuel; Roodman, Aaron; Ross, Ashley J.;
Ross, Nicholas P.; Rossi, Graziano; Rozo, Eduardo; Ruhlmann-Kleider,
Vanina; Rykoff, Eli S.; Sabiu, Cristiano; Samushia, Lado; Sanchez,
Eusebio; Sanchez, Javier; Schlegel, David J.; Schneider, Michael;
Schubnell, Michael; Secroun, Aurélia; Seljak, Uros; Seo, Hee-Jong;
Serrano, Santiago; Shafieloo, Arman; Shan, Huanyuan; Sharples, Ray;
Sholl, Michael J.; Shourt, William V.; Silber, Joseph H.; Silva,
David R.; Sirk, Martin M.; Slosar, Anze; Smith, Alex; Smoot, George
F.; Som, Debopam; Song, Yong-Seon; Sprayberry, David; Staten, Ryan;
Stefanik, Andy; Tarle, Gregory; Sien Tie, Suk; Tinker, Jeremy L.;
Tojeiro, Rita; Valdes, Francisco; Valenzuela, Octavio; Valluri,
Monica; Vargas-Magana, Mariana; Verde, Licia; Walker, Alistair R.;
Wang, Jiali; Wang, Yuting; Weaver, Benjamin A.; Weaverdyck, Curtis;
Wechsler, Risa H.; Weinberg, David H.; White, Martin; Yang, Qian;
Yeche, Christophe; Zhang, Tianmeng; Zhao, Gong-Bo; Zheng, Yi; Zhou,
Xu; Zhou, Zhimin; Zhu, Yaling; Zou, Hu; Zu, Ying
2016arXiv161100037D Altcode:
DESI (Dark Energy Spectropic Instrument) is a Stage IV ground-based
dark energy experiment that will study baryon acoustic oscillations
and the growth of structure through redshift-space distortions with a
wide-area galaxy and quasar redshift survey. The DESI instrument is
a robotically-actuated, fiber-fed spectrograph capable of taking up
to 5,000 simultaneous spectra over a wavelength range from 360 nm to
980 nm. The fibers feed ten three-arm spectrographs with resolution
$R= \lambda/\Delta\lambda$ between 2000 and 5500, depending on
wavelength. The DESI instrument will be used to conduct a five-year
survey designed to cover 14,000 deg$^2$. This powerful instrument will
be installed at prime focus on the 4-m Mayall telescope in Kitt Peak,
Arizona, along with a new optical corrector, which will provide a
three-degree diameter field of view. The DESI collaboration will also
deliver a spectroscopic pipeline and data management system to reduce
and archive all data for eventual public use.
---------------------------------------------------------
Title: Deep SDSS optical spectroscopy of distant halo
stars. III. Chemical analysis of extremely metal-poor stars
Authors: Fernández-Alvar, E.; Allende Prieto, C.; Beers, T. C.; Lee,
Y. S.; Masseron, T.; Schneider, D. P.
2016A&A...593A..28F Altcode: 2016arXiv160604811F
<BR /> Aims: We present the results of an analysis of 107 extremely
metal-poor (EMP) stars with metallicities lower than [Fe/H] =- 3.0,
identified in medium-resolution spectra in the Sloan Digital Sky Survey
(SDSS). Our analysis provides estimates of the stellar effective
temperatures and surface gravities, as well as iron, calcium, and
magnesium abundances. <BR /> Methods: We followed the same method as
in previous papers of this series. The method is based on comparisons
of the observed spectra with synthetic spectra. The abundances of
Fe, Ca, and Mg were determined by fitting spectral regions that
are dominated by lines of each element. In addition, we present a
technique to determine upper limits for elements whose features are
not detected in a given spectrum. We also analyzed our sample with the
SEGUE stellar parameter pipeline to obtain additional determinations
of the atmospheric parameters and iron and alpha-element abundances,
which we thend compare with ours. In addition, we used these parameters
to infer [C/Fe] ratios. <BR /> Results: Ca is typically the only element
in these spectra with a moderate to low signal-to-noise ratio and medium
resolution in this metallicity regime with lines that are sufficiently
strong to reliably measure its abundance. Fe and Mg exhibit weaker
features that in most cases only provide upper limits. We measured
[Ca/Fe] and [Mg/Fe] for EMP stars in the SDSS spectra and conclude that
most of the stars exhibit the typical enhancement level for α-elements,
~+0.4, although some stars for which only [Fe/H] upper limits could
be estimated indicate higher [α/Fe] ratios. We also find that 26%
of the stars in our sample can be classified as carbon-enhanced
metal-poor (CEMP) stars and that the frequency of CEMP stars also
increases with decreasing metallicity, as has been reported for
previous samples. We identify a rare, bright (g = 11.90) EMP star, SDSS
J134144.61+474128.6, with [Fe/H] =- 3.27, [C/Fe] = + 0.95, and elevated
magnesium ([Mg/Fe] =+ 0.62), an abundance pattern typical of CEMP-no
stars. <P />Tables 4-6 are only available at the CDS via anonymous ftp
to <A href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A>
(<A href="http://130.79.128.5">http://130.79.128.5</A>) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/593/A28">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/593/A28</A>
---------------------------------------------------------
Title: Chemical abundance gradients from open clusters in the Milky
Way disk: Results from the APOGEE survey
Authors: Cunha, K.; Frinchaboy, P. M.; Souto, D.; Thompson, B.;
Zasowski, G.; Allende Prieto, C.; Carrera, R.; Chiappini, C.; Donor,
J.; García-Hernández, D. A.; García Pérez, A. E.; Hayden, M. R.;
Holtzman, J.; Jackson, K. M.; Johnson, J. A.; Majewski, S. R.;
Mészáros, S.; Meyer, B.; Nidever, D. L.; O'Connell, J.; Schiavon,
R. P.; Schultheis, M.; Shetrone, M.; Simmons, A.; Smith, V. V.; et al.
2016AN....337..922C Altcode: 2016arXiv160103099C
Metallicity gradients provide strong constraints for understanding
the chemical evolution of the Galaxy. We report on radial abundance
gradients of Fe, Ni, Ca, Si, and Mg obtained from a sample of 304
red-giant members of 29 disk open clusters, mostly concentrated
at galactocentric distances between ∼ 8-15 kpc, but including
two open clusters in the outer disk. The observations are from the
APOGEE survey. The chemical abundances were derived automatically by
the ASPCAP pipeline and these are part of the SDSS III Data Release
12. The gradients, obtained from least squares fits to the data,
are relatively flat, with slopes ranging from -0.026 to -0.033 dex
kpc<SUP>-1</SUP> for the α-elements [O/H], [Ca/H], [Si/H], and [Mg/H],
and -0.035 dex kpc<SUP>-1</SUP> and -0.040 dex kpc<SUP>-1</SUP> for
[Fe/H] and [Ni/H], respectively. Our results are not at odds with
the possibility that metallicity ([Fe/H]) gradients are steeper in
the inner disk ({R_GC∼ 7}-12 kpc) and flatter towards the outer
disk. The open cluster sample studied spans a significant range in
age. When breaking the sample into age bins, there is some indication
that the younger open cluster population in our sample (log age <
8.7) has a flatter metallicity gradient when compared with the gradients
obtained from older open clusters.
---------------------------------------------------------
Title: Automated pipelines for spectroscopic analysis
Authors: Allende Prieto, C.
2016AN....337..837A Altcode: 2016arXiv160201115A
The Gaia mission will have a profound impact on our understanding
of the structure and dynamics of the Milky Way. Gaia is providing an
exhaustive census of stellar parallaxes, proper motions, positions,
colors and radial velocities, but also leaves some glaring holes in
an otherwise complete data set. The radial velocities measured with
the on-board high-resolution spectrograph will only reach some 10 %
of the full sample of stars with astrometry and photometry from the
mission, and detailed chemical information will be obtained for less
than 1 %. Teams all over the world are organizing large-scale projects
to provide complementary radial velocities and chemistry, since this
can now be done very efficiently from the ground thanks to large
and mid-size telescopes with a wide field-of-view and multi-object
spectrographs. As a result, automated data processing is taking an
ever increasing relevance, and the concept is applying to many more
areas, from targeting to analysis. In this paper, I provide a quick
overview of recent, ongoing, and upcoming spectroscopic surveys,
and the strategies adopted in their automated analysis pipelines.
---------------------------------------------------------
Title: VizieR Online Data Catalog: Seismology and spectroscopy of
CoRoGEE red giants (Anders+, 2017)
Authors: Anders, F.; Chiappini, C.; Rodrigues, T. S.; Miglio, A.;
Montalban, J.; Mosser, B.; Girardi, L.; Valentini, M.; Noels, A.;
Morel, T.; Johnson, J. A.; Schultheis, M.; Baudin, F.; de Assis
Peralta, R.; Hekker, S.; Themessl, N.; Kallinger, T.; Garcia, R. A.;
Mathur, S.; Baglin, A.; Santiago, B. X.; Martig, M.; Minchev, I.;
Steinmetz, M.; da Costa, L. N.; Maia, M. A. G.; Allende Prieto,
C.; Cunha, K.; Beers, T. C.; Epstein, C.; Garcia Perez, A. E.;
Garcia-Hernandez, D. A.; Harding, P.; Holtzman, J.; Majewski, S. R.;
Meszaros, Sz.; Nidever, D.; Pan, K.; Pinsonneault, M.; Schiavon,
R. P.; Schneider, D. P.; Shetrone, M. D.; Stassun, K.; Zamora, O.;
Zasowski, G.
2016yCat..35970030A Altcode:
For the 606 successfully observed stars, asteroseismic parameters from
CoRoT, spectroscopic data from APOGEE (SDSS DR12), wide-band photometry
from OBSCAT, APASS, SDSS, 2MASS, and WISE are presented. Additional
information from the EXODAT archive, stellar parameters from PARAM
(Rodrigues et al. 2014MNRAS.445.2758R), cross-matches to the APOGEE
red-clump catalogue (Bovy et al. 2014ApJ...790..127B), the UCAC-4
catalogue (Zacharias et al., 2013, Cat. I/322), and derived stellar
kinematics are also included. <P />(2 data files).
---------------------------------------------------------
Title: Final design and progress of WEAVE: the next generation
wide-field spectroscopy facility for the William Herschel Telescope
Authors: Dalton, Gavin; Trager, Scott; Abrams, Don Carlos; Bonifacio,
Piercarlo; Aguerri, J. Alfonso L.; Middleton, Kevin; Benn, Chris; Dee,
Kevin; Sayède, Frédéric; Lewis, Ian; Pragt, Johannes; Pico, Sergio;
Walton, Nic; Rey, Jeurg; Allende Prieto, Carlos; Peñate, José;
Lhome, Emilie; Agócs, Tibor; Alonso, José; Terrett, David; Brock,
Matthew; Gilbert, James; Schallig, Ellen; Ridings, Andy; Guinouard,
Isabelle; Verheijen, Marc; Tosh, Ian; Rogers, Kevin; Lee, Martin;
Steele, Iain; Stuik, Remko; Tromp, Niels; Jaskó, Attila; Carrasco,
Esperanza; Farcas, Szigfrid; Kragt, Jan; Lesman, Dirk; Kroes, Gabby;
Mottram, Chris; Bates, Stuart; Rodriguez, Luis Fernando; Gribbin,
Frank; Delgado, José Miguel; Herreros, José Miguel; Martin, Carlos;
Cano, Diego; Navarro, Ramon; Irwin, Mike; Lewis, Jim; Gonzalez Solares,
Eduardo; Murphy, David; Worley, Clare; Bassom, Richard; O'Mahoney,
Neil; Bianco, Andrea; Zurita, Christina; ter Horst, Rik; Molinari,
Emilio; Lodi, Marcello; Guerra, José; Martin, Adrian; Vallenari,
Antonella; Salasnich, Bernardo; Baruffolo, Andrea; Jin, Shoko; Hill,
Vanessa; Smith, Dan; Drew, Janet; Poggianti, Bianca; Pieri, Mat;
Dominquez Palmero, Lillian; Farina, Cecilia
2016SPIE.9908E..1GD Altcode:
We present the Final Design of the WEAVE next-generation spectroscopy
facility for the William Herschel Telescope (WHT), together with
a status update on the details of manufacturing, integration and
the overall project schedule now that all the major fabrication
contracts are in place. We also present a summary of the current
planning behind the 5-year initial phase of survey operations. WEAVE
will provide optical ground-based follow up of ground-based (LOFAR)
and space-based (Gaia) surveys. WEAVE is a multi-object and multi-IFU
facility utilizing a new 2-degree prime focus field of view at the
WHT, with a buffered pick-and-place positioner system hosting 1000
multi-object (MOS) fibres, 20 integral field units, or a single large
IFU for each observation. The fibres are fed to a single (dual-beam)
spectrograph, with total of 16k spectral pixels, located within the
WHT GHRIL enclosure on the telescope Nasmyth platform, supporting
observations at R 5000 over the full 370-1000nm wavelength range in
a single exposure, or a high resolution mode with limited coverage
in each arm at R 20000. The project is now in the manufacturing and
integration phase with first light expected for early of 2018.
---------------------------------------------------------
Title: Follow-up observations of extremely metal-poor stars identified
from SDSS
Authors: Aguado, D. S.; Allende Prieto, C.; González Hernández,
J. I.; Carrera, R.; Rebolo, R.; Shetrone, M.; Lambert, D. L.;
Fernández-Alvar, E.
2016A&A...593A..10A Altcode: 2016arXiv160600604A
Context. The most metal-poor stars in the Milky Way witnessed the
early phases of formation of the Galaxy, and have chemical compositions
that are close to the pristine mixture from Big Bang nucleosynthesis,
polluted by one or few supernovae. <BR /> Aims: Only two dozen stars
with ([Fe/H] < -4) are known, and they show a wide range of abundance
patterns. It is therefore important to enlarge this sample. We present
the first results of an effort to identify new extremely metal-poor
stars in the Milky Way halo. <BR /> Methods: Our targets have been
selected from low-resolution spectra obtained as part of the Sloan
Digital Sky Survey, and followed-up with medium resolution spectroscopy
on the 4.2 m William Herschel Telescope and, in a few cases, at high
resolution on the 9.2 m Hobby-Eberly Telescope. Stellar parameters
and the abundances of magnesium, calcium, iron, and strontium have
been inferred from the spectra using classical model atmospheres. We
have also derived carbon abundances from the G band. <BR /> Results:
We find consistency between the metallicities estimated from SDSS
and those from new data at the level of 0.3 dex. The analysis of
medium resolution data obtained with ISIS on the WHT allows us to
refine the metallicities and in some cases measure other elemental
abundances. Our sample contains 11 new metal-poor stars with [Fe/H] <
-3.0, one of them with an estimated metallicity of [Fe/H] ~ -4.0. We
also discuss metallicity discrepancies of some stars in common with
previous works in the literature. Only one of these stars is found
to be C-enhanced at about [C/Fe] ~ + 1, whereas the other metal-poor
stars show C abundances at the level of [C/Fe] ~ + 0.45. <P />Based
on observations obtained with the Hobby-Eberly Telescope, which is a
joint project of the University of Texas at Austin, the Pennsylvania
State University, Stanford University, Ludwig-Maximilians-Universität
München, and Georg-August-Universität Göttingen.The reduced spectra
as FITS files are only available at the CDS via anonymous ftp to <A
href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A>
(<A href="http://130.79.128.5">http://130.79.128.5</A>) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/593/A10">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/593/A10</A>
---------------------------------------------------------
Title: EELT-HIRES the high-resolution spectrograph for the E-ELT
Authors: Marconi, A.; Di Marcantonio, P.; D'Odorico, V.; Cristiani,
S.; Maiolino, R.; Oliva, E.; Origlia, L.; Riva, M.; Valenziano, L.;
Zerbi, F. M.; Abreu, M.; Adibekyan, V.; Allende Prieto, C.; Amado,
P. J.; Benz, W.; Boisse, I.; Bonfils, X.; Bouchy, F.; Buchhave,
L.; Buscher, D.; Cabral, A.; Canto Martins, B. L.; Chiavassa, A.;
Coelho, J.; Christensen, L. B.; Delgado-Mena, E.; de Medeiros, J. R.;
Di Varano, I.; Figueira, P.; Fisher, M.; Fynbo, J. P. U.; Glasse,
A. C. H.; Haehnelt, M.; Haniff, C.; Hansen, C. J.; Hatzes, A.; Huke,
P.; Korn, A. J.; Leão, I. C.; Liske, J.; Lovis, C.; Maslowski,
P.; Matute, I.; McCracken, R. A.; Martins, C. J. A. P.; Monteiro,
M. J. P. F. G.; Morris, S.; Morris, T.; Nicklas, H.; Niedzielski, A.;
Nunes, N. J.; Palle, E.; Parr-Burman, P. M.; Parro, V.; Parry, I.;
Pepe, F.; Piskunov, N.; Queloz, D.; Quirrenbach, A.; Rebolo Lopez,
R.; Reiners, A.; Reid, D. T.; Santos, N.; Seifert, W.; Sousa, S.;
Stempels, H. C.; Strassmeier, K.; Sun, X.; Udry, S.; Vanzi, L.;
Vestergaard, M.; Weber, M.; Zackrisson, E.
2016SPIE.9908E..23M Altcode: 2016arXiv160900497M
The first generation of E-ELT instruments will include an optic-infrared
High Resolution Spectrograph, conventionally indicated as EELT-HIRES,
which will be capable of providing unique breakthroughs in the fields
of exoplanets, star and planet formation, physics and evolution of
stars and galaxies, cosmology and fundamental physics. A 2-year long
phase A study for EELT-HIRES has just started and will be performed
by a consortium composed of institutes and organisations from Brazil,
Chile, Denmark, France, Germany, Italy, Poland, Portugal, Spain, Sweden,
Switzerland and United Kingdom. In this paper we describe the science
goals and the preliminary technical concept for EELT-HIRES which will
be developed during the phase A, as well as its planned development
and consortium organisation during the study.
---------------------------------------------------------
Title: VizieR Online Data Catalog: The SEGUE K giant
survey. II. Distances of 6036 stars (Xue+, 2014)
Authors: Xue, X. -X.; Ma, Z.; Rix, H. -W.; Morrison, H. L.; Harding,
P.; Beers, T. C.; Ivans, I. I.; Jacobson, H. R.; Johnson, J.; Lee,
Y. S.; Lucatello, S.; Rockosi, C. M.; Sobeck, J. S.; Yanny, B.; Zhao,
G.; Allende Prieto, C.
2016yCat..17840170X Altcode:
SDSS and its extensions use a dedicated 2.5m telescope to obtain
ugriz imaging and resolution (defined as R=λ/Δλ)~2000 spectra for
640 (SDSS spectrograph) or 1000 (BOSS spectrograph) objects over a
7deg<SUP>2</SUP> field. Sloan Extension for Galactic Understanding and
Exploration (SEGUE), one of the key projects executed during SDSS-II
and SDSS-III, obtained some 360000 spectra of stars in the Galaxy,
selected to explore the nature of stellar populations from 0.5kpc to
100kpc (Yanny et al. 2009, cat. J/AJ/137/4377; and C. M. Rockosi et al.,
in preparation). Data from SEGUE is a significant part of the ninth SDSS
public data release (DR9; Ahn et al. 2012, cat. V/139). <P />The SEGUE
project obtained spectra for a large number of different stellar types:
18 for SEGUE-1 (see Yanny et al. 2009, cat. J/AJ/137/4377, for details)
and 11 for SEGUE-2 (C. M. Rockosi et al. in preparation). Three of
these target types were specifically designed to detect K giants: these
are designated "l-color K giants", "red K giants", and "proper-motion
K giants." The K-giant targets from these three categories all have
0.5<(g-r)<SUB>0</SUB><1.3, 0.5<(u-g)<SUB>0</SUB><3.5,
and proper motions smaller than 11mas/yr. <P />We present a catalog
containing the distance moduli, observed information, and SEGUE Stellar
Parameter Pipeline (SSPP) atmospheric parameters for 6036 SEGUE K giants
(see Table4). For each object in the catalog, we also list some of the
basic observables such as (R.A., decl.), extinction-corrected apparent
magnitudes and dereddened colors, as well as the information obtained
from the spectra--heliocentric radial velocities plus SSPP atmospheric
parameters. In addition, we provide the Bayesian estimates of the
distance moduli, distances to the Sun, Galactocentric distances,
the absolute magnitudes and their uncertainties, along with the
distance moduli at (5%, 16%, 50%, 84%, 95%) confidence of L(DM). <P
/>(2 data files).
---------------------------------------------------------
Title: Spectral classification of the recurrent nova M31N 1990-10a
during its 2016 eruption with WHT/ACAM
Authors: Ederoclite, A.; Henze, M.; Aguado, D.; Allende Prieto, C.;
Williams, S.; Darnley, M. J.; Sala, G.; Shafter, A. W.; Hornoch, K.
2016ATel.9281....1E Altcode:
An optical spectrum of the fast recurrent nova candidate M31N 1990-10a
(see ATels #9276,#9280) was obtained on 2016-07-30.11 UT with the ACAM
instrument on the 4m William Herschel Telescope at the Roque de los
Muchachos Observatory (located in La Palma, Spain).
---------------------------------------------------------
Title: VizieR Online Data Catalog: ASPCAP weights for the 15 APOGEE
chemical elements (Garcia+, 2016)
Authors: Garcia Perez, A. E.; Allende Prieto, C.; Holtzman, J. A.;
Shetrone, M.; Meszaros, S.; Bizyaev, D.; Carrera, R.; Cunha, K.;
Garcia-Hernandez, D. A.; Johnson, J. A.; Majewski, S. R.; Nidever,
D. L.; Schiavon, R. P.; Shane, N.; Smith, V. V.; Sobeck, J.; Troup, N.;
Zamora, O.; Weinberg, D. H.; Bovy, J.; Eisenstein, D. J.; Feuillet,
D.; Frinchaboy, P. M.; Hayden, M. R.; Hearty, F. R.; Nguyen, D. C.;
O'Connell, R. W.; Pinsonneault, M. H.; Wilson, J. C.; Zasowski, G.
2016yCat..51510144G Altcode:
The Apache Point Observatory Galactic Evolution Experiment (APOGEE) has
built the largest moderately high-resolution (R~22500) spectroscopic
map of the stars across the Milky Way, and including dust-obscured
areas. <P />The APOGEE Stellar Parameter and Chemical Abundances
Pipeline (ASPCAP) is the software developed for the automated analysis
of these spectra. The pipeline matches the observations to a set of
synthetic spectrum templates using the {chi}<SUP>2</SUP> minimization in
a multidimensional parameter space. Stellar parameters are derived first
from the entire APOGEE spectral range, followed by the determination
of individual chemical abundances from spectral windows optimized for
each element. <P />Table3 gives the weights as a function of wavelength,
for the 15 APOGEE chemical elements. <P />(1 data file).
---------------------------------------------------------
Title: Solar and stellar photospheric abundances
Authors: Allende Prieto, Carlos
2016LRSP...13....1A Altcode: 2016arXiv160201121A
The determination of photospheric abundances in late-type stars from
spectroscopic observations is a well-established field, built on
solid theoretical foundations. Improving those foundations to refine
the accuracy of the inferred abundances has proven challenging, but
progress has been made. In parallel, developments on instrumentation,
chiefly regarding multi-object spectroscopy, have been spectacular,
and a number of projects are collecting large numbers of observations
for stars across the Milky Way and nearby galaxies, promising important
advances in our understanding of galaxy formation and evolution. After
providing a brief description of the basic physics and input data
involved in the analysis of stellar spectra, a review is made of the
analysis steps, and the available tools to cope with large observational
efforts. The paper closes with a quick overview of relevant ongoing
and planned spectroscopic surveys, and highlights of recent research
on photospheric abundances.
---------------------------------------------------------
Title: Chemical Tagging in the SDSS-III/APOGEE Survey: New
Identifications of Halo Stars with Globular Cluster Origins
Authors: Martell, Sarah L.; Shetrone, Matthew D.; Lucatello, Sara;
Schiavon, Ricardo P.; Mészáros, Szabolcs; Allende Prieto, Carlos;
García-Hernández, D. A.; Beers, Timothy C.; Nidever, David L.
2016ApJ...825..146M Altcode: 2016arXiv160505792M
We present new identifications of five red giant stars in the
Galactic halo with chemical abundance patterns that indicate they
originally formed in globular clusters. Using data from the Apache
Point Observatory Galactic Evolution Experiment (APOGEE) Survey
available through Sloan Digital Sky Survey (SDSS) Data Release 12,
we first identify likely halo giants, and then search those for
the well-known chemical tags associated with globular clusters,
specifically enrichment in nitrogen and aluminum. We find that 2%
of the halo giants in our sample have this chemical signature, in
agreement with previous results. Following the interpretation in our
previous work on this topic, this would imply that at least 13% of
halo stars originally formed in globular clusters. Recent developments
in the theoretical understanding of globular cluster formation raise
questions about that interpretation, and we concede the possibility that
these migrants represent a small fraction of the halo field. There are
roughly as many stars with the chemical tags of globular clusters in
the halo field as there are in globular clusters, whether or not they
are accompanied by a much larger chemically untaggable population of
former globular cluster stars.
---------------------------------------------------------
Title: ASPCAP: The APOGEE Stellar Parameter and Chemical Abundances
Pipeline
Authors: García Pérez, Ana E.; Allende Prieto, Carlos; Holtzman, Jon
A.; Shetrone, Matthew; Mészáros, Szabolcs; Bizyaev, Dmitry; Carrera,
Ricardo; Cunha, Katia; García-Hernández, D. A.; Johnson, Jennifer
A.; Majewski, Steven R.; Nidever, David L.; Schiavon, Ricardo P.;
Shane, Neville; Smith, Verne V.; Sobeck, Jennifer; Troup, Nicholas;
Zamora, Olga; Weinberg, David H.; Bovy, Jo; Eisenstein, Daniel J.;
Feuillet, Diane; Frinchaboy, Peter M.; Hayden, Michael R.; Hearty,
Fred R.; Nguyen, Duy C.; O'Connell, Robert W.; Pinsonneault, Marc H.;
Wilson, John C.; Zasowski, Gail
2016AJ....151..144G Altcode: 2015arXiv151007635G
The Apache Point Observatory Galactic Evolution Experiment (APOGEE)
has built the largest moderately high-resolution (R ≈ 22,500)
spectroscopic map of the stars across the Milky Way, and including
dust-obscured areas. The APOGEE Stellar Parameter and Chemical
Abundances Pipeline (ASPCAP) is the software developed for the automated
analysis of these spectra. ASPCAP determines atmospheric parameters
and chemical abundances from observed spectra by comparing observed
spectra to libraries of theoretical spectra, using χ<SUP>2</SUP>
minimization in a multidimensional parameter space. The package consists
of a fortran90 code that does the actual minimization and a wrapper IDL
code for book-keeping and data handling. This paper explains in detail
the ASPCAP components and functionality, and presents results from
a number of tests designed to check its performance. ASPCAP provides
stellar effective temperatures, surface gravities, and metallicities
precise to 2%, 0.1 dex, and 0.05 dex, respectively, for most APOGEE
stars, which are predominantly giants. It also provides abundances
for up to 15 chemical elements with various levels of precision,
typically under 0.1 dex. The final data release (DR12) of the Sloan
Digital Sky Survey III contains an APOGEE database of more than 150,000
stars. ASPCAP development continues in the SDSS-IV APOGEE-2 survey.
---------------------------------------------------------
Title: The HERMES solar atlas and the spectroscopic analysis of the
seismic solar analogue KIC 3241581
Authors: Beck, P. G.; Allende Prieto, C.; Van Reeth, T.; Tkachenko,
A.; Raskin, G.; van Winckel, H.; do Nascimento, J. -D., Jr.; Salabert,
D.; Corsaro, E.; García, R. A.
2016A&A...589A..27B Altcode: 2015arXiv151106583B
Context. Solar-analogue stars provide an excellent resource to study
the Sun's evolution, I.e. the changes with time in stellar structure,
activity, or rotation for solar-like stars. The unparalleled photometric
data from the NASA space telescope Kepler allows us to study and
characterise solar-like stars through asteroseismology. <BR /> Aims:
We aim to spectroscopically investigate the fundamental parameter
and chromospheric activity of solar analogues and twins, based on
observations obtained with the HERMES spectrograph and combine them
with asteroseismology. Therefore, we need to build a solar atlas for the
spectrograph, to provide accurate calibrations of the spectroscopically
determined abundances of solar- and late-type stars observed with this
instrument and thus perform differential spectroscopic comparisons. <BR
/> Methods: We acquire high-resolution and high signal-to-noise
(S/N) spectroscopy to construct three solar reference spectra by
observing the reflected light of the asteroids Vesta and Victoria
and the jovian moon Europa (100 ≲ S/N ≲ 450) with the HERMES
spectrograph. We then observe the Kepler solar analogue <ASTROBJ>KIC
3241581 </ASTROBJ>(S/N ~ 170). For this star, the fundamental spectral
parameters are extracted using a differential analysis. Sufficient S/N
in the near ultraviolet allows us to investigate the chromospheric
magnetic activity in both objects. <BR /> Results: We constructed
three solar spectrum atlases from 385 to 900 nm, obtained with the
HERMES spectrograph from observations of two bright asteroids and
a jovian moon. A comparison between our solar spectra atlas to the
Kurucz and HARPS solar spectrum shows an excellent agreement. KIC
3241581 was found to be a long-periodic binary system. The fundamental
parameter for the stellar primary component are T<SUB>eff</SUB>
= 5689 ± 11 K, log g = 4.385 ± 0.005, [Fe/H] = + 0.22 ± 0.01,
being in agreement with the published global seismic values, which
confirms its status as solar analogue. The chromospheric activity
level is compatible with the solar magnetic activity observed during
2014 and 2015. <BR /> Conclusions: Our solar atlas is an essential
tool for the analysis of solar-like stars and to characterise solar
analogues and twins with HERMES. The differential analysis, using the
presented solar atlas from HERMES observations allows us to obtain
the fundamental parameters with very high accuracy. KIC 3241581 is a
metal-rich solar analogue with a solar-like activity level in a binary
system of unknown period. <P />Based on observations made with the
HERMES spectrograph mounted on the 1.2 m Mercator Telescope at the
Spanish Observatorio del Roque de los Muchachos of the Instituto
de Astrofísica de Canarias.The solar atlases and the spectrum
(FITS file) are only available at the CDS via anonymous ftp to <A
href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/589/A27">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/589/A27</A>
---------------------------------------------------------
Title: VizieR Online Data Catalog: The ELM survey. VII. 15 new ELM
white dwarf cand. (Brown+, 2016)
Authors: Brown, W. R.; Gianninas, A.; Kilic, M.; Kenyon, S. J.;
Allende Prieto, C.
2016yCat..18180155B Altcode:
We present observations of 15 new extremely low-mass white dwarf
(ELM WD) candidates. Ten objects are selected by color for our
targeted spectroscopic ELM Survey program as described in Brown et
al. (2012ApJ...744..142B). Five objects come from follow-up spectroscopy
of the completed Hypervelocity Star survey. <P />We acquire spectra for
the 15 ELM WD candidates using the Blue Channel spectrograph on the 6.5m
MMT telescope. We configured the Blue Channel spectrograph to obtain
3650-4500Å spectral coverage with 1.0Å spectral resolution. We acquire
additional spectra for 5 objects using the KOSMOS spectrograph on the
Kitt Peak National Observatory 4m Mayall telescope on program numbers
2014B-0119 and 2015A-0082. We configured the KOSMOS spectrograph to
obtain 3500-6200Å spectral coverage with 2.0Å spectral resolution. We
also acquire spectra for objects with g<17mag using the FAST
spectrograph on the Fred Lawrence Whipple Observatory 1.5m Tillinghast
telescope. We configured the FAST spectrograph to obtain 3500-5500Å
spectral coverage with 1.7Å spectral resolution. <P />(3 data files).
---------------------------------------------------------
Title: Cosmic variance in [O/Fe] in the Galactic disk
Authors: Bertran de Lis, S.; Allende Prieto, C.; Majewski, S. R.;
Schiavon, R. P.; Holtzman, J. A.; Shetrone, M.; Carrera, R.; García
Pérez, A. E.; Mészáros, Sz.; Frinchaboy, P. M.; Hearty, F. R.;
Nidever, D. L.; Zasowski, G.; Ge, J.
2016A&A...590A..74B Altcode: 2016arXiv160305491B
We examine the distribution of the [O/Fe] abundance ratio in stars
across the Galactic disk using H-band spectra from the Apache Point
Galactic Evolution Experiment (APOGEE). We minimize systematic errors
by considering groups of stars with similar atmospheric parameters. The
APOGEE measurements in the Sloan Digital Sky Survey data release 12
reveal that the square root of the star-to-star cosmic variance in the
oxygen-to-iron ratio at a given metallicity is about 0.03-0.04 dex
in both the thin and thick disk. This is about twice as high as the
spread found for solar twins in the immediate solar neighborhood and the
difference is probably associated to the wider range of galactocentric
distances spanned by APOGEE stars. We quantify the uncertainties by
examining the spread among stars with the same parameters in clusters;
these errors are a function of effective temperature and metallicity,
ranging between 0.005 dex at 4000 K and solar metallicity, to about
0.03 dex at 4500 K and [Fe/H] ≃ -0.6. We argue that measuring the
spread in [O/Fe] and other abundance ratios provides strong constraints
for models of Galactic chemical evolution.
---------------------------------------------------------
Title: Division G Commission 36: Theory of Stellar Atmospheres
Authors: Puls, Joachim; Hubeny, Ivan; Asplund, Martin; Allard, France;
Allende Prieto, Carlos; Ayres, Thomas R.; Carlsson, Mats; Gustafsson,
Bengt; Kudritzki, Rolf-Peter; Ryabchikova, Tatiana A.
2016IAUTA..29..453P Altcode:
Different from previous triennial reports, this report covers the
activities of IAU Commission 36 `Theory of Stellar Atmospheres'
over the past six years†, and will be the last report from the
`old' Commission 36. After the General Assembly in Honolulu (August
2015), a new Commission `Stellar and Planetary Atmospheres' (C.G5,
under Division G, `Stars and Stellar Physics') has come into life,
and will continue our work devoted to the outer envelopes of stars,
as well as extend it to the atmospheres of planets (see Sect. 4).
---------------------------------------------------------
Title: Companions to APOGEE Stars. I. A Milky Way-spanning Catalog
of Stellar and Substellar Companion Candidates and Their Diverse Hosts
Authors: Troup, Nicholas W.; Nidever, David L.; De Lee, Nathan;
Carlberg, Joleen; Majewski, Steven R.; Fernandez, Martin; Covey, Kevin;
Chojnowski, S. Drew; Pepper, Joshua; Nguyen, Duy T.; Stassun, Keivan;
Nguyen, Duy Cuong; Wisniewski, John P.; Fleming, Scott W.; Bizyaev,
Dmitry; Frinchaboy, Peter M.; García-Hernández, D. A.; Ge, Jian;
Hearty, Fred; Meszaros, Szabolcs; Pan, Kaike; Allende Prieto, Carlos;
Schneider, Donald P.; Shetrone, Matthew D.; Skrutskie, Michael F.;
Wilson, John; Zamora, Olga
2016AJ....151...85T Altcode: 2016arXiv160100688T
In its three years of operation, the Sloan Digital Sky Survey Apache
Point Observatory Galactic Evolution Experiment (APOGEE-1) observed
>14,000 stars with enough epochs over a sufficient temporal
baseline for the fitting of Keplerian orbits. We present the custom
orbit-fitting pipeline used to create this catalog, which includes
novel quality metrics that account for the phase and velocity coverage
of a fitted Keplerian orbit. With a typical radial velocity precision
of ∼100-200 m s<SUP>-1</SUP>, APOGEE can probe systems with small
separation companions down to a few Jupiter masses. Here we present
initial results from a catalog of 382 of the most compelling stellar
and substellar companion candidates detected by APOGEE, which orbit a
variety of host stars in diverse Galactic environments. Of these, 376
have no previously known small separation companion. The distribution
of companion candidates in this catalog shows evidence for an extremely
truncated brown dwarf (BD) desert with a paucity of BD companions only
for systems with a\quad \lt 0.1-0.2 AU, with no indication of a desert
at larger orbital separation. We propose a few potential explanations of
this result, some which invoke this catalog’s many small separation
companion candidates found orbiting evolved stars. Furthermore, 16 BD
and planet candidates have been identified around metal-poor ([Fe/H]
< -0.5) stars in this catalog, which may challenge the core accretion
model for companions \gt 10{M}<SUB>{Jup</SUB>}. Finally, we find all
types of companions are ubiquitous throughout the Galactic disk with
candidate planetary-mass and BD companions to distances of ∼6 and
∼16 kpc, respectively.
---------------------------------------------------------
Title: New bright optical spectrophotometric standards: A-type stars
from the STIS Next Generation Spectral Library
Authors: Allende Prieto, C.; del Burgo, C.
2016MNRAS.455.3864A Altcode: 2015arXiv151102951A
Exoplanets have sparked interest in extremely high signal-to-noise
ratio spectroscopic observations of very bright stars, in a regime
where flux calibrators, in particular DA white dwarfs, are not
available. We argue that A-type stars offer a useful alternative and
reliable space-based spectrophotometry is now available for a number
of bright ones in the range 3 < V < 8 mag. By means of comparing
observed spectrophotometry and model fluxes, we identify 18 new very
bright trustworthy A-type flux standards for the optical range (400-800
nm), and provide scaled model fluxes for them. Our tests suggest that
the absolute fluxes for these stars in the optical are reliable to
within 3 per cent. We limit the spectral range to 400-800 nm, since
our models have difficulties to reproduce the observed fluxes in the
near-infrared and, especially, in the near-UV, where the discrepancies
rise up to ∼10 per cent. Based on our model fits, we derive angular
diameters with an estimated accuracy of about 1 per cent.
---------------------------------------------------------
Title: The ELM Survey. VII. Orbital Properties of Low-Mass White
Dwarf Binaries
Authors: Brown, Warren R.; Gianninas, A.; Kilic, Mukremin; Kenyon,
Scott J.; Allende Prieto, Carlos
2016ApJ...818..155B Altcode: 2016arXiv160404268B
We present the discovery of 15 extremely low-mass (5\lt {log}g\lt
7) white dwarf (WD) candidates, 9 of which are in ultra-compact
double-degenerate binaries. Our targeted extremely low-mass Survey
sample now includes 76 binaries. The sample has a lognormal distribution
of orbital periods with a median period of 5.4 hr. The velocity
amplitudes imply that the binary companions have a normal distribution
of mass with 0.76 M<SUB>⊙</SUB> mean and 0.25 M<SUB>⊙</SUB>
dispersion. Thus extremely low-mass WDs are found in binaries with
a typical mass ratio of 1:4. Statistically speaking, 95% of the WD
binaries have a total mass below the Chandrasekhar mass, and thus are
not type Ia supernova progenitors. Yet half of the observed binaries
will merge in less than 6 Gyr due to gravitational wave radiation;
probable outcomes include single massive WDs and stable mass transfer
AM CVn binaries. <P />Based on observations obtained at the MMT
Observatory, a joint facility of the Smithsonian Institution and the
University of Arizona.
---------------------------------------------------------
Title: VizieR Online Data Catalog: SDSS-III APOGEE H-band spectral
line lists (Shetrone+, 2015)
Authors: Shetrone, M.; Bizyaev, D.; Lawler, J. E.; Allende Prieto, C.;
Johnson, J. A.; Smith, V. V.; Cunha, K.; Holtzman, J.; Garcia Perez,
A. E.; Meszaros, Sz.; Sobeck, J.; Zamora, O.; Garcia-Hernandez, D. A.;
Souto, D.; Chojnowski, D.; Koesterke, L.; Majewski, S.; Zasowski, G.
2016yCat..22210024S Altcode:
The Apache Point Observatory Galactic Evolution Experiment (APOGEE)
obtained high-resolution (R~22500) and high signal-to-noise ratio
(S/N>100) spectra in the H band (1.51-1.70um), using the Sloan
Foundation 2.5-m Telescope, for more than 100000 cool giant stars
(see Zasowski et al. 2013AJ....146...81Z, for more information about
targeting) spanning all components of the Milky Way. Stellar parameters
and individual chemical abundances are derived from the combined
APOGEE spectra (Nidever et al. 2015AJ....150..173N) with the APOGEE
Stellar Parameters and Chemical Abundances Pipeline (ASPCAP), which is
described in detail in Garcia Perez et al. (2015arXiv151007635G). <P
/>(4 data files).
---------------------------------------------------------
Title: Stellar parametrization from Gaia RVS spectra
Authors: Recio-Blanco, A.; de Laverny, P.; Allende Prieto, C.; Fustes,
D.; Manteiga, M.; Arcay, B.; Bijaoui, A.; Dafonte, C.; Ordenovic,
C.; Ordoñez Blanco, D.
2016A&A...585A..93R Altcode: 2015arXiv151000111R
Context. Among the myriad of data collected by the ESA Gaia satellite,
about 150 million spectra will be delivered by the Radial Velocity
Spectrometer (RVS) for stars as faint as G<SUB>RVS</SUB>~ 16. A specific
stellar parametrization will be performed on most of these RVS spectra,
I.e. those with enough high signal-to-noise ratio (S/N), which should
correspond to single stars that have a magnitude in the RVS band
brighter than ~14.5. Some individual chemical abundances will also
be estimated for the brightest targets. <BR /> Aims: We describe the
different parametrization codes that have been specifically developed
or adapted for RVS spectra within the GSP-Spec working group of the
analysis consortium. The tested codes are based on optimisation (FERRE
and GAUGUIN), projection (MATISSE), or pattern-recognition methods
(Artificial Neural Networks). We present and discuss each of their
expected performances in the recovered stellar atmospheric parameters
(effective temperature, surface gravity, overall metallicity) for
B- to K-type stars. The performances for determining of [α/Fe]
ratios are also presented for cool stars. <BR /> Methods: Each code
has been homogeneously tested with a large grid of RVS simulated
synthetic spectra of BAFGK-spectral types (dwarfs and giants), with
metallicities varying from 10<SUP>-2.5</SUP> to 10<SUP>+ 0.5</SUP>
the solar metallicity, and taking variations of ±0.4 dex in the
composition of the α-elements into consideration. The tests were
performed for S/N ranging from ten to 350. <BR /> Results: For all
the stellar types we considered, stars brighter than G<SUB>RVS</SUB>~
12.5 are very efficiently parametrized by the GSP-Spec pipeline,
including reliable estimations of [α/Fe]. Typical internal errors
for FGK metal-rich and metal-intermediate stars are around 40 K in
T<SUB>eff</SUB>, 0.10 dex in log(g), 0.04 dex in [M/H], and 0.03
dex in [α/Fe] at G<SUB>RVS</SUB> = 10.3. They degrade to 155 K in
T<SUB>eff</SUB>, 0.15 dex in log(g), 0.10 dex in [M/H], and 0.1 dex in
[α/Fe] at G<SUB>RVS</SUB>~ 12. Similar accuracies in T<SUB>eff</SUB>
and [M/H] are found for A-type stars, while the log(g) derivation is
more accurate (errors of 0.07 and 0.12 dex at G<SUB>RVS</SUB> = 12.6 and
13.4, respectively). For the faintest stars, with G<SUB>RVS</SUB>≳
13-14, a T<SUB>eff</SUB> input from the spectrophotometric-derived
parameters will allow the final GSP-Spec parametrization to be
improved. <BR /> Conclusions: The reported results, while neglecting
possible mismatches between synthetic and real spectra, show that the
contribution of the RVS-based stellar parameters will be unique in
the brighter part of the Gaia survey, which allows for crucial age
estimations and accurate chemical abundances. This will constitute
a unique and precious sample, providing many pieces of the Milky Way
history puzzle with unprecedented precision and statistical relevance.
---------------------------------------------------------
Title: Combing the Brown Dwarf Desert with the APOGEE Catalog of
Stellar and Substellar Companion Candidates
Authors: Troup, Nicholas William; De Lee, Nathan M.; Carlberg, Joleen
K.; Nidever, David L.; Majewski, Steven R.; Stassun, Keivan; Covey,
Kevin R.; Skrutskie, Michael F.; Allende-Prieto, Carlos; Hearty,
Fred R.; APOGEE Substellar Companions Working Group
2016AAS...22714213T Altcode:
While both exoplanets and stellar-mass companions have been found in
extremely short-period orbits, there has been a paucity of brown dwarf
(BD) companions orbiting Sun-like stars, a phenomenon known as the
"Brown Dwarf Desert." However, more recent work has shown that this
Desert might be limited in extent, only existing for small separation
(a < 5-10 AU) companions, and may not be as "dry" as initially
thought. It has been previously suggested that there may be an "F
Dwarf Oasis," where the BD Desert observed for Solar-like stars ceases
to exist for F dwarf stars. The Sloan Digital Sky Survey (SDSS-III)
Apache Point Galactic Evolution Experiment (APOGEE) has compiled
a catalog of ~400 of its most compelling stellar and substellar
companion candidates orbiting host stars of various spectral types and
evolutionary states. Among these candidates, approximately 100 had
a derived companion mass in the BD regime (13-80 M<SUB>Jup</SUB>),
which is a significant increase compared to the number of known
small separation (a < 1 AU) BD companions. Our sample appears to
manifest the BD desert, but only for seperations < 0.2 AU rather
than the previously held 5 AU. This is explained by one of the unique
qualities of our sample when compared to previous companions surveys:
Two-thirds of the BD candidates in our sample are orbiting evolved
stars, most of which were F dwarfs during their main sequence lifetime,
consistent with the notion of an F Dwarf Oasis. Using this sample, we
further test this hypothesis by constraining the formation mechanisms
of BD companions, and exploring their orbital evolution as their host
evolves off the main sequence.
---------------------------------------------------------
Title: The EChO science case
Authors: Tinetti, Giovanna; Drossart, Pierre; Eccleston, Paul; Hartogh,
Paul; Isaak, Kate; Linder, Martin; Lovis, Christophe; Micela, Giusi;
Ollivier, Marc; Puig, Ludovic; Ribas, Ignasi; Snellen, Ignas; Swinyard,
Bruce; Allard, France; Barstow, Joanna; Cho, James; Coustenis, Athena;
Cockell, Charles; Correia, Alexandre; Decin, Leen; de Kok, Remco;
Deroo, Pieter; Encrenaz, Therese; Forget, Francois; Glasse, Alistair;
Griffith, Caitlin; Guillot, Tristan; Koskinen, Tommi; Lammer, Helmut;
Leconte, Jeremy; Maxted, Pierre; Mueller-Wodarg, Ingo; Nelson, Richard;
North, Chris; Pallé, Enric; Pagano, Isabella; Piccioni, Guseppe;
Pinfield, David; Selsis, Franck; Sozzetti, Alessandro; Stixrude,
Lars; Tennyson, Jonathan; Turrini, Diego; Zapatero-Osorio, Mariarosa;
Beaulieu, Jean-Philippe; Grodent, Denis; Guedel, Manuel; Luz, David;
Nørgaard-Nielsen, Hans Ulrik; Ray, Tom; Rickman, Hans; Selig,
Avri; Swain, Mark; Banaszkiewicz, Marek; Barlow, Mike; Bowles, Neil;
Branduardi-Raymont, Graziella; du Foresto, Vincent Coudé; Gerard,
Jean-Claude; Gizon, Laurent; Hornstrup, Allan; Jarchow, Christopher;
Kerschbaum, Franz; Kovacs, Géza; Lagage, Pierre-Olivier; Lim, Tanya;
Lopez-Morales, Mercedes; Malaguti, Giuseppe; Pace, Emanuele; Pascale,
Enzo; Vandenbussche, Bart; Wright, Gillian; Ramos Zapata, Gonzalo;
Adriani, Alberto; Azzollini, Ruymán; Balado, Ana; Bryson, Ian;
Burston, Raymond; Colomé, Josep; Crook, Martin; Di Giorgio, Anna;
Griffin, Matt; Hoogeveen, Ruud; Ottensamer, Roland; Irshad, Ranah;
Middleton, Kevin; Morgante, Gianluca; Pinsard, Frederic; Rataj, Mirek;
Reess, Jean-Michel; Savini, Giorgio; Schrader, Jan-Rutger; Stamper,
Richard; Winter, Berend; Abe, L.; Abreu, M.; Achilleos, N.; Ade, P.;
Adybekian, V.; Affer, L.; Agnor, C.; Agundez, M.; Alard, C.; Alcala,
J.; Allende Prieto, C.; Alonso Floriano, F. J.; Altieri, F.; Alvarez
Iglesias, C. A.; Amado, P.; Andersen, A.; Aylward, A.; Baffa, C.;
Bakos, G.; Ballerini, P.; Banaszkiewicz, M.; Barber, R. J.; Barrado,
D.; Barton, E. J.; Batista, V.; Bellucci, G.; Belmonte Avilés,
J. A.; Berry, D.; Bézard, B.; Biondi, D.; Błęcka, M.; Boisse, I.;
Bonfond, B.; Bordé, P.; Börner, P.; Bouy, H.; Brown, L.; Buchhave,
L.; Budaj, J.; Bulgarelli, A.; Burleigh, M.; Cabral, A.; Capria,
M. T.; Cassan, A.; Cavarroc, C.; Cecchi-Pestellini, C.; Cerulli,
R.; Chadney, J.; Chamberlain, S.; Charnoz, S.; Christian Jessen,
N.; Ciaravella, A.; Claret, A.; Claudi, R.; Coates, A.; Cole, R.;
Collura, A.; Cordier, D.; Covino, E.; Danielski, C.; Damasso, M.;
Deeg, H. J.; Delgado-Mena, E.; Del Vecchio, C.; Demangeon, O.; De Sio,
A.; De Wit, J.; Dobrijévic, M.; Doel, P.; Dominic, C.; Dorfi, E.;
Eales, S.; Eiroa, C.; Espinoza Contreras, M.; Esposito, M.; Eymet,
V.; Fabrizio, N.; Fernández, M.; Femenía Castella, B.; Figueira,
P.; Filacchione, G.; Fletcher, L.; Focardi, M.; Fossey, S.; Fouqué,
P.; Frith, J.; Galand, M.; Gambicorti, L.; Gaulme, P.; García López,
R. J.; Garcia-Piquer, A.; Gear, W.; Gerard, J. -C.; Gesa, L.; Giani,
E.; Gianotti, F.; Gillon, M.; Giro, E.; Giuranna, M.; Gomez, H.;
Gomez-Leal, I.; Gonzalez Hernandez, J.; González Merino, B.; Graczyk,
R.; Grassi, D.; Guardia, J.; Guio, P.; Gustin, J.; Hargrave, P.; Haigh,
J.; Hébrard, E.; Heiter, U.; Heredero, R. L.; Herrero, E.; Hersant,
F.; Heyrovsky, D.; Hollis, M.; Hubert, B.; Hueso, R.; Israelian, G.;
Iro, N.; Irwin, P.; Jacquemoud, S.; Jones, G.; Jones, H.; Justtanont,
K.; Kehoe, T.; Kerschbaum, F.; Kerins, E.; Kervella, P.; Kipping, D.;
Koskinen, T.; Krupp, N.; Lahav, O.; Laken, B.; Lanza, N.; Lellouch,
E.; Leto, G.; Licandro Goldaracena, J.; Lithgow-Bertelloni, C.; Liu,
S. J.; Lo Cicero, U.; Lodieu, N.; Lognonné, P.; Lopez-Puertas,
M.; Lopez-Valverde, M. A.; Lundgaard Rasmussen, I.; Luntzer, A.;
Machado, P.; MacTavish, C.; Maggio, A.; Maillard, J. -P.; Magnes, W.;
Maldonado, J.; Mall, U.; Marquette, J. -B.; Mauskopf, P.; Massi, F.;
Maurin, A. -S.; Medvedev, A.; Michaut, C.; Miles-Paez, P.; Montalto,
M.; Montañés Rodríguez, P.; Monteiro, M.; Montes, D.; Morais, H.;
Morales, J. C.; Morales-Calderón, M.; Morello, G.; Moro Martín,
A.; Moses, J.; Moya Bedon, A.; Murgas Alcaino, F.; Oliva, E.; Orton,
G.; Palla, F.; Pancrazzi, M.; Pantin, E.; Parmentier, V.; Parviainen,
H.; Peña Ramírez, K. Y.; Peralta, J.; Perez-Hoyos, S.; Petrov, R.;
Pezzuto, S.; Pietrzak, R.; Pilat-Lohinger, E.; Piskunov, N.; Prinja,
R.; Prisinzano, L.; Polichtchouk, I.; Poretti, E.; Radioti, A.; Ramos,
A. A.; Rank-Lüftinger, T.; Read, P.; Readorn, K.; Rebolo López,
R.; Rebordão, J.; Rengel, M.; Rezac, L.; Rocchetto, M.; Rodler, F.;
Sánchez Béjar, V. J.; Sanchez Lavega, A.; Sanromá, E.; Santos,
N.; Sanz Forcada, J.; Scandariato, G.; Schmider, F. -X.; Scholz,
A.; Scuderi, S.; Sethenadh, J.; Shore, S.; Showman, A.; Sicardy, B.;
Sitek, P.; Smith, A.; Soret, L.; Sousa, S.; Stiepen, A.; Stolarski,
M.; Strazzulla, G.; Tabernero, H. M.; Tanga, P.; Tecsa, M.; Temple,
J.; Terenzi, L.; Tessenyi, M.; Testi, L.; Thompson, S.; Thrastarson,
H.; Tingley, B. W.; Trifoglio, M.; Martín Torres, J.; Tozzi, A.;
Turrini, D.; Varley, R.; Vakili, F.; de Val-Borro, M.; Valdivieso,
M. L.; Venot, O.; Villaver, E.; Vinatier, S.; Viti, S.; Waldmann,
I.; Waltham, D.; Ward-Thompson, D.; Waters, R.; Watkins, C.; Watson,
D.; Wawer, P.; Wawrzaszk, A.; White, G.; Widemann, T.; Winek, W.;
Wiśniowski, T.; Yelle, R.; Yung, Y.; Yurchenko, S. N.
2015ExA....40..329T Altcode: 2015ExA...tmp...67T; 2015arXiv150205747T
The discovery of almost two thousand exoplanets has revealed an
unexpectedly diverse planet population. We see gas giants in few-day
orbits, whole multi-planet systems within the orbit of Mercury,
and new populations of planets with masses between that of the Earth
and Neptune—all unknown in the Solar System. Observations to date
have shown that our Solar System is certainly not representative of
the general population of planets in our Milky Way. The key science
questions that urgently need addressing are therefore: What are
exoplanets made of? Why are planets as they are? How do planetary
systems work and what causes the exceptional diversity observed as
compared to the Solar System? The EChO (Exoplanet Characterisation
Observatory) space mission was conceived to take up the challenge to
explain this diversity in terms of formation, evolution, internal
structure and planet and atmospheric composition. This requires
in-depth spectroscopic knowledge of the atmospheres of a large and
well-defined planet sample for which precise physical, chemical and
dynamical information can be obtained. In order to fulfil this ambitious
scientific program, EChO was designed as a dedicated survey mission
for transit and eclipse spectroscopy capable of observing a large,
diverse and well-defined planet sample within its 4-year mission
lifetime. The transit and eclipse spectroscopy method, whereby the
signal from the star and planet are differentiated using knowledge of
the planetary ephemerides, allows us to measure atmospheric signals
from the planet at levels of at least 10<SUP>-4</SUP> relative to
the star. This can only be achieved in conjunction with a carefully
designed stable payload and satellite platform. It is also necessary
to provide broad instantaneous wavelength coverage to detect as many
molecular species as possible, to probe the thermal structure of the
planetary atmospheres and to correct for the contaminating effects of
the stellar photosphere. This requires wavelength coverage of at least
0.55 to 11 μm with a goal of covering from 0.4 to 16 μm. Only modest
spectral resolving power is needed, with R ~ 300 for wavelengths less
than 5 μm and R ~ 30 for wavelengths greater than this. The transit
spectroscopy technique means that no spatial resolution is required. A
telescope collecting area of about 1 m<SUP>2</SUP> is sufficiently
large to achieve the necessary spectro-photometric precision: for the
Phase A study a 1.13 m<SUP>2</SUP> telescope, diffraction limited at 3
μm has been adopted. Placing the satellite at L2 provides a cold and
stable thermal environment as well as a large field of regard to allow
efficient time-critical observation of targets randomly distributed over
the sky. EChO has been conceived to achieve a single goal: exoplanet
spectroscopy. The spectral coverage and signal-to-noise to be achieved
by EChO, thanks to its high stability and dedicated design, would be
a game changer by allowing atmospheric composition to be measured
with unparalleled exactness: at least a factor 10 more precise and
a factor 10 to 1000 more accurate than current observations. This
would enable the detection of molecular abundances three orders of
magnitude lower than currently possible and a fourfold increase from
the handful of molecules detected to date. Combining these data with
estimates of planetary bulk compositions from accurate measurements
of their radii and masses would allow degeneracies associated with
planetary interior modelling to be broken, giving unique insight
into the interior structure and elemental abundances of these alien
worlds. EChO would allow scientists to study exoplanets both as a
population and as individuals. The mission can target super-Earths,
Neptune-like, and Jupiter-like planets, in the very hot to temperate
zones (planet temperatures of 300-3000 K) of F to M-type host stars. The
EChO core science would be delivered by a three-tier survey. The EChO
Chemical Census: This is a broad survey of a few-hundred exoplanets,
which allows us to explore the spectroscopic and chemical diversity of
the exoplanet population as a whole. The EChO Origin: This is a deep
survey of a subsample of tens of exoplanets for which significantly
higher signal to noise and spectral resolution spectra can be obtained
to explain the origin of the exoplanet diversity (such as formation
mechanisms, chemical processes, atmospheric escape). The EChO Rosetta
Stones: This is an ultra-high accuracy survey targeting a subsample
of select exoplanets. These will be the bright "benchmark" cases
for which a large number of measurements would be taken to explore
temporal variations, and to obtain two and three dimensional spatial
information on the atmospheric conditions through eclipse-mapping
techniques. If EChO were launched today, the exoplanets currently
observed are sufficient to provide a large and diverse sample. The
Chemical Census survey would consist of > 160 exoplanets with a range
of planetary sizes, temperatures, orbital parameters and stellar host
properties. Additionally, over the next 10 years, several new ground-
and space-based transit photometric surveys and missions will come
on-line (e.g. NGTS, CHEOPS, TESS, PLATO), which will specifically focus
on finding bright, nearby systems. The current rapid rate of discovery
would allow the target list to be further optimised in the years prior
to EChO's launch and enable the atmospheric characterisation of hundreds
of planets.
---------------------------------------------------------
Title: Evidence for a metal-poor population in the inner Galactic
bulge
Authors: Schultheis, M.; Cunha, K.; Zasowski, G.; García Pérez,
A. E.; Sellgren, K.; Smith, V.; García-Hernández, D. A.; Zamora, O.;
Fritz, T. K.; Anders, F.; Allende Prieto, C.; Bizyaev, D.; Kinemuchi,
K.; Pan, K.; Malanushenko, E.; Malanushenko, V.; Shetrone, M. D.
2015A&A...584A..45S Altcode: 2015arXiv150907104S
The inner Galactic bulge has, until recently, been avoided in
chemical evolution studies because of extreme extinction and stellar
crowding. Large, near-IR spectroscopic surveys, such as the Apache
Point Observatory Galactic Evolution Experiment (APOGEE), for the
first time allow the measurement of metallicities in the inner region
of our Galaxy. We study metallicities of 33 K/M giants situated in
the Galactic center region from observations obtained with the APOGEE
survey. We selected K/M giants with reliable stellar parameters from the
APOGEE/ASPCAP pipeline. Distances, interstellar extinction values, and
radial velocities were checked to confirm that these stars are indeed
situated in the inner Galactic bulge. We find a metal-rich population
centered at [M/H] = +0.4 dex, in agreement with earlier studies of
other bulge regions, but we also discovered a peak at low metallicity
around [M/H] = -1.0 dex. This finding suggests the presence of a
metal-poor population, which has not previously been detected in the
central region. Our results indicate a dominant metal-rich population
with a metal-poor component that is enhanced in the α-elements. This
metal-poor population may be associated with the classical bulge and
a fast formation scenario.
---------------------------------------------------------
Title: The SDSS-III APOGEE Spectral Line List for H-band Spectroscopy
Authors: Shetrone, M.; Bizyaev, D.; Lawler, J. E.; Allende Prieto, C.;
Johnson, J. A.; Smith, V. V.; Cunha, K.; Holtzman, J.; García Pérez,
A. E.; Mészáros, Sz.; Sobeck, J.; Zamora, O.; García-Hernández,
D. A.; Souto, D.; Chojnowski, D.; Koesterke, L.; Majewski, S.;
Zasowski, G.
2015ApJS..221...24S Altcode: 2015arXiv150204080S
We present the H-band spectral line lists adopted by the Apache Point
Observatory Galactic Evolution Experiment (APOGEE). The APOGEE line
lists comprise astrophysical, theoretical, and laboratory sources from
the literature, as well as newly evaluated astrophysical oscillator
strengths and damping parameters. We discuss the construction of the
APOGEE line list, which is one of the critical inputs for the APOGEE
Stellar Parameters and Chemical Abundances Pipeline, and present
three different versions that have been used at various stages of the
project. The methodology for the newly calculated astrophysical line
lists is reviewed. The largest of these three line lists contains
134,457 molecular and atomic transitions. In addition to the format
adopted to store the data, the line lists are available in MOOG,
Synspec, and Turbospectrum formats. The limitations of the line
lists along with guidance for its use on different spectral types are
discussed. We also present a list of H-band spectral features that are
either poorly represented or completely missing in our line list. This
list is based on the average of a large number of spectral fit residuals
for APOGEE observations spanning a wide range of stellar parameters.
---------------------------------------------------------
Title: The Data Reduction Pipeline for the Apache Point Observatory
Galactic Evolution Experiment
Authors: Nidever, David L.; Holtzman, Jon A.; Allende Prieto, Carlos;
Beland, Stephane; Bender, Chad; Bizyaev, Dmitry; Burton, Adam;
Desphande, Rohit; Fleming, Scott W.; García Pérez, Ana E.; Hearty,
Fred R.; Majewski, Steven R.; Mészáros, Szabolcs; Muna, Demitri;
Nguyen, Duy; Schiavon, Ricardo P.; Shetrone, Matthew; Skrutskie,
Michael F.; Sobeck, Jennifer S.; Wilson, John C.
2015AJ....150..173N Altcode: 2015arXiv150103742N
The Apache Point Observatory Galactic Evolution Experiment (APOGEE),
part of the Sloan Digital Sky Survey III, explores the stellar
populations of the Milky Way using the Sloan 2.5-m telescope linked
to a high resolution (R ∼ 22,500), near-infrared (1.51-1.70 μm)
spectrograph with 300 optical fibers. For over 150,000 predominantly
red giant branch stars that APOGEE targeted across the Galactic bulge,
disks and halo, the collected high signal-to-noise ratio (>100
per half-resolution element) spectra provide accurate (∼0.1 km
s<SUP>-1</SUP>) RVs, stellar atmospheric parameters, and precise
(≲0.1 dex) chemical abundances for about 15 chemical species. Here
we describe the basic APOGEE data reduction software that reduces
multiple 3D raw data cubes into calibrated, well-sampled, combined
1D spectra, as implemented for the SDSS-III/APOGEE data releases
(DR10, DR11 and DR12). The processing of the near-IR spectral data of
APOGEE presents some challenges for reduction, including automated sky
subtraction and telluric correction over a 3°-diameter field and the
combination of spectrally dithered spectra. We also discuss areas for
future improvement.
---------------------------------------------------------
Title: Abundances, Stellar Parameters, and Spectra from the
SDSS-III/APOGEE Survey
Authors: Holtzman, Jon A.; Shetrone, Matthew; Johnson, Jennifer A.;
Allende Prieto, Carlos; Anders, Friedrich; Andrews, Brett; Beers,
Timothy C.; Bizyaev, Dmitry; Blanton, Michael R.; Bovy, Jo; Carrera,
Ricardo; Chojnowski, S. Drew; Cunha, Katia; Eisenstein, Daniel J.;
Feuillet, Diane; Frinchaboy, Peter M.; Galbraith-Frew, Jessica;
García Pérez, Ana E.; García-Hernández, D. A.; Hasselquist, Sten;
Hayden, Michael R.; Hearty, Fred R.; Ivans, Inese; Majewski, Steven R.;
Martell, Sarah; Meszaros, Szabolcs; Muna, Demitri; Nidever, David;
Nguyen, Duy Cuong; O'Connell, Robert W.; Pan, Kaike; Pinsonneault,
Marc; Robin, Annie C.; Schiavon, Ricardo P.; Shane, Neville; Sobeck,
Jennifer; Smith, Verne V.; Troup, Nicholas; Weinberg, David H.;
Wilson, John C.; Wood-Vasey, W. M.; Zamora, Olga; Zasowski, Gail
2015AJ....150..148H Altcode: 2015arXiv150104110H
The SDSS-III/Apache Point Observatory Galactic Evolution Experiment
(APOGEE) survey operated from 2011-2014 using the APOGEE spectrograph,
which collects high-resolution (R ∼ 22,500), near-IR (1.51-1.70 μm)
spectra with a multiplexing (300 fiber-fed objects) capability. We
describe the survey data products that are publicly available, which
include catalogs with radial velocity, stellar parameters, and 15
elemental abundances for over 150,000 stars, as well as the more than
500,000 spectra from which these quantities are derived. Calibration
relations for the stellar parameters ({T}<SUB>{eff</SUB>}, {log} g,
[M/H], [α/M]) and abundances (C, N, O, Na, Mg, Al, Si, S, K, Ca, Ti,
V, Mn, Fe, Ni) are presented and discussed. The internal scatter of
the abundances within clusters indicates that abundance precision is
generally between 0.05 and 0.09 dex across a broad temperature range; it
is smaller for some elemental abundances within more limited ranges and
at high signal-to-noise ratio. We assess the accuracy of the abundances
using comparison of mean cluster metallicities with literature values,
APOGEE observations of the solar spectrum and of Arcturus, comparison
of individual star abundances with other measurements, and consideration
of the locus of derived parameters and abundances of the entire sample,
and find that it is challenging to determine the absolute abundance
scale; external accuracy may be good to 0.1-0.2 dex. Uncertainties
may be larger at cooler temperatures ({T}<SUB>{eff</SUB>} \lt 4000
{{K}}). Access to the public data release and data products is
described, and some guidance for using the data products is provided.
---------------------------------------------------------
Title: The Gaia-ESO Survey: chemical signatures of rocky accretion
in a young solar-type star
Authors: Spina, L.; Palla, F.; Randich, S.; Sacco, G.; Jeffries,
R.; Magrini, L.; Franciosini, E.; Meyer, M. R.; Tautvaišienė, G.;
Gilmore, G.; Alfaro, E. J.; Allende Prieto, C.; Bensby, T.; Bragaglia,
A.; Flaccomio, E.; Koposov, S. E.; Lanzafame, A. C.; Costado, M. T.;
Hourihane, A.; Lardo, C.; Lewis, J.; Monaco, L.; Morbidelli, L.;
Sousa, S. G.; Worley, C. C.; Zaggia, S.
2015A&A...582L...6S Altcode: 2015arXiv150900933S
It is well known that newly formed planetary systems undergo processes
of orbital reconfiguration and planetary migration. As a result,
planets or protoplanetary objects may accrete onto the central star,
being fused and mixed into its external layers. If the accreted
mass is sufficiently high and the star has a sufficiently thin
convective envelope, such events may result in a modification of the
chemical composition of the stellar photosphere in an observable way,
enhancing it with elements that were abundant in the accreted mass. The
recent Gaia-ESO Survey observations of the 10-20 Myr old Gamma Velorum
cluster have enabled identifying a star that is significantly enriched
in iron with respect to other cluster members. In this Letter we
further investigate the abundance pattern of this star, showing that
its abundance anomaly is not limited to iron, but is also present in
the refractory elements, whose overabundances are correlated with the
condensation temperature. This finding strongly supports the hypothesis
of a recent accretion of rocky material. <P />Based on observations
made with the ESO/VLT, at Paranal Observatory, under program 188.B-3002
(The Gaia-ESO Public Spectroscopic Survey).
---------------------------------------------------------
Title: The Gaia-ESO Survey: Empirical determination of the precision
of stellar radial velocities and projected rotation velocities
Authors: Jackson, R. J.; Jeffries, R. D.; Lewis, J.; Koposov, S. E.;
Sacco, G. G.; Randich, S.; Gilmore, G.; Asplund, M.; Binney, J.;
Bonifacio, P.; Drew, J. E.; Feltzing, S.; Ferguson, A. M. N.;
Micela, G.; Neguerela, I.; Prusti, T.; Rix, H. -W.; Vallenari,
A.; Alfaro, E. J.; Allende Prieto, C.; Babusiaux, C.; Bensby, T.;
Blomme, R.; Bragaglia, A.; Flaccomio, E.; Francois, P.; Hambly, N.;
Irwin, M.; Korn, A. J.; Lanzafame, A. C.; Pancino, E.; Recio-Blanco,
A.; Smiljanic, R.; Van Eck, S.; Walton, N.; Bayo, A.; Bergemann, M.;
Carraro, G.; Costado, M. T.; Damiani, F.; Edvardsson, B.; Franciosini,
E.; Frasca, A.; Heiter, U.; Hill, V.; Hourihane, A.; Jofré, P.; Lardo,
C.; de Laverny, P.; Lind, K.; Magrini, L.; Marconi, G.; Martayan, C.;
Masseron, T.; Monaco, L.; Morbidelli, L.; Prisinzano, L.; Sbordone,
L.; Sousa, S. G.; Worley, C. C.; Zaggia, S.
2015A&A...580A..75J Altcode: 2015arXiv150507019J
Context. The Gaia-ESO Survey (GES) is a large public spectroscopic
survey at the European Southern Observatory Very Large Telescope. <BR
/> Aims: A key aim is to provide precise radial velocities (RVs) and
projected equatorial velocities (vsini) for representative samples
of Galactic stars, which will complement information obtained by the
Gaia astrometry satellite. <BR /> Methods: We present an analysis
to empirically quantify the size and distribution of uncertainties
in RV and vsini using spectra from repeated exposures of the same
stars. <BR /> Results: We show that the uncertainties vary as simple
scaling functions of signal-to-noise ratio (S/N) and vsini, that the
uncertainties become larger with increasing photospheric temperature,
but that the dependence on stellar gravity, metallicity and age is
weak. The underlying uncertainty distributions have extended tails
that are better represented by Student's t-distributions than by
normal distributions. <BR /> Conclusions: Parametrised results are
provided, which enable estimates of the RV precision for almost all GES
measurements, and estimates of the vsini precision for stars in young
clusters, as a function of S/N, vsini and stellar temperature. The
precision of individual high S/N GES RV measurements is 0.22-0.26 km
s<SUP>-1</SUP>, dependent on instrumental configuration. <P />Based on
observations collected with the FLAMES spectrograph at VLT/UT2 telescope
(Paranal Observatory, ESO, Chile), for the Gaia- ESO Large Public Survey
(188.B-3002).Full Table 2 is only available at the CDS via anonymous ftp
to <A href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/580/A75">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/580/A75</A>
---------------------------------------------------------
Title: Chemical Cartography with APOGEE: Metallicity Distribution
Functions and the Chemical Structure of the Milky Way Disk
Authors: Hayden, Michael R.; Bovy, Jo; Holtzman, Jon A.; Nidever, David
L.; Bird, Jonathan C.; Weinberg, David H.; Andrews, Brett H.; Majewski,
Steven R.; Allende Prieto, Carlos; Anders, Friedrich; Beers, Timothy
C.; Bizyaev, Dmitry; Chiappini, Cristina; Cunha, Katia; Frinchaboy,
Peter; García-Herńandez, D. A.; García Pérez, Ana E.; Girardi,
Léo; Harding, Paul; Hearty, Fred R.; Johnson, Jennifer A.; Mészáros,
Szabolcs; Minchev, Ivan; O'Connell, Robert; Pan, Kaike; Robin, Annie
C.; Schiavon, Ricardo P.; Schneider, Donald P.; Schultheis, Mathias;
Shetrone, Matthew; Skrutskie, Michael; Steinmetz, Matthias; Smith,
Verne; Wilson, John C.; Zamora, Olga; Zasowski, Gail
2015ApJ...808..132H Altcode: 2015arXiv150302110H
Using a sample of 69,919 red giants from the SDSS-III/APOGEE Data
Release 12, we measure the distribution of stars in the [α/Fe] versus
[Fe/H] plane and the metallicity distribution functions (MDFs) across
an unprecedented volume of the Milky Way disk, with radius 3 < R
< 15 kpc and height | z| \lt 2 kpc. Stars in the inner disk (R <
5 kpc) lie along a single track in [α/Fe] versus [Fe/H], starting with
α-enhanced, metal-poor stars and ending at [α/Fe] ∼ 0 and [Fe/H] ∼
+0.4. At larger radii we find two distinct sequences in [α/Fe] versus
[Fe/H] space, with a roughly solar-α sequence that spans a decade in
metallicity and a high-α sequence that merges with the low-α sequence
at super-solar [Fe/H]. The location of the high-α sequence is nearly
constant across the disk however, there are very few high-α stars at R
> 11 kpc. The peak of the midplane MDF shifts to lower metallicity at
larger R, reflecting the Galactic metallicity gradient. Most strikingly,
the shape of the midplane MDF changes systematically with radius,
from a negatively skewed distribution at 3 < R < 7 kpc, to a
roughly Gaussian distribution at the solar annulus, to a positively
skewed shape in the outer Galaxy. For stars with | z| \gt 1 kpc or
[α/Fe] > 0.18, the MDF shows little dependence on R. The positive
skewness of the outer-disk MDF may be a signature of radial migration;
we show that blurring of stellar populations by orbital eccentricities
is not enough to explain the reversal of MDF shape, but a simple model
of radial migration can do so.
---------------------------------------------------------
Title: An equatorial ultra iron-poor star identified in BOSS
Authors: Allende Prieto, C.; Fernández-Alvar, E.; Aguado, D. S.;
González Hernández, J. I.; Rebolo, R.; Lee, Y. S.; Beers, T. C.;
Rockosi, C. M.; Ge, J.
2015A&A...579A..98A Altcode: 2015arXiv150505555A
We report the discovery of SDSS J131326.89-001941.4, an ultra iron-poor
red giant star ([Fe/H] ≃ -4.3) with a very high carbon abundance
([C/Fe] ≃ +2.5). This object is the fifth star in this rare class, and
the combination of a fairly low effective temperature (T<SUB>eff</SUB>
≃ 5300 K), which enhances line absorption, with its brightness
(g = 16.9), makes it possible to measure the abundances of calcium,
carbon and iron using a low-resolution spectrum from the Sloan Digital
Sky Survey. We examine the carbon and iron abundance ratios in this
star and other similar objects in the light of predicted yields from
metal-free massive stars, and conclude that they are consistent. By
way of comparison, stars with similarly low iron abundances but lower
carbon-to-iron ratios deviate from the theoretical predictions.
---------------------------------------------------------
Title: Rapid Rotation of Low-mass Red Giants Using APOKASC: A Measure
of Interaction Rates on the Post-main-sequence
Authors: Tayar, Jamie; Ceillier, Tugdual; García-Hernández, D. A.;
Troup, Nicholas W.; Mathur, Savita; García, Rafael A.; Zamora, O.;
Johnson, Jennifer A.; Pinsonneault, Marc H.; Mészáros, Szabolcs;
Allende Prieto, Carlos; Chaplin, William J.; Elsworth, Yvonne; Hekker,
Saskia; Nidever, David L.; Salabert, David; Schneider, Donald P.;
Serenelli, Aldo; Shetrone, Matthew; Stello, Dennis
2015ApJ...807...82T Altcode: 2015arXiv150503536T
We investigate the occurrence rate of rapidly rotating (v{sin}i >10
km s<SUP>-1</SUP>), low-mass giant stars in the Apache Point Observatory
Galaxy Evolution Experiment-Kepler (APOKASC) fields with asteroseismic
mass and surface gravity measurements. Such stars are likely merger
products and their frequency places interesting constraints on stellar
population models. We also identify anomalous rotators, i.e., stars
with 5 km s<SUP>-1</SUP> < v{sin}i < 10 km s<SUP>-1</SUP> that
are rotating significantly faster than both angular momentum evolution
predictions and the measured rates of similar stars. Our data set
contains fewer rapid rotators than one would expect given measurements
of the Galactic field star population, which likely indicates that
asteroseismic detections are less common in rapidly rotating red
giants. The number of low-mass moderate (5-10 km s<SUP>-1</SUP>)
rotators in our sample gives a lower limit of 7% for the rate at which
low-mass stars interact on the upper red giant branch because single
stars in this mass range are expected to rotate slowly. Finally,
we classify the likely origin of the rapid or anomalous rotation
where possible. KIC 10293335 is identified as a merger product and
KIC 6501237 is a possible binary system of two oscillating red giants.
---------------------------------------------------------
Title: The Eleventh and Twelfth Data Releases of the Sloan Digital
Sky Survey: Final Data from SDSS-III
Authors: Alam, Shadab; Albareti, Franco D.; Allende Prieto, Carlos;
Anders, F.; Anderson, Scott F.; Anderton, Timothy; Andrews, Brett
H.; Armengaud, Eric; Aubourg, Éric; Bailey, Stephen; Basu, Sarbani;
Bautista, Julian E.; Beaton, Rachael L.; Beers, Timothy C.; Bender,
Chad F.; Berlind, Andreas A.; Beutler, Florian; Bhardwaj, Vaishali;
Bird, Jonathan C.; Bizyaev, Dmitry; Blake, Cullen H.; Blanton, Michael
R.; Blomqvist, Michael; Bochanski, John J.; Bolton, Adam S.; Bovy,
Jo; Shelden Bradley, A.; Brandt, W. N.; Brauer, D. E.; Brinkmann,
J.; Brown, Peter J.; Brownstein, Joel R.; Burden, Angela; Burtin,
Etienne; Busca, Nicolás G.; Cai, Zheng; Capozzi, Diego; Carnero
Rosell, Aurelio; Carr, Michael A.; Carrera, Ricardo; Chambers,
K. C.; Chaplin, William James; Chen, Yen-Chi; Chiappini, Cristina;
Chojnowski, S. Drew; Chuang, Chia-Hsun; Clerc, Nicolas; Comparat,
Johan; Covey, Kevin; Croft, Rupert A. C.; Cuesta, Antonio J.; Cunha,
Katia; da Costa, Luiz N.; Da Rio, Nicola; Davenport, James R. A.;
Dawson, Kyle S.; De Lee, Nathan; Delubac, Timothée; Deshpande,
Rohit; Dhital, Saurav; Dutra-Ferreira, Letícia; Dwelly, Tom; Ealet,
Anne; Ebelke, Garrett L.; Edmondson, Edward M.; Eisenstein, Daniel J.;
Ellsworth, Tristan; Elsworth, Yvonne; Epstein, Courtney R.; Eracleous,
Michael; Escoffier, Stephanie; Esposito, Massimiliano; Evans, Michael
L.; Fan, Xiaohui; Fernández-Alvar, Emma; Feuillet, Diane; Filiz Ak,
Nurten; Finley, Hayley; Finoguenov, Alexis; Flaherty, Kevin; Fleming,
Scott W.; Font-Ribera, Andreu; Foster, Jonathan; Frinchaboy, Peter M.;
Galbraith-Frew, J. G.; García, Rafael A.; García-Hernández, D. A.;
García Pérez, Ana E.; Gaulme, Patrick; Ge, Jian; Génova-Santos,
R.; Georgakakis, A.; Ghezzi, Luan; Gillespie, Bruce A.; Girardi, Léo;
Goddard, Daniel; Gontcho, Satya Gontcho A.; González Hernández, Jonay
I.; Grebel, Eva K.; Green, Paul J.; Grieb, Jan Niklas; Grieves, Nolan;
Gunn, James E.; Guo, Hong; Harding, Paul; Hasselquist, Sten; Hawley,
Suzanne L.; Hayden, Michael; Hearty, Fred R.; Hekker, Saskia; Ho,
Shirley; Hogg, David W.; Holley-Bockelmann, Kelly; Holtzman, Jon A.;
Honscheid, Klaus; Huber, Daniel; Huehnerhoff, Joseph; Ivans, Inese
I.; Jiang, Linhua; Johnson, Jennifer A.; Kinemuchi, Karen; Kirkby,
David; Kitaura, Francisco; Klaene, Mark A.; Knapp, Gillian R.; Kneib,
Jean-Paul; Koenig, Xavier P.; Lam, Charles R.; Lan, Ting-Wen; Lang,
Dustin; Laurent, Pierre; Le Goff, Jean-Marc; Leauthaud, Alexie; Lee,
Khee-Gan; Lee, Young Sun; Licquia, Timothy C.; Liu, Jian; Long,
Daniel C.; López-Corredoira, Martín; Lorenzo-Oliveira, Diego;
Lucatello, Sara; Lundgren, Britt; Lupton, Robert H.; Mack, Claude E.,
III; Mahadevan, Suvrath; Maia, Marcio A. G.; Majewski, Steven R.;
Malanushenko, Elena; Malanushenko, Viktor; Manchado, A.; Manera, Marc;
Mao, Qingqing; Maraston, Claudia; Marchwinski, Robert C.; Margala,
Daniel; Martell, Sarah L.; Martig, Marie; Masters, Karen L.; Mathur,
Savita; McBride, Cameron K.; McGehee, Peregrine M.; McGreer, Ian D.;
McMahon, Richard G.; Ménard, Brice; Menzel, Marie-Luise; Merloni,
Andrea; Mészáros, Szabolcs; Miller, Adam A.; Miralda-Escudé, Jordi;
Miyatake, Hironao; Montero-Dorta, Antonio D.; More, Surhud; Morganson,
Eric; Morice-Atkinson, Xan; Morrison, Heather L.; Mosser, Benôit;
Muna, Demitri; Myers, Adam D.; Nandra, Kirpal; Newman, Jeffrey A.;
Neyrinck, Mark; Nguyen, Duy Cuong; Nichol, Robert C.; Nidever,
David L.; Noterdaeme, Pasquier; Nuza, Sebastián E.; O'Connell,
Julia E.; O'Connell, Robert W.; O'Connell, Ross; Ogando, Ricardo
L. C.; Olmstead, Matthew D.; Oravetz, Audrey E.; Oravetz, Daniel J.;
Osumi, Keisuke; Owen, Russell; Padgett, Deborah L.; Padmanabhan,
Nikhil; Paegert, Martin; Palanque-Delabrouille, Nathalie; Pan, Kaike;
Parejko, John K.; Pâris, Isabelle; Park, Changbom; Pattarakijwanich,
Petchara; Pellejero-Ibanez, M.; Pepper, Joshua; Percival, Will J.;
Pérez-Fournon, Ismael; Pérez-Ràfols, Ignasi; Petitjean, Patrick;
Pieri, Matthew M.; Pinsonneault, Marc H.; Porto de Mello, Gustavo
F.; Prada, Francisco; Prakash, Abhishek; Price-Whelan, Adrian M.;
Protopapas, Pavlos; Raddick, M. Jordan; Rahman, Mubdi; Reid, Beth A.;
Rich, James; Rix, Hans-Walter; Robin, Annie C.; Rockosi, Constance M.;
Rodrigues, Thaíse S.; Rodríguez-Torres, Sergio; Roe, Natalie A.;
Ross, Ashley J.; Ross, Nicholas P.; Rossi, Graziano; Ruan, John J.;
Rubiño-Martín, J. A.; Rykoff, Eli S.; Salazar-Albornoz, Salvador;
Salvato, Mara; Samushia, Lado; Sánchez, Ariel G.; Santiago, Basílio;
Sayres, Conor; Schiavon, Ricardo P.; Schlegel, David J.; Schmidt,
Sarah J.; Schneider, Donald P.; Schultheis, Mathias; Schwope, Axel
D.; Scóccola, C. G.; Scott, Caroline; Sellgren, Kris; Seo, Hee-Jong;
Serenelli, Aldo; Shane, Neville; Shen, Yue; Shetrone, Matthew; Shu,
Yiping; Silva Aguirre, V.; Sivarani, Thirupathi; Skrutskie, M. F.;
Slosar, Anže; Smith, Verne V.; Sobreira, Flávia; Souto, Diogo;
Stassun, Keivan G.; Steinmetz, Matthias; Stello, Dennis; Strauss,
Michael A.; Streblyanska, Alina; Suzuki, Nao; Swanson, Molly E. C.;
Tan, Jonathan C.; Tayar, Jamie; Terrien, Ryan C.; Thakar, Aniruddha
R.; Thomas, Daniel; Thomas, Neil; Thompson, Benjamin A.; Tinker,
Jeremy L.; Tojeiro, Rita; Troup, Nicholas W.; Vargas-Magaña, Mariana;
Vazquez, Jose A.; Verde, Licia; Viel, Matteo; Vogt, Nicole P.; Wake,
David A.; Wang, Ji; Weaver, Benjamin A.; Weinberg, David H.; Weiner,
Benjamin J.; White, Martin; Wilson, John C.; Wisniewski, John P.;
Wood-Vasey, W. M.; Ye`che, Christophe; York, Donald G.; Zakamska,
Nadia L.; Zamora, O.; Zasowski, Gail; Zehavi, Idit; Zhao, Gong-Bo;
Zheng, Zheng; Zhou, Xu; Zhou, Zhimin; Zou, Hu; Zhu, Guangtun
2015ApJS..219...12A Altcode: 2015arXiv150100963A
The third generation of the Sloan Digital Sky Survey (SDSS-III) took
data from 2008 to 2014 using the original SDSS wide-field imager, the
original and an upgraded multi-object fiber-fed optical spectrograph,
a new near-infrared high-resolution spectrograph, and a novel optical
interferometer. All of the data from SDSS-III are now made public. In
particular, this paper describes Data Release 11 (DR11) including all
data acquired through 2013 July, and Data Release 12 (DR12) adding data
acquired through 2014 July (including all data included in previous
data releases), marking the end of SDSS-III observing. Relative to our
previous public release (DR10), DR12 adds one million new spectra of
galaxies and quasars from the Baryon Oscillation Spectroscopic Survey
(BOSS) over an additional 3000 deg<SUP>2</SUP> of sky, more than
triples the number of H-band spectra of stars as part of the Apache
Point Observatory (APO) Galactic Evolution Experiment (APOGEE), and
includes repeated accurate radial velocity measurements of 5500 stars
from the Multi-object APO Radial Velocity Exoplanet Large-area Survey
(MARVELS). The APOGEE outputs now include the measured abundances of
15 different elements for each star. In total, SDSS-III added 5200
deg<SUP>2</SUP> of ugriz imaging; 155,520 spectra of 138,099 stars as
part of the Sloan Exploration of Galactic Understanding and Evolution
2 (SEGUE-2) survey; 2,497,484 BOSS spectra of 1,372,737 galaxies,
294,512 quasars, and 247,216 stars over 9376 deg<SUP>2</SUP>; 618,080
APOGEE spectra of 156,593 stars; and 197,040 MARVELS spectra of 5513
stars. Since its first light in 1998, SDSS has imaged over 1/3 of
the Celestial sphere in five bands and obtained over five million
astronomical spectra.
---------------------------------------------------------
Title: VizieR Online Data Catalog: Velocity precision in the Gaia-ESO
Survey (Jackson+, 2015)
Authors: Jackson, R. J.; Jeffries, R. D.; Lewis, J.; Koposov, S. E.;
Sacco, G. G.; Randich, S.; Gilmore, G.; Asplund, M.; Binney, J.;
Bonifacio, P.; Drew, J. E.; Feltzing, S.; Ferguson, A. M. N.;
Micela, G.; Neguerela, I.; Prusti, T.; Rix, H. -W.; Vallenari,
A.; Alfaro, E. J.; Allende Prieto, C.; Babusiaux, C.; Bensby, T.;
Blomme, R.; Bragaglia, A.; Flaccomio, E.; Francois, P.; Hambly, N.;
Irwin, M.; Korn, A. J.; Lanzafame, A. C.; Pancino, E.; Recio-Blanco,
A.; Smiljanic, R.; Van Eck, S.; Walton, N.; Bayo, A.; Bergemann, M.;
Carraro, G.; Costado, M. T.; Damiani, F.; Edvardsson, B.; Franciosini,
E.; Frasca, A.; Heiter, U.; Hill, V.; Hourihane, A.; Jof, P.; Lardo,
C.; de Laverny, P.; Lind, K.; Magrini, L.; Marconi, G.; Martayan, C.;
Masseron, T.; Monaco, L.; Morbidelli, L.; Prisinzano, L.; Sbordone,
L.; Sousa, S. G.; Worley, C. C.; Zaggia, S.
2015yCat..35800075J Altcode:
The Gaia-ESO Survey (GES) is a large public spectroscopic survey at
the European Southern Observatory Very LargeTelescope. A key aim is
to provide precise radial velocities (RVs) and projected equatorial
velocities (vsini) for representative samples of Galactic stars,
which will complement information obtained by the Gaia astrometry
satellite. We present an analysis to empirically quantify the size
and distribution of uncertainties in RV and vsini using spectra from
repeated exposures of the same stars. We show that the uncertainties
vary as simple scaling functions of signal-to-noise ratio (S/N) and
vsini, that the uncertainties become larger with increasing photospheric
temperature, but that the dependence on stellar gravity, metallicity
and age is weak. The underlying uncertainty distributions have extended
tails that are better represented by Students t-distributions than
by normal distributions. Parametrised results are provided, which
enable estimates of the RV precision for almost all GES measurements,
and estimates of the vsini precision for stars in young clusters,
as a function of S/N, vsini and stellar temperature. The precision of
individual high S/N GES RV measurements is 0.22-0.26km/s, dependent
on instrumental configuration. <P />(1 data file).
---------------------------------------------------------
Title: New H-band Stellar Spectral Libraries for the SDSS-III/APOGEE
Survey
Authors: Zamora, O.; García-Hernández, D. A.; Allende Prieto, C.;
Carrera, R.; Koesterke, L.; Edvardsson, B.; Castelli, F.; Plez,
B.; Bizyaev, D.; Cunha, K.; García Pérez, A. E.; Gustafsson,
B.; Holtzman, J. A.; Lawler, J. E.; Majewski, S. R.; Manchado, A.;
Mészáros, Sz.; Shane, N.; Shetrone, M.; Smith, V. V.; Zasowski, G.
2015AJ....149..181Z Altcode: 2015arXiv150205237Z
The Sloan Digital Sky Survey-III (SDSS-III) Apache Point Observatory
Galactic Evolution Experiment (APOGEE) has obtained high-resolution
(R ∼ 22,500), high signal-to-noise ratio (\gt 100) spectra in
the H-band (∼1.5-1.7 μm) for about 146,000 stars in the Milky Way
galaxy. We have computed spectral libraries with effective temperature
({{T}<SUB>eff</SUB>}) ranging from 3500 to 8000 K for the automated
chemical analysis of the survey data. The libraries, used to derive
stellar parameters and abundances from the APOGEE spectra in the
SDSS-III data release 12 (DR12), are based on ATLAS9 model atmospheres
and the ASSɛT spectral synthesis code. We present a second set of
libraries based on MARCS model atmospheres and the spectral synthesis
code Turbospectrum. The ATLAS9/ASSɛT ({{T}<SUB>eff</SUB>} = 3500-8000
K) and MARCS/Turbospectrum ({{T}<SUB>eff</SUB>} = 3500-5500 K) grids
cover a wide range of metallicity (-2.5 ≤slant [M/H] ≤slant +0.5
dex), surface gravity (0 ≤ log g ≤slant 5 dex), microturbulence
(0.5 ≤slant ξ ≤slant 8 km s<SUP>-1</SUP>), carbon (-1 ≤slant
[C/M] ≤slant +1 dex), nitrogen (-1 ≤slant [N/M] ≤slant +1 dex),
and α-element (-1 ≤slant [α/M] ≤slant +1 dex) variations,
having thus seven dimensions. We compare the ATLAS9/ASSɛT and
MARCS/Turbospectrum libraries and apply both of them to the analysis
of the observed H-band spectra of the Sun and the K2 giant Arcturus,
as well as to a selected sample of well-known giant stars observed at
very high resolution. The new APOGEE libraries are publicly available
and can be employed for chemical studies in the H-band using other
high-resolution spectrographs.
---------------------------------------------------------
Title: The Open Cluster Chemical Abundances from Spanish Observatories
survey (OCCASO)
Authors: Carrera, R.; Casamiquela, L.; Balaguer-Núñez, L.;
Jordi, C.; Pancino, E.; Allende-Prieto, C.; Blanco-Cuaresma, S.;
Martínez-Vázquez, C. E.; Murabito, S.; del Pino, A.; Aparicio, A.;
Gallart, C.; Recio-Blanco, A.
2015hsa8.conf..453C Altcode: 2014arXiv1412.3509C
We present the motivation, design and current status of the Open Cluster
Chemical Abundances from Spanish Observatories survey (OCCASO). Using
the high resolution spectroscopic facilities available at Spanish
observatories, OCCASO will derive chemical abundances in a sample of
20 to 25 OCs older than 0.5 Gyr. This sample will be used to study
in detail de formation and evolution of the Galactic disc using OCs
as tracers.
---------------------------------------------------------
Title: VizieR Online Data Catalog: KIC giants Bayesian distances
and extinctions (Rodrigues+ 2014)
Authors: Rodrigues, T. S.; Girardi, L.; Miglio, A.; Bossini, D.;
Bovy, J.; Epstein, C.; Pinsonneault, M. H.; Stello, D.; Zasowski,
G.; Allende Prieto, C.; Chaplin, W. J.; Hekker, S.; Johnson, J. A.;
Meszaros, S.; Mosser, B.; Anders, F.; Basu, S.; Beers, T. C.;
Chiappini, C.; da Costa, L. A. N.; Elsworth, Y.; Garcia, R. A.;
Garcia Perez, A. E.; Hearty, F. R.; Maia, M. A. G.; Majewski, S. R.;
Mathur, S.; Montalban, J.; Nidever, D. L.; Santiago, B.; Schultheis,
M.; Serenelli, A.; Shetrone, M.
2015yCat..74452758R Altcode:
APOGEE uses a high-resolution infrared spectrograph, mounted at the
Apache Point Observatory 2.5m telescope, with a mean resolution of
~22500 in the H band (spectral coverage: 1.51-1.70um). APOGEE has
already observed more than 100000 stars selected from 2MASS photometry,
at typical signal-to-noise ratios of ~140 per resolution element. The
targeted stars are mostly red giant branch (RGB), red clump (RC), and
asymptotic giant branch stars (Zasowski et al., 2013AJ....146...81Z),
and are spread over all regions of the MW, including the bulge, disc,
and halo. <P />The Kepler space telescope has observed ~196400 stars
(Huber et al., 2014ApJS..211....2H, Cat. J/ApJS/211/2) in a field
of 105deg<SUP>2</SUP> towards the constellations of Cygnus and Lyra
(Borucki et al., 2010Sci...327..977B...327..997B). Apart from the
discovery of exoplanets and multiple stellar systems, the high temporal
and photometric quality of the data provides the possibility to study
red giants by detection of solar-like oscillations (e.g. Huber et al.,
2010ApJ...723.1607H; Chaplin et al., 2011Sci...332..213C). <P />In
addition to the spectroscopic and asteroseismic parameters, stars
in the APOKASC catalogue have measured apparent magnitudes in SDSS
griz and DDO51, as measured by the KIC team (Brown et al., 2011,
Cat. J/AJ/142/112), and corrected by Pinsonneault et al. (2012,
Cat. J/ApJS/199/30); <P />JHKs from 2MASS (Cutri et al., 2003,
Cat. II/246; Skrutskie et al., 2006, Cat. VII/233); <P />the Kepler
magnitude, Kp, as derived from a combination of the griz magnitudes
(Brown et al., 2011, Cat. J/AJ/142/112); <P />WISE photometry (at 3.35,
4.6, 11.6 and 22.1um, or W1 to W4) from the Preliminary Release Source
Catalog (Wright et al., 2010AJ....140.1868W). <P />(1 data file).
---------------------------------------------------------
Title: Deep SDSS optical spectroscopy of distant halo stars. II. Iron,
calcium, and magnesium abundances
Authors: Fernández-Alvar, E.; Allende Prieto, C.; Schlesinger, K. J.;
Beers, T. C.; Robin, A. C.; Schneider, D. P.; Lee, Y. S.; Bizyaev,
D.; Ebelke, G.; Malanushenko, E.; Malanushenko, V.; Oravetz, D.; Pan,
K.; Simmons, A.
2015A&A...577A..81F Altcode: 2015arXiv150304362F
<BR /> Aims: We analyze a sample of 3944 low-resolution (R ~ 2000)
optical spectra from the Sloan Digital Sky Survey (SDSS), focusing
on stars with effective temperatures 5800 ≤ T<SUB>eff</SUB> ≤
6300 K, and distances from the Milky Way plane in excess of 5 kpc,
and determine their abundances of Fe, Ca, and Mg. <BR /> Methods:
We followed the same methodology as in the previous paper in this
series, deriving atmospheric parameters by χ<SUP>2</SUP> minimization,
but this time we obtained the abundances of individual elements by
fitting their associated spectral lines. Distances were calculated
from absolute magnitudes obtained by a statistical comparison
of our stellar parameters with stellar-evolution models. <BR />
Results: The observations reveal a decrease in the abundances of
iron, calcium, and magnesium at large distances from the Galactic
center. The median abundances for the halo stars analyzed are fairly
constant up to a Galactocentric distance r ~ 20 kpc, rapidly decrease
between r ~ 20 and r ~ 40 kpc, and flatten out to significantly lower
values at larger distances, consistent with previous studies. In
addition, we examine [Ca/Fe] and [Mg/Fe] as a function of [Fe/H]
and Galactocentric distance. Our results show that the most distant
parts of the halo show a steeper variation of [Ca/Fe] and [Mg/Fe]
with iron. We found that at the range -1.6 < [Fe/H] < -0.4,
[Ca/Fe] decreases with distance, in agreement with earlier results
based on local stars. However, the opposite trend is apparent for
[Mg/Fe]. Our conclusion that the outer regions of the halo are more
metal-poor than the inner regions, based on in situ observations of
distant stars, agrees with recent results based on inferences from the
kinematics of more local stars, and with predictions of recent galaxy
formation simulations for galaxies similar to the Milky Way. <P />Table
1 and beginning of Tables 2 and 3 are available in electronic form at <A
href="http://www.aanda.org/10.1051/0004-6361/201425455/olm">http://www.aanda.org</A>Full
Tables 2 and 3 are only available at the CDS via anonymous ftp to <A
href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/577/A81">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/577/A81</A>
---------------------------------------------------------
Title: Exploring Anticorrelations and Light Element Variations in
Northern Globular Clusters Observed by the APOGEE Survey
Authors: Mészáros, Szabolcs; Martell, Sarah L.; Shetrone, Matthew;
Lucatello, Sara; Troup, Nicholas W.; Bovy, Jo; Cunha, Katia;
García-Hernández, Domingo A.; Overbeek, Jamie C.; Allende Prieto,
Carlos; Beers, Timothy C.; Frinchaboy, Peter M.; García Pérez,
Ana E.; Hearty, Fred R.; Holtzman, Jon; Majewski, Steven R.; Nidever,
David L.; Schiavon, Ricardo P.; Schneider, Donald P.; Sobeck, Jennifer
S.; Smith, Verne V.; Zamora, Olga; Zasowski, Gail
2015AJ....149..153M Altcode: 2015arXiv150105127M
We investigate the light-element behavior of red giant stars in
northern globular clusters (GCs) observed by the SDSS-III Apache Point
Observatory Galactic Evolution Experiment. We derive abundances of 9
elements (Fe, C, N, O, Mg, Al, Si, Ca, and Ti) for 428 red giant stars
in 10 GCs. The intrinsic abundance range relative to measurement errors
is examined, and the well-known C-N and Mg-Al anticorrelations are
explored using an extreme-deconvolution code for the first time in a
consistent way. We find that Mg and Al drive the population membership
in most clusters, except in M107 and M71, the two most metal-rich
clusters in our study, where the grouping is most sensitive to N. We
also find a diversity in the abundance distributions, with some clusters
exhibiting clear abundance bimodalities (for example M3 and M53)
while others show extended distributions. The spread of Al abundances
increases significantly as cluster average metallicity decreases as
previously found by other works, which we take as evidence that low
metallicity, intermediate mass AGB polluters were more common in the
more metal-poor clusters. The statistically significant correlation
of [Al/Fe] with [Si/Fe] in M15 suggests that <SUP>28</SUP>Si leakage
has occurred in this cluster. We also present C, N, and O abundances
for stars cooler than 4500 K and examine the behavior of A(C+N+O)
in each cluster as a function of temperature and [Al/Fe]. The
scatter of A(C+N+O) is close to its estimated uncertainty in all
clusters and independent of stellar temperature. A(C+N+O) exhibits
small correlations and anticorrelations with [Al/Fe] in M3 and M13,
but we cannot be certain about these relations given the size of our
abundance uncertainties. Star-to-star variations of α-element (Si, Ca,
Ti) abundances are comparable to our estimated errors in all clusters.
---------------------------------------------------------
Title: The APOGEE Spectroscopic Survey of Kepler Planet Hosts:
Feasibility, Efficiency, and First Results
Authors: Fleming, Scott W.; Mahadevan, Suvrath; Deshpande, Rohit;
Bender, Chad F.; Terrien, Ryan C.; Marchwinski, Robert C.; Wang,
Ji; Roy, Arpita; Stassun, Keivan G.; Allende Prieto, Carlos; Cunha,
Katia; Smith, Verne V.; Agol, Eric; Ak, Hasan; Bastien, Fabienne A.;
Bizyaev, Dmitry; Crepp, Justin R.; Ford, Eric B.; Frinchaboy, Peter
M.; García-Hernández, Domingo Aníbal; García Pérez, Ana Elia;
Gaudi, B. Scott; Ge, Jian; Hearty, Fred; Ma, Bo; Majewski, Steve R.;
Mészáros, Szabolcs; Nidever, David L.; Pan, Kaike; Pepper, Joshua;
Pinsonneault, Marc H.; Schiavon, Ricardo P.; Schneider, Donald P.;
Wilson, John C.; Zamora, Olga; Zasowski, Gail
2015AJ....149..143F Altcode: 2015arXiv150205035F
The Kepler mission has yielded a large number of planet candidates
from among the Kepler Objects of Interest (KOIs), but spectroscopic
follow-up of these relatively faint stars is a serious bottleneck in
confirming and characterizing these systems. We present motivation
and survey design for an ongoing project with the Sloan Digital Sky
Survey III multiplexed Apache Point Observatory Galactic Evolution
Experiment (APOGEE) near-infrared spectrograph to monitor hundreds of
KOI host stars. We report some of our first results using representative
targets from our sample, which include current planet candidates that
we find to be false positives, as well as candidates listed as false
positives that we do not find to be spectroscopic binaries. With this
survey, KOI hosts are observed over ∼20 epochs at a radial velocity
(RV) precision of 100-200 m s<SUP>-1</SUP>. These observations can
easily identify a majority of false positives caused by physically
associated stellar or substellar binaries, and in many cases, fully
characterize their orbits. We demonstrate that APOGEE is capable of
achieving RV precision at the 100-200 m s<SUP>-1</SUP> level over long
time baselines, and that APOGEE’s multiplexing capability makes it
substantially more efficient at identifying false positives due to
binaries than other single-object spectrographs working to confirm
KOIs as planets. These APOGEE RVs enable ancillary science projects,
such as studies of fundamental stellar astrophysics or intrinsically
rare substellar companions. The coadded APOGEE spectra can be used
to derive stellar properties (T<SUB>eff</SUB>, log g) and chemical
abundances of over a dozen elements to probe correlations of planet
properties with individual elemental abundances.
---------------------------------------------------------
Title: Young [α/Fe]-enhanced stars discovered by CoRoT and APOGEE:
What is their origin?
Authors: Chiappini, C.; Anders, F.; Rodrigues, T. S.; Miglio, A.;
Montalbán, J.; Mosser, B.; Girardi, L.; Valentini, M.; Noels, A.;
Morel, T.; Minchev, I.; Steinmetz, M.; Santiago, B. X.; Schultheis,
M.; Martig, M.; da Costa, L. N.; Maia, M. A. G.; Allende Prieto, C.;
de Assis Peralta, R.; Hekker, S.; Themeßl, N.; Kallinger, T.; García,
R. A.; Mathur, S.; Baudin, F.; Beers, T. C.; Cunha, K.; Harding, P.;
Holtzman, J.; Majewski, S.; Mészáros, Sz.; Nidever, D.; Pan, K.;
Schiavon, R. P.; Shetrone, M. D.; Schneider, D. P.; Stassun, K.
2015A&A...576L..12C Altcode: 2015arXiv150306990C
We report the discovery of a group of apparently young CoRoT red-giant
stars exhibiting enhanced [α/Fe] abundance ratios (as determined
from APOGEE spectra) with respect to solar values. Their existence
is not explained bystandard chemical evolution models of the Milky
Way, and shows that the chemical-enrichment history of the Galactic
disc is more complex. We find similar stars in previously published
samples for which isochrone-ages could be reliably obtained, although
in smaller relative numbers. This might explain why these stars have
not previously received attention. The young [α/Fe]-rich stars
are much more numerous in the CoRoT-APOGEE (CoRoGEE) inner-field
sample than in any other high-resolution sample available at present
because only CoRoGEE can explore the inner-disc regions and provide
ages for its field stars. The kinematic properties of the young
[α/Fe]-rich stars are not clearly thick-disc like, despite their
rather large distances from the Galactic mid-plane. Our tentative
interpretation of these and previous intriguing observations in
the Milky Way is that these stars were formed close to the end of
the Galactic bar, near corotation - a region where gas can be kept
inert for longer times than in other regions that are more frequently
shocked by the passage of spiral arms. Moreover, this is where the
mass return from older inner-disc stellar generations is expected
to be highest (according to an inside-out disc-formation scenario),
which additionally dilutes the in-situ gas. Other possibilities to
explain these observations (e.g., a recent gas-accretion event) are
also discussed. <P />Appendix A is available in electronic form at <A
href="http://www.aanda.org/10.1051/0004-6361/201525865/olm">http://www.aanda.org</A>
---------------------------------------------------------
Title: Gaia-ESO Survey: Analysis of pre-main sequence stellar spectra
Authors: Lanzafame, A. C.; Frasca, A.; Damiani, F.; Franciosini, E.;
Cottaar, M.; Sousa, S. G.; Tabernero, H. M.; Klutsch, A.; Spina, L.;
Biazzo, K.; Prisinzano, L.; Sacco, G. G.; Randich, S.; Brugaletta, E.;
Delgado Mena, E.; Adibekyan, V.; Montes, D.; Bonito, R.; Gameiro,
J. F.; Alcalá, J. M.; González Hernández, J. I.; Jeffries,
R.; Messina, S.; Meyer, M.; Gilmore, G.; Asplund, M.; Binney, J.;
Bonifacio, P.; Drew, J. E.; Feltzing, S.; Ferguson, A. M. N.; Micela,
G.; Negueruela, I.; Prusti, T.; Rix, H. -W.; Vallenari, A.; Alfaro,
E. J.; Allende Prieto, C.; Babusiaux, C.; Bensby, T.; Blomme, R.;
Bragaglia, A.; Flaccomio, E.; Francois, P.; Hambly, N.; Irwin, M.;
Koposov, S. E.; Korn, A. J.; Smiljanic, R.; Van Eck, S.; Walton, N.;
Bayo, A.; Bergemann, M.; Carraro, G.; Costado, M. T.; Edvardsson,
B.; Heiter, U.; Hill, V.; Hourihane, A.; Jackson, R. J.; Jofré, P.;
Lardo, C.; Lewis, J.; Lind, K.; Magrini, L.; Marconi, G.; Martayan,
C.; Masseron, T.; Monaco, L.; Morbidelli, L.; Sbordone, L.; Worley,
C. C.; Zaggia, S.
2015A&A...576A..80L Altcode: 2015arXiv150104450L
Context. The Gaia-ESO Public Spectroscopic Survey is obtaining
high-quality spectroscopy of some 100 000 Milky Way stars using the
FLAMES spectrograph at the VLT, down to V = 19 mag, systematically
covering all the main components of the Milky Way and providing the
first homogeneous overview of the distributions of kinematics and
chemical element abundances in the Galaxy. Observations of young open
clusters, in particular, are giving new insights into their initial
structure, kinematics, and their subsequent evolution. <BR /> Aims:
This paper describes the analysis of UVES and GIRAFFE spectra acquired
in the fields of young clusters whose population includes pre-main
sequence (PMS) stars. The analysis is applied to all stars in such
fields, regardless of any prior information on membership, and provides
fundamental stellar atmospheric parameters, elemental abundances, and
PMS-specific parameters such as veiling, accretion, and chromospheric
activity. <BR /> Methods: When feasible, different methods were used
to derive raw parameters (e.g. line equivalent widths) fundamental
atmospheric parameters and derived parameters (e.g. abundances). To
derive some of these parameters, we used methods that have been
extensively used in the past and new ones developed in the context
of the Gaia-ESO survey enterprise. The internal precision of these
quantities was estimated by inter-comparing the results obtained by
these different methods, while the accuracy was estimated by comparison
with independent external data, such as effective temperature and
surface gravity derived from angular diameter measurements, on a
sample of benchmarks stars. A validation procedure based on these
comparisons was applied to discard spurious or doubtful results and
produce recommended parameters. Specific strategies were implemented to
resolve problems of fast rotation, accretion signatures, chromospheric
activity, and veiling. <BR /> Results: The analysis carried out on
spectra acquired in young cluster fields during the first 18 months
of observations, up to June 2013, is presented in preparation of the
first release of advanced data products. These include targets in
the fields of the <ASTROBJ>ρ Oph</ASTROBJ>, <ASTROBJ>Cha I</ASTROBJ>,
<ASTROBJ>NGC 2264</ASTROBJ>, <ASTROBJ>γ Vel</ASTROBJ>, and <ASTROBJ>NGC
2547</ASTROBJ> clusters. Stellar parameters obtained with the higher
resolution and larger wavelength coverage from UVES are reproduced with
comparable accuracy and precision using the smaller wavelength range
and lower resolution of the GIRAFFE setup adopted for young stars,
which allows us to provide stellar parameters with confidence for the
much larger GIRAFFE sample. Precisions are estimated to be ≈120 K
rms in T<SUB>eff</SUB>, ≈0.3 dex rms in log g, and ≈0.15 dex rms in
[Fe/H] for the UVES and GIRAFFE setups.
---------------------------------------------------------
Title: The Puzzling Li-rich Red Giant Associated with NGC 6819
Authors: Carlberg, Joleen K.; Smith, Verne V.; Cunha, Katia; Majewski,
Steven R.; Mészáros, Szabolcs; Shetrone, Matthew; Allende Prieto,
Carlos; Bizyaev, Dmitry; Stassun, Keivan G.; Fleming, Scott W.;
Zasowski, Gail; Hearty, Fred; Nidever, David L.; Schneider, Donald P.;
Holtzman, Jon A.; Frinchaboy, Peter M.
2015ApJ...802....7C Altcode: 2015arXiv150105625C
A Li-rich red giant (RG) star (2M19411367+4003382) recently discovered
in the direction of NGC 6819 belongs to the rare subset of Li-rich stars
that have not yet evolved to the luminosity bump, an evolutionary stage
where models predict Li can be replenished. The currently favored model
to explain Li enhancement in first-ascent RGs like 2M19411367+4003382
requires deep mixing into the stellar interior. Testing this model
requires a measurement of <SUP>12</SUP>C/<SUP>13</SUP>C, which is
possible to obtain from Apache Point Observatory Galactic Evolution
Experiment (APOGEE) spectra. However, the Li-rich star also has abnormal
asteroseismic properties that call into question its membership in the
cluster, even though its radial velocity and location on color-magnitude
diagrams are consistent with membership. To address these puzzles,
we have measured a wide array of abundances in the Li-rich star
and three comparison stars using spectra taken as part of the APOGEE
survey to determine the degree of stellar mixing, address the question
of membership, and measure the surface gravity. We confirm that the
Li-rich star is a RG with the same overall chemistry as the other
cluster giants. However, its log g is significantly lower, consistent
with the asteroseismology results and suggestive of a very low mass
if the star is indeed a cluster member. Regardless of the cluster
membership, the <SUP>12</SUP>C/<SUP>13</SUP>C and C/N ratios of the
Li-rich star are consistent with standard first dredge-up, indicating
that Li dilution has already occurred, and inconsistent with internal
Li enrichment scenarios that require deep mixing.
---------------------------------------------------------
Title: The Gaia-ESO Survey: A globular cluster escapee in the
Galactic halo
Authors: Lind, K.; Koposov, S. E.; Battistini, C.; Marino, A. F.;
Ruchti, G.; Serenelli, A.; Worley, C. C.; Alves-Brito, A.; Asplund,
M.; Barklem, P. S.; Bensby, T.; Bergemann, M.; Blanco-Cuaresma, S.;
Bragaglia, A.; Edvardsson, B.; Feltzing, S.; Gruyters, P.; Heiter,
U.; Jofre, P.; Korn, A. J.; Nordlander, T.; Ryde, N.; Soubiran,
C.; Gilmore, G.; Randich, S.; Ferguson, A. M. N.; Jeffries, R. D.;
Vallenari, A.; Allende Prieto, C.; Pancino, E.; Recio-Blanco, A.;
Romano, D.; Smiljanic, R.; Bellazzini, M.; Damiani, F.; Hill, V.;
de Laverny, P.; Jackson, R. J.; Lardo, C.; Zaggia, S.
2015A&A...575L..12L Altcode: 2015arXiv150203934L
A small fraction of the halo field is made up of stars that share the
light element (Z ≤ 13) anomalies characteristic of second generation
globular cluster (GC) stars. The ejected stars shed light on the
formation of the Galactic halo by tracing the dynamical history of
the clusters, which are believed to have once been more massive. Some
of these ejected stars are expected to show strong Al enhancement at
the expense of shortage of Mg, but until now no such star has been
found. We search for outliers in the Mg and Al abundances of the few
hundreds of halo field stars observed in the first eighteen months of
the Gaia-ESO public spectroscopic survey. One halo star at the base
of the red giant branch, here referred to as 22593757-4648029 is found
to have [ Mg/Fe ] = -0.36 ± 0.04 and [ Al/Fe ] = 0.99 ± 0.08, which
is compatible with the most extreme ratios detected in GCs so far. We
compare the orbit of 22593757-4648029 to GCs of similar metallicity
andfind it unlikely that this star has been tidally stripped with low
ejection velocity from any of the clusters. However, both chemical
and kinematic arguments render it plausible that the star has been
ejected at high velocity from the anomalous GC ω Centauri within
the last few billion years. We cannot rule out other progenitor GCs,
because some may have disrupted fully, and the abundance and orbital
data are inadequate for many of those that are still intact. <P
/>Based on data acquired by the Gaia-ESO Survey, programme ID
188.B-3002. Observations were made with ESO Telescopes at the La Silla
Paranal Observatory.Appendix A is available in electronic form at <A
href="http://www.aanda.org/10.1051/0004-6361/201425554/olm">http://www.aanda.org</A>
---------------------------------------------------------
Title: The Gaia-ESO survey: Discovery of a spatially extended low-mass
population in the Vela OB2 association
Authors: Sacco, G. G.; Jeffries, R. D.; Randich, S.; Franciosini, E.;
Jackson, R. J.; Cottaar, M.; Spina, L.; Palla, F.; Mapelli, M.; Alfaro,
E. J.; Bonito, R.; Damiani, F.; Frasca, A.; Klutsch, A.; Lanzafame,
A.; Bayo, A.; Barrado, D.; Jiménez-Esteban, F.; Gilmore, G.; Micela,
G.; Vallenari, A.; Allende Prieto, C.; Flaccomio, E.; Carraro, G.;
Costado, M. T.; Jofré, P.; Lardo, C.; Magrini, L.; Morbidelli, L.;
Prisinzano, L.; Sbordone, L.
2015A&A...574L...7S Altcode: 2015arXiv150101330S
The nearby (distance ~ 350-400 pc), rich Vela OB2 association, includes
γ<SUP>2</SUP> Velorum, one of the most massive binaries in the
solar neighbourhood and an excellent laboratory for investigating the
formation and early evolution of young clusters. Recent Gaia-ESO survey
observations have led to the discovery of two kinematically distinct
populations in the young (10-15 Myr) cluster immediately surrounding
γ<SUP>2</SUP> Velorum. Here we analyse the results of Gaia-ESO
survey observations of NGC 2547, a 35 Myr cluster located two degrees
south of γ<SUP>2</SUP> Velorum. The radial velocity distribution of
lithium-rich pre-main sequence stars shows a secondary population
that is kinematically distinct from and younger than NGC 2547. The
radial velocities, lithium absorption lines, and the positions in a
colour-magnitude diagram of this secondary population are consistent
with those of one of the components discovered around γ<SUP>2</SUP>
Velorum. This result shows that there is a young, low-mass stellar
population spread over at least several square degrees in the Vela
OB2 association. This population could have originally been part of a
cluster around γ<SUP>2</SUP> Velorum that expanded after gas expulsion
or formed in a less dense environment that is spread over the whole Vela
OB2 region. <P />Based on observations made with the ESO/VLT, at Paranal
Observatory, under program 188.B-3002 (The Gaia-ESO Public Spectroscopic
Survey).Table 1 is only available at the CDS via anonymous ftp to <A
href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/574/L7">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/574/L7</A>
---------------------------------------------------------
Title: VizieR Online Data Catalog: Deep SDSS Optical
Spectroscopy. II. (Fernandez-Alvar+, 2015)
Authors: Fernandez-Alvar, E.; Allende Prieto, C.; Schlesinger, K. J.;
Beers, T. C.; Robin, A. C.; Schneider, D. P.; Lee, Y. S.; Bizyaev,
D.; Ebelke, G.; Malanushenko, E.; Malanushenko, V.; Oravetz, D.; Pan,
K.; Simmons, A.
2015yCat..35770081F Altcode:
The tables include the stellar parameters, chemical abundances ([Fe/H],
[Ca/H] and [Mg/H]) and distance estimates (from the Sun, the center
of the Galaxy and the Galactic plane) for our analyzed samples of halo
stars. <P />(2 data files).
---------------------------------------------------------
Title: VizieR Online Data Catalog: Deep SDSS Optical
Spectroscopy. II. (Fernandez-Alvar+, 2015)
Authors: Fernandez-Alvar, E.; Allende Prieto, C.; Schlesinger, K. J.;
Beers, T. C.; Robin, A. C.; Schneider, D. P.; Lee, Y. S.; Bizyaev,
D.; Ebelke, G.; Malanushenko, E.; Malanushenko, V.; Oravetz, D.; Pan,
K.; Simmons, A.
2015yCat..35779081F Altcode:
The tables include the stellar parameters, chemical abundances ([Fe/H],
[Ca/H] and [Mg/H]) and distance estimates (from the Sun, the center
of the Galaxy and the Galactic plane) for our analyzed samples of halo
stars. <P />(2 data files).
---------------------------------------------------------
Title: VizieR Online Data Catalog: APOKASC catalog of Kepler red
giants (Pinsonneault+, 2014)
Authors: Pinsonneault, M. H.; Elsworth, Y.; Epstein, C.; Hekker,
S.; Meszaros, Sz.; Chaplin, W. J.; Johnson, J. A.; Garcia, R. A.;
Holtzman, J.; Mathur, S.; Garcia Perez, A.; Silva Aguirre, V.; Girardi,
L.; Basu, S.; Shetrone, M.; Stello, D.; Allende Prieto, C.; An, D.;
Beck, P.; Beers, T. C.; Bizyaev, D.; Bloemen, S.; Bovy, J.; Cunha, K.;
De Ridder, J.; Frinchaboy, P. M.; Garcia-Hernandez, D. A.; Gilliland,
R.; Harding, P.; Hearty, F. R.; Huber, D.; Ivans, I.; Kallinger, T.;
Majewski, S. R.; Metcalfe, T. S.; Miglio, A.; Mosser, B.; Muna, D.;
Nidever, D. L.; Schneider, D. P.; Serenelli, A.; Smith, V. V.; Tayar,
J.; Zamora, O.; Zasowski, G.
2015yCat..22150019P Altcode:
In this paper we present the first release of the joint APOKASC
asteroseismic and spectroscopic survey for targets with both
high-resolution Apache Point Observatory Galactic Evolution Experiment
(APOGEE) spectra analyzed by members of the third Sloan Digital
Sky Survey (SDSS-III) and asteroseismic data obtained by the Kepler
mission and analyzed by members of the Kepler Asteroseismology Science
Consortium (KASC). <P />(4 data files).
---------------------------------------------------------
Title: Chemical Abundance Comparisons Between ASPCAP and Manual
Analyses in Open Cluster Red Giants
Authors: Smith, Verne V.; Cunha, Katia M. L.; Souto, Diogo; Shetrone,
Matthew D.; Meszaros, Szabolcs; Allende-Prieto, Carlos; Bizyaev,
Dmitry; Carlberg, Joleen K.; García Pérez, Ana; Hasselquist, Sten;
Holtzman, Jon A.; Johnson, Jennifer; Majewski, Steven R.; Schiavon,
Ricardo P.; Sobeck, Jennifer; Troup, Nicholas William
2015AAS...22530206S Altcode:
The APOGEE Stellar Parameter and Chemical Abundance Pipeline (ASPCAP)
has now produced individual chemical abundances for 15 different
elements: C, N, O, Na, Mg, Al, Si, S, K, Ca, Ti, V, Mn, Fe, and Ni. We
will present comparisons of the ASPCAP abundances for stars in clusters
with those derived from manual stellar parameter and abundance analyses
of the same stars using the APOGEE spectra. These comparisons can be
used to assess whether any of the elemental results from the automated
pipeline contain larger than expected scatter, systematic offsets, or
trends with stellar parameters, such as effective temperature, surface
gravity, or metallicity. Using the subset of trustworthy abundances,
we present early results of peculiar chemical substructures found in
the APOGEE dataset.
---------------------------------------------------------
Title: A Pipeline for the Analysis of APOGEE Spectra Based on
Equivalent Widths
Authors: Arfon Williams, Rob; Bosley, Corinne; Jones, Hayden; Schiavon,
Ricardo P.; Allende-Prieto, Carlos; Bizyaev, Dmitry; Carrera, Ricardo;
Cunha, Katia M. L.; Nguyen, Duy; Feuillet, Diane; Frinchaboy, Peter M.;
García Pérez, Ana; Hasselquist, Sten; Hayden, Michael R.; Hearty,
Fred R.; Holtzman, Jon A.; Johnson, Jennifer; Majewski, Steven R.;
Meszaros, Szabolcs; Nidever, David L.; Shetrone, Matthew D.; Smith,
Verne V.; Sobeck, Jennifer; Troup, Nicholas William; Wilson, John C.;
Zasowski, Gail
2015AAS...22534002A Altcode:
The Apache Point Galactic Evolution Experiment (APOGEE) forms part of
the third Sloan Digital Sky Survey and has obtained high resolution,
high signal-to-noise infrared spectra for ~1.3 x 10<SUP>5</SUP>
stars across the galactic bulge, disc and halo. From these, stellar
parameters are derived together with abundances for various elements
using the APOGEE Stellar Parameters and Chemical Abundance Pipeline
(ASPCAP). In this poster we report preliminary results from application
of an alternative stellar parameters and abundances pipeline, based
on measurements of equivalent widths of absorption lines in APOGEE
spectra. The method is based on a sequential grid inversion algorithm,
originally designed for the derivation of ages and elemental abundances
of stellar populations from line indices in their integrated spectra. It
allows for the rapid processing of large spectroscopic data sets from
both current and future surveys, such as APOGEE and APOGEE 2, and it
is easily adaptable for application to other very large data sets that
are being/will be generated by other massive surveys of the stellar
populations of the Galaxy. It will also allow the cross checking of
ASPCAP results using an independent method. In this poster we present
preliminary results showing estimates of effective temperature and
iron abundance [Fe/H] for a subset of the APOGEE sample, comparing
with DR12 numbers produced by the ASPCAP pipeline.
---------------------------------------------------------
Title: Detection of Neodymium in APOGEE H-band Spectra and its
Application to Chemical Tagging
Authors: Hasselquist, Sten; Shetrone, Matthew D.; Smith, Verne V.;
Holtzman, Jon A.; Lawler, James E.; Ivans, Inese I.; Majewski, Steven
R.; Schiavon, Ricardo P.; Zasowski, Gail; Nidever, David L.; Hearty,
Fred; Allende-Prieto, Carlos; Beers, Timothy C.; García Pérez, Ana;
Sobeck, Jennifer; Apogee Team
2015AAS...22531905H Altcode:
We report the successful detection of the rare earth element Neodymium
(Nd) in the high-resolution, H-band spectra from the SDSS III Apache
Point Observatory Galactic Evolution Experiment (APOGEE). Using the
Nd II transition at 16058.014 angstroms, we have detected significant
Nd enhancements in all stars observed by APOGEE belonging to the
Sagittarius (Sgr) Dwarf Spheroidal (dSph) galaxy. Because Sgr is
known to be enhanced in heavy s-process elements such as Nd, we can
use this feature to identify and chemically tag Sgr stream members
that have been observed in the Galactic halo by APOGEE. We also use
this feature to characterize rare earth element abundance variations
in clusters observed by APOGEE.
---------------------------------------------------------
Title: Using APOGEE Data to Examine Late-K and Early-M Dwarfs
Authors: Schmidt, Sarah J.; Wagoner, Erika L.; Johnson, Jennifer;
Gregorio Fernandez Trincado, Jose; Robin, Annie; Reyle, Celine;
Terrien, Ryan; Allende-Prieto, Carlos; Hearty, Fred; Majewski, Steven
R.; Schiavon, Ricardo P.
2015AAS...22513810S Altcode:
The Apache Point Galactic Evolution Experiment (APOGEE) has obtained
high resolution (R~22,500) near-infrared spectra of over 100,000
stars, including a subset of ~4000 low-mass dwarfs with estimated
effective temperatures of 3500 K < Teff < 4200 K. We use data
from standard stars to confirm the accuracy of APOGEE parameters for
these stars, which sit at the low temperature, high gravity end of the
APOGEE model grid. We then cross-match these late-K and early-M dwarfs
with photometry from SDSS, 2MASS, and WISE to examine the relationships
between effective temperature, metallicity, and color for these low mass
stars. In this effective temperature regime, u-g, g-r, and W1-W2 colors
are metallicity sensitive, while r-z is a better tracer of Teff. We
compare Teff, metallicity, and colors with parameters derived from
the Padova, Dartmouth, and BT-Settl model grids, finding that while no
set of models fits exactly, each set reproduces similar general trends.
---------------------------------------------------------
Title: The Gaia-ESO Survey: Kinematics of seven Galactic globular
clusters
Authors: Lardo, C.; Pancino, E.; Bellazzini, M.; Bragaglia, A.; Donati,
P.; Gilmore, G.; Randich, S.; Feltzing, S.; Jeffries, R. D.; Vallenari,
A.; Alfaro, E. J.; Allende Prieto, C.; Flaccomio, E.; Koposov, S. E.;
Recio-Blanco, A.; Bergemann, M.; Carraro, G.; Costado, M. T.; Damiani,
F.; Hourihane, A.; Jofré, P.; de Laverny, P.; Marconi, G.; Masseron,
T.; Morbidelli, L.; Sacco, G. G.; Worley, C. C.
2015A&A...573A.115L Altcode: 2014arXiv1411.4886L
The Gaia-ESO survey is a large public spectroscopic survey aimed
at investigating the origin and formation history of our Galaxy by
collecting spectroscopy of representative samples (about 10<SUP>5</SUP>
Milky Way stars) of all Galactic stellar populations, in the field
and in clusters. The survey uses globular clusters as intra- and
inter-survey calibrators, deriving stellar atmospheric parameters and
abundances of a significant number of stars in clusters, along with
radial velocity determinations. We used precise radial velocities
of a large number of stars in seven globular clusters (NGC 1851,
NGC 2808, NGC 4372, NGC 4833, NGC 5927, NGC 6752, and NGC 7078) to
validate pipeline results and to preliminarily investigate the cluster
internal kinematics. Radial velocity measurements were extracted
from FLAMES/GIRAFFE spectra processed by the survey pipeline as
part of the second internal data release of data products to ESO. We
complemented our sample with ESO archival data obtained with different
instrument configurations. Reliable radial velocity measurements
for 1513 bona fide cluster star members were obtained in total. We
measured systemic rotation, estimated central velocity dispersions,
and present velocity dispersion profiles of all the selected clusters,
providing the first velocity dispersion curve and the first estimate
of the central velocitydispersion for the cluster NGC 5927. Finally,
we explore the possible link between cluster kinematics and other
physical parameters. The analysis we present here demonstrates that
Gaia-ESO survey data are sufficiently accurate to be used in studies
of kinematics of stellar systems and stellar populations in the Milky
Way. <P />Full Table 3 is only available at the CDS via anonymous ftp to
<A href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/573/A115">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/573/A115</A>Based
on data products from observations made with ESO telescopes at the
La Silla Paranal Observatory under programme 188.B-3002 (the public
Gaia-ESO spectroscopic survey, PIs Gilmore & Randich) and on
the archive data of the programmes 62.N-0236, 63.L-0439, 65.L-0561,
68.D-0212, 68.D-0265, 69.D-0582, 064.L-0255, 065.L-0463, 071.D-0205,
073.D-0211, 073.D-0695, 075.D-0492, 077.D-0246, 077.D-0652, 079.D-0645,
080.B-0489, 080.D-0106, 081.D-0253, 082.B-0386, 083.B-0083, 083.D-0208,
083.D-0798, 085.D-0205, 086.D-0141, 088.A-9012, 088.B-0403, 088.B-0492,
088.D-0026, 088.D-0519, 089.D-0038, 164.O-0561, 386.D-0086.
---------------------------------------------------------
Title: Sodium and Oxygen Abundances in the Open Cluster NGC 6791
from APOGEE H-band Spectroscopy
Authors: Cunha, Katia; Smith, Verne V.; Johnson, Jennifer A.;
Bergemann, Maria; Mészáros, Szabolcs; Shetrone, Matthew D.; Souto,
Diogo; Allende Prieto, Carlos; Schiavon, Ricardo P.; Frinchaboy, Peter;
Zasowski, Gail; Bizyaev, Dmitry; Holtzman, Jon; García Pérez, Ana E.;
Majewski, Steven R.; Nidever, David; Beers, Timothy; Carrera, Ricardo;
Geisler, Doug; Gunn, James; Hearty, Fred; Ivans, Inese; Martell,
Sarah; Pinsonneault, Marc; Schneider, Donald P.; Sobeck, Jennifer;
Stello, Dennis; Stassun, Keivan G.; Skrutskie, Michael; Wilson, John C.
2015ApJ...798L..41C Altcode: 2014arXiv1411.2034C
The open cluster NGC 6791 is among the oldest, most massive,
and metal-rich open clusters in the Galaxy. High-resolution H-band
spectra from the Apache Point Observatory Galactic Evolution Experiment
(APOGEE) of 11 red giants in NGC 6791 are analyzed for their chemical
abundances of iron, oxygen, and sodium. The abundances of these three
elements are found to be homogeneous (with abundance dispersions at
the level of ~0.05-0.07 dex) in these cluster red giants, which span
much of the red-giant branch (T <SUB>eff</SUB> ~ 3500-4600 K), and
include two red clump giants. From the infrared spectra, this cluster
is confirmed to be among the most metal-rich clusters in the Galaxy
(lang[Fe/H]rang = 0.34 ± 0.06) and is found to have a roughly solar
value of [O/Fe] and slightly enhanced [Na/Fe]. Our non-LTE calculations
for the studied Na I lines in the APOGEE spectral region (16373.86 Å
and 16388.85 Å) indicate only small departures from LTE (<=0.04
dex) for the parameter range and metallicity of the studied stars. The
previously reported double population of cluster members with different
Na abundances is not found among the studied sample.
---------------------------------------------------------
Title: Stellar Populations with APOGEE and Kepler
Authors: Johnson, Jennifer; Pinsonneault, Marc H.; Elsworth, Yvonne P.;
Epstein, Courtney R.; Hekker, Saskia; Meszaros, Szabolcs; Chaplin,
William J.; Garcia, Rafael; Holtzman, Jon A.; Mathur, Savita;
García Pérez, Ana; Basu, Sarbani; Girardi, Leo; Silva Aguirre,
Víctor; Shetrone, Matthew D.; Stello, Dennis; Rodrigues, Thaise;
Allende-Prieto, Carlos; An, Deokkeun; Beck, Paul; Bizyaev, Dmitry;
Bovy, Jo; Cunha, Katia M. L.; De Ridder, Joris; Garcia-Hernandez, D.
2015AAS...22530202J Altcode:
The history of the Milky Way is recorded in its stars, but dissecting
stellar populations is not a straighforward process. Key information
is gained by analyzing the absorption lines from high-resolution
spectroscopy of stellar atmospheres by the APOGEE survey and analyzing
the frequencies in power spectra of photometric lightcurves by Kepler
Asteroseismic Science Consortium, in particular the large frequency
separation and the frequency of maximum power. From spectroscopy,
we measure effective temperature, rotation, metallicity and abundance
ratios, while seismology provides gravities, rotation,and evolutionary
state. Combined, these two techniques yield other fundamental parameters
such as mass and radius. I will discuss revolutionary insights into
Galactic evolution gained by this extensive dataset.
---------------------------------------------------------
Title: Chemical Cartography with SDSS-III APOGEE: DR12 Results
Authors: Hayden, Michael R.; Holtzman, Jon A.; Bovy, Jo; Majewski,
Steven R.; Nidever, David L.; Zasowski, Gail; Schiavon, Ricardo P.;
Frinchaboy, Peter M.; Hearty, Fred; Allende-Prieto, Carlos; García
Pérez, Ana; Robin, Annie; Cunha, Katia M. L.; Beers, Timothy C.;
Apogee Team
2015AAS...22531902H Altcode:
The SDSS-III Apache Point Observatory Galactic Evolution Experiment
(APOGEE) spectrograph provides an unprecedented view of the Milky Way
disk, due in part to its ability to observe in the infrared, where the
effects of extinction are significantly reduced compared to optical
surveys. We present updated results on mean metallicity and chemical
abundance gradients using the full three years of APOGEE1 observations
and new results of the metallicity distribution function (MDF) and
the [α/Fe] vs. [Fe/H] plane at different locations in the Milky Way
disk. Our sample comprises nearly high signal-to-noise observations of
nearly 100,000 red giant stars taken from SDSS DR12. These observations
span the entire Milky Way visible from the northern hemisphere,
ranging from the bulge to the edge of the disk (0
---------------------------------------------------------
Title: The APOGEE Low-Mass Star Ancillary Project
Authors: Blake, Cullen; Mahadevan, Suvrath; Deshpande, Rohit; Bender,
Chad F.; Terrien, Ryan; Crepp, Justin R.; Carlberg, Joleen K.;
Nidever, David L.; Stassun, Keivan; Hawley, Suzanne L.; Hearty, Fred;
Allende-Prieto, Carlos
2015AAS...22530205B Altcode:
As a high-resolution, near-infrared, fiber-fed instrument, APOGEE
presents a unique opportunity to obtain multi-epoch radial velocity
measurements of a large number of low-mass stars. These observations
will reveal unseen companions, improving our understanding of
stellar multiplicity at the bottom of the Main Sequence, and may even
identify candidate sub-stellar companions. These same data contains an
unprecedented wealth of information about the kinematics, rotation,
and metallicities of these stars. I will describe the status of our
Ancillary Science program, and ongoing efforts to get the best possible
radial velocity precision from the APOGEE data.
---------------------------------------------------------
Title: FERRE: A Code for Spectroscopic Analysis
Authors: Allende-Prieto, Carlos; Apogee Team
2015AAS...22542207A Altcode:
FERRE is a data analysis code written in FORTRAN90. It matches models to
data, taking a set of observations and identifying the model parameters
that best reproduce the data, in a chi-squared sense. Model predictions
are to be given as an array whose values are a function of the model
parameters, i.e. numerically. FERRE holds this array in memory, or
in a direct-access binary file, and interpolates in it to evaluate
model predictions. The code returns, in addition to the optimal set of
parameters, their uncertainties, covariances, and the corresponding
model prediction. The code is used at the core of the APOGEE Stellar
Parameters and Chemical Abundances Pipeline, and it is now publicly
available.
---------------------------------------------------------
Title: A Detailed Characterization of the Milky Way Bulge with APOGEE
Authors: García Pérez, Ana E.; Johnson, Jennifer; Allende-Prieto,
Carlos; Cunha, Katia M. L.; Hearty, Fred; Holtzman, Jon A.; Majewski,
Steven R.; Nidever, David L.; Schiavon, Ricardo P.; Sobeck, Jennifer;
Zasowski, Gail
2015AAS...22531906G Altcode:
An important part of the history of the Milky Way is encoded in the
dynamics and chemistry of the inner Galaxy, which contains about
30% of its mass. It is only in the last few years that a composite
picture of the bulge has begun to emerge: recent evidence points
towards a population made of multiple components. The origin of
the bulge appears to be in the disk and the disk-instabilities,
although a component associated with mergers (a classical bulge) may
also exist. The high-resolution (R=22,500), near-infrared (H-band)
SDSS-III/APOGEE-1 survey provides a more complete characterization
of the entire bulge as it penetrates the dust and probes down to the
Galactic plane. APOGEE-1 collected spectra for approximately 15,000
inner Galaxy stars and derived the associated chemical composition
data via an automated spectral analysis based on accurate stellar
spectra models. Our statistical analysis of the highly accurate (~0.1
dex) bulge metallicities confirms the presence of multiple bulge
components, which change in proportion to each other as a function
of height from the plane. There are two metal-rich components that
seem to dissipate in our high latitude fields (b ≥ 12<SUP>o</SUP>),
and the metal-poor components become very weak at low latitude (|b|
< 4<SUP>o</SUP>). We are analyzing and comparing the individual
element abundances for this sample (which includes α and C, among
other elements) to that of other Galactic components. This enhances the
characterization of the bulge and permits a thorough exploration of the
origin and formation of its component populations (e.g., a classical
bulge or a thick disk component).
---------------------------------------------------------
Title: A Puzzling Li-rich Red Giant in the APOGEE Field
Authors: Carlberg, Joleen K.; Smith, Verne V.; Cunha, Katia M. L.;
Majewski, Steven R.; Meszaros, Szabolcs; Shetrone, Matthew D.;
Allende-Prieto, Carlos; Bizyaev, Dmitry; Stassun, Keivan; Fleming,
Scott W.; Zasowski, Gail; Hearty, Fred; Nidever, David L.; Schneider,
Donald P.; Holtzman, Jon A.; Frinchaboy, Peter M.
2015AAS...22534001C Altcode:
We report on a spectroscopic study of the unusual Li-rich red giant (RG)
recently discovered in NGC 6819. This star was observed by the Apache
Point Observatory Galactic Evolution Experiment (APOGEE) survey as part
of the survey's calibration cluster sample. We use the high-resolution,
near-infrared APOGEE spectrum to address its questionable cluster
membership and test the hypothesis that Li was regenerated by nuclear
processes and mixed to the surface. Previously reported [Fe/H] and
radial velocity (RV) of the Li-rich star are consistent with cluster
membership, and the star's optical and infrared colors place it on
the cluster's red giant branch (RGB), below the luminosity bump. Most
models of internal Li regeneration on the RGB can only explain Li-rich
stars at the luminosity bump, but the currently favored model for the
Li-rich star is a relatively new variation on Li regeneration that can
explain the star's lower RGB position. This model predicts that the
ratio of 12C/13C at the stellar surface should be reduced compared
to normal Li-poor RGs, a signature we sought to measure. However,
the Li-rich star's recently reported asterosesmic properties are
inconsistent with cluster membership. Specifically, the log g inferred
from asteroseismology is significantly lower than that of similar RGs in
the cluster. We find the membership question to be unresolved with our
analysis — our spectroscopic measurement of surface gravity confirms
the asteroseismic result, but the detailed abundances and RVs that we
measure are still consistent with cluster membership. Our Li-enrichment
test is more conclusive. We find a C/N ratio that demonstrates that
Li dilution should have occurred, but the 12C/13C is consistent with
normal dredge-up and inconsistent with Li-enrichment mechanisms that
require unusually deep mixing.
---------------------------------------------------------
Title: Tracing Chemical Evolution over the Extent of the Milky Way's
Disk with APOGEE Red Giant Stars
Authors: Nidever, D.; Bovy; Andrews; Hayden, Bird, Holtzman; Majewski;
Robin; Allende Prieto; Garcia Perez; Zasowski; et al.
2015cdem.confE...2N Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The Gaia-ESO Survey: the chemical structure of the Galactic
discs from the first internal data release
Authors: Mikolaitis, Š.; Hill, V.; Recio-Blanco, A.; de Laverny, P.;
Allende Prieto, C.; Kordopatis, G.; Tautvaišiene, G.; Romano, D.;
Gilmore, G.; Randich, S.; Feltzing, S.; Micela, G.; Vallenari, A.;
Alfaro, E. J.; Bensby, T.; Bragaglia, A.; Flaccomio, E.; Lanzafame,
A. C.; Pancino, E.; Smiljanic, R.; Bergemann, M.; Carraro, G.; Costado,
M. T.; Damiani, F.; Hourihane, A.; Jofré, P.; Lardo, C.; Magrini,
L.; Maiorca, E.; Morbidelli, L.; Sbordone, L.; Sousa, S. G.; Worley,
C. C.; Zaggia, S.
2014A&A...572A..33M Altcode: 2014arXiv1408.6687M
<BR /> Aims: Until recently, most high-resolution spectroscopic studies
of the Galactic thin and thick discs were mostly confined to objects
in the solar vicinity. Here we aim at enlarging the volume in which
individual chemical abundances are used to characterise the thin and
thick discs, using the first internal data release of the Gaia-ESO
survey (GES iDR1). <BR /> Methods: We used the spectra of around 2000
FGK dwarfs and giants from the GES iDR1, obtained at resolutions of
up to R ~ 20 000 with the FLAMES/GIRAFFE spectrograph. We derive
and discuss the abundances of eight elements (Mg, Al, Si, Ca, Ti,
Fe, Cr, Ni, and Y). <BR /> Results: We show that the trends of these
elemental abundances with iron are very similar to those in the solar
neighbourhood. We find a natural division between α-rich and α-poor
stars, best seen in the bimodality of the [Mg/M] distributions in bins
of metallicity, which we attribute to thick- and thin-disc sequences,
respectively. This separation is visible for most α-elements and for
aluminium. With the possible exception of Al, the observed dispersion
around the trends is well described by the expected errors, leaving
little room for astrophysical dispersion. Using previously derived
distances from the first paper from this series for our sample, we
further find that the thick-disc is more extended vertically and is more
centrally concentrated towards the inner Galaxy than the thin-disc,
which indicates a shorter scale-length. We derive the radial (4 to 12
kpc) and vertical (0 to 3.5 kpc) gradients in metallicity, iron, four
α-element abundances, and aluminium for the two populations, taking
into account the identified correlation between R<SUB>GC</SUB> and |
Z |. Similarly to other works, a radial metallicity gradient is found
in the thin disc. The positive radial individual [α/M] gradients found
are at variance from the gradients observed in the RAVE survey. The
thin disc also hosts a negative vertical metallicity gradient in the
solar cylinder, accompanied by positive individual [α/M] and [Al/M]
gradients. The thick-disc, on the other hand, presents no radial
metallicity gradient, a shallower vertical metallicity gradient than
the thin-disc, an α-elements-to-iron radial gradient in the opposite
sense than that of the thin disc, and positive vertical individual
[α/M] and [Al/M] gradients. We examine several thick-disc formation
scenarii in the light of these radial and vertical trends. <P />Based
on observations collected at ESO telescopes under Gaia-ESO survey
programme.Full Table 2 is only available at the CDS via anonymous ftp to
<A href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/572/A33">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/572/A33</A>
---------------------------------------------------------
Title: The Gaia-ESO Survey: the most metal-poor stars in the
Galactic bulge
Authors: Howes, L. M.; Asplund, M.; Casey, A. R.; Keller, S. C.; Yong,
D.; Gilmore, G.; Lind, K.; Worley, C.; Bessell, M. S.; Casagrande, L.;
Marino, A. F.; Nataf, D. M.; Owen, C. I.; Da Costa, G. S.; Schmidt,
B. P.; Tisserand, P.; Randich, S.; Feltzing, S.; Vallenari, A.;
Allende Prieto, C.; Bensby, T.; Flaccomio, E.; Korn, A. J.; Pancino,
E.; Recio-Blanco, A.; Smiljanic, R.; Bergemann, M.; Costado, M. T.;
Damiani, F.; Heiter, U.; Hill, V.; Hourihane, A.; Jofré, P.; Lardo,
C.; de Laverny, P.; Magrini, L.; Maiorca, E.; Masseron, T.; Morbidelli,
L.; Sacco, G. G.; Minniti, D.; Zoccali, M.
2014MNRAS.445.4241H Altcode: 2014arXiv1409.7952H
We present the first results of the EMBLA survey (Extremely
Metal-poor BuLge stars with AAOmega), aimed at finding metal-poor
stars in the Milky Way bulge, where the oldest stars should now
preferentially reside. EMBLA utilizes SkyMapper photometry to
pre-select metal-poor candidates, which are subsequently confirmed
using AAOmega spectroscopy. We describe the discovery and analysis
of four bulge giants with -2.72 ≤ [Fe/H] ≤ -2.48, the lowest
metallicity bulge stars studied with high-resolution spectroscopy to
date. Using FLAMES/UVES spectra through the Gaia-ESO Survey we have
derived abundances of twelve elements. Given the uncertainties, we
find a chemical similarity between these bulge stars and halo stars
of the same metallicity, although the abundance scatter may be larger,
with some of the stars showing unusual [α/Fe] ratios.
---------------------------------------------------------
Title: Bayesian distances and extinctions for giants observed by
Kepler and APOGEE
Authors: Rodrigues, Thaíse S.; Girardi, Léo; Miglio, Andrea; Bossini,
Diego; Bovy, Jo; Epstein, Courtney; Pinsonneault, Marc H.; Stello,
Dennis; Zasowski, Gail; Allende Prieto, Carlos; Chaplin, William
J.; Hekker, Saskia; Johnson, Jennifer A.; Mészáros, Szabolcs;
Mosser, Benoît; Anders, Friedrich; Basu, Sarbani; Beers, Timothy C.;
Chiappini, Cristina; da Costa, Luiz A. N.; Elsworth, Yvonne; García,
Rafael A.; García Pérez, Ana E.; Hearty, Fred R.; Maia, Marcio A. G.;
Majewski, Steven R.; Mathur, Savita; Montalbán, Josefina; Nidever,
David L.; Santiago, Basilio; Schultheis, Mathias; Serenelli, Aldo;
Shetrone, Matthew
2014MNRAS.445.2758R Altcode: 2014arXiv1410.1350R
We present a first determination of distances and extinctions for
individual stars in the first release of the APOKASC catalogue,
built from the joint efforts of the Apache Point Observatory Galactic
Evolution Experiment (APOGEE) and the Kepler Asteroseismic Science
Consortium (KASC). Our method takes into account the spectroscopic
constraints derived from the APOGEE Stellar Parameters and Chemical
Abundances Pipeline, together with the asteroseismic parameters
from KASC. These parameters are then employed to estimate intrinsic
stellar properties, including absolute magnitudes, using the Bayesian
tool PARAM. We then find the distance and extinction that best fit
the observed photometry in Sloan Digital Sky Survey (SDSS), 2MASS,
and WISE passbands. The first 1989 giants targetted by APOKASC are
found at typical distances between 0.5 and 5 kpc, with individual
uncertainties of just ∼1.8 per cent. Our extinction estimates are
systematically smaller than provided in the Kepler Input Catalogue
and by the Schlegel et al. maps. Distances to individual stars in the
NGC 6791 and NGC 6819 star clusters agree to within their credible
intervals. Comparison with the APOGEE red clump and SAGA catalogues
provide another useful check, exhibiting agreement with our measurements
to within a few per cent. Overall, present methods seem to provide
excellent distance and extinction determinations for the bulk of the
APOKASC sample. Approximately one third of the stars present broad
or multiple-peaked probability density functions and hence increased
uncertainties. Uncertainties are expected to be reduced in future
releases of the catalogue, when a larger fraction of the stars will
have seismically determined evolutionary status classifications.
---------------------------------------------------------
Title: The APOKASC Catalog: An Asteroseismic and Spectroscopic Joint
Survey of Targets in the Kepler Fields
Authors: Pinsonneault, Marc H.; Elsworth, Yvonne; Epstein, Courtney;
Hekker, Saskia; Mészáros, Sz.; Chaplin, William J.; Johnson,
Jennifer A.; García, Rafael A.; Holtzman, Jon; Mathur, Savita;
García Pérez, Ana; Silva Aguirre, Victor; Girardi, Léo; Basu,
Sarbani; Shetrone, Matthew; Stello, Dennis; Allende Prieto, Carlos;
An, Deokkeun; Beck, Paul; Beers, Timothy C.; Bizyaev, Dmitry; Bloemen,
Steven; Bovy, Jo; Cunha, Katia; De Ridder, Joris; Frinchaboy, Peter M.;
García-Hernández, D. A.; Gilliland, Ronald; Harding, Paul; Hearty,
Fred R.; Huber, Daniel; Ivans, Inese; Kallinger, Thomas; Majewski,
Steven R.; Metcalfe, Travis S.; Miglio, Andrea; Mosser, Benoit; Muna,
Demitri; Nidever, David L.; Schneider, Donald P.; Serenelli, Aldo;
Smith, Verne V.; Tayar, Jamie; Zamora, Olga; Zasowski, Gail
2014ApJS..215...19P Altcode: 2014arXiv1410.2503P
We present the first APOKASC catalog of spectroscopic and
asteroseismic properties of 1916 red giants observed in the Kepler
fields. The spectroscopic parameters provided from the Apache Point
Observatory Galactic Evolution Experiment project are complemented
with asteroseismic surface gravities, masses, radii, and mean
densities determined by members of the Kepler Asteroseismology
Science Consortium. We assess both random and systematic sources of
error and include a discussion of sample selection for giants in the
Kepler fields. Total uncertainties in the main catalog properties are
of the order of 80 K in T <SUB>eff</SUB>, 0.06 dex in [M/H], 0.014
dex in log g, and 12% and 5% in mass and radius, respectively; these
reflect a combination of systematic and random errors. Asteroseismic
surface gravities are substantially more precise and accurate than
spectroscopic ones, and we find good agreement between their mean
values and the calibrated spectroscopic surface gravities. There are,
however, systematic underlying trends with T <SUB>eff</SUB> and log
g. Our effective temperature scale is between 0 and 200 K cooler
than that expected from the infrared flux method, depending on the
adopted extinction map, which provides evidence for a lower value on
average than that inferred for the Kepler Input Catalog (KIC). We
find a reasonable correspondence between the photometric KIC and
spectroscopic APOKASC metallicity scales, with increased dispersion
in KIC metallicities as the absolute metal abundance decreases, and
offsets in T <SUB>eff</SUB> and log g consistent with those derived
in the literature. We present mean fitting relations between APOKASC
and KIC observables and discuss future prospects, strengths, and
limitations of the catalog data.
---------------------------------------------------------
Title: VizieR Online Data Catalog: Radial velocities in seven globular
clusters (Lardo+, 2015)
Authors: Lardo, C.; Pancino, E.; Bellazzini, M.; Bragaglia, A.; Donati,
P.; Gilmore, G.; Randich, S.; Feltzing, S.; Jeffries, R. D.; Vallenari,
A.; Alfaro, E. J.; Allende Prieto, C.; Flaccomio, E.; Koposov, S. E.;
Recio-Blanco, A.; Bergemann, M.; Carraro, G.; Costado, M. T.; Damiani,
F.; Hourihane, A.; Jofree, P.; de Laverny, P.; Marconi, G.; Masseron,
T.; Morbidelli, L.; Sacco, G. G.; Worley, C. C.
2014yCat..35730115L Altcode: 2014yCat..35739115L
Velocities are given for 1826 stars in the field of the globular
clusters NGC 1851, NGC 2808, NGC 4372, NGC 4833, NGC 5927, NGC 6752,
and NGC 7078 observed with FLAMES/GIRAFFE@VLT. The table provides the
individual identifications, coordinates, V magnitudes, velocities and
their associated uncertainties for each star. <P />(2 data files).
---------------------------------------------------------
Title: Tracing Chemical Evolution over the Extent of the Milky Way's
Disk with APOGEE Red Clump Stars
Authors: Nidever, David L.; Bovy, Jo; Bird, Jonathan C.; Andrews, Brett
H.; Hayden, Michael; Holtzman, Jon; Majewski, Steven R.; Smith, Verne;
Robin, Annie C.; García Pérez, Ana E.; Cunha, Katia; Allende Prieto,
Carlos; Zasowski, Gail; Schiavon, Ricardo P.; Johnson, Jennifer A.;
Weinberg, David H.; Feuillet, Diane; Schneider, Donald P.; Shetrone,
Matthew; Sobeck, Jennifer; García-Hernández, D. A.; Zamora, O.; Rix,
Hans-Walter; Beers, Timothy C.; Wilson, John C.; O'Connell, Robert
W.; Minchev, Ivan; Chiappini, Cristina; Anders, Friedrich; Bizyaev,
Dmitry; Brewington, Howard; Ebelke, Garrett; Frinchaboy, Peter M.;
Ge, Jian; Kinemuchi, Karen; Malanushenko, Elena; Malanushenko, Viktor;
Marchante, Moses; Mészáros, Szabolcs; Oravetz, Daniel; Pan, Kaike;
Simmons, Audrey; Skrutskie, Michael F.
2014ApJ...796...38N Altcode: 2014arXiv1409.3566N
We employ the first two years of data from the near-infrared,
high-resolution SDSS-III/APOGEE spectroscopic survey to investigate
the distribution of metallicity and α-element abundances of stars
over a large part of the Milky Way disk. Using a sample of ≈10,
000 kinematically unbiased red-clump stars with ~5% distance accuracy
as tracers, the [α/Fe] versus [Fe/H] distribution of this sample
exhibits a bimodality in [α/Fe] at intermediate metallicities, -0.9
< [Fe/H] <-0.2, but at higher metallicities ([Fe/H] ~+0.2) the
two sequences smoothly merge. We investigate the effects of the APOGEE
selection function and volume filling fraction and find that these have
little qualitative impact on the α-element abundance patterns. The
described abundance pattern is found throughout the range 5 < R
< 11 kpc and 0 < |Z| < 2 kpc across the Galaxy. The [α/Fe]
trend of the high-α sequence is surprisingly constant throughout the
Galaxy, with little variation from region to region (~10%). Using simple
galactic chemical evolution models, we derive an average star-formation
efficiency (SFE) in the high-α sequence of ~4.5 × 10<SUP>-10</SUP>
yr<SUP>-1</SUP>, which is quite close to the nearly constant value
found in molecular-gas-dominated regions of nearby spirals. This
result suggests that the early evolution of the Milky Way disk was
characterized by stars that shared a similar star-formation history and
were formed in a well-mixed, turbulent, and molecular-dominated ISM with
a gas consumption timescale (SFE<SUP>-1</SUP>) of ~2 Gyr. Finally, while
the two α-element sequences in the inner Galaxy can be explained by
a single chemical evolutionary track, this cannot hold in the outer
Galaxy, requiring, instead, a mix of two or more populations with
distinct enrichment histories.
---------------------------------------------------------
Title: VizieR Online Data Catalog: Gaia-ESO Survey: Li-rich stars
in NGC2547 (Sacco+, 2015)
Authors: Sacco, G. G.; Jeffries, R. D.; Randich, S.; Franciosini, E.;
Jackson, R. J.; Cottaar, M.; Spina, L.; Palla, F.; Mapelli, M.; Alfaro,
E. J.; Bonito, R.; Damiani, F.; Frasca, A.; Klutsch, A.; Lanzafame,
A.; Bayo, A.; Barrado, D.; Jimenez-Esteban, F.; Gilmore, G.; Micela,
M.; Vallenari, A.; Allende-Prieto, C.; Flaccomio, E.; Carraro, G.;
Costado, M. T.; Jofre, P.; Lardo, C.; Magrini, L.; Morbidelli, L.;
Prisinzano, L.; Sbordone, L.
2014yCat..35749007S Altcode:
Main properties of the Li-rich stars in the field of view of the open
clusters NGC 2547 observed by the Gaia-ESO Survey. The Table include
coordinates, photometry from the literature, spectroscopic data derived
by the Gaia-ESO observations, and the probability for a star to be
part of the primary population of NGC 2547. <P />(1 data file).
---------------------------------------------------------
Title: VizieR Online Data Catalog: The ELM survey. V. White dwarf
binaries (Brown+, 2013)
Authors: Brown, W. R.; Kilic, M.; Allende Prieto, C.; Gianninas, A.;
Kenyon, S. J.
2014yCat..17690066B Altcode:
Observations were obtained over the course of seven observing runs at
the 6.5m Multiple Mirror Telescope (MMT) between 2011 March and 2013
February. <P />(3 data files).
---------------------------------------------------------
Title: The Gaia-ESO Survey: The analysis of high-resolution UVES
spectra of FGK-type stars
Authors: Smiljanic, R.; Korn, A. J.; Bergemann, M.; Frasca, A.;
Magrini, L.; Masseron, T.; Pancino, E.; Ruchti, G.; San Roman,
I.; Sbordone, L.; Sousa, S. G.; Tabernero, H.; Tautvaišienė,
G.; Valentini, M.; Weber, M.; Worley, C. C.; Adibekyan, V. Zh.;
Allende Prieto, C.; Barisevičius, G.; Biazzo, K.; Blanco-Cuaresma,
S.; Bonifacio, P.; Bragaglia, A.; Caffau, E.; Cantat-Gaudin, T.;
Chorniy, Y.; de Laverny, P.; Delgado-Mena, E.; Donati, P.; Duffau,
S.; Franciosini, E.; Friel, E.; Geisler, D.; González Hernández,
J. I.; Gruyters, P.; Guiglion, G.; Hansen, C. J.; Heiter, U.; Hill, V.;
Jacobson, H. R.; Jofre, P.; Jönsson, H.; Lanzafame, A. C.; Lardo, C.;
Ludwig, H. -G.; Maiorca, E.; Mikolaitis, Š.; Montes, D.; Morel, T.;
Mucciarelli, A.; Muñoz, C.; Nordlander, T.; Pasquini, L.; Puzeras,
E.; Recio-Blanco, A.; Ryde, N.; Sacco, G.; Santos, N. C.; Serenelli,
A. M.; Sordo, R.; Soubiran, C.; Spina, L.; Steffen, M.; Vallenari,
A.; Van Eck, S.; Villanova, S.; Gilmore, G.; Randich, S.; Asplund,
M.; Binney, J.; Drew, J.; Feltzing, S.; Ferguson, A.; Jeffries, R.;
Micela, G.; Negueruela, I.; Prusti, T.; Rix, H. -W.; Alfaro, E.;
Babusiaux, C.; Bensby, T.; Blomme, R.; Flaccomio, E.; François, P.;
Irwin, M.; Koposov, S.; Walton, N.; Bayo, A.; Carraro, G.; Costado,
M. T.; Damiani, F.; Edvardsson, B.; Hourihane, A.; Jackson, R.; Lewis,
J.; Lind, K.; Marconi, G.; Martayan, C.; Monaco, L.; Morbidelli, L.;
Prisinzano, L.; Zaggia, S.
2014A&A...570A.122S Altcode: 2014arXiv1409.0568S
Context. The ongoing Gaia-ESO Public Spectroscopic Survey is using
FLAMES at the VLT to obtain high-quality medium-resolution Giraffe
spectra for about 10<SUP>5</SUP> stars and high-resolution UVES spectra
for about 5000 stars. With UVES, the Survey has already observed
1447 FGK-type stars. <BR /> Aims: These UVES spectra are analyzed
in parallel by several state-of-the-art methodologies. Our aim is
to present how these analyses were implemented, to discuss their
results, and to describe how a final recommended parameter scale is
defined. We also discuss the precision (method-to-method dispersion)
and accuracy (biases with respect to the reference values) of the
final parameters. These results are part of the Gaia-ESO second
internal release and will be part of its first public release of
advanced data products. <BR /> Methods: The final parameter scale is
tied to the scale defined by the Gaia benchmark stars, a set of stars
with fundamental atmospheric parameters. In addition, a set of open
and globular clusters is used to evaluate the physical soundness
of the results. Each of the implemented methodologies is judged
against the benchmark stars to define weights in three different
regions of the parameter space. The final recommended results are
the weighted medians of those from the individual methods. <BR />
Results: The recommended results successfully reproduce the atmospheric
parameters of the benchmark stars and the expected T<SUB>eff</SUB>-log
g relation of the calibrating clusters. Atmospheric parameters and
abundances have been determined for 1301 FGK-type stars observed with
UVES. The median of the method-to-method dispersion of the atmospheric
parameters is 55 K for T<SUB>eff</SUB>, 0.13 dex for log g and 0.07
dex for [Fe/H]. Systematic biases are estimated to be between 50-100
K for T<SUB>eff</SUB>, 0.10-0.25 dex for log g and 0.05-0.10 dex for
[Fe/H]. Abundances for 24 elements were derived: C, N, O, Na, Mg, Al,
Si, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Mo, Ba, Nd, and
Eu. The typical method-to-method dispersion of the abundances varies
between 0.10 and 0.20 dex. <BR /> Conclusions: The Gaia-ESO sample of
high-resolution spectra of FGK-type stars will be among the largest of
its kind analyzed in a homogeneous way. The extensive list of elemental
abundances derived in these stars will enable significant advances in
the areas of stellar evolution and Milky Way formation and evolution. <P
/>Based on observations made with the ESO/VLT, at Paranal Observatory,
under program 188.B-3002 (The Gaia-ESO Public Spectroscopic Survey, PIs
Gilmore and Randich). Appendices are available in electronic form at <A
href="http://www.aanda.org/10.1051/0004-6361/201423937/olm">http://www.aanda.org</A>
---------------------------------------------------------
Title: Improvement and analysis of MILES spectral library for stellar
population modelling
Authors: Milone, A. de C.; Sansom, A.; Vazdekis, A.;
Sánchez-Blázquez, P.; Allende Prieto, C.; Falcón-Barroso, J.;
da Silva, R.
2014RMxAC..44...49M Altcode:
We are improving the MILES empirical library of stellar spectra
(Sánchez-Blázquez et al. 2006, Cenarro et al. 2007) in order to
build more realistic simple stellar population (SSP) models with
variable α-enhancement: (i) compilation of [E/Fe], (ii) comparisons
of stellar spectral models against MILES data plus empirical analysis
of the blue spectral region, (iii) Galactic kinematic classification
of library stars, and (iv) expansion of the library observing stars
with known parameters.
---------------------------------------------------------
Title: A new gravitational wave verification source.
Authors: Kilic, M.; Brown, W. R.; Gianninas, A.; Hermes, J. J.;
Allende Prieto, C.; Kenyon, S. J.
2014MNRAS.444L...1K Altcode: 2014arXiv1406.3346K
We report the discovery of a detached 20-min orbital period binary
white dwarf (WD). WD 0931+444 (SDSS J093506.93+441106.9) was previously
classified as a WD + M dwarf system based on its optical spectrum. Our
time-resolved optical spectroscopy observations obtained at the 8 m
Gemini and 6.5 m MMT reveal peak-to-peak radial velocity variations
of ≈400 km s<SUP>-1</SUP> every 20 min for the WD, but no velocity
variations for the M dwarf. In addition, high-speed photometry from the
McDonald 2.1 m telescope shows no evidence of variability nor evidence
of a reflection effect. An M dwarf companion is physically too large
to fit into a 20 min orbit. Thus, the orbital motion of the WD is
almost certainly due to an invisible WD companion. The M dwarf must be
either an unrelated background object or the tertiary component of a
hierarchical triple system. WD 0931+444 contains a pair of WDs, a 0.32
M<SUB>⊙</SUB> primary and a ≥0.14 M<SUB>⊙</SUB> secondary, at a
separation of ≥0.19 R<SUB>⊙</SUB>. After J0651+2844, WD 0931+444
becomes the second shortest period detached binary WD currently
known. The two WDs will lose angular momentum through gravitational
wave radiation and merge in ≤9 Myr. The log h ≃ -22 gravitational
wave strain from WD 0931+444 is strong enough to make it a verification
source for gravitational wave missions in the milli-Hertz frequency
range, e.g. the evolved Laser Interferometer Space Antenna (eLISA),
bringing the total number of known eLISA verification sources to nine.
---------------------------------------------------------
Title: VizieR Online Data Catalog: Abundances from Gaia-ESO Survey
(Mikolaitis+, 2014)
Authors: Mikolaitis, S.; Hill, V.; Recio-Blanco, A.; de Laverny, P.;
Allende Prieto, C.; Kordopatis, G.; Tautvaisiene, G.; Romano, D.;
Gilmore, G.; Randich, S.; Feltzing, S.; Micela, G.; Vallenari, A.;
Alfaro, E. J.; Bensby, T.; Bragaglia, A.; Flaccomio, E.; Lanzafame,
A. C.; Pancino, E.; Smiljanic, R.; Bergemann, M.; Carraro, G.; Costado,
M. T.; Damiani, F.; Hourihane, A.; Jofre, P.; Lardo, C.; Magrini,
L.; Maiorca, E.; Morbidelli, L.; Sbordone, L.; Sousa, S. G.; Worley,
C. C.; Zaggia, S.
2014yCat..35720033M Altcode: 2014yCat..35729033M
Table2 contains chemical abundances of 1916 stars from GES DR1. <P
/>(1 data file).
---------------------------------------------------------
Title: HIRES: the high resolution spectrograph for the E-ELT
Authors: Zerbi, F. M.; Bouchy, F.; Fynbo, J.; Maiolino, R.; Piskunov,
N.; Rebolo Lopez, R.; Santos, N.; Strassmeier, K.; Udry, S.; Vanzi,
L.; Riva, M.; Basden, A.; Boisse, I.; Bonfils, X.; Buscher, D.; Cabral,
A.; Dimarcantonio, P.; Di Varano, I.; Henry, D.; Monteiro, M.; Morris,
T.; Murray, G.; Oliva, Ernesto; Parry, I.; Pepe, F.; Quirrenbach, A.;
Rasilla, J. L.; Rees, P.; Stempels, E.; Valenziano, L.; Wells, M.;
Wildi, F.; Origlia, L.; Allende Prieto, C.; Chiavassa, A.; Cristiani,
S.; Figueira, P.; Gustafsson, B.; Hatzes, A.; Haehnelt, M.; Heng,
K.; Israelian, G.; Kochukhov, O.; Lovis, C.; Marconi, A.; Martins,
C. J. A. P.; Noterdaeme, P.; Petitjean, P.; Puzia, T.; Queloz, D.;
Reiners, A.; Zoccali, M.
2014SPIE.9147E..23Z Altcode:
The current instrumentation plan for the E-ELT foresees a High
Resolution Spectrograph conventionally indicated as HIRES. Shaped
on the study of extra-solar planet atmospheres, Pop-III stars and
fundamental physical constants, HIRES is intended to embed observing
modes at high-resolution (up to R=150000) and large spectral range
(from the blue limit to the K band) useful for a large suite of science
cases that can exclusively be tackled by the E-ELT. We present in
this paper the solution for HIRES envisaged by the "HIRES initiative",
the international collaboration established in 2013 to pursue a HIRES
on E-ELT.
---------------------------------------------------------
Title: The Vertical Metallicity Gradient of the Milky Way Disk:
Transitions in [α/Fe] Populations
Authors: Schlesinger, Katharine J.; Johnson, Jennifer A.; Rockosi,
Constance M.; Lee, Young Sun; Beers, Timothy C.; Harding, Paul;
Allende Prieto, Carlos; Bird, Jonathan C.; Schönrich, Ralph; Yanny,
Brian; Schneider, Donald P.; Weaver, Benjamin A.; Brinkmann, Jon
2014ApJ...791..112S Altcode: 2014arXiv1405.6724S
Using G dwarfs from the Sloan Extension for Galactic Understanding
and Exploration (SEGUE) survey, we have determined the vertical
metallicity gradient in the Milky Way's disk and examined how this
gradient varies for different [α/Fe] subsamples. Our sample contains
over 40,000 stars with low-resolution spectroscopy over 144 lines of
sight. It also covers a significant disk volume, between ~0.3 and 1.6
kpc from the Galactic plane, and allows us to examine the disk in situ,
whereas previous analyses were more limited in scope. Furthermore, this
work does not presuppose a disk structure, whether composed of a single
complex population or distinct thin and thick disk components. We employ
the SEGUE Stellar Parameter Pipeline to obtain estimates of stellar
parameters, [Fe/H], and [α/Fe] and extract multiple volume-complete
subsamples of approximately 1000 stars each. Based on SEGUE's
target-selection algorithm, we adjust each subsample to determine
an unbiased picture of disk chemistry; consequently, each individual
star represents the properties of many. The metallicity gradient is
-0.243<SUP>+0.039</SUP><SUB>-0.053</SUB> dex kpc<SUP>-1</SUP> for the
entire sample, which we compare to various literature results. This
gradient stems from the different [α/Fe] populations inhabiting
different ranges of height above the Galactic plane. Each [α/Fe]
subsample shows little change in median [Fe/H] with height. If we
associate [α/Fe] with age, the negligible gradients of our [α/Fe]
subsamples suggest that stars formed in different epochs exhibit
comparable vertical structure, implying similar star formation processes
and evolution.
---------------------------------------------------------
Title: The APOGEE Red-clump Catalog: Precise Distances, Velocities,
and High-resolution Elemental Abundances over a Large Area of the
Milky Way's Disk
Authors: Bovy, Jo; Nidever, David L.; Rix, Hans-Walter; Girardi,
Léo; Zasowski, Gail; Chojnowski, S. Drew; Holtzman, Jon; Epstein,
Courtney; Frinchaboy, Peter M.; Hayden, Michael R.; Rodrigues, Thaíse
S.; Majewski, Steven R.; Johnson, Jennifer A.; Pinsonneault, Marc H.;
Stello, Dennis; Allende Prieto, Carlos; Andrews, Brett; Basu, Sarbani;
Beers, Timothy C.; Bizyaev, Dmitry; Burton, Adam; Chaplin, William J.;
Cunha, Katia; Elsworth, Yvonne; García, Rafael A.; García-Herńandez,
Domingo A.; García Pérez, Ana E.; Hearty, Fred R.; Hekker, Saskia;
Kallinger, Thomas; Kinemuchi, Karen; Koesterke, Lars; Mészáros,
Szabolcs; Mosser, Benoît; O'Connell, Robert W.; Oravetz, Daniel; Pan,
Kaike; Robin, Annie C.; Schiavon, Ricardo P.; Schneider, Donald P.;
Schultheis, Mathias; Serenelli, Aldo; Shetrone, Matthew; Silva Aguirre,
Victor; Simmons, Audrey; Skrutskie, Michael; Smith, Verne V.; Stassun,
Keivan; Weinberg, David H.; Wilson, John C.; Zamora, Olga
2014ApJ...790..127B Altcode: 2014arXiv1405.1032B
The Sloan Digital Sky Survey III's Apache Point Observatory Galactic
Evolution Experiment (APOGEE) is a high-resolution near-infrared
spectroscopic survey covering all of the major components of the Galaxy,
including the dust-obscured regions of the inner Milky Way disk and
bulge. Here we present a sample of 10,341 likely red-clump stars (RC)
from the first two years of APOGEE operations, selected based on their
position in color-metallicity-surface-gravity-effective-temperature
space using a new method calibrated using stellar evolution models and
high-quality asteroseismology data. The narrowness of the RC locus in
color-metallicity-luminosity space allows us to assign distances to
the stars with an accuracy of 5%-10%. The sample extends to typical
distances of about 3 kpc from the Sun, with some stars out to 8 kpc,
and spans a volume of approximately 100 kpc<SUP>3</SUP> over 5 kpc
<~ R <~ 14 kpc, |Z| <~ 2 kpc, and -15° <~ Galactocentric
azimuth <~ 30°. The APOGEE red-clump (APOGEE-RC) catalog contains
photometry from the Two Micron All Sky Survey, reddening estimates,
distances, line-of-sight velocities, stellar parameters and elemental
abundances determined from the high-resolution APOGEE spectra, and
matches to major proper motion catalogs. We determine the survey
selection function for this data set and discuss how the RC selection
samples the underlying stellar populations. We use this sample to
limit any azimuthal variations in the median metallicity within the
≈45° azimuthal region covered by the current sample to be <=0.02
dex, which is more than an order of magnitude smaller than the radial
metallicity gradient. This result constrains coherent non-axisymmetric
flows within a few kiloparsecs from the Sun.
---------------------------------------------------------
Title: Deep SDSS optical spectroscopy of distant halo
stars. I. Atmospheric parameters and stellar metallicity distribution
Authors: Allende Prieto, C.; Fernández-Alvar, E.; Schlesinger, K. J.;
Lee, Y. S.; Morrison, H. L.; Schneider, D. P.; Beers, T. C.; Bizyaev,
D.; Ebelke, G.; Malanushenko, E.; Malanushenko, V.; Oravetz, D.; Pan,
K.; Simmons, A.; Simmerer, J.; Sobeck, J.; Robin, A. C.
2014A&A...568A...7A Altcode: 2014arXiv1406.4997A
<BR /> Aims: We analyze a sample of tens of thousands of spectra of
halo turnoff stars, obtained with the optical spectrographs of the Sloan
Digital Sky Survey (SDSS), to characterize the stellar halo population
"in situ" out to a distance of a few tens of kpc from the Sun. In this
paper we describe the derivation of atmospheric parameters. We also
derive the overall stellar metallicity distribution based on F-type
stars observed as flux calibrators for the Baryonic Oscillations
Spectroscopic Survey (BOSS). <BR /> Methods: Our analysis is based
on an automated method that determines the set of parameters of a
model atmosphere that reproduces each observed spectrum best. We
used an optimization algorithm and evaluate model fluxes by means
of interpolation in a precomputed grid. In our analysis, we account
for the spectrograph's varying resolution as a function of fiber
and wavelength. Our results for early SDSS (pre-BOSS upgrade) data
compare well with those from the SEGUE Stellar Parameter Pipeline
(SSPP), except for stars with log g (cgs units) lower than 2.5. <BR />
Results: An analysis of stars in the globular cluster M 13 reveals a
dependence of the inferred metallicity on surface gravity for stars
with log g < 2.5, confirming the systematics identified in the
comparison with the SSPP. We find that our metallicity estimates
are significantly more precise than the SSPP results. We also find
excellent agreement with several independent analyses. We show that
the SDSS color criteria for selecting F-type halo turnoff stars as flux
calibrators efficiently excludes stars with high metallicities, but does
not significantly distort the shape of the metallicity distribution
at low metallicity. We obtain a halo metallicity distribution that
is narrower and more asymmetric than in previous studies. The lowest
gravity stars in our sample, at tens of kpc from the Sun, indicate a
shift of the metallicity distribution to lower abundances, consistent
with what is expected from a dual halo system in the Milky Way. <P
/>Full Table 1 is only available at the CDS via anonymous ftp to <A
href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/568/A7">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/568/A7</A>
---------------------------------------------------------
Title: The Gaia-ESO Survey: the Galactic thick to thin disc transition
Authors: Recio-Blanco, A.; de Laverny, P.; Kordopatis, G.; Helmi,
A.; Hill, V.; Gilmore, G.; Wyse, R.; Adibekyan, V.; Randich, S.;
Asplund, M.; Feltzing, S.; Jeffries, R.; Micela, G.; Vallenari, A.;
Alfaro, E.; Allende Prieto, C.; Bensby, T.; Bragaglia, A.; Flaccomio,
E.; Koposov, S. E.; Korn, A.; Lanzafame, A.; Pancino, E.; Smiljanic,
R.; Jackson, R.; Lewis, J.; Magrini, L.; Morbidelli, L.; Prisinzano,
L.; Sacco, G.; Worley, C. C.; Hourihane, A.; Bergemann, M.; Costado,
M. T.; Heiter, U.; Joffre, P.; Lardo, C.; Lind, K.; Maiorca, E.
2014A&A...567A...5R Altcode: 2014arXiv1403.7568R
<BR /> Aims: The nature of the thick disc and its relation to the
thin disc is presently an important subject of debate. In fact, the
structural and chemo-dynamical transition between disc populations can
be used as a test of the proposed models of Galactic disc formation
and evolution. <BR /> Methods: We used the atmospheric parameters,
[α/Fe] abundances, and radial velocities, which were determined from
the Gaia-ESO Survey GIRAFFE spectra of FGK-type stars (first nine months
of observations) to provide a chemo-kinematical characterisation of
the disc stellar populations. We focussed on a subsample of 1016 stars
with high-quality parameters, covering the volume | Z | < 4.5 kpc
and R in the range 2-13 kpc. <BR /> Results: We have identified a thin
to thick disc separation in the [α/Fe] vs. [M/H] plane, thanks to the
presence of a low-density region in the number density distribution. The
thick disc stars seem to lie in progressively thinner layers above the
Galactic plane, as metallicity increases and [α/Fe] decreases. In
contrast, the thin disc population presents a constant value of the
mean distance to the Galactic plane at all metallicities. In addition,
our data confirm the already known correlations between V<SUB>φ</SUB>
and [M/H] for the two discs. For the thick disc sequence, a study of
the possible contamination by thin disc stars suggests a gradient up
to 64 ± 9 km s<SUP>-1</SUP> dex<SUP>-1</SUP>. The distributions of
azimuthal velocity, vertical velocity, and orbital parameters are
also analysed for the chemically separated samples. Concerning the
gradients with galactocentric radius, we find, for the thin disc, a
flat behaviour of the azimuthal velocity, a metallicity gradient equal
to -0.058 ± 0.008 dex kpc<SUP>-1</SUP> and a very small positive
[α/Fe] gradient. For the thick disc, flat gradients in [M/H] and
[α/Fe] are derived. <BR /> Conclusions: Our chemo-kinematical analysis
suggests a picture where the thick disc seems to have experienced a
settling process, during which its rotation increased progressively
and, possibly, the azimuthal velocity dispersion decreased. At [M/H]
≈ -0.25 dex and [α/Fe]≈ 0.1 dex, the mean characteristics of
the thick disc in vertical distance to the Galactic plane, rotation,
rotational dispersion, and stellar orbits' eccentricity agree with
that of the thin disc stars of the same metallicity, suggesting
a possible connection between these two populations at a certain
epoch of the disc evolution. Finally, the results presented here,
based only on the first months of the Gaia ESO Survey observations,
confirm how crucial large high-resolution spectroscopic surveys
outside the solar neighbourhood are today for our understanding of
the Milky Way history. <P />Based on observations collected with the
FLAMES spectrograph at the VLT/UT2 telescope (Paranal Observatory, ESO,
Chile), for the Gaia-ESO Large Public Survey, programme 188.B-3002.Full
Table 1 is only available at the CDS via anonymous ftp to <A
href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/567/A5">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/567/A5</A>
---------------------------------------------------------
Title: H.O.R.S. a new visiting instrument for G.T.C. based on the
Utrecht Echelle Spectrograph
Authors: Peñate, José; Gracia, Felix; Allende Prieto, Carlos; Calvo,
Juan; Santana, Samuel
2014SPIE.9147E..8JP Altcode:
The High Optical Resolution Spectrograph (HORS) is a proposed
high-resolution spectrograph for the 10-m Gran Telescopio Canarias
(GTC) based on components from UES, a spectrograph which was in use at
the 4.2-m William Herschel Telescope (WHT) between 1992 and 2001. HORS
is designed as a cross-dispersed echelle spectrograph to observe in the
range 380-800 nm with a FWHM resolving power of about 50,000. HORS would
operate on the GTC as a general-purpose high-resolution spectrograph,
and it would serve as a test-bed for some of the technologies proposed
for ESPRESSO - an ultra-high stability spectrograph planned for the
Very Large Telescope (VLT) of the European Southern Observatory. The
HORS spectrograph will be placed in the Coudé room, where it can
enjoy excellent thermal and mechanical stability, fiber fed from the
Nasmyth focus, which is shared with OSIRIS. Inside the spectrograph,
incoming light will hit a small folder mirror before reaching the
collimator. After a second folder, the light will go through a set of
three prisms and an Echelle grating before entering the spectrograph
camera and, finally, reaching the detector. This manuscript contains
a summary of the whole process that has transformed UES into HORS,
with all the mechanical and optical modifications that have been
introduced to reach the final layout.
---------------------------------------------------------
Title: ESPRESSO: the radial velocity machine for the VLT
Authors: Mégevand, Denis; Zerbi, Filippo M.; Di Marcantonio,
Paolo; Cabral, Alexandre; Riva, Marco; Abreu, Manuel; Pepe,
Francesco; Cristiani, Stefano; Rebolo Lopez, Rafael; Santos, Nuno
C.; Dekker, Hans; Aliverti, Matteo; Allende Prieto, Carlos; Amate,
Manuel; Avila, Gerardo; Baldini, Veronica; Bandy, Timothy; Bristow,
Paul; Broeg, Christopher; Cirami, Roberto; Coelho, João.; Conconi,
Paolo; Coretti, Igor; Cupani, Guido; D'Odorico, Valentina; De Caprio,
Vincenzo; Delabre, Bernard; Dorn, Reinhold; Figueira, Pedro; Fragoso,
Ana; Galeotta, Samuele; Genolet, Ludovic; Gomes, Ricardo; González
Hernández, Jonay; Hughes, Ian; Iwert, Olaf; Kerber, Florian; Landoni,
Marco; Lizon, Jean-Louis; Lovis, Christophe; Maire, Charles; Mannetta,
Marco; Martins, Carlos C. J. A. P.; Molaro, Paolo; Monteiro, Manuel
A. S.; Moschetti, Manuele; Oliveira, Antonio; Zapatero Osorio, Maria
Rosa; Poretti, Ennio; Rasilla, José L.; Santana Tschudi, Samuel;
Santos, Pedro; Sosnowska, Danuta; Sousa, Sérgio; Tenegi, Fabio;
Toso, Giorgio; Vanzella, Eros; Viel, Matteo
2014SPIE.9147E..1HM Altcode:
ESPRESSO is the next generation ground based European exoplanets
hunter. It will combine the efficiency of modern echelle spectrograph
with extreme radial-velocity and spectroscopic precision. It will be
installed at Paranal's VLT in order to achieve two magnitudes gain with
respect to its predecessor HARPS, and the instrumental radial-velocity
precision will be improved to reach 10 cm/s level. We have constituted
a Consortium of astronomical research institutes to fund, design
and build ESPRESSO on behalf of and in collaboration with ESO, the
European Southern Observatory. The spectrograph will be installed at
the Combined Coudé Laboratory (CCL) of the VLT, it will be linked
to the four 8.2 meters Unit Telescopes through four optical "Coudé
trains" and will be operated either with a single telescope or with
up to four UTs, enabling an additional 1.5 magnitude gain. Thanks to
its characteristics and ability of combining incoherently the light
of 4 large telescopes, ESPRESSO will offer new possibilities in many
fields of astronomy. Our main scientific objectives are, however, the
search and characterization of rocky exoplanets in the habitable zone
of quiet, near-by G to M-dwarfs, and the analysis of the variability
of fundamental physical constants. The project is, for most of its
workpackages, in the procurement or development phases, and the CCL
infrastructure is presently under adaptation work. In this paper,
we present the scientific objectives, the capabilities of ESPRESSO,
the technical solutions for the system and its subsystems. The project
aspects of this facility are also described, from the consortium and
partnership structure to the planning phases and milestones.
---------------------------------------------------------
Title: Project overview and update on WEAVE: the next generation
wide-field spectroscopy facility for the William Herschel Telescope
Authors: Dalton, Gavin; Trager, Scott; Abrams, Don Carlos; Bonifacio,
Piercarlo; López Aguerri, J. Alfonso; Middleton, Kevin; Benn, Chris;
Dee, Kevin; Sayède, Frédéric; Lewis, Ian; Pragt, Johan; Pico,
Sergio; Walton, Nic; Rey, Juerg; Allende Prieto, Carlos; Peñate,
José; Lhome, Emilie; Agócs, Tibor; Alonso, José; Terrett, David;
Brock, Matthew; Gilbert, James; Ridings, Andy; Guinouard, Isabelle;
Verheijen, Marc; Tosh, Ian; Rogers, Kevin; Steele, Iain; Stuik, Remko;
Tromp, Neils; Jasko, Attila; Kragt, Jan; Lesman, Dirk; Mottram, Chris;
Bates, Stuart; Gribbin, Frank; Fernando Rodriguez, Luis; Delgado,
José M.; Martin, Carlos; Cano, Diego; Navarro, Ramón; Irwin, Mike;
Lewis, Jim; Gonzalez Solares, Eduardo; O'Mahony, Neil; Bianco, Andrea;
Zurita, Christina; ter Horst, Rik; Molinari, Emilio; Lodi, Marcello;
Guerra, José; Vallenari, Antonella; Baruffolo, Andrea
2014SPIE.9147E..0LD Altcode: 2014arXiv1412.0843D
We present an overview of and status report on the WEAVE next-generation
spectroscopy facility for the William Herschel Telescope (WHT). WEAVE
principally targets optical ground-based follow up of upcoming
ground-based (LOFAR) and space-based (Gaia) surveys. WEAVE is
a multi-object and multi-IFU facility utilizing a new 2-degree
prime focus field of view at the WHT, with a buffered pick-and-place
positioner system hosting 1000 multi-object (MOS) fibres, 20 integral
field units, or a single large IFU for each observation. The fibres
are fed to a single spectrograph, with a pair of 8k(spectral) x 6k
(spatial) pixel cameras, located within the WHT GHRIL enclosure on
the telescope Nasmyth platform, supporting observations at R~5000
over the full 370-1000nm wavelength range in a single exposure, or a
high resolution mode with limited coverage in each arm at R~20000. The
project is now in the final design and early procurement phase, with
commissioning at the telescope expected in 2017.
---------------------------------------------------------
Title: Extinction Maps toward the Milky Way Bulge: Two-dimensional
and Three-dimensional Tests with APOGEE
Authors: Schultheis, M.; Zasowski, G.; Allende Prieto, C.; Anders, F.;
Beaton, R. L.; Beers, T. C.; Bizyaev, D.; Chiappini, C.; Frinchaboy,
P. M.; García Pérez, A. E.; Ge, J.; Hearty, F.; Holtzman, J.;
Majewski, S. R.; Muna, D.; Nidever, D.; Shetrone, M.; Schneider, D. P.
2014AJ....148...24S Altcode: 2014arXiv1405.2180S
Galactic interstellar extinction maps are powerful and necessary tools
for Milky Way structure and stellar population analyses, particularly
toward the heavily reddened bulge and in the midplane. However,
due to the difficulty of obtaining reliable extinction measures and
distances for a large number of stars that are independent of these
maps, tests of their accuracy and systematics have been limited. Our
goal is to assess a variety of photometric stellar extinction
estimates, including both two-dimensional and three-dimensional
extinction maps, using independent extinction measures based on a
large spectroscopic sample of stars toward the Milky Way bulge. We
employ stellar atmospheric parameters derived from high-resolution
H-band Apache Point Observatory Galactic Evolution Experiment (APOGEE)
spectra, combined with theoretical stellar isochrones, to calculate
line-of-sight extinction and distances for a sample of more than 2400
giants toward the Milky Way bulge. We compare these extinction values
to those predicted by individual near-IR and near+mid-IR stellar colors,
two-dimensional bulge extinction maps, and three-dimensional extinction
maps. The long baseline, near+mid-IR stellar colors are, on average,
the most accurate predictors of the APOGEE extinction estimates, and
the two-dimensional and three-dimensional extinction maps derived from
different stellar populations along different sightlines show varying
degrees of reliability. We present the results of all of the comparisons
and discuss reasons for the observed discrepancies. We also demonstrate
how the particular stellar atmospheric models adopted can have a strong
impact on this type of analysis, and discuss related caveats.
---------------------------------------------------------
Title: WEAVE core processing system
Authors: Walton, Nicholas A.; Irwin, Mike; Lewis, James R.;
Gonzalez-Solares, Eduardo; Dalton, Gavin; Trager, Scott; Aguerri,
J. Alfonso L.; Allende Prieto, Carlos; Benn, Chris R.; Abrams, Don
Carlos; Picó, Sergio; Middleton, Kevin; Lodi, Marcello; Bonifacio,
Piercarlo
2014SPIE.9152E..0RW Altcode:
WEAVE is an approved massive wide field multi-object optical
spectrograph (MOS) currently entering its build phase, destined for use
on the 4.2-m William Herschel Telescope (WHT). It will be commissioned
and begin survey operations in 2017. This paper describes the core
processing system (CPS) system being developed to process the bulk
data flow from WEAVE. We describe the processes and techniques to be
used in producing the scientifically validated 'Level 1' data products
from the WEAVE data. CPS outputs will include calibrated one-d spectra
and initial estimates of basic parameters such as radial velocities
(for stars) and redshifts (for galaxies).
---------------------------------------------------------
Title: VizieR Online Data Catalog: Model SDSS colors for halo stars
(Allende Prieto+, 2014)
Authors: Allende Prieto, C.; Fernandez-Alvar, E.; Schlesinger, K. J.;
Lee, Y. S.; Morrison, H. L.; Schneider, D. P.; Beers, T. C.; Bizyaev,
D.; Ebelke, G.; Malanushenko, E.; Oravetz, D.; Pan, K.; Simmons, A.;
Simmerer, J.; Sobeck, J.; Robin, A. C.
2014yCat..35680007A Altcode: 2014yCat..35689007A
We analyze a sample of tens of thousands of spectra of halo turnoff
stars, obtained with the optical spectrographs of the Sloan Digital
Sky Survey (SDSS), to characterize the stellar halo population "in
situ" out to a distance of a few tens of kpc from the Sun. In this
paper we describe the derivation of atmospheric parameters. We also
derive the overall stellar metallicity distribution based on F-type
stars observed as flux calibrators for the Baryonic Oscillations
Spectroscopic Survey (BOSS). Our analysis is based on an automated
method that determines the set of parameters of a model atmosphere
that best reproduces each observed spectrum. We use an optimization
algorithm and evaluate model fluxes by means of interpolation in a
pre-computed grid. In our analysis, we account for the spectrograph's
varying resolution as a function of fiber and wavelength. Our results
for early SDSS (pre-BOSS upgrade) data compare well with those from the
SEGUE Stellar Parameter Pipeline (SSPP), except for stars at logg (cgs
units) lower than 2.5. <P />An analysis of stars in the globular cluster
M13 reveals a dependence of the inferred metallicity on surface gravity
for stars with logg<2.5, confirming the systematics identified in
the comparison with the SSPP. We find that our metallicity estimates
are significantly more precise than the SSPP results. We also find
excellent agreement with several independent analyses. We show that
the SDSS color criteria for selecting F-type halo turnoff stars as flux
calibrators efficiently excludes stars with high metallicities, but does
not significantly distort the shape of the metallicity distribution
at low metallicity. We obtain a halo metallicity distribution that
is narrower and more asymmetric than in previous studies. The lowest
gravity stars in our sample, at tens of kpc from the Sun, indicate a
shift of the metallicity distribution to lower abundances, consistent
with that expected from a dual halo system in the Milky Way. <P />(1
data file).
---------------------------------------------------------
Title: The Gaia-ESO Survey: processing FLAMES-UVES spectra
Authors: Sacco, G. G.; Morbidelli, L.; Franciosini, E.; Maiorca, E.;
Randich, S.; Modigliani, A.; Gilmore, G.; Asplund, M.; Binney, J.;
Bonifacio, P.; Drew, J.; Feltzing, S.; Ferguson, A.; Jeffries, R.;
Micela, G.; Negueruela, I.; Prusti, T.; Rix, H. -W.; Vallenari, A.;
Alfaro, E.; Allende Prieto, C.; Babusiaux, C.; Bensby, T.; Blomme,
R.; Bragaglia, A.; Flaccomio, E.; Francois, P.; Hambly, N.; Irwin,
M.; Koposov, S.; Korn, A.; Lanzafame, A.; Pancino, E.; Recio-Blanco,
A.; Smiljanic, R.; Van Eck, S.; Walton, N.; Bergemann, M.; Costado,
M. T.; de Laverny, P.; Heiter, U.; Hill, V.; Hourihane, A.; Jackson,
R.; Jofre, P.; Lewis, J.; Lind, K.; Lardo, C.; Magrini, L.; Masseron,
T.; Prisinzano, L.; Worley, C.
2014A&A...565A.113S Altcode: 2014arXiv1403.4865S
The Gaia-ESO Survey is a large public spectroscopic survey that
aims to derive radial velocities and fundamental parameters
of about 10<SUP>5</SUP> Milky Way stars in the field and in
clusters. Observations are carried out with the multi-object optical
spectrograph FLAMES, using simultaneously the medium-resolution (R ~
20 000) GIRAFFE spectrograph and the high-resolution (R ~ 47 000) UVES
spectrograph. In this paper we describe the methods and the software
used for the data reduction, the derivation of the radial velocities,
and the quality control of the FLAMES-UVES spectra. Data reduction
has been performed using a workflow specifically developed for this
project. This workflow runs the ESO public pipeline optimizing the
data reduction for the Gaia-ESO Survey, automatically performs sky
subtraction, barycentric correction and normalisation, and calculates
radial velocities and a first guess of the rotational velocities. The
quality control is performed using the output parameters from the ESO
pipeline, by a visual inspection of the spectra and by the analysis
of the signal-to-noise ratio of the spectra. Using the observations
of the first 18 months, specifically targets observed multiple times
at different epochs, stars observed with both GIRAFFE and UVES, and
observations of radial velocity standards, we estimated the precision
and the accuracy of the radial velocities. The statistical error on the
radial velocities is σ ~ 0.4 km s<SUP>-1</SUP> and is mainly due to
uncertainties in the zero point of the wavelength calibration. However,
we found a systematic bias with respect to the GIRAFFE spectra (~0.9 km
s<SUP>-1</SUP>) and to the radial velocities of the standard stars (~0.5
km s<SUP>-1</SUP>) retrieved from the literature. This bias will be
corrected in the future data releases, when a common zero point for all
the set-ups and instruments used for the survey is be established. <P
/>Based on observations made with the ESO/VLT, at Paranal Observatory,
under programme 188.B-3002 (The Gaia-ESO Public Spectroscopic Survey).
---------------------------------------------------------
Title: The Gaia-ESO Survey: radial metallicity gradients and
age-metallicity relation of stars in the Milky Way disk
Authors: Bergemann, M.; Ruchti, G. R.; Serenelli, A.; Feltzing, S.;
Alves-Brito, A.; Asplund, M.; Bensby, T.; Gruyters, P.; Heiter, U.;
Hourihane, A.; Korn, A.; Lind, K.; Marino, A.; Jofre, P.; Nordlander,
T.; Ryde, N.; Worley, C. C.; Gilmore, G.; Randich, S.; Ferguson,
A. M. N.; Jeffries, R. D.; Micela, G.; Negueruela, I.; Prusti, T.; Rix,
H. -W.; Vallenari, A.; Alfaro, E. J.; Allende Prieto, C.; Bragaglia,
A.; Koposov, S. E.; Lanzafame, A. C.; Pancino, E.; Recio-Blanco, A.;
Smiljanic, R.; Walton, N.; Costado, M. T.; Franciosini, E.; Hill,
V.; Lardo, C.; de Laverny, P.; Magrini, L.; Maiorca, E.; Masseron,
T.; Morbidelli, L.; Sacco, G.; Kordopatis, G.; Tautvaišienė, G.
2014A&A...565A..89B Altcode: 2014arXiv1401.4437B
We study the relationship between age, metallicity, and α-enhancement
of FGK stars in the Galactic disk. The results are based upon the
analysis of high-resolution UVES spectra from the Gaia-ESO large
stellar survey. We explore the limitations of the observed dataset,
i.e. the accuracy of stellar parameters and the selection effects
that are caused by the photometric target preselection. We find that
the colour and magnitude cuts in the survey suppress old metal-rich
stars and young metal-poor stars. This suppression may be as high as
97% in some regions of the age-metallicity relationship. The dataset
consists of 144 stars with a wide range of ages from 0.5 Gyr to 13.5
Gyr, Galactocentric distances from 6 kpcto 9.5 kpc, and vertical
distances from the plane 0 < |Z| < 1.5 kpc. On this basis, we
find that i) the observed age-metallicity relation is nearly flat in
the range of ages between 0 Gyr and 8 Gyr; ii) at ages older than 9
Gyr, we see a decrease in [Fe/H] and a clear absence of metal-rich
stars; this cannot be explained by the survey selection functions;
iii) there is a significant scatter of [Fe/H] at any age; and iv)
[Mg/Fe] increases with age, but the dispersion of [Mg/Fe] at ages >9
Gyr is not as small as advocated by some other studies. In agreement
with earlier work, we find that radial abundance gradients change as
a function of vertical distance from the plane. The [Mg/Fe] gradient
steepens and becomes negative. In addition, we show that the inner disk
is not only more α-rich compared to the outer disk, but also older,
as traced independently by the ages and Mg abundances of stars. <P
/>Based on observations made with the ESO/VLT, at Paranal Observatory,
under programme 188.B-3002 (The Gaia-ESO Public Spectroscopic Survey).
---------------------------------------------------------
Title: Chemical Cartography with APOGEE: Large-scale Mean Metallicity
Maps of the Milky Way Disk
Authors: Hayden, Michael R.; Holtzman, Jon A.; Bovy, Jo; Majewski,
Steven R.; Johnson, Jennifer A.; Allende Prieto, Carlos; Beers,
Timothy C.; Cunha, Katia; Frinchaboy, Peter M.; García Pérez, Ana
E.; Girardi, Léo; Hearty, Fred R.; Lee, Young Sun; Nidever, David;
Schiavon, Ricardo P.; Schlesinger, Katharine J.; Schneider, Donald P.;
Schultheis, Mathias; Shetrone, Matthew; Smith, Verne V.; Zasowski,
Gail; Bizyaev, Dmitry; Feuillet, Diane; Hasselquist, Sten; Kinemuchi,
Karen; Malanushenko, Elena; Malanushenko, Viktor; O'Connell, Robert;
Pan, Kaike; Stassun, Keivan
2014AJ....147..116H Altcode: 2013arXiv1311.4569H
We present Galactic mean metallicity maps derived from the first year
of the SDSS-III APOGEE experiment. Mean abundances in different zones
of projected Galactocentric radius (0 < R < 15 kpc) at a range
of heights above the plane (0 < |z| < 3 kpc), are derived from
a sample of nearly 20,000 giant stars with unprecedented coverage,
including stars in the Galactic mid-plane at large distances. We also
split the sample into subsamples of stars with low- and high-[α/M]
abundance ratios. We assess possible biases in deriving the mean
abundances, and find that they are likely to be small except in the
inner regions of the Galaxy. A negative radial metallicity gradient
exists over much of the Galaxy; however, the gradient appears to flatten
for R < 6 kpc, in particular near the Galactic mid-plane and for
low-[α/M] stars. At R > 6 kpc, the gradient flattens as one moves
off the plane, and is flatter at all heights for high-[α/M] stars than
for low-[α/M] stars. Alternatively, these gradients can be described
as vertical gradients that flatten at larger Galactocentric radius;
these vertical gradients are similar for both low- and high-[α/M]
populations. Stars with higher [α/M] appear to have a flatter radial
gradient than stars with lower [α/M]. This could suggest that the
metallicity gradient has grown steeper with time or, alternatively,
that gradients are washed out over time by migration of stars.
---------------------------------------------------------
Title: The SEGUE K Giant Survey. II. A Catalog of Distance
Determinations for the SEGUE K Giants in the Galactic Halo
Authors: Xue, Xiang-Xiang; Ma, Zhibo; Rix, Hans-Walter; Morrison,
Heather L.; Harding, Paul; Beers, Timothy C.; Ivans, Inese I.;
Jacobson, Heather R.; Johnson, Jennifer; Lee, Young Sun; Lucatello,
Sara; Rockosi, Constance M.; Sobeck, Jennifer S.; Yanny, Brian; Zhao,
Gang; Allende Prieto, Carlos
2014ApJ...784..170X Altcode: 2012arXiv1211.0549X
We present an online catalog of distance determinations for 6036 K
giants, most of which are members of the Milky Way's stellar halo. Their
medium-resolution spectra from the Sloan Digital Sky Survey/Sloan
Extension for Galactic Understanding and Exploration are used to
derive metallicities and rough gravity estimates, along with radial
velocities. Distance moduli are derived from a comparison of each star's
apparent magnitude with the absolute magnitude of empirically calibrated
color-luminosity fiducials, at the observed (g - r)<SUB>0</SUB> color
and spectroscopic [Fe/H]. We employ a probabilistic approach that makes
it straightforward to properly propagate the errors in metallicities,
magnitudes, and colors into distance uncertainties. We also fold in
prior information about the giant-branch luminosity function and the
different metallicity distributions of the SEGUE K-giant targeting
sub-categories. We show that the metallicity prior plays a small role
in the distance estimates, but that neglecting the luminosity prior
could lead to a systematic distance modulus bias of up to 0.25 mag,
compared to the case of using the luminosity prior. We find a median
distance precision of 16%, with distance estimates most precise for
the least metal-poor stars near the tip of the red giant branch. The
precision and accuracy of our distance estimates are validated with
observations of globular and open clusters. The stars in our catalog
are up to 125 kpc from the Galactic center, with 283 stars beyond 50
kpc, forming the largest available spectroscopic sample of distant
tracers in the Galactic halo.
---------------------------------------------------------
Title: Chemodynamics of the Milky Way. I. The first year of APOGEE
data
Authors: Anders, F.; Chiappini, C.; Santiago, B. X.; Rocha-Pinto,
H. J.; Girardi, L.; da Costa, L. N.; Maia, M. A. G.; Steinmetz, M.;
Minchev, I.; Schultheis, M.; Boeche, C.; Miglio, A.; Montalbán,
J.; Schneider, D. P.; Beers, T. C.; Cunha, K.; Allende Prieto, C.;
Balbinot, E.; Bizyaev, D.; Brauer, D. E.; Brinkmann, J.; Frinchaboy,
P. M.; García Pérez, A. E.; Hayden, M. R.; Hearty, F. R.; Holtzman,
J.; Johnson, J. A.; Kinemuchi, K.; Majewski, S. R.; Malanushenko, E.;
Malanushenko, V.; Nidever, D. L.; O'Connell, R. W.; Pan, K.; Robin,
A. C.; Schiavon, R. P.; Shetrone, M.; Skrutskie, M. F.; Smith, V. V.;
Stassun, K.; Zasowski, G.
2014A&A...564A.115A Altcode: 2013arXiv1311.4549A
Context. The Apache Point Observatory Galactic Evolution Experiment
(APOGEE) features the first multi-object high-resolution fiber
spectrograph in the near-infrared ever built, thus making the survey
unique in its capabilities: APOGEE is able to peer through the dust that
obscures stars in the Galactic disc and bulge in the optical wavelength
range. Here we explore the APOGEE data included as part of the Sloan
Digital Sky Survey's 10th data release (SDSS DR10). <BR /> Aims: The
goal of this paper is to a) investigate the chemo-kinematic properties
of the Milky Way disc by exploring the first year of APOGEE data; and b)
to compare our results to smaller optical high-resolution samples in the
literature, as well as results from lower resolution surveys such as
the Geneva-Copenhagen Survey (GCS) and the RAdial Velocity Experiment
(RAVE). <BR /> Methods: We select a high-quality (HQ) sample in terms
of chemistry (amounting to around 20 000 stars) and, after computing
distances and orbital parameters for this sample, we employ a number
of useful subsets to formulate constraints on Galactic chemical and
chemodynamical evolution processes in the solar neighbourhood and beyond
(e.g., metallicity distributions - MDFs, [α/Fe] vs. [Fe/H] diagrams,
and abundance gradients). <BR /> Results: Our red giant sample spans
distances as large as 10 kpc from the Sun. Given our chemical quality
requirements, most of the stars are located between 1 and 6 kpc from
the Sun, increasing by at least a factor of eight the studied volume
with respect to the most recent chemodynamical studies based on the
two largest samples obtained from RAVE and the Sloan Extension for
Galactic Understanding and Exploration (SEGUE). We find remarkable
agreement between the MDF of the recently published local (d <
100 pc) high-resolution high-S/N HARPS sample and our local HQ sample
(d < 1 kpc). The local MDF peaks slightly below solar metallicity,
and exhibits an extended tail towards [Fe/H]= -1, whereas a sharper
cutoff is seen at larger metallicities (the APOGEE sample shows a
slight overabundance of stars with metallicities larger than ≃+0.3
with respect to the HARPS sample). Both samples also compare extremely
well in an [α/Fe] vs. [Fe/H] diagram. The APOGEE data also confirm the
existence of a gap in the abundance diagram. When expanding our sample
to cover three different Galactocentric distance bins (inner disc,
solar vicinity and outer disc), we find the high-[α/Fe] stars to be
rare towards the outer zones (implying a shorter scale-length of the
thick disc with respect to the thin disc), as previously suggested
in the literature. Finally, we measure the gradients in [Fe/H] and
[α/Fe], and their respective MDFs, over a range of 6 < R <
11 kpc in Galactocentric distance, and a 0 < z < 3 kpc range
of distance from the Galactic plane. We find a good agreement with
the gradients traced by the GCS and RAVE dwarf samples. For stars
with 1.5 < z < 3 kpc (not present in the previous samples),
we find a positive metallicity gradient and a negative gradient in
[α/Fe]. <P />Appendix A is available in electronic form at <A
href="http://www.aanda.org/10.1051/0004-6361/201323038/olm">http://www.aanda.org</A>
---------------------------------------------------------
Title: The Tenth Data Release of the Sloan Digital Sky Survey:
First Spectroscopic Data from the SDSS-III Apache Point Observatory
Galactic Evolution Experiment
Authors: Ahn, Christopher P.; Alexandroff, Rachael; Allende Prieto,
Carlos; Anders, Friedrich; Anderson, Scott F.; Anderton, Timothy;
Andrews, Brett H.; Aubourg, Éric; Bailey, Stephen; Bastien, Fabienne
A.; Bautista, Julian E.; Beers, Timothy C.; Beifiori, Alessandra;
Bender, Chad F.; Berlind, Andreas A.; Beutler, Florian; Bhardwaj,
Vaishali; Bird, Jonathan C.; Bizyaev, Dmitry; Blake, Cullen H.;
Blanton, Michael R.; Blomqvist, Michael; Bochanski, John J.; Bolton,
Adam S.; Borde, Arnaud; Bovy, Jo; Shelden Bradley, Alaina; Brandt,
W. N.; Brauer, Dorothée; Brinkmann, J.; Brownstein, Joel R.; Busca,
Nicolás G.; Carithers, William; Carlberg, Joleen K.; Carnero, Aurelio
R.; Carr, Michael A.; Chiappini, Cristina; Chojnowski, S. Drew; Chuang,
Chia-Hsun; Comparat, Johan; Crepp, Justin R.; Cristiani, Stefano;
Croft, Rupert A. C.; Cuesta, Antonio J.; Cunha, Katia; da Costa, Luiz
N.; Dawson, Kyle S.; De Lee, Nathan; Dean, Janice D. R.; Delubac,
Timothée; Deshpande, Rohit; Dhital, Saurav; Ealet, Anne; Ebelke,
Garrett L.; Edmondson, Edward M.; Eisenstein, Daniel J.; Epstein,
Courtney R.; Escoffier, Stephanie; Esposito, Massimiliano; Evans,
Michael L.; Fabbian, D.; Fan, Xiaohui; Favole, Ginevra; Femenía
Castellá, Bruno; Fernández Alvar, Emma; Feuillet, Diane; Filiz
Ak, Nurten; Finley, Hayley; Fleming, Scott W.; Font-Ribera, Andreu;
Frinchaboy, Peter M.; Galbraith-Frew, J. G.; García-Hernández, D. A.;
García Pérez, Ana E.; Ge, Jian; Génova-Santos, R.; Gillespie, Bruce
A.; Girardi, Léo; González Hernández, Jonay I.; Gott, J. Richard,
III; Gunn, James E.; Guo, Hong; Halverson, Samuel; Harding, Paul;
Harris, David W.; Hasselquist, Sten; Hawley, Suzanne L.; Hayden,
Michael; Hearty, Frederick R.; Herrero Davó, Artemio; Ho, Shirley;
Hogg, David W.; Holtzman, Jon A.; Honscheid, Klaus; Huehnerhoff,
Joseph; Ivans, Inese I.; Jackson, Kelly M.; Jiang, Peng; Johnson,
Jennifer A.; Kinemuchi, K.; Kirkby, David; Klaene, Mark A.; Kneib,
Jean-Paul; Koesterke, Lars; Lan, Ting-Wen; Lang, Dustin; Le Goff,
Jean-Marc; Leauthaud, Alexie; Lee, Khee-Gan; Lee, Young Sun; Long,
Daniel C.; Loomis, Craig P.; Lucatello, Sara; Lupton, Robert H.;
Ma, Bo; Mack, Claude E., III; Mahadevan, Suvrath; Maia, Marcio
A. G.; Majewski, Steven R.; Malanushenko, Elena; Malanushenko,
Viktor; Manchado, A.; Manera, Marc; Maraston, Claudia; Margala,
Daniel; Martell, Sarah L.; Masters, Karen L.; McBride, Cameron K.;
McGreer, Ian D.; McMahon, Richard G.; Ménard, Brice; Mészáros,
Sz.; Miralda-Escudé, Jordi; Miyatake, Hironao; Montero-Dorta,
Antonio D.; Montesano, Francesco; More, Surhud; Morrison, Heather
L.; Muna, Demitri; Munn, Jeffrey A.; Myers, Adam D.; Nguyen, Duy
Cuong; Nichol, Robert C.; Nidever, David L.; Noterdaeme, Pasquier;
Nuza, Sebastián E.; O'Connell, Julia E.; O'Connell, Robert W.;
O'Connell, Ross; Olmstead, Matthew D.; Oravetz, Daniel J.; Owen,
Russell; Padmanabhan, Nikhil; Palanque-Delabrouille, Nathalie; Pan,
Kaike; Parejko, John K.; Parihar, Prachi; Pâris, Isabelle; Pepper,
Joshua; Percival, Will J.; Pérez-Ràfols, Ignasi; Dotto Perottoni,
Hélio; Petitjean, Patrick; Pieri, Matthew M.; Pinsonneault, M. H.;
Prada, Francisco; Price-Whelan, Adrian M.; Raddick, M. Jordan; Rahman,
Mubdi; Rebolo, Rafael; Reid, Beth A.; Richards, Jonathan C.; Riffel,
Rogério; Robin, Annie C.; Rocha-Pinto, H. J.; Rockosi, Constance
M.; Roe, Natalie A.; Ross, Ashley J.; Ross, Nicholas P.; Rossi,
Graziano; Roy, Arpita; Rubiño-Martin, J. A.; Sabiu, Cristiano G.;
Sánchez, Ariel G.; Santiago, Basílio; Sayres, Conor; Schiavon,
Ricardo P.; Schlegel, David J.; Schlesinger, Katharine J.; Schmidt,
Sarah J.; Schneider, Donald P.; Schultheis, Mathias; Sellgren, Kris;
Seo, Hee-Jong; Shen, Yue; Shetrone, Matthew; Shu, Yiping; Simmons,
Audrey E.; Skrutskie, M. F.; Slosar, Anže; Smith, Verne V.; Snedden,
Stephanie A.; Sobeck, Jennifer S.; Sobreira, Flavia; Stassun, Keivan
G.; Steinmetz, Matthias; Strauss, Michael A.; Streblyanska, Alina;
Suzuki, Nao; Swanson, Molly E. C.; Terrien, Ryan C.; Thakar, Aniruddha
R.; Thomas, Daniel; Thompson, Benjamin A.; Tinker, Jeremy L.; Tojeiro,
Rita; Troup, Nicholas W.; Vandenberg, Jan; Vargas Magaña, Mariana;
Viel, Matteo; Vogt, Nicole P.; Wake, David A.; Weaver, Benjamin A.;
Weinberg, David H.; Weiner, Benjamin J.; White, Martin; White, Simon
D. M.; Wilson, John C.; Wisniewski, John P.; Wood-Vasey, W. M.;
Yèche, Christophe; York, Donald G.; Zamora, O.; Zasowski, Gail;
Zehavi, Idit; Zhao, Gong-Bo; Zheng, Zheng; Zhu, Guangtun
2014ApJS..211...17A Altcode: 2013arXiv1307.7735A
The Sloan Digital Sky Survey (SDSS) has been in operation since 2000
April. This paper presents the Tenth Public Data Release (DR10) from
its current incarnation, SDSS-III. This data release includes the first
spectroscopic data from the Apache Point Observatory Galaxy Evolution
Experiment (APOGEE), along with spectroscopic data from the Baryon
Oscillation Spectroscopic Survey (BOSS) taken through 2012 July. The
APOGEE instrument is a near-infrared R ~ 22,500 300 fiber spectrograph
covering 1.514-1.696 μm. The APOGEE survey is studying the chemical
abundances and radial velocities of roughly 100,000 red giant star
candidates in the bulge, bar, disk, and halo of the Milky Way. DR10
includes 178,397 spectra of 57,454 stars, each typically observed three
or more times, from APOGEE. Derived quantities from these spectra
(radial velocities, effective temperatures, surface gravities, and
metallicities) are also included. DR10 also roughly doubles the number
of BOSS spectra over those included in the Ninth Data Release. DR10
includes a total of 1,507,954 BOSS spectra comprising 927,844 galaxy
spectra, 182,009 quasar spectra, and 159,327 stellar spectra selected
over 6373.2 deg<SUP>2</SUP>.
---------------------------------------------------------
Title: Making MILES better for stellar population modelling
Authors: Milone, A. de C.; Sansom, A.; Vazdekis, A.; Sanchez-Blazquez,
P.; Allende Prieto, C.; Falcon-Barroso, J.; da Silva, R.
2014arXiv1402.0751M Altcode:
In order to build more realistic single stellar population (SSP)
models with variable alpha-enhancement, we have recently determined
[Mg/Fe] in a uniform scale with a precision of about 0.1 dex for 752
stars in the MILES empirical library. The [alpha/Fe] abundance ratio
is commonly used as a good temporal scale indicator of star formation,
taking Mg as a template for alpha elements. Calcium is another element
whose abundance is currently being investigated for the MILES stars. The
MILES library is also being expanded by around 20% by including stars
with known Teff, log g, [Fe/H] and [Mg/Fe]. The transformation of their
photospheric parameters to the MILES system has been carried out, but
the calibration of their [Mg/Fe] is still in progress. In parallel,
C, N and O abundances are also being compiled from literature for the
library stars because they play an important role in the photospheric
opacity, particularly influencing the blue spectral region. The Galactic
kinematic classification of MILES stars with compiled [Mg/Fe] has been
just computed such that this information can be considered in the SSP
modeling. Comparisons of theoretical stellar predictions of the Lick
line-strength indices against the MILES data have revealed the good
behaviour of Fe-sensitive indices predictions, while highlighting areas
for improvement in some models for the higher order H-Balmer features.
---------------------------------------------------------
Title: New Red Jewels in Coma Berenices
Authors: Terrien, Ryan C.; Mahadevan, Suvrath; Deshpande, Rohit;
Bender, Chad F.; Cargile, Phillip A.; Hearty, Frederick R.; Cottaar,
Michiel; Allende Prieto, Carlos; Fleming, Scott W.; Frinchaboy, Peter
M.; Jackson, Kelly M.; Johnson, Jennifer A.; Majewski, Steven R.;
Nidever, David L.; Pepper, Joshua; Rodriguez, Joseph E.; Schneider,
Donald P.; Siverd, Robert J.; Stassun, Keivan G.; Weaver, Benjamin A.;
Wilson, John C.
2014ApJ...782...61T Altcode: 2014arXiv1401.1217T
We have used Sloan Digital Sky Survey-III (SDSS-III) Apache Point
Observatory Galactic Evolution Experiment (APOGEE) radial velocity
observations in the near-infrared H-band to explore the membership
of the nearby (86.7 ± 0.9 pc) open cluster Coma Berenices (Melotte
111), concentrating on the poorly populated low-mass end of the main
sequence. Using SDSS-III APOGEE radial velocity measurements, we confirm
the membership of eight K/M dwarf members, providing the first confirmed
low-mass members of the Coma Berenices cluster. Using R ~ 2000 spectra
from IRTF-SpeX, we confirm the independently luminosity classes of
these targets, and find their metallicities to be consistent with
the known solar mean metallicity of Coma Berenices and of M dwarfs in
the solar neighborhood. In addition, the APOGEE spectra have enabled
measurement of vsin i for each target and detection for the first
time of the low-mass secondary components of the known binary systems
Melotte 111 102 and Melotte 111 120, as well as identification of the
previously unknown binary system 2MASS J12214070+2707510. Finally,
we use Kilodegree Extremely Little Telescope photometry to measure
photometric variability and rotation periods for a subset of the Coma
Berenices members.
---------------------------------------------------------
Title: Erratum: "Hypervelocity Star Candidates in the SEGUE G &
K Dwarf Sample" <A href="/abs/2014ApJ...780....7P">(2014, ApJ,
780, 7)</A>
Authors: Palladino, Lauren E.; Schlesinger, Katharine J.;
Holley-Bockelmann, Kelly; Allende Prieto, Carlos; Beers, Timothy C.;
Lee, Young Sun; Schneider, Donald P.
2014ApJ...782...57P Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Mapping the Bulge Metallicity Distribution Function with APOGEE
Authors: Elia Garcia Perez, Ana; Johnson, J.; Cunha, K. M.;
Allende-Prieto, C.; Shetrone, M. D.; Majewski, S. R.; Schiavon,
R. P.; Frinchaboy, P. M.; Hayden, M. R.; Nidever, D. L.; Robin, A.;
Schultheis, M.; Zasowski, G.
2014AAS...22340303G Altcode: 2014AAS...22340303E
The origin and formation of the Milky Way bulge remains poorly
understood, in part because high quality observations of the bulge have
generally been restricted to regions of low extinction. In the presence
of dust, infrared observations confer a distinct advantage over those
at optical wavelengths, and the advent of the Apache Point Observatory
Galactic Evolution Experiment (APOGEE) enables us to exploit widely
this advantage for the study of the kinematics and chemistry across
the entire bulge, including high extinction fields near the Galactic
plane. Present APOGEE coverage includes Northern Hemisphere-accessible
bulge fields spanning a 20 degree radius from the Galactic Center. The
analysis of the high quality (R ~ 22,500 and a typical S/N > 100)
stellar spectra from the first two years of APOGEE observations (and
including data from the instrument commissioning phase) is revealing
an interesting multi-dimensional view of the inner bulge and its metal
distribution. We will present these new results and discuss them in
the context of a bar scenario for bulge formation, as suggested by
recently published observations from other surveys.
---------------------------------------------------------
Title: The APOGEE Stellar Parameters and Chemical Abundances Pipeline
(ASPCAP)
Authors: Elia Garcia Perez, Ana; Allende-Prieto, C.; Cunha, K. M.;
Holtzman, J. A.; Johnson, J.; Majewski, S.; Meszaros, Sz.; Schiavon,
R. P.; Shetrone, M. D.; Smith, V. V.; SDSS-III/APOGEE Collaboration
2014AAS...22344007G Altcode: 2014AAS...22344007E
The Apache Point Observatory Galactic Evolution Experiment (APOGEE) of
Sloan Digital Sky Survey III (SDSS-III) will be providing high quality
(R ∼ 22,500 and a typical S/N > 100) near-infrared spectra for
~100,000, predominantly cool stars (mostly giant stars). In principle
these spectra can be used to ascertain the stellar atmospheric
parameters of those stars as well as the chemical abundances for
approximately 15 chemical species expressed in the APOGEE wavelength
region via both atomic and molecular line transitions. Detailed
analysis of such an enormous database of infrared stellar spectra ---
each blanketed with a multitude of lines and bands --- is obviously not
viable manually, but is also a challenge to automate and simultaneously
achieve the survey goals of high, 0.1 (0.2) dex internal (external)
abundances precision. The APOGEE Stellar Parameters and Chemical
Abundances Pipeline (ASPCAP) has been designed to estimate the above
parameters via comparison to large, multi-dimensional libraries
of synthetic spectral templates. To make the problem tractable and
efficient, ASPCAP conducts this analysis in two phases. First the entire
wavelength range is template-matched to derive the primary stellar
parameters affecting the spectral energy distribution of the stars
(Teff, log g, microturbulence, along with the bulk stellar metallicity
and carbon, nitrogen and α-elements abundances). After an appropriate
stellar template is matched or interpolated from the synthetic library,
the abundances of other chemical species (e.g., C, N, O, Mg, Na,
Al, Si, S, K, Ca, Ti, V, Mn, Cr, Co, Fe, and Ni) are derived using
restricted windows around particularly sensitive atomic or molecular
transitions. We will present an overview of ASPCAP, its calibration
and measured performance, as evaluated with data from the first year
of APOGEE observations as released in SDSS-III Data Release 10.
---------------------------------------------------------
Title: Hypervelocity Star Candidates in the SEGUE G and K Dwarf Sample
Authors: Palladino, Lauren E.; Schlesinger, Katharine J.;
Holley-Bockelmann, Kelly; Allende Prieto, Carlos; Beers, Timothy C.;
Lee, Young Sun; Schneider, Donald P.
2014ApJ...780....7P Altcode: 2013arXiv1308.3495P
We present 20 candidate hypervelocity stars from the Sloan Extension
for Galactic Understanding and Exploration (SEGUE) G and K dwarf
samples. Previous searches for hypervelocity stars have only focused
on large radial velocities; in this study, we also use proper motions
to select the candidates. We determine the hypervelocity likelihood
of each candidate by means of Monte Carlo simulations, considering the
significant errors often associated with high proper motion stars. We
find that nearly half of the candidates exceed their escape velocities
with at least 98% probability. Every candidate also has less than a 25%
chance of being a high-velocity fluke within the SEGUE sample. Based
on orbits calculated using the observed six-dimensional positions
and velocities, few, if any, of these candidates originate from the
Galactic center. If these candidates are truly hypervelocity stars,
they were not ejected by interactions with the Milky Way's supermassive
black hole. This calls for a more serious examination of alternative
hypervelocity-star ejection scenarios.
---------------------------------------------------------
Title: ESPRESSO: The next European exoplanet hunter
Authors: Pepe, F.; Molaro, P.; Cristiani, S.; Rebolo, R.; Santos,
N. C.; Dekker, H.; Mégevand, D.; Zerbi, F. M.; Cabral, A.; Di
Marcantonio, P.; Abreu, M.; Affolter, M.; Aliverti, M.; Allende Prieto,
C.; Amate, M.; Avila, G.; Baldini, V.; Bristow, P.; Broeg, C.; Cirami,
R.; Coelho, J.; Conconi, P.; Coretti, I.; Cupani, G.; D'Odorico,
V.; De Caprio, V.; Delabre, B.; Dorn, R.; Figueira, P.; Fragoso, A.;
Galeotta, S.; Genolet, L.; Gomes, R.; González Hernández, J. I.;
Hughes, I.; Iwert, O.; Kerber, F.; Landoni, M.; Lizon, J. -L.; Lovis,
C.; Maire, C.; Mannetta, M.; Martins, C.; Monteiro, M.; Oliveira, A.;
Poretti, E.; Rasilla, J. L.; Riva, M.; Santana Tschudi, S.; Santos, P.;
Sosnowska, D.; Sousa, S.; Spanó, P.; Tenegi, F.; Toso, G.; Vanzella,
E.; Viel, M.; Zapatero Osorio, M. R.
2014arXiv1401.5918P Altcode:
The acronym ESPRESSO stems for Echelle SPectrograph for Rocky Exoplanets
and Stable Spectroscopic Observations; this instrument will be the next
VLT high resolution spectrograph. The spectrograph will be installed at
the Combined-Coudé Laboratory of the VLT and linked to the four 8.2
m Unit Telescopes (UT) through four optical Coudé trains. ESPRESSO
will combine efficiency and extreme spectroscopic precision. ESPRESSO
is foreseen to achieve a gain of two magnitudes with respect to its
predecessor HARPS, and to improve the instrumental radial-velocity
precision to reach the 10 cm/s level. It can be operated either with
a single UT or with up to four UTs, enabling an additional gain in
the latter mode. The incoherent combination of four telescopes and
the extreme precision requirements called for many innovative design
solutions while ensuring the technical heritage of the successful
HARPS experience. ESPRESSO will allow to explore new frontiers in most
domains of astrophysics that require precision and sensitivity. The
main scientific drivers are the search and characterization of rocky
exoplanets in the habitable zone of quiet, nearby G to M-dwarfs and the
analysis of the variability of fundamental physical constants. The
project passed the final design review in May 2013 and entered
the manufacturing phase. ESPRESSO will be installed at the Paranal
Observatory in 2016 and its operation is planned to start by the end
of the same year.
---------------------------------------------------------
Title: ESPRESSO: The next European exoplanet hunter
Authors: Pepe, F.; Molaro, P.; Cristiani, S.; Rebolo, R.; Santos,
N. C.; Dekker, H.; Mégevand, D.; Zerbi, F. M.; Cabral, A.; Di
Marcantonio, P.; Abreu, M.; Affolter, M.; Aliverti, M.; Allende Prieto,
C.; Amate, M.; Avila, G.; Baldini, V.; Bristow, P.; Broeg, C.; Cirami,
R.; Coelho, J.; Conconi, P.; Coretti, I.; Cupani, G.; D'Odorico,
V.; De Caprio, V.; Delabre, B.; Dorn, R.; Figueira, P.; Fragoso, A.;
Galeotta, S.; Genolet, L.; Gomes, R.; González Hernández, J. I.;
Hughes, I.; Iwert, O.; Kerber, F.; Landoni, M.; Lizon, J. -L.; Lovis,
C.; Maire, C.; Mannetta, M.; Martins, C.; Monteiro, M.; Oliveira, A.;
Poretti, E.; Rasilla, J. L.; Riva, M.; Santana Tschudi, S.; Santos, P.;
Sosnowska, D.; Sousa, S.; Spanó, P.; Tenegi, F.; Toso, G.; Vanzella,
E.; Viel, M.; Zapatero Osorio, M. R.
2014AN....335....8P Altcode:
The acronym ESPRESSO stems for Echelle SPectrograph for Rocky Exoplanets
and Stable Spectroscopic Observations; this instrument will be the
next VLT high resolution spectrograph. The spectrograph will be
installed at the Combined-Coudé Laboratory of the VLT and linked
to the four 8.2 m Unit Telescopes (UT) through four optical Coudé
trains. ESPRESSO will combine efficiency and extreme spectroscopic
precision. ESPRESSO is foreseen to achieve a gain of two magnitudes
with respect to its predecessor HARPS, and to improve the instrumental
radial-velocity precision to reach the 10 cm s<SUP>-1</SUP> level. It
can be operated either with a single UT or with up to four UTs, enabling
an additional gain in the latter mode. The incoherent combination
of four telescopes and the extreme precision requirements called
for many innovative design solutions while ensuring the technical
heritage of the successful HARPS experience. ESPRESSO will allow to
explore new frontiers in most domains of astrophysics that require
precision and sensitivity. The main scientific drivers are the search
and characterization of rocky exoplanets in the habitable zone of
quiet, nearby G to M-dwarfs and the analysis of the variability of
fundamental physical constants. The project passed the final design
review in May 2013 and entered the manufacturing phase. ESPRESSO will
be installed at the Paranal Observatory in 2016 and its operation is
planned to start by the end of the same year.
---------------------------------------------------------
Title: Making MILES better for stellar population modelling
Authors: de C. Milone, A.; Sansom, A.; Vazdekis, A.;
Sánchez-Blázquez, P.; Allende Prieto, C.; Falcón-Barroso, J.;
da Silva, R.
2014ASInC..11..117D Altcode:
In order to build more realistic single stellar population (SSP)
models with variable α-enhancement, we have recently determined
[Mg/Fe] in a uniform scale with a precision of about 0.1 dex for 752
stars in the MILES empirical library. The [α/Fe] abundance ratio is
commonly used as a good temporal scale indicator of star formation,
taking Mg as a template for α elements. Calcium is another element
whose abundance is currently being investigated for the MILES stars. The
MILES library is also being expanded by around 20% by including stars
with known T_eff, log g, [Fe/H] and [Mg/Fe]. The transformation of
their photospheric parameters to the MILES system has been carried out,
but the calibration of their [Mg/Fe] is still in progress. In parallel,
C, N and O abundances are also being compiled from literature for the
library stars because they play an important role in the photospheric
opacity, particularly influencing the blue spectral region. The Galactic
kinematic classification of MILES stars with compiled [Mg/Fe] has been
just computed such that this information can be considered in the SSP
modelling. Comparisons of theoretical stellar predictions of the Lick
line-strength indices against the MILES data have revealed the good
behaviour of Fe-sensitive indices predictions, while highlighting areas
for improvement in some models for the higher order H-Balmer features.
---------------------------------------------------------
Title: DR10 SDSS-III release of APOGEE data
Authors: Shetrone, Matthew D.; Allende-Prieto, C.; Beers, T. C.;
Cunha, K. M.; Fabbian, D.; Feuillet, D.; Frinchaboy, P. M.; Garcia
Perez, A.; Johnson, J.; Majewski, S. R.; Nidever, D. L.; Pinsonneault,
M. H.; Smith, V. V.; Zasowski, G.; SDSS-III/APOGEE Collaboration
2014AAS...22344002S Altcode:
SDSS-III's newest release is Data Release 10 (DR10). DR10 contains the
first spectra of the APO Galactic Evolution Experiment (APOGEE). APOGEE
is the first high-resolution (R ~ 22,500), high signal-to-noise ratio
(S/N >= 100 per resolution element), H-band (1.51 - 1.70 um) survey
of all Galactic stellar populations (bulge, bar, disks, halo) with a
uniform set of stellar tracers and spectral diagnostics. This poster
will briefly describe the stellar sample included in DR10, review the
data made available in DR10, consisting of fully calibrated, 1-d spectra
radial velocities and the by-products of the APOGEE Stellar Parameters
and Chemical Abundance Pipeline (ASPCAP): effective temperature, surface
gravity, metallicity, and alpha, carbon and nitrogen abundances. We
will also present the web tools that are available to the public and
highlight the most critical warning and bad data flags.
---------------------------------------------------------
Title: Chemical Cartography with APOGEE
Authors: Holtzman, Jon A.; Hayden, M. R.; Bovy, J.; Majewski, S.;
Johnson, J.; Zasowski, G.; Girardi, L.; Allende-Prieto, C.; Garcia
Perez, A.; Meszaros, Sz.; Nidever, D. L.; Schiavon, R. P.; Shetrone,
M. D.
2014AAS...22340302H Altcode:
The SDSS-III APOGEE experiment is obtaining high-resolution near-IR
spectra to provide measurements of stellar parameters and chemical
abundances for stars in many different regions of the Galaxy. I will
discuss initial results on the spatial variations of abundances derived
from APOGEE data to date. In particular, I focus on mean metallicities
in the Milky Way disk over a large range of Galactocentric radius
(3<R<15) and distance from the Galactic midplane (|z|< 3kpc),
and the metallicity gradients that are derived from these. Issues
involving distance estimates and potential biases in the mean
metallicities will also be discussed, as well as directions for
extending this work.
---------------------------------------------------------
Title: Ages of Solar Neighborhood Stars Using APOGEE
Authors: Feuillet, Diane; Holtzman, J. A.; Girardi, L.; Allende-Prieto,
C.; Beers, T. C.; Cunha, K. M.; Fabbian, D.; Frinchaboy, P. M.;
Hayden, M. R.; Majewski, S.
2014AAS...22315209F Altcode:
The SDSS-III Apache Point Observatory Galactic Evolution Experiment
(APOGEE) is a high resolution (R ~23,000) near-IR (H-band) spectroscopic
survey of 100,000 Milky Way stars designed to chemically trace the
formation and evolution of Galactic stellar populations. In addition
to the primary survey, the APOGEE spectrograph has been fitted with
10 fibers from the robotically controlled NMSU 1 m telescope to
maximize the use of this instrument when not on sky with the Sloan
2.5 m telescope. This allows for single object observations with this
high resolution NIR spectrograph. Using this new capability provided
by the 1 m, we are conducting a survey of bright stars (H < 8)
with accurate Hipparcos parallax measurements (μ_err < 10%),
which are not accessible to the main APOGEE survey. These data can be
reduced and analyzed in the same way as main survey data, resulting
in detailed chemical information for hundreds of nearby stars. The
atmospheric parameters combined with the Hipparcos distances allow
for age estimates of these stars. We present initial age estimates
from isochrone matching to Padova isochrones, and an age-metallicity
relation for the current sample.
---------------------------------------------------------
Title: In situ Ca and Mg abundancies in the stellar halo of the Galaxy
Authors: Fernandez-Alvar, Emma; Allende-Prieto, C.
2014AAS...22341506F Altcode:
We still have a very limited knowledge about the formation of the
early Milky Way. A line of research has focused on understanding the
nature of the stellar halo, finding kinematical and chemical evidence
of substructure. The existence of substructure is in line with
the hierarchical formation scenario predicted by ΛCDM simulations
for large galaxies such as ours. Studies based on high resolution
spectroscopy have been limited to stars in the solar neighbourhood,
and their conclusions rely on correlations between kinematics and
chemistry. In this work, we have searched for halo stars in situ,
using mid-resolution ( 2000) spectra included in the SDSS/SEGUE survey
for stars at distances between 5 kpc and 100 kpc. We have analyzed a
sample of stars with effective temperatures in the range 5800 <
T<SUP>eff</SUP> < 6300 K, surface gravities between 0.0 <
logg < 5.0 dex and metallicities between -2.0 < [Fe/H] <
-0.4 dex. We have derived Ca/Fe and Mg/Fe abundance ratios from the
spectra and found clear correlations with metallicity and distance
from the Galactic center.
---------------------------------------------------------
Title: Model Stellar Spectral Libraries for Analysis of the SDSS-III
Apache Point Observatory Galactic Evolution Experiment (APOGEE)
Authors: Allende-Prieto, Carlos; Koesterke, L.; Shetrone, M. D.;
Zamora, O.; Ruffoni, M. P.; Smith, V. V.; Cunha, K. M.; Lawler,
J. E.; Pickering, J. C.; Nave, G.; Garcia Perez, A.; Bizyaev, D.;
Edvardsson, B.; Gustafsson, B.; Plez, B.; Castelli, F.; Majewski,
S. R.; Schiavon, R. P.; Meszaros, Sz.; de Vicente, A.
2014AAS...22344005A Altcode:
The Apache Point Observatory Galactic Evolution Experiment (APOGEE)
is obtaining high resolution ( 22,500), high signal-to-noise (>
100) spectra in the 1510-1690 nm spectral region for 100,000 cool,
predominantly post-main sequence stars. To ascertain the stellar
atmospheric parameters and measure chemical abundances for the numerous
chemical elements with line transitions in this wavelength region, the
APOGEE Atmospheric Parameters and Chemical Abundances Pipeline (ASPCAP)
relies on an optimization algorithm that identifies the best-fitting
model for each of the observed APOGEE spectra. The fitting algorithm
speeds up the model evaluation by interpolation in pre-computed grids of
synthetic spectra that have been compressed using Principal Component
Analysis. Here we describe the main model grids used in ASPCAP for
the tenth data release of the Sloan Digital Sky Survey (SDSS DR10),
how they were calculated. We also provide a description of ongoing
and planned upgrades.
---------------------------------------------------------
Title: The SDSS-III APOGEE Radial Velocity Survey of M
Dwarfs. I. Description of the Survey and Science Goals
Authors: Deshpande, R.; Blake, C. H.; Bender, C. F.; Mahadevan, S.;
Terrien, R. C.; Carlberg, J. K.; Zasowski, G.; Crepp, J.; Rajpurohit,
A. S.; Reylé, C.; Nidever, D. L.; Schneider, D. P.; Allende Prieto,
C.; Bizyaev, D.; Ebelke, G.; Fleming, S. W.; Frinchaboy, P. M.; Ge,
J.; Hearty, F.; Hernández, J.; Malanushenko, E.; Malanushenko, V.;
Majewski, S. R.; Marchwinski, R.; Muna, D.; Oravetz, D.; Pan, K.;
Schiavon, R. P.; Shetrone, M.; Simmons, A.; Stassun, K. G.; Wilson,
J. C.; Wisniewski, J. P.
2013AJ....146..156D Altcode: 2013arXiv1307.8121D
We are carrying out a large ancillary program with the Sloan Digital
Sky Survey, SDSS-III, using the fiber-fed multi-object near-infrared
APOGEE spectrograph, to obtain high-resolution H-band spectra of
more than 1200 M dwarfs. These observations will be used to measure
spectroscopic rotational velocities, radial velocities, physical
stellar parameters, and variability of the target stars. Here, we
describe the target selection for this survey, as well as results from
the first year of scientific observations based on spectra that will
be publicly available in the SDSS-III DR10 data release. As part of
this paper we present radial velocities and rotational velocities of
over 200 M dwarfs, with a vsin i precision of ~2 km s<SUP>-1</SUP>
and a measurement floor at vsin i = 4 km s<SUP>-1</SUP>. This
survey significantly increases the number of M dwarfs studied for
rotational velocities and radial velocity variability (at ~100-200 m
s<SUP>-1</SUP>), and will inform and advance the target selection for
planned radial velocity and photometric searches for low-mass exoplanets
around M dwarfs, such as the Habitable Zone Planet Finder, CARMENES,
and TESS. Multiple epochs of radial velocity observations enable us
to identify short period binaries, and adaptive optics imaging of a
subset of stars enables the detection of possible stellar companions
at larger separations. The high-resolution APOGEE spectra, covering
the entire H band, provide the opportunity to measure physical stellar
parameters such as effective temperatures and metallicities for many of
these stars. At the culmination of this survey, we will have obtained
multi-epoch spectra and radial velocities for over 1400 stars spanning
the spectral range M0-L0, providing the largest set of near-infrared M
dwarf spectra at high resolution, and more than doubling the number
of known spectroscopic vsin i values for M dwarfs. Furthermore,
by modeling telluric lines to correct for small instrumental radial
velocity shifts, we hope to achieve a relative velocity precision
floor of 50 m s<SUP>-1</SUP> for bright M dwarfs. With three or more
epochs, this precision is adequate to detect substellar companions,
including giant planets with short orbital periods, and flag them
for higher-cadence followup. We present preliminary, and promising,
results of this telluric modeling technique in this paper.
---------------------------------------------------------
Title: Infrared Laboratory Oscillator Strengths of Fe I in the H-band
Authors: Ruffoni, M. P.; Allende Prieto, C.; Nave, G.; Pickering, J. C.
2013ApJ...779...17R Altcode: 2013arXiv1309.4733R
We report experimental oscillator strengths for 28 infrared Fe I
transitions, for which no previous experimental values exist. These
transitions were selected to address an urgent need for oscillator
strengths of lines in the H-band (between 1.4 μm and 1.7 μm)
required for the analysis of spectra obtained from the Sloan Digital
Sky Survey (SDSS-III) Apache Point Galactic Evolution Experiment
(APOGEE). Upper limits have been placed on the oscillator strengths
of an additional seven transitions, predicted to be significant by
published semi-empirical calculations, but not observed to be so.
---------------------------------------------------------
Title: Calibrations of Atmospheric Parameters Obtained from the
First Year of SDSS-III APOGEE Observations
Authors: Mészáros, Sz.; Holtzman, J.; García Pérez, A. E.; Allende
Prieto, C.; Schiavon, R. P.; Basu, S.; Bizyaev, D.; Chaplin, W. J.;
Chojnowski, S. D.; Cunha, K.; Elsworth, Y.; Epstein, C.; Frinchaboy,
P. M.; García, R. A.; Hearty, F. R.; Hekker, S.; Johnson, J. A.;
Kallinger, T.; Koesterke, L.; Majewski, S. R.; Martell, S. L.; Nidever,
D.; Pinsonneault, M. H.; O'Connell, J.; Shetrone, M.; Smith, V. V.;
Wilson, J. C.; Zasowski, G.
2013AJ....146..133M Altcode: 2013arXiv1308.6617M
The Sloan Digital Sky Survey III (SDSS-III) Apache Point Observatory
Galactic Evolution Experiment (APOGEE) is a three-year survey that is
collecting 10<SUP>5</SUP> high-resolution spectra in the near-IR across
multiple Galactic populations. To derive stellar parameters and chemical
compositions from this massive data set, the APOGEE Stellar Parameters
and Chemical Abundances Pipeline (ASPCAP) has been developed. Here,
we describe empirical calibrations of stellar parameters presented
in the first SDSS-III APOGEE data release (DR10). These calibrations
were enabled by observations of 559 stars in 20 globular and open
clusters. The cluster observations were supplemented by observations of
stars in NASA's Kepler field that have well determined surface gravities
from asteroseismic analysis. We discuss the accuracy and precision
of the derived stellar parameters, considering especially effective
temperature, surface gravity, and metallicity; we also briefly discuss
the derived results for the abundances of the α-elements, carbon, and
nitrogen. Overall, we find that ASPCAP achieves reasonably accurate
results for temperature and metallicity, but suffers from systematic
errors in surface gravity. We derive calibration relations that bring
the raw ASPCAP results into better agreement with independently
determined stellar parameters. The internal scatter of ASPCAP
parameters within clusters suggests that metallicities are measured
with a precision better than 0.1 dex, effective temperatures better
than 150 K, and surface gravities better than 0.2 dex. The understanding
provided by the clusters and Kepler giants on the current accuracy and
precision will be invaluable for future improvements of the pipeline.
---------------------------------------------------------
Title: Discovery of a Dynamical Cold Point in the Heart of the
Sagittarius dSph Galaxy with Observations from the APOGEE Project
Authors: Majewski, Steven R.; Hasselquist, Sten; Łokas, Ewa L.;
Nidever, David L.; Frinchaboy, Peter M.; García Pérez, Ana E.;
Johnston, Kathryn V.; Mészáros, Szabolcs; Shetrone, Matthew; Allende
Prieto, Carlos; Beaton, Rachael L.; Beers, Timothy C.; Bizyaev,
Dmitry; Cunha, Katia; Damke, Guillermo; Ebelke, Garrett; Eisenstein,
Daniel J.; Hearty, Fred; Holtzman, Jon; Johnson, Jennifer A.; Law,
David R.; Malanushenko, Viktor; Malanushenko, Elena; O'Connell, Robert
W.; Oravetz, Daniel; Pan, Kaike; Schiavon, Ricardo P.; Schneider,
Donald P.; Simmons, Audrey; Skrutskie, Michael F.; Smith, Verne V.;
Wilson, John C.; Zasowski, Gail
2013ApJ...777L..13M Altcode: 2013arXiv1309.5535M
The dynamics of the core of the Sagittarius (Sgr) dwarf spheroidal
(dSph) galaxy are explored using high-resolution (R ~ 22, 500),
H-band, near-infrared spectra of over 1000 giant stars in the central
3 deg<SUP>2</SUP> of the system, of which 328 are identified as Sgr
members. These data, among some of the earliest observations from
the Sloan Digital Sky Survey III/Apache Point Observatory Galactic
Evolution Experiment (APOGEE) and the largest published sample of high
resolution Sgr dSph spectra to date, reveal a distinct gradient in the
velocity dispersion of Sgr from 11 to 14 km s<SUP>-1</SUP> for radii
>0.°8 from center to a dynamical cold point of 8 km s<SUP>-1</SUP>
in the Sgr center—a trend differing from that found in previous
kinematical analyses of Sgr over larger scales that suggests a more or
less flat dispersion profile at these radii. Well-fitting mass models
with either cored and cusped dark matter distributions can be found
to match the kinematical results, although the cored profile succeeds
with significantly more isotropic stellar orbits than required for a
cusped profile. It is unlikely that the cold point reflects an unusual
mass distribution. The dispersion gradient may arise from variations in
the mixture of populations with distinct kinematics within the dSph;
this explanation is suggested (e.g., by detection of a metallicity
gradient across similar radii), but not confirmed, by the present
data. Despite these remaining uncertainties about their interpretation,
these early test data (including some from instrument commissioning)
demonstrate APOGEE's usefulness for precision dynamical studies,
even for fields observed at extreme airmasses.
---------------------------------------------------------
Title: The Open Cluster Chemical Analysis and Mapping Survey: Local
Galactic Metallicity Gradient with APOGEE Using SDSS DR10
Authors: Frinchaboy, Peter M.; Thompson, Benjamin; Jackson, Kelly M.;
O'Connell, Julia; Meyer, Brianne; Zasowski, Gail; Majewski, Steven
R.; Chojnowksi, S. Drew; Johnson, Jennifer A.; Allende Prieto,
Carlos; Beers, Timothy C.; Bizyaev, Dmitry; Brewington, Howard;
Cunha, Katia; Ebelke, Garrett; García Pérez, Ana Elia; Hearty,
Frederick R.; Holtzman, Jon; Kinemuchi, Karen; Malanushenko, Elena;
Malanushenko, Viktor; Marchante, Moses; Mészáros, Szabolcs; Muna,
Demitri; Nidever, David L.; Oravetz, Daniel; Pan, Kaike; Schiavon,
Ricardo P.; Schneider, Donald P.; Shetrone, Matthew; Simmons, Audrey;
Snedden, Stephanie; Smith, Verne V.; Wilson, John C.
2013ApJ...777L...1F Altcode: 2013arXiv1308.4195F
The Open Cluster Chemical Analysis and Mapping (OCCAM) survey aims
to produce a comprehensive, uniform, infrared-based data set for
hundreds of open clusters, and constrain key Galactic dynamical and
chemical parameters from this sample. This first contribution from
the OCCAM survey presents analysis of 141 members stars in 28 open
clusters with high-resolution metallicities derived from a large
uniform sample collected as part of the Sloan Digital Sky Survey
III/Apache Point Observatory Galactic Evolution Experiment. This
sample includes the first high-resolution metallicity measurements for
22 open clusters. With this largest ever uniformly observed sample
of open cluster stars we investigate the Galactic disk gradients
of both [M/H] and [α/M]. We find basically no gradient in [α/M]
across 7.9 kpc <= R <SUB>GC</SUB> <= 14.5 kpc, but [M/H] does
show a gradient for R <SUB>GC</SUB> < 10 kpc and a significant
flattening beyond R <SUB>GC</SUB> = 10 kpc. In particular, whereas
fitting a single linear trend yields an [M/H] gradient of -0.09 ±
0.03 dex kpc<SUP>-1</SUP>—similar to previously measure gradients
inside 13 kpc—by independently fitting inside and outside 10 kpc
separately we find a significantly steeper gradient near the Sun
(7.9 <= R <SUB>GC</SUB> <= 10) than previously found (-0.20
± 0.08 dex kpc<SUP>-1</SUP>) and a nearly flat trend beyond 10 kpc
(-0.02 ± 0.09 dex kpc<SUP>-1</SUP>).
---------------------------------------------------------
Title: Target Selection for the Apache Point Observatory Galactic
Evolution Experiment (APOGEE)
Authors: Zasowski, G.; Johnson, Jennifer A.; Frinchaboy, P. M.;
Majewski, S. R.; Nidever, D. L.; Rocha Pinto, H. J.; Girardi, L.;
Andrews, B.; Chojnowski, S. D.; Cudworth, K. M.; Jackson, K.; Munn, J.;
Skrutskie, M. F.; Beaton, R. L.; Blake, C. H.; Covey, K.; Deshpande,
R.; Epstein, C.; Fabbian, D.; Fleming, S. W.; Garcia Hernandez, D. A.;
Herrero, A.; Mahadevan, S.; Mészáros, Sz.; Schultheis, M.; Sellgren,
K.; Terrien, R.; van Saders, J.; Allende Prieto, C.; Bizyaev, D.;
Burton, A.; Cunha, K.; da Costa, L. N.; Hasselquist, S.; Hearty,
F.; Holtzman, J.; García Pérez, A. E.; Maia, M. A. G.; O'Connell,
R. W.; O'Donnell, C.; Pinsonneault, M.; Santiago, B. X.; Schiavon,
R. P.; Shetrone, M.; Smith, V.; Wilson, J. C.
2013AJ....146...81Z Altcode: 2013arXiv1308.0351Z
The Apache Point Observatory Galactic Evolution Experiment (APOGEE) is
a high-resolution infrared spectroscopic survey spanning all Galactic
environments (i.e., bulge, disk, and halo), with the principal goal
of constraining dynamical and chemical evolution models of the Milky
Way. APOGEE takes advantage of the reduced effects of extinction
at infrared wavelengths to observe the inner Galaxy and bulge at
an unprecedented level of detail. The survey's broad spatial and
wavelength coverage enables users of APOGEE data to address numerous
Galactic structure and stellar populations issues. In this paper
we describe the APOGEE targeting scheme and document its various
target classes to provide the necessary background and reference
information to analyze samples of APOGEE data with awareness of the
imposed selection criteria and resulting sample properties. APOGEE's
primary sample consists of ~10<SUP>5</SUP> red giant stars, selected
to minimize observational biases in age and metallicity. We present the
methodology and considerations that drive the selection of this sample
and evaluate the accuracy, efficiency, and caveats of the selection and
sampling algorithms. We also describe additional target classes that
contribute to the APOGEE sample, including numerous ancillary science
programs, and we outline the targeting data that will be included in
the public data releases.
---------------------------------------------------------
Title: A Community Science Case for E-ELT HIRES
Authors: Maiolino, R.; Haehnelt, M.; Murphy, M. T.; Queloz, D.;
Origlia, L.; Alcala, J.; Alibert, Y.; Amado, P. J.; Allende Prieto, C.;
Ammler-von Eiff, M.; Asplund, M.; Barstow, M.; Becker, G.; Bonfils, X.;
Bouchy, F.; Bragaglia, A.; Burleigh, M. R.; Chiavassa, A.; Cimatti,
D. A.; Cirasuolo, M.; Cristiani, S.; D'Odorico, V.; Dravins, D.;
Emsellem, E.; Farihi, J.; Figueira, P.; Fynbo, J.; Gansicke, B. T.;
Gillon, M.; Gustafsson, B.; Hill, V.; Israelyan, G.; Korn, A.; Larsen,
S.; De Laverny, P.; Liske, J.; Lovis, C.; Marconi, A.; Martins, C.;
Molaro, P.; Nisini, B.; Oliva, E.; Petitjean, P.; Pettini, M.; Recio
Blanco, A.; Rebolo, R.; Reiners, A.; Rodriguez-Lopez, C.; Ryde, N.;
Santos, N. C.; Savaglio, S.; Snellen, I.; Strassmeier, K.; Tanvir, N.;
Testi, L.; Tolstoy, E.; Triaud, A.; Vanzi, L.; Viel, M.; Volonteri, M.
2013arXiv1310.3163M Altcode:
Building on the experience of the high-resolution community with the
suite of VLT high-resolution spectrographs, which has been tremendously
successful, we outline here the (science) case for a high-fidelity,
high-resolution spectrograph with wide wavelength coverage at the
E-ELT. Flagship science drivers include: the study of exo-planetary
atmospheres with the prospect of the detection of signatures of life
on rocky planets; the chemical composition of planetary debris on the
surface of white dwarfs; the spectroscopic study of protoplanetary and
proto-stellar disks; the extension of Galactic archaeology to the Local
Group and beyond; spectroscopic studies of the evolution of galaxies
with samples that, unlike now, are no longer restricted to strongly
star forming and/or very massive galaxies; the unraveling of the
complex roles of stellar and AGN feedback; the study of the chemical
signatures imprinted by population III stars on the IGM during the
epoch of reionization; the exciting possibility of paradigm-changing
contributions to fundamental physics. The requirements of these science
cases can be met by a stable instrument with a spectral resolution
of R~100,000 and broad, simultaneous spectral coverage extending
from 370nm to 2500nm. Most science cases do not require spatially
resolved information, and can be pursued in seeing-limited mode,
although some of them would benefit by the E-ELT diffraction limited
resolution. Some multiplexing would also be beneficial for some of
the science cases. (Abridged)
---------------------------------------------------------
Title: ESPRESSO — An Echelle SPectrograph for Rocky Exoplanets
Search and Stable Spectroscopic Observations
Authors: Pepe, F.; Cristiani, S.; Rebolo, R.; Santos, N. C.;
Dekker, H.; Mégevand, D.; Zerbi, F. M.; Cabral, A.; Molaro, P.; Di
Marcantonio, P.; Abreu, M.; Affolter, M.; Aliverti, M.; Allende Prieto,
C.; Amate, M.; Avila, G.; Baldini, V.; Bristow, P.; Broeg, C.; Cirami,
R.; Coelho, J.; Conconi, P.; Coretti, I.; Cupani, G.; D'Odorico,
V.; De Caprio, V.; Delabre, B.; Dorn, R.; Figueira, P.; Fragoso, A.;
Galeotta, S.; Genolet, L.; Gomes, R.; González Hernández, J. I.;
Hughes, I.; Iwert, O.; Kerber, F.; Landoni, M.; Lizon, J. -L.; Lovis,
C.; Maire, C.; Mannetta, M.; Martins, C.; Monteiro, M. A.; Oliveira,
A.; Poretti, E.; Rasilla, J. L.; Riva, M.; Santana Tschudi, S.;
Santos, P.; Sosnowska, D.; Sousa, S.; Spanò, P.; Tenegi, F.; Toso,
G.; Vanzella, E.; Viel, M.; Zapatero Osorio, M. R.
2013Msngr.153....6P Altcode:
ESPRESSO is the next generation European exoplanet hunter, combining the
efficiency of a modern echelle spectrograph with extreme radial velocity
and spectroscopic precision. ESPRESSO will be installed in the Combined
Coudé Laboratory of the VLT and linked to the four Unit Telescopes
(UT) through optical coudé trains, operated either with a single
UT or with up to four UTs for 1.5 magnitude gain. The instrumental
radial velocity precision will reach the 10 cm s<SUP>-1</SUP> level
and ESPRESSO will achieve a gain of two magnitudes with respect to
its predecessor HARPS. This is the first VLT instrument using the
incoherent combination of light from four telescopes and, together
with the extreme precision requirements, calls for many innovative
design solutions while ensuring the technical heritage of HARPS.
---------------------------------------------------------
Title: Very Low Mass Stellar and Substellar Companions to Solar-like
Stars from MARVELS. IV. A Candidate Brown Dwarf or Low-mass Stellar
Companion to HIP 67526
Authors: Jiang, Peng; Ge, Jian; Cargile, Phillip; Crepp, Justin R.;
De Lee, Nathan; Porto de Mello, Gustavo F.; Esposito, Massimiliano;
Ferreira, Letícia D.; Femenia, Bruno; Fleming, Scott W.; Gaudi,
B. Scott; Ghezzi, Luan; González Hernández, Jonay I.; Hebb, Leslie;
Lee, Brian L.; Ma, Bo; Stassun, Keivan G.; Wang, Ji; Wisniewski, John
P.; Agol, Eric; Bizyaev, Dmitry; Brewington, Howard; Chang, Liang;
Nicolaci da Costa, Luiz; Eastman, Jason D.; Ebelke, Garrett; Gary,
Bruce; Kane, Stephen R.; Li, Rui; Liu, Jian; Mahadevan, Suvrath; Maia,
Marcio A. G.; Malanushenko, Viktor; Malanushenko, Elena; Muna, Demitri;
Nguyen, Duy Cuong; Ogando, Ricardo L. C.; Oravetz, Audrey; Oravetz,
Daniel; Pan, Kaike; Pepper, Joshua; Paegert, Martin; Allende Prieto,
Carlos; Rebolo, Rafael; Santiago, Basilio X.; Schneider, Donald P.;
Shelden Bradley, Alaina C.; Sivarani, Thirupathi; Snedden, Stephanie;
van Eyken, J. C.; Wan, Xiaoke; Weaver, Benjamin A.; Zhao, Bo
2013AJ....146...65J Altcode: 2013arXiv1307.3308J
We report the discovery of a candidate brown dwarf (BD) or a very
low mass stellar companion (MARVELS-5b) to the star HIP 67526 from
the Multi-object Apache point observatory Radial Velocity Exoplanet
Large-area Survey (MARVELS). The radial velocity curve for this object
contains 31 epochs spread over 2.5 yr. Our Keplerian fit, using a
Markov Chain Monte Carlo approach, reveals that the companion has an
orbital period of 90.2695^{+0.0188}_{-0.0187} days, an eccentricity of
0.4375 ± 0.0040, and a semi-amplitude of 2948.14^{+16.65}_{-16.55} m
s<SUP>-1</SUP>. Using additional high-resolution spectroscopy, we find
the host star has an effective temperature T <SUB>eff</SUB> = 6004 ±
34 K, a surface gravity log g (cgs) =4.55 ± 0.17, and a metallicity
[Fe/H] =+0.04 ± 0.06. The stellar mass and radius determined through
the empirical relationship of Torres et al. yields 1.10 ± 0.09 M
<SUB>⊙</SUB> and 0.92 ± 0.19 R <SUB>⊙</SUB>. The minimum mass
of MARVELS-5b is 65.0 ± 2.9M <SUB>Jup</SUB>, indicating that it is
likely to be either a BD or a very low mass star, thus occupying a
relatively sparsely populated region of the mass function of companions
to solar-type stars. The distance to this system is 101 ± 10 pc
from the astrometric measurements of Hipparcos. No stellar tertiary
is detected in the high-contrast images taken by either FastCam lucky
imaging or Keck adaptive optics imaging, ruling out any star with mass
greater than 0.2 M <SUB>⊙</SUB> at a separation larger than 40 AU.
---------------------------------------------------------
Title: VizieR Online Data Catalog: Radial velocities of TYC
4110-01037-1 (Wisniewski+, 2012)
Authors: Wisniewski, J. P.; Ge, J.; Crepp, J. R.; de, Lee N.; Eastman,
J.; Esposito, M.; Fleming, S. W.; Gaudi, B. S.; Ghezzi, L.; Gonzalez
Hernandez, J. I.; Lee, B. L.; Stassun, K. G.; Agol, E.; Allende Prieto,
C.; Barnes, R.; Bizyaev, D.; Cargile, P.; Chang, L.; da Costa, L. N.;
Porto de Mello, G. F.; Femenia, B.; Ferreira, L. D.; Gary, B.; Hebb,
L.; Holtzman, J.; Liu, J.; Ma, B.; Mack, C. E.; Mahadevan, S.; Maia,
M. A. G.; Nguyen, D. C.; Ogando, R. L. C.; Oravetz, D. J.; Paegert,
M.; Pan, K.; Pepper, J.; Rebolo, R.; Santiago, B.; Schneider, D. P.;
Shelden, A. C.; Simmons, A.; Tofflemire, B. M.; Wan, X.; Wang, J.;
Zhao, B.
2013yCat..51430107W Altcode:
The Multi-object APO Radial Velocity Exoplanet Large-area Survey
(MARVELS), one of the three surveys being executed during the Sloan
Digital Sky Survey (SDSS) III (Eisenstein et al., 2011AJ....142...72E),
is a four-year program which is monitoring the radial velocities
of ~3300 V=7.6-12 FGK-type dwarfs and subgiants. <P />Our primary
RV observations of TYC 4110-01037-1 were obtained during the first
two years of the SDSS-III MARVELS survey, which uses a dispersed
fixed-delay interferometer on the SDSS 2.5m telescope. A total of 32
observations were obtained over the course of ~2 years. Each 50minute
observation yielded two fringing spectra from the interferometer
spanning the wavelength regime ~500-570nm with R~12000. <P />Supporting
RV observations were obtained with the 3.6m Telescopio Nazionale Galileo
(TNG) using its SARG spectrograph. The 0.8"*5.3" slit provided R~57000
spectroscopy between 462-792nm. <P />(1 data file).
---------------------------------------------------------
Title: Very Low Mass Stellar and Substellar Companions to Solar-like
Stars from MARVELS. V. A Low Eccentricity Brown Dwarf from the Driest
Part of the Desert, MARVELS-6b
Authors: De Lee, Nathan; Ge, Jian; Crepp, Justin R.; Eastman, Jason;
Esposito, Massimiliano; Femenía, Bruno; Fleming, Scott W.; Gaudi,
B. Scott; Ghezzi, Luan; González Hernández, Jonay I.; Lee, Brian
L.; Stassun, Keivan G.; Wisniewski, John P.; Wood-Vasey, W. Michael;
Agol, Eric; Allende Prieto, Carlos; Barnes, Rory; Bizyaev, Dmitry;
Cargile, Phillip; Chang, Liang; Da Costa, Luiz N.; Porto De Mello,
G. F.; Ferreira, Leticia D.; Gary, Bruce; Hebb, Leslie; Holtzman, Jon;
Liu, Jian; Ma, Bo; Mack, Claude E., III; Mahadevan, Suvrath; Maia,
Marcio A. G.; Nguyen, Duy Cuong; Oravetz, Audrey; Oravetz, Daniel J.;
Paegert, Martin; Pan, Kaike; Pepper, Joshua; Malanushenko, Elena;
Malanushenko, Viktor; Rebolo, Rafael; Santiago, Basilio X.; Schneider,
Donald P.; Shelden Bradley, Alaina C.; Wan, Xiaoke; Wang, Ji; Zhao, Bo
2013AJ....145..155D Altcode: 2013arXiv1304.2815D
We describe the discovery of a likely brown dwarf (BD) companion with a
minimum mass of 31.7 ± 2.0 M <SUB>Jup</SUB> to GSC 03546-01452 from the
MARVELS radial velocity survey, which we designate as MARVELS-6b. For
reasonable priors, our analysis gives a probability of 72% that
MARVELS-6b has a mass below the hydrogen-burning limit of 0.072 M
<SUB>⊙</SUB>, and thus it is a high-confidence BD companion. It
has a moderately long orbital period of 47.8929^{+0.0063}_{-0.0062}
days with a low eccentricity of 0.1442^{+0.0078}_{-0.0073}, and
a semi-amplitude of 1644^{+12}_{-13} m s<SUP>-1</SUP>. Moderate
resolution spectroscopy of the host star has determined the following
parameters: T <SUB>eff</SUB> = 5598 ± 63, log g = 4.44 ± 0.17, and
[Fe/H] = +0.40 ± 0.09. Based upon these measurements, GSC 03546-01452
has a probable mass and radius of M <SUB>*</SUB> = 1.11 ± 0.11 M
<SUB>⊙</SUB> and R <SUB>*</SUB> = 1.06 ± 0.23 R <SUB>⊙</SUB>
with an age consistent with less than ~6 Gyr at a distance of 219 ±
21 pc from the Sun. Although MARVELS-6b is not observed to transit,
we cannot definitively rule out a transiting configuration based on our
observations. There is a visual companion detected with Lucky Imaging at
7.”7 from the host star, but our analysis shows that it is not bound
to this system. The minimum mass of MARVELS-6b exists at the minimum
of the mass functions for both stars and planets, making this a rare
object even compared to other BDs. It also exists in an underdense
region in both period/eccentricity and metallicity/eccentricity space.
---------------------------------------------------------
Title: The ELM Survey. V. Merging Massive White Dwarf Binaries
Authors: Brown, Warren R.; Kilic, Mukremin; Allende Prieto, Carlos;
Gianninas, A.; Kenyon, Scott J.
2013ApJ...769...66B Altcode: 2013arXiv1304.4248B
We present the discovery of 17 low-mass white dwarfs (WDs) in
short-period (P <= 1 day) binaries. Our sample includes four objects
with remarkable log g ~= 5 surface gravities and orbital solutions
that require them to be double degenerate binaries. All of the lowest
surface gravity WDs have metal lines in their spectra implying long
gravitational settling times or ongoing accretion. Notably, six of
the WDs in our sample have binary merger times <10 Gyr. Four have
gsim0.9 M <SUB>⊙</SUB> companions. If the companions are massive
WDs, these four binaries will evolve into stable mass transfer AM
CVn systems and possibly explode as underluminous supernovae. If the
companions are neutron stars, then these may be millisecond pulsar
binaries. These discoveries increase the number of detached, double
degenerate binaries in the ELM Survey to 54; 31 of these binaries will
merge within a Hubble time. <P />Based on observations obtained at
the MMT Observatory, a joint facility of the Smithsonian Institution
and the University of Arizona.
---------------------------------------------------------
Title: A PCA approach to stellar effective temperatures
Authors: Muñoz Bermejo, J.; Asensio Ramos, A.; Allende Prieto, C.
2013A&A...553A..95M Altcode: 2013arXiv1303.7218M
Context. The derivation of the effective temperature of
a star is a critical first step in a detailed spectroscopic
analysis. Spectroscopic methods suffer from systematic errors related
to model simplifications. Photometric methods may be more robust, but
are exposed to the distortions caused by interstellar reddening. Direct
methods are difficult to apply, since fundamental data of high accuracy
are hard to obtain. <BR /> Aims: We explore a new approach in which the
spectrum is used to characterize a star's effective temperature based
on a calibration established by a small set of standard stars. <BR
/> Methods: We perform principal component analysis on homogeneous
libraries of stellar spectra, then calibrate a relationship between
the principal components and the effective temperature using a set of
stars with reliable effective temperatures. <BR /> Results: We find
that our procedure gives excellent consistency when spectra from a
homogenous set of observations are used. Systematic offsets may appear
when combining observations from different sources. Using as reference
the spectra of stars with high-quality spectroscopic temperatures
in the Elodie library, we define a temperature scale for FG-type
disk dwarfs with an internal consistency of about 50 K, in excellent
agreement with temperatures from direct determinations and widely used
scales based on the infrared flux method. <P />Tables 2, 4, 5, and
reduced spectra are only available at the CDS via anonymous ftp to
<A href="http://cdsarc.u-strasbg.fr>cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <a
href=">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/553/A95</A>
---------------------------------------------------------
Title: A Cautionary Tale: MARVELS Brown Dwarf Candidate Reveals
Itself to be a Very Long Period, Highly Eccentric Spectroscopic
Stellar Binary
Authors: Mack, Claude E., III; Ge, Jian; Deshpande, Rohit; Wisniewski,
John P.; Stassun, Keivan G.; Gaudi, B. Scott; Fleming, Scott W.;
Mahadevan, Suvrath; De Lee, Nathan; Eastman, Jason; Ghezzi, Luan;
González Hernández, Jonay I.; Femenía, Bruno; Ferreira, Letícia;
Porto de Mello, Gustavo; Crepp, Justin R.; Mata Sánchez, Daniel;
Agol, Eric; Beatty, Thomas G.; Bizyaev, Dmitry; Brewington, Howard;
Cargile, Phillip A.; da Costa, Luiz N.; Esposito, Massimiliano;
Ebelke, Garret; Hebb, Leslie; Jiang, Peng; Kane, Stephen R.; Lee,
Brian; Maia, Marcio A. G.; Malanushenko, Elena; Malanushenko, Victor;
Oravetz, Daniel; Paegert, Martin; Pan, Kaike; Allende Prieto, Carlos;
Pepper, Joshua; Rebolo, Rafael; Roy, Arpita; Santiago, Basílio X.;
Schneider, Donald P.; Simmons, Audrey; Siverd, Robert J.; Snedden,
Stephanie; Tofflemire, Benjamin M.
2013AJ....145..139M Altcode: 2013arXiv1306.3157M
We report the discovery of a highly eccentric, double-lined
spectroscopic binary star system (TYC 3010-1494-1), comprising two
solar-type stars that we had initially identified as a single star
with a brown dwarf companion. At the moderate resolving power of
the MARVELS spectrograph and the spectrographs used for subsequent
radial-velocity (RV) measurements (R <~ 30, 000), this particular
stellar binary mimics a single-lined binary with an RV signal that would
be induced by a brown dwarf companion (Msin i ~ 50 M <SUB>Jup</SUB>)
to a solar-type primary. At least three properties of this system allow
it to masquerade as a single star with a very-low-mass companion:
its large eccentricity (e ~ 0.8), its relatively long period (P ~
238 days), and the approximately perpendicular orientation of the
semi-major axis with respect to the line of sight (ω ~ 189°). As
a result of these properties, for ~95% of the orbit the two sets of
stellar spectral lines are completely blended, and the RV measurements
based on centroiding on the apparently single-lined spectrum is very
well fit by an orbit solution indicative of a brown dwarf companion
on a more circular orbit (e ~ 0.3). Only during the ~5% of the orbit
near periastron passage does the true, double-lined nature and large
RV amplitude of ~15 km s<SUP>-1</SUP> reveal itself. The discovery of
this binary system is an important lesson for RV surveys searching for
substellar companions; at a given resolution and observing cadence,
a survey will be susceptible to these kinds of astrophysical false
positives for a range of orbital parameters. Finally, for surveys like
MARVELS that lack the resolution for a useful line bisector analysis,
it is imperative to monitor the peak of the cross-correlation function
for suspicious changes in width or shape, so that such false positives
can be flagged during the candidate vetting process.
---------------------------------------------------------
Title: Parses Pipeline For Determining The Stellar Parameters
Authors: Jovanovic, M.; Weber, M.; Allende Prieto, C.
2013POBeo..92..169J Altcode:
PARSES is a pipeline for determining physical parameters of a star
from the stellar spectra -- effective temperature, metallicity,
surface gravity and rotational velocity. It utilizes the grid of
templates based on synthetic spectra, and the search routine is based
on the Minimum Distance Method. In order to calibrate the routine,
we tested it with different wavelength ranges used for fitting the
observed spectra. Results for stellar parameters are compared with the
literature values from the ELODIE library. The last step was to choose
final solution for full implementation on the data produced with the
STELLA telescope. The modified version of the pipeline is going to be
used in processing the data from the ELODIE spectral library and also
tested on some Gaia ESO data.
---------------------------------------------------------
Title: PHASES: A Project to Perform Absolute Spectrophotometry
from Space
Authors: del Burgo, C.; Vather, D.; Allende Prieto, C.; Murphy, N.
2013ASPC..472..291D Altcode:
This paper presents the current status of the opto-mechanical design of
PHASES (Planet Hunting and AsteroSeismology Explorer Spectrophotometer),
which is a project to develop a space-borne telescope to obtain
absolute flux calibrated spectra of bright stars. The science
payload is intended to be housed in a micro-satellite launched into
a low-earth Sun-synchronous orbit with an inclination to the equator
of 98.7° and a local time ascending node LTAN of 6:00 AM. PHASES
will be able to measure micromagnitude photometric variations due to
stellar oscillations/activity and planet/moon transits. It consists
of a 20 cm aperture modified Baker telescope feeding two detectors:
the tracking detector provides the fine telescope guidance system
with a required pointing stability of 0.2″, and the science detector
performs spectrophotometry in the wavelength range 370-960 nm with a
resolving power between 200 and 900. The spectrograph is designed to
provide 1% RMS flux calibrated spectra with signal-to-noise ratios >
100 for stars with V < 10 in short integration times. Our strategy to
calibrate the system using A type stars is explained. From comparison
with model atmospheres it would be possible to determine the stellar
angular diameters with an uncertainty of approximately 0.5%. In the case
of a star hosting a transiting planet it would be possible to derive
its light curve, and then the planet to stellar radius ratio. Bright
stars have high precision Hipparcos parallaxes and the expected level
of accuracy for their fluxes will be propagated to the stellar radii,
and more significantly to the planetary radii. The scientific drivers
for PHASES give rise to some design challenges, which are particularly
related to the opto-mechanics for extreme environmental conditions. The
optical design has been developed with the primary goal of avoiding
stray light reaching the science detector. Three different proposals
for the opto-mechanical design are under investigation.
---------------------------------------------------------
Title: On the interpolation of model atmospheres and high-resolution
synthetic stellar spectra
Authors: Mészáros, Sz.; Allende Prieto, C.
2013MNRAS.430.3285M Altcode: 2013arXiv1301.4843M; 2013MNRAS.tmp..790M
We present tests carried out on optical and infrared stellar spectra to
evaluate the accuracy of different types of interpolation. Both model
atmospheres and continuum normalized fluxes were interpolated. In the
first case, we used linear interpolation, and in the second linear,
cubic spline, cubic Bezier and quadratic Bezier methods. We generated
400 ATLAS9 model atmospheres with random values of the atmospheric
parameters for these tests, spanning between -2.5 and +0.5 in [Fe/H],
from 4500 to 6250 K in effective temperature, and 1.5 to 4.5 dex in
surface gravity. Synthesized spectra were created from these model
atmospheres, and compared with spectra derived by interpolation. We
found that the most accurate interpolation algorithm among those
considered in flux space is cubic Bezier, closely followed by
quadratic Bezier and cubic splines. Linear interpolation of model
atmospheres results in errors about a factor of 2 larger than linear
interpolation of fluxes, and about a factor of 4 larger than high-order
flux interpolations.
---------------------------------------------------------
Title: Very Metal-poor Stars in the Outer Galactic Bulge Found by
the APOGEE Survey
Authors: García Pérez, Ana E.; Cunha, Katia; Shetrone, Matthew;
Majewski, Steven R.; Johnson, Jennifer A.; Smith, Verne V.; Schiavon,
Ricardo P.; Holtzman, Jon; Nidever, David; Zasowski, Gail; Allende
Prieto, Carlos; Beers, Timothy C.; Bizyaev, Dmitry; Ebelke, Garrett;
Eisenstein, Daniel J.; Frinchaboy, Peter M.; Girardi, Léo; Hearty,
Fred R.; Malanushenko, Elena; Malanushenko, Viktor; Meszaros, Szabolcs;
O'Connell, Robert W.; Oravetz, Daniel; Pan, Kaike; Robin, Annie C.;
Schneider, Donald P.; Schultheis, Mathias; Skrutskie, Michael F.;
Simmonsand, Audrey; Wilson, John C.
2013ApJ...767L...9G Altcode: 2013arXiv1301.1367G
Despite its importance for understanding the nature of early
stellar generations and for constraining Galactic bulge formation
models, at present little is known about the metal-poor stellar
content of the central Milky Way. This is a consequence of the
great distances involved and intervening dust obscuration, which
challenge optical studies. However, the Apache Point Observatory
Galactic Evolution Experiment (APOGEE), a wide-area, multifiber,
high-resolution spectroscopic survey within Sloan Digital Sky Survey
III, is exploring the chemistry of all Galactic stellar populations
at infrared wavelengths, with particular emphasis on the disk and the
bulge. An automated spectral analysis of data on 2403 giant stars in 12
fields in the bulge obtained during APOGEE commissioning yielded five
stars with low metallicity ([Fe/H] <= -1.7), including two that are
very metal-poor [Fe/H] ~ -2.1 by bulge standards. Luminosity-based
distance estimates place the 5 stars within the outer bulge, where
1246 of the other analyzed stars may reside. A manual reanalysis of
the spectra verifies the low metallicities, and finds these stars
to be enhanced in the α-elements O, Mg, and Si without significant
α-pattern differences with other local halo or metal-weak thick-disk
stars of similar metallicity, or even with other more metal-rich bulge
stars. While neither the kinematics nor chemistry of these stars can
yet definitively determine which, if any, are truly bulge members,
rather than denizens of other populations co-located with the bulge,
the newly identified stars reveal that the chemistry of metal-poor
stars in the central Galaxy resembles that of metal-weak thick-disk
stars at similar metallicity.
---------------------------------------------------------
Title: VizieR Online Data Catalog: PCA approach to stellar effective
temperatures (Bermejo+, 2013)
Authors: Bermejo, J. M.; Asensio Ramos, A.; Allende Prieto, C.
2013yCat..35530095B Altcode: 2013yCat..35539095B
Effective temperatures, derived for stars with observations in the
Elodie library or the Elodie archive, from a PCA-based spectroscopic
calibration. <P />(3 data files).
---------------------------------------------------------
Title: Chemical Abundances in Field Red Giants from High-resolution
H-band Spectra Using the APOGEE Spectral Linelist
Authors: Smith, Verne V.; Cunha, Katia; Shetrone, Matthew D.; Meszaros,
Szabolcs; Allende Prieto, Carlos; Bizyaev, Dmitry; García Pérez,
Ana; Majewski, Steven R.; Schiavon, Ricardo; Holtzman, Jon; Johnson,
Jennifer A.
2013ApJ...765...16S Altcode: 2012arXiv1212.4091S
High-resolution H-band spectra of five bright field K, M, and MS giants,
obtained from the archives of the Kitt Peak National Observatory
Fourier transform spectrometer, are analyzed to determine chemical
abundances of 16 elements. The abundances were derived via spectrum
synthesis using the detailed linelist prepared for the Sloan Digital
Sky Survey III Apache Point Galactic Evolution Experiment (APOGEE),
which is a high-resolution near-infrared spectroscopic survey to derive
detailed chemical abundance distributions and precise radial velocities
for 100,000 red giants sampling all Galactic stellar populations. The
red giant sample studied here was chosen to probe which chemical
elements can be derived reliably from the H-band APOGEE spectral
region. These red giants consist of two K-giants (α Boo and μ Leo),
two M-giants (β And and δ Oph), and one thermally pulsing asymptotic
giant branch (TP-AGB) star of spectral type MS (HD 199799). Measured
chemical abundances include the cosmochemically important isotopes
<SUP>12</SUP>C, <SUP>13</SUP>C, <SUP>14</SUP>N, and <SUP>16</SUP>O,
along with Mg, Al, Si, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, and Cu. The K
and M giants exhibit the abundance signature of the first dredge-up of
CN-cycle material, while the TP-AGB star shows clear evidence of the
addition of <SUP>12</SUP>C synthesized during <SUP>4</SUP>He-burning
thermal pulses and subsequent third dredge-up. A comparison of the
abundances derived here with published values for these stars reveals
consistent results to ~0.1 dex. The APOGEE spectral region and linelist
is thus well suited for probing both Galactic chemical evolution,
as well as internal nucleosynthesis and mixing in populations of red
giants via high-resolution spectroscopy.
---------------------------------------------------------
Title: Spectroscopic followup of three bright halo stars selected
from SDSS and GALEX photometry
Authors: Sahin, Timur; Lambert, David L.; Allende Prieto, Carlos
2013arXiv1303.4853S Altcode:
We aim to reveal the nature of the Sloan Digital Sky Survey
(SDSS) stars: SDSSJ100921.40+375233.9, SDSSJ015717.04+135535.9, and
SDSSJ171422.43+283657.2, showing apparently high NUV excesses for their
g-z colors, as expected for extremely low-metallicity stars. High
resolution (R=60 000) spectra of the stars with a wide wavelength
coverage were obtained to determine their chemical compositions with
the Tull echelle spectrograph on the 2.7 m telescope at the McDonald
Observatory. We derived the spectroscopic parameters Teff =5820+-125 K,
log g =3.9+-0.2, and vt =1.1+-0.5 km/s for SDSSJ100921.40+375233.9,
Teff=6250+-125 K, log g =3.7+-0.2, and vt =4.0+-0.5 km/s for
SDSSJ015717.04+135535.9, and Teff=6320+-125 K, log g =4.1+-0.3,
and vt =1.5+-0.5 km/s for SDSS J171422.43+283657.2, and elemental
abundances were computed for 21 elements for J100921 and J171422 and
for 19 elements for J015717 for the first time. We find metallicities
of [Fe/H]= -1.30, -0.94, and -0.80 for SDSSJ100921.40+375233.9,
J015717.04+135535.9, and J171422.43+283657.2, respectively. On the
basis of calculated abundance ratios for J171422.43+283657.2 and
J015717.04+135535.9, we also report that these two program stars
have the expected composition of main-sequence halo turnoff stars,
but with low-alpha abundances, i.e., the [alpha/Fe] ratio is ~0.0 for
J171422.43+283657.2 and ~0.1 for J015717.04+135535.9. The latter one
shows typical halo or thick-disk alpha-element abundances, but has a
substantial rotational line broadening and vsini=40 +- 0.5 km/s.
---------------------------------------------------------
Title: VizieR Online Data Catalog: PCA approach to stellar effective
temperatures (Bermejo+, 2013)
Authors: Munoz Bermejo, J.; Asensio Ramos, A.; Allende Prieto, C.
2013yCat..35530095M Altcode: 2013yCat..35539095M
Effective temperatures, derived for stars with observations in the
Elodie library or the Elodie archive, from a PCA-based spectroscopic
calibration. <P />(3 data files).
---------------------------------------------------------
Title: Convective line shifts for the Gaia RVS from the CIFIST 3D
model atmosphere grid
Authors: Allende Prieto, C.; Koesterke, L.; Ludwig, H. -G.; Freytag,
B.; Caffau, E.
2013A&A...550A.103A Altcode: 2013arXiv1301.3703A
Context. To derive space velocities of stars along the line of sight
from wavelength shifts in stellar spectra requires accounting for a
number of second-order effects. For most stars, gravitational redshifts,
convective blueshifts, and transverse stellar motion are the dominant
contributors. <BR /> Aims: We provide theoretical corrections for the
net velocity shifts due to convection expected for the measurements
from the Gaia Radial Velocity Spectrometer (RVS). <BR /> Methods: We
used a set of three-dimensional time-dependent simulations of stellar
surface convection computed with CO5BOLD to calculate spectra of
late-type stars in the Gaia RVS range and to infer the net velocity
offset that convective motions will induce in radial velocities
derived by cross-correlation. <BR /> Results: The net velocity shifts
derived by cross-correlation depend both on the wavelength range and
spectral resolution of the observations. Convective shifts for Gaia
RVS observations are less than 0.1 km s<SUP>-1</SUP> for late-K-type
stars, and they increase with stellar mass, reaching about 0.3 km
s<SUP>-1</SUP> or more for early F-type dwarfs. This tendency is the
result of an increase with effective temperature in both temperature
and velocity fluctuations in the line-forming region. Our simulations
also indicate that the net RVS convective shifts can be positive
(i.e. redshifts) in some cases. Overall, the blueshifts weaken
slightly with increasing surface gravity, and are enhanced at low
metallicity. Gravitational redshifts amount to 0.7 km s<SUP>-1</SUP>
and dominate convective blueshifts for dwarfs, but become much
weaker for giants. <P />Appendix A is available in electronic form
at <A href="http://www.aanda.org">http://www.aanda.org</A>Model
spectra from the 1D and 3D calculations are only available
in electronic form at the CDS via anonymous ftp to <A
href="http://cdsarc.u-strasbg.fr">cdsarc.u-strasbg.fr</A><A
href="http://130.79.128.5">130.79.128.5</A> or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/550/A103">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/550/A103</A>
---------------------------------------------------------
Title: Oxygen Abundances in Nearby FGK Stars and the Galactic Chemical
Evolution of the Local Disk and Halo
Authors: Ramírez, I.; Allende Prieto, C.; Lambert, D. L.
2013ApJ...764...78R Altcode: 2013arXiv1301.1582R
Atmospheric parameters and oxygen abundances of 825 nearby FGK
stars are derived using high-quality spectra and a non-local
thermodynamic equilibrium analysis of the 777 nm O I triplet
lines. We assign a kinematic probability for the stars to be
thin-disk (P <SUB>1</SUB>), thick-disk (P <SUB>2</SUB>), and halo
(P <SUB>3</SUB>) members. We confirm previous findings of enhanced
[O/Fe] in thick-disk (P <SUB>2</SUB> > 0.5) relative to thin-disk
(P <SUB>1</SUB> > 0.5) stars with [Fe/H] <~ -0.2, as well as a
"knee" that connects the mean [O/Fe]-[Fe/H] trend of thick-disk stars
with that of thin-disk members at [Fe/H] >~ -0.2. Nevertheless,
we find that the kinematic membership criterion fails at separating
perfectly the stars in the [O/Fe]-[Fe/H] plane, even when a very
restrictive kinematic separation is employed. Stars with "intermediate"
kinematics (P <SUB>1</SUB> < 0.7, P <SUB>2</SUB> < 0.7) do not
all populate the region of the [O/Fe]-[Fe/H] plane intermediate between
the mean thin-disk and thick-disk trends, but their distribution is
not necessarily bimodal. Halo stars (P <SUB>3</SUB> > 0.5) show
a large star-to-star scatter in [O/Fe]-[Fe/H], but most of it is
due to stars with Galactocentric rotational velocity V < -200 km
s<SUP>-1</SUP> halo stars with V > -200 km s<SUP>-1</SUP> follow
an [O/Fe]-[Fe/H] relation with almost no star-to-star scatter. Early
mergers with satellite galaxies explain most of our observations, but
the significant fraction of disk stars with "ambiguous" kinematics
and abundances suggests that scattering by molecular clouds and
radial migration have both played an important role in determining
the kinematic and chemical properties of solar neighborhood stars.
---------------------------------------------------------
Title: SDSS-III/APOGEE: Science and Survey Calibrations and using
Open Clusters
Authors: Frinchaboy, Peter M.; O'Connell, J.; Meszaros, Sz.; Cunha,
K. M.; Smith, V. V.; Garcia Perez, A.; Shetrone, M. D.; Allende
Prieto, C.; Johnson, J.; Zasowski, G.; Majewski, S. R.; Schiavon,
R. P.; Holtzman, J. A.; Nidever, D.; Bizyaev, D.; Hearty, F. R.;
Jackson, K.; Thompson, B. A.; Wilson, J. C.; Beers, T. C.
2013AAS...22125034F Altcode:
We present results from the first year of the SDSS-III/Apache Point
Obseratory Galactic Evolution Experiment (APOGEE) survey of open cluster
targets. APOGEE is studying several key open clusters for calibration
and science (e.g., M67, NGC 6791), and here we present early science
results and comparison to previous work on a number of clusters focusing
on radial velocities, stellar parameters, and abundances. Funding
for SDSS-III has been provided by the Alfred P. Sloan Foundation,
the Participating Institutions, the National Science Foundation,
and the U.S. Department of Energy Office of Science. The SDSS-III web
site is http://www.sdss3.org/. SDSS-III is managed by the Astrophysical
Research Consortium for the Participating Institutions of the SDSS-III
Collaboration including the University of Arizona, the Brazilian
Participation Group, Brookhaven National Laboratory, University of
Cambridge, Carnegie Mellon University, University of Florida, the
French Participation Group, the German Participation Group, Harvard
University, the Instituto de Astrofisica de Canarias, the Michigan
State/Notre Dame/JINA Participation Group, Johns Hopkins University,
Lawrence Berkeley National Laboratory, Max Planck Institute for
Astrophysics, Max Planck Institute for Extraterrestrial Physics, New
Mexico State University, New York University, Ohio State University,
Pennsylvania State University, University of Portsmouth, Princeton
University, the Spanish Participation Group, University of Tokyo,
University of Utah, Vanderbilt University, University of Virginia,
University of Washington, and Yale University.
---------------------------------------------------------
Title: APOGEE Observations of the Center of the Sagittarius dSph
Galaxy
Authors: Hasselquist, Sten; Majewski, S. R.; Lokas, E.; Nidever,
D.; Shetrone, M. D.; Beaton, R.; Johnston, K. V.; Holtzman, J. A.;
Zasowski, G.; Allende Prieto, C.; Beers, T. C.; Bizyaev, D.; Cunha,
K. M.; Damke, G.; Frinchaboy, P. M.; Garcia Perez, A.; Johnson, J.;
Law, D. R.; Meszaros, Sz.; Schiavon, R. P.; Smith, V. V.; Wilson, J. C.
2013AAS...22124201H Altcode:
As a system currently in the state of merging with the Milky Way --
and therefore a prototype for substructures that participate in the
hierarchical build-up of our galaxy -- the structure of the Sagittarius
(Sgr) dSph system is of particular interest. The APOGEE survey is
ideally suited for the study of Sgr stars because of its ability to
sample numerous stars over a large field of view; its high spectral
resolution, which allows precision abundances and kinematics to be
measured in these stars; and its infrared sensitivity, which allows
these dust-extinguished fields to be explored more easily. Initial
APOGEE observations of Sgr have provided accurate radial velocities,
stellar parameters, and chemical abundances of over 200 confirmed Sgr
members in the dwarf galaxy’s central 2.5 degrees. The < 1 km/s
precision RVs have verified with strong significance the existence of a
dynamical cold point in the center of the Sgr dSph. We explore various
explanations for this phenomenon in terms of the distribution of both
dark matter and stellar populations. The data also shows evidence
of a metallicity gradient over the same radial range, demonstrating
that the velocity dispersion variations span, and may be related to,
differences in the distributions and dynamics of multiple stellar
populations within the satellite.
---------------------------------------------------------
Title: Automated Unsupervised Classification of the Sloan Digital
Sky Survey Stellar Spectra using k-means Clustering
Authors: Sánchez Almeida, J.; Allende Prieto, C.
2013ApJ...763...50S Altcode: 2012arXiv1211.5321S
Large spectroscopic surveys require automated methods of analysis. This
paper explores the use of k-means clustering as a tool for automated
unsupervised classification of massive stellar spectral catalogs. The
classification criteria are defined by the data and the algorithm,
with no prior physical framework. We work with a representative set
of stellar spectra associated with the Sloan Digital Sky Survey (SDSS)
SEGUE and SEGUE-2 programs, which consists of 173,390 spectra from 3800
to 9200 Å sampled on 3849 wavelengths. We classify the original spectra
as well as the spectra with the continuum removed. The second set only
contains spectral lines, and it is less dependent on uncertainties of
the flux calibration. The classification of the spectra with continuum
renders 16 major classes. Roughly speaking, stars are split according
to their colors, with enough finesse to distinguish dwarfs from giants
of the same effective temperature, but with difficulties to separate
stars with different metallicities. There are classes corresponding
to particular MK types, intrinsically blue stars, dust-reddened,
stellar systems, and also classes collecting faulty spectra. Overall,
there is no one-to-one correspondence between the classes we derive
and the MK types. The classification of spectra without continuum
renders 13 classes, the color separation is not so sharp, but it
distinguishes stars of the same effective temperature and different
metallicities. Some classes thus obtained present a fairly small
range of physical parameters (200 K in effective temperature, 0.25
dex in surface gravity, and 0.35 dex in metallicity), so that the
classification can be used to estimate the main physical parameters
of some stars at a minimum computational cost. We also analyze the
outliers of the classification. Most of them turn out to be failures
of the reduction pipeline, but there are also high redshift QSOs,
multiple stellar systems, dust-reddened stars, galaxies, and, finally,
odd spectra whose nature we have not deciphered. The template spectra
representative of the classes are publicly available in the online
journal and at ftp://stars:kmeans@ftp.iac.es.
---------------------------------------------------------
Title: Optical High Resolution Spectra of APOGEE Stars
Authors: Feuillet, Diane; Holtzman, J. A.; Cunha, K. M.; Garcia Perez,
A.; Ghezzi, L.; Hayden, M. R.; Meszaros, Sz.; Allende Prieto, C.;
Shetrone, M. D.; Smith, V. V.; Zasowski, G.
2013AAS...22125413F Altcode:
The Apache Point Observatory Galactic Evolution Experiment (APOGEE)
is an SDSS-III survey that is obtaining high resolution near-IR (H
band) spectra of 100,000 Milky Way stars in an effort to chemically
trace formation and evolution of Galactic stellar populations. Optical
echelle spectra of a small subset of survey targets have been obtained
with the ARC 3.5m telescope for the purpose of 1) helping to understand
and calibrate the abundance analysis of the APOGEE IR spectra, and 2)
measuring abundances of elements that do not have spectral features
in the APOGEE wavelength region, which will ideally include neutron
capture elements. We present our current sample of ~130 (out of a
projected 500) stars, which is drawn from the brightest APOGEE targets
and covers a range of stellar parameters (temperature, metallicity,
and surface gravity), and compare some optically derived quantities
with those from the APOGEE abundance pipeline.
---------------------------------------------------------
Title: Milky Way Abundance Gradients from SDSS-III/APOGEE Observations
Authors: Hayden, Michael R.; Holtzman, J. A.; Majewski, S. R.;
Hearty, F. R.; Smith, V. V.; Johnson, J.; Frinchaboy, P. M.; Schiavon,
R. P.; Allende Prieto, C.; Shetrone, M. D.; Cunha, K. M.; Bizyaev,
D.; Nidever, D.; Perez, A.; Zasowski, G.; Wilson, J. C.; Skrutskie,
M. F.; Sellgren, K.; Bovy, J.; Robin, A.; Beers, T. C.; Meszaros, Sz.
2013AAS...22125414H Altcode:
We present initial abundance gradients in the Milky Way as determined
from high-resolution (R > 20,000) spectra of red giant stars. Our
observations were taken with the SDSS-III APO Galactic Evolution
Experiment (APOGEE) and have a S/N of at least 100. APOGEE is able
to sample a large range of Galactocentric radii (R<SUP>GC</SUP>)
including the bulge and inner disk regions of the galaxy by working
in the near-IR. From a sample of nearly 30,000 stars taken during
the first year of APOGEE operation, we estimate distances using
spectroscopically-derived surface gravities combined with extinction
estimates from near- and mid-IR photometry. This sample includes stars
with 0 < R<SUP>GC</SUP> < 20 kpc, and is constrained to a range
of heights about the plane, Z, from 0 to 2 kpc. We determine radial
abundance gradients for subsamples that include different heights
about the plane and different [α/Fe] ratios. We find that the radial
abundance gradient is steeper in the plane than above it for stars
with near-solar [α/Fe], and mostly flat for stars with higher [α/Fe]
at all Z.
---------------------------------------------------------
Title: Very-low-mass Stellar and Substellar Companions to Solar-like
Stars from Marvels. III. A Short-period Brown Dwarf Candidate around
an Active G0IV Subgiant
Authors: Ma, Bo; Ge, Jian; Barnes, Rory; Crepp, Justin R.; De Lee,
Nathan; Dutra-Ferreira, Leticia; Esposito, Massimiliano; Femenia,
Bruno; Fleming, Scott W.; Gaudi, B. Scott; Ghezzi, Luan; Hebb,
Leslie; Gonzalez Hernandez, Jonay I.; Lee, Brian L.; Porto de Mello,
G. F.; Stassun, Keivan G.; Wang, Ji; Wisniewski, John P.; Agol, Eric;
Bizyaev, Dmitry; Cargile, Phillip; Chang, Liang; Nicolaci da Costa,
Luiz; Eastman, Jason D.; Gary, Bruce; Jiang, Peng; Kane, Stephen R.;
Li, Rui; Liu, Jian; Mahadevan, Suvrath; Maia, Marcio A. G.; Muna,
Demitri; Nguyen, Duy Cuong; Ogando, Ricardo L. C.; Oravetz, Daniel;
Pepper, Joshua; Paegert, Martin; Allende Prieto, Carlos; Rebolo,
Rafael; Santiago, Basilio X.; Schneider, Donald P.; Shelden, Alaina;
Simmons, Audrey; Sivarani, Thirupathi; van Eyken, J. C.; Wan, Xiaoke;
Weaver, Benjamin A.; Zhao, Bo
2013AJ....145...20M Altcode: 2012arXiv1211.6140M
We present an eccentric, short-period brown dwarf candidate orbiting
the active, slightly evolved subgiant star TYC 2087-00255-1, which
has effective temperature T <SUB>eff</SUB> = 5903 ± 42 K, surface
gravity log (g) = 4.07 ± 0.16 (cgs), and metallicity [Fe/H] = -0.23 ±
0.07. This candidate was discovered using data from the first two years
of the Multi-object APO Radial Velocity Exoplanets Large-area Survey,
which is part of the third phase of Sloan Digital Sky Survey. From our
38 radial velocity measurements spread over a two-year time baseline, we
derive a Keplerian orbital fit with semi-amplitude K = 3.571 ± 0.041 km
s<SUP>-1</SUP>, period P = 9.0090 ± 0.0004 days, and eccentricity e =
0.226 ± 0.011. Adopting a mass of 1.16 ± 0.11 M <SUB>⊙</SUB> for the
subgiant host star, we infer that the companion has a minimum mass of
40.0 ± 2.5 M <SUB>Jup</SUB>. Assuming an edge-on orbit, the semimajor
axis is 0.090 ± 0.003 AU. The host star is photometrically variable
at the ~1% level with a period of ~13.16 ± 0.01 days, indicating that
the host star spin and companion orbit are not synchronized. Through
adaptive optics imaging we also found a point source 643 ± 10 mas away
from TYC 2087-00255-1, which would have a mass of 0.13 M <SUB>⊙</SUB>
if it is physically associated with TYC 2087-00255-1 and has the same
age. Future proper motion observation should be able to resolve if
this tertiary object is physically associated with TYC 2087-00255-1
and make TYC 2087-00255-1 a triple body system. Core Ca II H and K
line emission indicate that the host is chromospherically active,
at a level that is consistent with the inferred spin period and
measured v <SUB>rot</SUB>sin i, but unusual for a subgiant of this
T <SUB>eff</SUB>. This activity could be explained by ongoing tidal
spin-up of the host star by the companion.
---------------------------------------------------------
Title: The Metallicity Distribution Functions of SEGUE G and K Dwarfs:
Constraints for Disk Chemical Evolution and Formation
Authors: Schlesinger, Katharine J.; Johnson, Jennifer A.; Rockosi,
Constance M.; Lee, Young Sun; Morrison, Heather L.; Schönrich, Ralph;
Allende Prieto, Carlos; Beers, Timothy C.; Yanny, Brian; Harding, Paul;
Schneider, Donald P.; Chiappini, Cristina; da Costa, Luiz N.; Maia,
Marcio A. G.; Minchev, Ivan; Rocha-Pinto, Helio; Santiago, Basílio X.
2012ApJ...761..160S Altcode: 2011arXiv1112.2214S
We present the metallicity distribution function (MDF) for 24,270 G
and 16,847 K dwarfs at distances from 0.2 to 2.3 kpc from the Galactic
plane, based on spectroscopy from the Sloan Extension for Galactic
Understanding and Exploration (SEGUE) survey. This stellar sample
is significantly larger in both number and volume than previous
spectroscopic analyses, which were limited to the solar vicinity,
making it ideal for comparison with local volume-limited samples and
Galactic models. For the first time, we have corrected the MDF for the
various observational biases introduced by the SEGUE target-selection
strategy. SEGUE is particularly notable for its sample of K dwarfs,
which are too faint to examine spectroscopically far from the solar
neighborhood. The MDF of both spectral types becomes more metal-poor
with increasing |Z|, which reflects the transition from a sample with
small [α/Fe] values at small heights to one with enhanced [α/Fe]
above 1 kpc. Comparison of our SEGUE distributions to those of two
different Milky Way models reveals that both are more metal-rich than
our observed distributions at all heights above the plane. Our unbiased
observations of G and K dwarfs provide valuable constraints over the
|Z|-height range of the Milky Way disk for chemical and dynamical Galaxy
evolution models, previously only calibrated to the solar neighborhood,
with particular utility for thin- and thick-disk formation models.
---------------------------------------------------------
Title: The Ninth Data Release of the Sloan Digital Sky Survey:
First Spectroscopic Data from the SDSS-III Baryon Oscillation
Spectroscopic Survey
Authors: Ahn, Christopher P.; Alexandroff, Rachael; Allende Prieto,
Carlos; Anderson, Scott F.; Anderton, Timothy; Andrews, Brett H.;
Aubourg, Éric; Bailey, Stephen; Balbinot, Eduardo; Barnes, Rory;
Bautista, Julian; Beers, Timothy C.; Beifiori, Alessandra; Berlind,
Andreas A.; Bhardwaj, Vaishali; Bizyaev, Dmitry; Blake, Cullen H.;
Blanton, Michael R.; Blomqvist, Michael; Bochanski, John J.; Bolton,
Adam S.; Borde, Arnaud; Bovy, Jo; Brandt, W. N.; Brinkmann, J.; Brown,
Peter J.; Brownstein, Joel R.; Bundy, Kevin; Busca, N. G.; Carithers,
William; Carnero, Aurelio R.; Carr, Michael A.; Casetti-Dinescu,
Dana I.; Chen, Yanmei; Chiappini, Cristina; Comparat, Johan;
Connolly, Natalia; Crepp, Justin R.; Cristiani, Stefano; Croft,
Rupert A. C.; Cuesta, Antonio J.; da Costa, Luiz N.; Davenport,
James R. A.; Dawson, Kyle S.; de Putter, Roland; De Lee, Nathan;
Delubac, Timothée; Dhital, Saurav; Ealet, Anne; Ebelke, Garrett L.;
Edmondson, Edward M.; Eisenstein, Daniel J.; Escoffier, S.; Esposito,
Massimiliano; Evans, Michael L.; Fan, Xiaohui; Femenía Castellá,
Bruno; Fernández Alvar, Emma; Ferreira, Leticia D.; Filiz Ak, N.;
Finley, Hayley; Fleming, Scott W.; Font-Ribera, Andreu; Frinchaboy,
Peter M.; García-Hernández, D. A.; García Pérez, A. E.; Ge,
Jian; Génova-Santos, R.; Gillespie, Bruce A.; Girardi, Léo;
González Hernández, Jonay I.; Grebel, Eva K.; Gunn, James E.; Guo,
Hong; Haggard, Daryl; Hamilton, Jean-Christophe; Harris, David W.;
Hawley, Suzanne L.; Hearty, Frederick R.; Ho, Shirley; Hogg, David W.;
Holtzman, Jon A.; Honscheid, Klaus; Huehnerhoff, J.; Ivans, Inese I.;
Ivezić, Željko; Jacobson, Heather R.; Jiang, Linhua; Johansson,
Jonas; Johnson, Jennifer A.; Kauffmann, Guinevere; Kirkby, David;
Kirkpatrick, Jessica A.; Klaene, Mark A.; Knapp, Gillian R.; Kneib,
Jean-Paul; Le Goff, Jean-Marc; Leauthaud, Alexie; Lee, Khee-Gan;
Lee, Young Sun; Long, Daniel C.; Loomis, Craig P.; Lucatello, Sara;
Lundgren, Britt; Lupton, Robert H.; Ma, Bo; Ma, Zhibo; MacDonald,
Nicholas; Mack, Claude E.; Mahadevan, Suvrath; Maia, Marcio A. G.;
Majewski, Steven R.; Makler, Martin; Malanushenko, Elena; Malanushenko,
Viktor; Manchado, A.; Mandelbaum, Rachel; Manera, Marc; Maraston,
Claudia; Margala, Daniel; Martell, Sarah L.; McBride, Cameron K.;
McGreer, Ian D.; McMahon, Richard G.; Ménard, Brice; Meszaros,
Sz.; Miralda-Escudé, Jordi; Montero-Dorta, Antonio D.; Montesano,
Francesco; Morrison, Heather L.; Muna, Demitri; Munn, Jeffrey A.;
Murayama, Hitoshi; Myers, Adam D.; Neto, A. F.; Nguyen, Duy Cuong;
Nichol, Robert C.; Nidever, David L.; Noterdaeme, Pasquier; Nuza,
Sebastián E.; Ogando, Ricardo L. C.; Olmstead, Matthew D.; Oravetz,
Daniel J.; Owen, Russell; Padmanabhan, Nikhil; Palanque-Delabrouille,
Nathalie; Pan, Kaike; Parejko, John K.; Parihar, Prachi; Pâris,
Isabelle; Pattarakijwanich, Petchara; Pepper, Joshua; Percival,
Will J.; Pérez-Fournon, Ismael; Pérez-Ràfols, Ignasi; Petitjean,
Patrick; Pforr, Janine; Pieri, Matthew M.; Pinsonneault, Marc H.;
Porto de Mello, G. F.; Prada, Francisco; Price-Whelan, Adrian M.;
Raddick, M. Jordan; Rebolo, Rafael; Rich, James; Richards, Gordon
T.; Robin, Annie C.; Rocha-Pinto, Helio J.; Rockosi, Constance M.;
Roe, Natalie A.; Ross, Ashley J.; Ross, Nicholas P.; Rossi, Graziano;
Rubiño-Martin, J. A.; Samushia, Lado; Sanchez Almeida, J.; Sánchez,
Ariel G.; Santiago, Basílio; Sayres, Conor; Schlegel, David J.;
Schlesinger, Katharine J.; Schmidt, Sarah J.; Schneider, Donald P.;
Schultheis, Mathias; Schwope, Axel D.; Scóccola, C. G.; Seljak,
Uros; Sheldon, Erin; Shen, Yue; Shu, Yiping; Simmerer, Jennifer;
Simmons, Audrey E.; Skibba, Ramin A.; Skrutskie, M. F.; Slosar, A.;
Sobreira, Flavia; Sobeck, Jennifer S.; Stassun, Keivan G.; Steele,
Oliver; Steinmetz, Matthias; Strauss, Michael A.; Streblyanska, Alina;
Suzuki, Nao; Swanson, Molly E. C.; Tal, Tomer; Thakar, Aniruddha R.;
Thomas, Daniel; Thompson, Benjamin A.; Tinker, Jeremy L.; Tojeiro,
Rita; Tremonti, Christy A.; Vargas Magaña, M.; Verde, Licia; Viel,
Matteo; Vikas, Shailendra K.; Vogt, Nicole P.; Wake, David A.; Wang,
Ji; Weaver, Benjamin A.; Weinberg, David H.; Weiner, Benjamin J.;
West, Andrew A.; White, Martin; Wilson, John C.; Wisniewski, John P.;
Wood-Vasey, W. M.; Yanny, Brian; Yèche, Christophe; York, Donald G.;
Zamora, O.; Zasowski, Gail; Zehavi, Idit; Zhao, Gong-Bo; Zheng, Zheng;
Zhu, Guangtun; Zinn, Joel C.
2012ApJS..203...21A Altcode: 2012arXiv1207.7137S
The Sloan Digital Sky Survey III (SDSS-III) presents the first
spectroscopic data from the Baryon Oscillation Spectroscopic Survey
(BOSS). This ninth data release (DR9) of the SDSS project includes
535,995 new galaxy spectra (median z ~ 0.52), 102,100 new quasar
spectra (median z ~ 2.32), and 90,897 new stellar spectra, along
with the data presented in previous data releases. These spectra were
obtained with the new BOSS spectrograph and were taken between 2009
December and 2011 July. In addition, the stellar parameters pipeline,
which determines radial velocities, surface temperatures, surface
gravities, and metallicities of stars, has been updated and refined with
improvements in temperature estimates for stars with T <SUB>eff</SUB>
< 5000 K and in metallicity estimates for stars with [Fe/H] >
-0.5. DR9 includes new stellar parameters for all stars presented in
DR8, including stars from SDSS-I and II, as well as those observed as
part of the SEGUE-2. The astrometry error introduced in the DR8 imaging
catalogs has been corrected in the DR9 data products. The next data
release for SDSS-III will be in Summer 2013, which will present the
first data from the APOGEE along with another year of data from BOSS,
followed by the final SDSS-III data release in 2014 December.
---------------------------------------------------------
Title: VizieR Online Data Catalog: Model 1D (LHD) and 3D (CO5BOLD)
spectra (Allende Prieto+, 2013)
Authors: Allende Prieto, C.; Koesterke, L. Ludwig H. -G.; Freytag,
B.; Caffau, E.
2012yCat..35500103A Altcode: 2012yCat..35509103A
Model spectral fluxes for late-type stars computed from 3D
hydrodynamical simulations of surface convection performed with the
CO5BOLD code. Their 1D hydrostatic counterparts are included, based on
the LHD code, sharing the same microphysics as the CO5BOLD models. The
fluxes for both the 3D and 1D models are calculated with the same
opacities and radiative transfer code (ASSET). <P />(6 data files).
---------------------------------------------------------
Title: The Milky Way's Circular-velocity Curve between 4 and 14 kpc
from APOGEE data
Authors: Bovy, Jo; Allende Prieto, Carlos; Beers, Timothy C.;
Bizyaev, Dmitry; da Costa, Luiz N.; Cunha, Katia; Ebelke, Garrett L.;
Eisenstein, Daniel J.; Frinchaboy, Peter M.; García Pérez, Ana Elia;
Girardi, Léo; Hearty, Fred R.; Hogg, David W.; Holtzman, Jon; Maia,
Marcio A. G.; Majewski, Steven R.; Malanushenko, Elena; Malanushenko,
Viktor; Mészáros, Szabolcs; Nidever, David L.; O'Connell, Robert
W.; O'Donnell, Christine; Oravetz, Audrey; Pan, Kaike; Rocha-Pinto,
Helio J.; Schiavon, Ricardo P.; Schneider, Donald P.; Schultheis,
Mathias; Skrutskie, Michael; Smith, Verne V.; Weinberg, David H.;
Wilson, John C.; Zasowski, Gail
2012ApJ...759..131B Altcode: 2012arXiv1209.0759B
We measure the Milky Way's rotation curve over the Galactocentric
range 4 kpc <~ R <~ 14 kpc from the first year of data from
the Apache Point Observatory Galactic Evolution Experiment. We model
the line-of-sight velocities of 3365 stars in 14 fields with b =
0° between 30° <= l <= 210° out to distances of 10 kpc
using an axisymmetric kinematical model that includes a correction
for the asymmetric drift of the warm tracer population (σ<SUB> R
</SUB> ≈ 35 km s<SUP>-1</SUP>). We determine the local value of the
circular velocity to be V<SUB>c</SUB> (R <SUB>0</SUB>) = 218 ± 6 km
s<SUP>-1</SUP> and find that the rotation curve is approximately flat
with a local derivative between -3.0 km s<SUP>-1</SUP> kpc<SUP>-1</SUP>
and 0.4 km s<SUP>-1</SUP> kpc<SUP>-1</SUP>. We also measure the Sun's
position and velocity in the Galactocentric rest frame, finding the
distance to the Galactic center to be 8 kpc < R <SUB>0</SUB> < 9
kpc, radial velocity V <SUB> R, ⊙</SUB> = -10 ± 1 km s<SUP>-1</SUP>,
and rotational velocity V <SUB>phi, ⊙</SUB> = 242<SUP>+10</SUP> <SUB>-
3</SUB> km s<SUP>-1</SUP>, in good agreement with local measurements
of the Sun's radial velocity and with the observed proper motion of
Sgr A*. We investigate various systematic uncertainties and find that
these are limited to offsets at the percent level, ~2 km s<SUP>-1</SUP>
in V<SUB>c</SUB> . Marginalizing over all the systematics that we
consider, we find that V<SUB>c</SUB> (R <SUB>0</SUB>) < 235 km
s<SUP>-1</SUP> at >99 % confidence. We find an offset between the
Sun's rotational velocity and the local circular velocity of 26 ± 3
km s<SUP>-1</SUP>, which is larger than the locally measured solar
motion of 12 km s<SUP>-1</SUP>. This larger offset reconciles our
value for V<SUB>c</SUB> with recent claims that V<SUB>c</SUB> >~
240 km s<SUP>-1</SUP>. Combining our results with other data, we find
that the Milky Way's dark-halo mass within the virial radius is ~8 ×
10<SUP>11</SUP> M <SUB>⊙</SUB>.
---------------------------------------------------------
Title: EChO. Exoplanet characterisation observatory
Authors: Tinetti, G.; Beaulieu, J. P.; Henning, T.; Meyer, M.;
Micela, G.; Ribas, I.; Stam, D.; Swain, M.; Krause, O.; Ollivier,
M.; Pace, E.; Swinyard, B.; Aylward, A.; van Boekel, R.; Coradini,
A.; Encrenaz, T.; Snellen, I.; Zapatero-Osorio, M. R.; Bouwman, J.;
Cho, J. Y. -K.; Coudé de Foresto, V.; Guillot, T.; Lopez-Morales, M.;
Mueller-Wodarg, I.; Palle, E.; Selsis, F.; Sozzetti, A.; Ade, P. A. R.;
Achilleos, N.; Adriani, A.; Agnor, C. B.; Afonso, C.; Allende Prieto,
C.; Bakos, G.; Barber, R. J.; Barlow, M.; Batista, V.; Bernath, P.;
Bézard, B.; Bordé, P.; Brown, L. R.; Cassan, A.; Cavarroc, C.;
Ciaravella, A.; Cockell, C.; Coustenis, A.; Danielski, C.; Decin,
L.; De Kok, R.; Demangeon, O.; Deroo, P.; Doel, P.; Drossart, P.;
Fletcher, L. N.; Focardi, M.; Forget, F.; Fossey, S.; Fouqué, P.;
Frith, J.; Galand, M.; Gaulme, P.; González Hernández, J. I.;
Grasset, O.; Grassi, D.; Grenfell, J. L.; Griffin, M. J.; Griffith,
C. A.; Grözinger, U.; Guedel, M.; Guio, P.; Hainaut, O.; Hargreaves,
R.; Hauschildt, P. H.; Heng, K.; Heyrovsky, D.; Hueso, R.; Irwin, P.;
Kaltenegger, L.; Kervella, P.; Kipping, D.; Koskinen, T. T.; Kovács,
G.; La Barbera, A.; Lammer, H.; Lellouch, E.; Leto, G.; Lopez Morales,
M.; Lopez Valverde, M. A.; Lopez-Puertas, M.; Lovis, C.; Maggio, A.;
Maillard, J. P.; Maldonado Prado, J.; Marquette, J. B.; Martin-Torres,
F. J.; Maxted, P.; Miller, S.; Molinari, S.; Montes, D.; Moro-Martin,
A.; Moses, J. I.; Mousis, O.; Nguyen Tuong, N.; Nelson, R.; Orton,
G. S.; Pantin, E.; Pascale, E.; Pezzuto, S.; Pinfield, D.; Poretti,
E.; Prinja, R.; Prisinzano, L.; Rees, J. M.; Reiners, A.; Samuel,
B.; Sánchez-Lavega, A.; Forcada, J. Sanz; Sasselov, D.; Savini, G.;
Sicardy, B.; Smith, A.; Stixrude, L.; Strazzulla, G.; Tennyson, J.;
Tessenyi, M.; Vasisht, G.; Vinatier, S.; Viti, S.; Waldmann, I.;
White, G. J.; Widemann, T.; Wordsworth, R.; Yelle, R.; Yung, Y.;
Yurchenko, S. N.
2012ExA....34..311T Altcode: 2012ExA...tmp...35T; 2011arXiv1112.2728T
A dedicated mission to investigate exoplanetary atmospheres represents
a major milestone in our quest to understand our place in the
universe by placing our Solar System in context and by addressing the
suitability of planets for the presence of life. EChO—the Exoplanet
Characterisation Observatory—is a mission concept specifically geared
for this purpose. EChO will provide simultaneous, multi-wavelength
spectroscopic observations on a stable platform that will allow very
long exposures. The use of passive cooling, few moving parts and well
established technology gives a low-risk and potentially long-lived
mission. EChO will build on observations by Hubble, Spitzer and
ground-based telescopes, which discovered the first molecules and
atoms in exoplanetary atmospheres. However, EChO's configuration
and specifications are designed to study a number of systems in a
consistent manner that will eliminate the ambiguities affecting prior
observations. EChO will simultaneously observe a broad enough spectral
region—from the visible to the mid-infrared—to constrain from
one single spectrum the temperature structure of the atmosphere, the
abundances of the major carbon and oxygen bearing species, the expected
photochemically-produced species and magnetospheric signatures. The
spectral range and resolution are tailored to separate bands belonging
to up to 30 molecules and retrieve the composition and temperature
structure of planetary atmospheres. The target list for EChO includes
planets ranging from Jupiter-sized with equilibrium temperatures T
<SUB>eq</SUB> up to 2,000 K, to those of a few Earth masses, with
T <SUB>eq</SUB> u223c 300 K. The list will include planets with no
Solar System analog, such as the recently discovered planets GJ1214b,
whose density lies between that of terrestrial and gaseous planets,
or the rocky-iron planet 55 Cnc e, with day-side temperature close to
3,000 K. As the number of detected exoplanets is growing rapidly each
year, and the mass and radius of those detected steadily decreases, the
target list will be constantly adjusted to include the most interesting
systems. We have baselined a dispersive spectrograph design covering
continuously the 0.4-16 μm spectral range in 6 channels (1 in the
visible, 5 in the InfraRed), which allows the spectral resolution to
be adapted from several tens to several hundreds, depending on the
target brightness. The instrument will be mounted behind a 1.5 m class
telescope, passively cooled to 50 K, with the instrument structure and
optics passively cooled to u223c45 K. EChO will be placed in a grand
halo orbit around L2. This orbit, in combination with an optimised
thermal shield design, provides a highly stable thermal environment and
a high degree of visibility of the sky to observe repeatedly several
tens of targets over the year. Both the baseline and alternative
designs have been evaluated and no critical items with Technology
Readiness Level (TRL) less than 4-5 have been identified. We have also
undertaken a first-order cost and development plan analysis and find
that EChO is easily compatible with the ESA M-class mission framework.
---------------------------------------------------------
Title: New ATLAS9 and MARCS Model Atmosphere Grids for the Apache
Point Observatory Galactic Evolution Experiment (APOGEE)
Authors: Mészáros, Sz.; Allende Prieto, C.; Edvardsson, B.; Castelli,
F.; García Pérez, A. E.; Gustafsson, B.; Majewski, S. R.; Plez,
B.; Schiavon, R.; Shetrone, M.; de Vicente, A.
2012AJ....144..120M Altcode: 2012arXiv1208.1916M
We present a new grid of model photospheres for the SDSS-III/APOGEE
survey of stellar populations of the Galaxy, calculated using the
ATLAS9 and MARCS codes. New opacity distribution functions were
generated to calculate ATLAS9 model photospheres. MARCS models were
calculated based on opacity sampling techniques. The metallicity
([M/H]) spans from -5 to 1.5 for ATLAS and -2.5 to 0.5 for MARCS
models. There are three main differences with respect to previous
ATLAS9 model grids: a new corrected H<SUB>2</SUB>O line list, a wide
range of carbon ([C/M]) and α element [α/M] variations, and solar
reference abundances from Asplund et al. The added range of varying
carbon and α-element abundances also extends the previously calculated
MARCS model grids. Altogether, 1980 chemical compositions were used for
the ATLAS9 grid and 175 for the MARCS grid. Over 808,000 ATLAS9 models
were computed spanning temperatures from 3500 K to 30,000 K and log g
from 0 to 5, where larger temperatures only have high gravities. The
MARCS models span from 3500 K to 5500 K, and log g from 0 to 5. All
model atmospheres are publicly available online.
---------------------------------------------------------
Title: Rapid Orbital Decay in the 12.75-minute Binary White Dwarf
J0651+2844
Authors: Hermes, J. J.; Kilic, Mukremin; Brown, Warren R.; Winget,
D. E.; Allende Prieto, Carlos; Gianninas, A.; Mukadam, Anjum S.;
Cabrera-Lavers, Antonio; Kenyon, Scott J.
2012ApJ...757L..21H Altcode: 2012arXiv1208.5051H
We report the detection of orbital decay in the 12.75-minute,
detached binary white dwarf (WD) SDSS J065133.338+284423.37 (hereafter
J0651). Our photometric observations over a 13 month baseline constrain
the orbital period to 765.206543(55) s and indicate that the orbit
is decreasing at a rate of (- 9.8 ± 2.8) × 10<SUP>-12</SUP> s
s<SUP>-1</SUP> (or -0.31 ± 0.09 ms yr<SUP>-1</SUP>). We revise the
system parameters based on our new photometric and spectroscopic
observations: J0651 contains two WDs with M <SUB>1</SUB> = 0.26
± 0.04 M <SUB>⊙</SUB> and M <SUB>2</SUB> = 0.50 ± 0.04 M
<SUB>⊙</SUB>. General relativity predicts orbital decay due to
gravitational wave radiation of (- 8.2 ± 1.7) × 10<SUP>-12</SUP>
s s<SUP>-1</SUP> (or -0.26 ± 0.05 ms yr<SUP>-1</SUP>). Our observed
rate of orbital decay is consistent with this expectation. J0651 is
currently the second-loudest gravitational wave source known in the
milli-Hertz range and the loudest non-interacting binary, which makes it
an excellent verification source for future missions aimed at directly
detecting gravitational waves. Our work establishes the feasibility
of monitoring this system's orbital period decay at optical wavelengths.
---------------------------------------------------------
Title: Very Low Mass Stellar and Substellar Companions to Solar-like
Stars from MARVELS. II. A Short-period Companion Orbiting an F Star
with Evidence of a Stellar Tertiary and Significant Mutual Inclination
Authors: Fleming, Scott W.; Ge, Jian; Barnes, Rory; Beatty, Thomas G.;
Crepp, Justin R.; De Lee, Nathan; Esposito, Massimiliano; Femenia,
Bruno; Ferreira, Leticia; Gary, Bruce; Gaudi, B. Scott; Ghezzi,
Luan; González Hernández, Jonay I.; Hebb, Leslie; Jiang, Peng;
Lee, Brian; Nelson, Ben; Porto de Mello, Gustavo F.; Shappee,
Benjamin J.; Stassun, Keivan; Thompson, Todd A.; Tofflemire,
Benjamin M.; Wisniewski, John P.; Wood-Vasey, W. Michael; Agol,
Eric; Allende Prieto, Carlos; Bizyaev, Dmitry; Brewington, Howard;
Cargile, Phillip A.; Coban, Louis; Costello, Korena S.; da Costa,
Luis N.; Good, Melanie L.; Hua, Nelson; Kane, Stephen R.; Lander,
Gary R.; Liu, Jian; Ma, Bo; Mahadevan, Suvrath; Maia, Marcio A. G.;
Malanushenko, Elena; Malanushenko, Viktor; Muna, Demitri; Nguyen, Duy
Cuong; Oravetz, Daniel; Paegert, Martin; Pan, Kaike; Pepper, Joshua;
Rebolo, Rafael; Roebuck, Eric J.; Santiago, Basilio X.; Schneider,
Donald P.; Shelden, Alaina; Simmons, Audrey; Sivarani, Thirupathi;
Snedden, Stephanie; Vincent, Chelsea L. M.; Wan, Xiaoke; Wang, Ji;
Weaver, Benjamin A.; Weaver, Gwendolyn M.; Zhao, Bo
2012AJ....144...72F Altcode: 2012arXiv1206.5514F
We report the discovery via radial velocity (RV) measurements of
a short-period (P = 2.430420 ± 0.000006 days) companion to the
F-type main-sequence star TYC 2930-00872-1. A long-term trend in the
RV data also suggests the presence of a tertiary stellar companion
with P > 2000 days. High-resolution spectroscopy of the host star
yields T <SUB>eff</SUB> = 6427 ± 33 K, log g = 4.52 ± 0.14, and
[Fe/H] = -0.04 ± 0.05. These parameters, combined with the broadband
spectral energy distribution (SED) and a parallax, allow us to infer
a mass and radius of the host star of M <SUB>1</SUB> = 1.21 ± 0.08
M <SUB>⊙</SUB> and R <SUB>1</SUB> = 1.09<SUP>+0.15</SUP> <SUB>-
0.13</SUB> R <SUB>⊙</SUB>. The minimum mass of the inner companion is
below the hydrogen-burning limit; however, the true mass is likely to
be substantially higher. We are able to exclude transits of the inner
companion with high confidence. Further, the host star spectrum exhibits
a clear signature of Ca H and K core emission, indicating stellar
activity, but a lack of photometric variability and small vsin I suggest
that the primary's spin axis is oriented in a pole-on configuration. The
rotational period of the primary estimated through an activity-rotation
relation matches the orbital period of the inner companion to within
1.5 σ, suggesting that the primary and inner companion are tidally
locked. If the inner companion's orbital angular momentum vector is
aligned with the stellar spin axis as expected through tidal evolution,
then it has a stellar mass of ~0.3-0.4 M <SUB>⊙</SUB>. Direct imaging
limits the existence of stellar companions to projected separations
<30 AU. No set of spectral lines and no significant flux contribution
to the SED from either companion are detected, which places individual
upper mass limits of M <SUB>{2, 3}</SUB> <~ 1.0 M <SUB>⊙</SUB>,
provided they are not stellar remnants. If the tertiary is not a stellar
remnant, then it likely has a mass of ~0.5-0.6 M <SUB>⊙</SUB>, and
its orbit is likely significantly inclined from that of the secondary,
suggesting that the Kozai-Lidov mechanism may have driven the dynamical
evolution of this system.
---------------------------------------------------------
Title: Performance of the Apache Point Observatory Galactic Evolution
Experiment (APOGEE) high-resolution near-infrared multi-object
fiber spectrograph
Authors: Wilson, John C.; Hearty, F.; Skrutskie, M. F.; Majewski,
S. R.; Schiavon, R.; Eisenstein, D.; Gunn, J.; Holtzman, J.; Nidever,
D.; Gillespie, B.; Weinberg, D.; Blank, B.; Henderson, C.; Smee,
S.; Barkhouser, R.; Harding, A.; Hope, S.; Fitzgerald, G.; Stolberg,
T.; Arns, J.; Nelson, M.; Brunner, S.; Burton, A.; Walker, E.; Lam,
C.; Maseman, P.; Barr, J.; Leger, F.; Carey, L.; MacDonald, N.;
Ebelke, G.; Beland, S.; Horne, T.; Young, E.; Rieke, G.; Rieke, M.;
O'Brien, T.; Crane, J.; Carr, M.; Harrison, C.; Stoll, R.; Vernieri,
M.; Shetrone, M.; Allende-Prieto, C.; Johnson, J.; Frinchaboy, P.;
Zasowski, G.; Garcia Perez, A.; Bizyaev, D.; Cunha, K.; Smith, V. V.;
Meszaros, Sz.; Zhao, B.; Hayden, M.; Chojnowski, S. D.; Andrews, B.;
Loomis, C.; Owen, R.; Klaene, M.; Brinkmann, J.; Stauffer, F.; Long,
D.; Jordan, W.; Holder, D.; Cope, F.; Naugle, T.; Pfaffenberger, B.;
Schlegel, D.; Blanton, M.; Muna, D.; Weaver, B.; Snedden, S.; Pan,
K.; Brewington, H.; Malanushenko, E.; Malanushenko, V.; Simmons, A.;
Oravetz, D.; Mahadevan, S.; Halverson, S.
2012SPIE.8446E..0HW Altcode:
The Apache Point Observatory Galactic Evolution Experiment (APOGEE) uses
a dedicated 300-fiber, narrow-band near-infrared (1.51-1.7 μm), high
resolution (R~22,500) spectrograph to survey approximately 100,000 giant
stars across the Milky Way. This three-year survey, in operation since
late-summer 2011 as part of the Sloan Digital Sky Survey III (SDSS III),
will revolutionize our understanding of the kinematical and chemical
enrichment histories of all Galactic stellar populations. We present
the performance of the instrument from its first year in operation. The
instrument is housed in a separate building adjacent to the 2.5-m SDSS
telescope and fed light via approximately 45-meter fiber runs from
the telescope. The instrument design includes numerous innovations
including a gang connector that allows simultaneous connection of all
fibers with a single plug to a telescope cartridge that positions
the fibers on the sky, numerous places in the fiber train in which
focal ratio degradation had to be minimized, a large mosaic-VPH (290
mm x 475 mm elliptically-shaped recorded area), an f/1.4 six-element
refractive camera featuring silicon and fused silica elements with
diameters as large as 393 mm, three near-infrared detectors mounted
in a 1 x 3 mosaic with sub-pixel translation capability, and all of
these components housed within a custom, LN2-cooled, stainless steel
vacuum cryostat with dimensions 1.4-m x 2.3-m x 1.3-m.
---------------------------------------------------------
Title: Lithium Abundances in nearby FGK Dwarf and Subgiant Stars:
Internal Destruction, Galactic Chemical Evolution, and Exoplanets
Authors: Ramírez, I.; Fish, J. R.; Lambert, D. L.; Allende Prieto, C.
2012ApJ...756...46R Altcode: 2012arXiv1207.0499R
We derive atmospheric parameters and lithium abundances for 671
stars and include our measurements in a literature compilation of
1381 dwarf and subgiant stars. First, a "lithium desert" in the
effective temperature (T <SUB>eff</SUB>) versus lithium abundance
(A <SUB>Li</SUB>) plane is observed such that no stars with T
<SUB>eff</SUB> ~= 6075 K and A <SUB>Li</SUB> ~= 1.8 are found. We
speculate that most of the stars on the low A <SUB>Li</SUB> side of
the desert have experienced a short-lived period of severe surface
lithium destruction as main-sequence or subgiant stars. Next, we search
for differences in the lithium content of thin-disk and thick-disk
stars, but we find that internal processes have erased from the
stellar photospheres their possibly different histories of lithium
enrichment. Nevertheless, we note that the maximum lithium abundance
of thick-disk stars is nearly constant from [Fe/H] = -1.0 to -0.1,
at a value that is similar to that measured in very metal-poor halo
stars (A <SUB>Li</SUB> ~= 2.2). Finally, differences in the lithium
abundance distribution of known planet-host stars relative to otherwise
ordinary stars appear when restricting the samples to narrow ranges
of T <SUB>eff</SUB> or mass, but they are fully explained by age
and metallicity biases. We confirm the lack of a connection between
low lithium abundance and planets. However, we find that no low A
<SUB>Li</SUB> planet-hosts are found in the desert T <SUB>eff</SUB>
window. Provided that subtle sample biases are not responsible for
this observation, this suggests that the presence of gas giant planets
inhibit the mechanism responsible for the lithium desert.
---------------------------------------------------------
Title: The Apache Point Observatory Galactic Evolution Experiment:
First Detection of High-velocity Milky Way Bar Stars
Authors: Nidever, David L.; Zasowski, Gail; Majewski, Steven R.;
Bird, Jonathan; Robin, Annie C.; Martinez-Valpuesta, Inma; Beaton,
Rachael L.; Schönrich, Ralph; Schultheis, Mathias; Wilson, John
C.; Skrutskie, Michael F.; O'Connell, Robert W.; Shetrone, Matthew;
Schiavon, Ricardo P.; Johnson, Jennifer A.; Weiner, Benjamin; Gerhard,
Ortwin; Schneider, Donald P.; Allende Prieto, Carlos; Sellgren, Kris;
Bizyaev, Dmitry; Brewington, Howard; Brinkmann, Jon; Eisenstein,
Daniel J.; Frinchaboy, Peter M.; García Pérez, Ana Elia; Holtzman,
Jon; Hearty, Fred R.; Malanushenko, Elena; Malanushenko, Viktor;
Muna, Demitri; Oravetz, Daniel; Pan, Kaike; Simmons, Audrey; Snedden,
Stephanie; Weaver, Benjamin A.
2012ApJ...755L..25N Altcode: 2012arXiv1207.3797N
Commissioning observations with the Apache Point Observatory Galactic
Evolution Experiment (APOGEE), part of the Sloan Digital Sky Survey
III, have produced radial velocities (RVs) for ~4700 K/M-giant
stars in the Milky Way (MW) bulge. These high-resolution (R ~ 22,
500), high-S/N (>100 per resolution element), near-infrared (NIR;
1.51-1.70 μm) spectra provide accurate RVs (epsilon<SUB>V</SUB> ~
0.2 km s<SUP>-1</SUP>) for the sample of stars in 18 Galactic bulge
fields spanning -1° <l < 20°, |b| < 20°, and δ >
-32°. This represents the largest NIR high-resolution spectroscopic
sample of giant stars ever assembled in this region of the Galaxy. A
cold (σ<SUB>V</SUB> ~ 30 km s<SUP>-1</SUP>), high-velocity peak
(V <SUB>GSR</SUB> ≈ +200 km s<SUP>-1</SUP>) is found to comprise a
significant fraction (~10%) of stars in many of these fields. These
high RVs have not been detected in previous MW surveys and are not
expected for a simple, circularly rotating disk. Preliminary distance
estimates rule out an origin from the background Sagittarius tidal
stream or a new stream in the MW disk. Comparison to various Galactic
models suggests that these high RVs are best explained by stars in
orbits of the Galactic bar potential, although some observational
features remain unexplained.
---------------------------------------------------------
Title: An empirical spectral library of chemically well characterized
stars for stellar population modelling
Authors: de Castro Milone, André; Sansom, Anne E.; Sánchez-Blázquez,
Patricia; Vazdekis, Alexandre; Falcón-Barroso, Jesus; Allende Prieto,
Carlos
2012IAUS..284...29D Altcode:
With the goal of assembling a new generation of more realistic
single stellar population (SSP) models, we have obtained magnesium
abundances for nearly 80% of the stars of the widely employed MILES
empirical spectral library. Additional spectroscopic observations
of carefully selected stars have recently been obtained to improve
the parametric coverage of this library. Here we report on: (i) the
framework of Mg abundance determination carried out at mid-resolution,
(ii) the newly acquired data, and (iii) the preliminary steps towards
modelling stellar populations.
---------------------------------------------------------
Title: The ELM Survey. IV. 24 White Dwarf Merger Systems
Authors: Kilic, Mukremin; Brown, Warren R.; Allende Prieto, Carlos;
Kenyon, S. J.; Heinke, Craig O.; Agüeros, M. A.; Kleinman, S. J.
2012ApJ...751..141K Altcode: 2012arXiv1204.0028K
We present new radial velocity and X-ray observations of extremely
low mass (ELM, ~0.2 M <SUB>⊙</SUB>) white dwarf (WD) candidates in
the Sloan Digital Sky Survey Data Release 7 area. We identify seven
new binary systems with 1-18 hr orbital periods. Five of the systems
will merge due to gravitational wave radiation within 10 Gyr, bringing
the total number of merger systems found in the ELM Survey to 24. The
ELM Survey has now quintupled the known merger WD population. It has
also discovered the eight shortest period detached binary WD systems
currently known. We discuss the characteristics of the merger and
non-merger systems observed in the ELM Survey, including their future
evolution. About half of the systems have extreme mass ratios. These
are the progenitors of the AM Canum Venaticorum systems and Type Ia
supernovae. The remaining targets will lead to the formation of extreme
helium stars, subdwarfs, or massive WDs. We identify three targets that
are excellent gravitational wave sources. These should be detected by
the Laser Interferometer Space Antenna like missions within the first
year of operation. The remaining targets are important indicators
of what the Galactic foreground may look like for gravitational
wave observatories. <P />Based on observations obtained at the MMT
Observatory, a joint facility of the Smithsonian Institution and the
University of Arizona.
---------------------------------------------------------
Title: Very Low Mass Stellar and Substellar Companions to Solar-like
Stars from MARVELS. I. A Low-mass Ratio Stellar Companion to TYC
4110-01037-1 in a 79 Day Orbit
Authors: Wisniewski, John P.; Ge, Jian; Crepp, Justin R.; De Lee,
Nathan; Eastman, Jason; Esposito, Massimiliano; Fleming, Scott W.;
Gaudi, B. Scott; Ghezzi, Luan; Gonzalez Hernandez, Jonay I.; Lee,
Brian L.; Stassun, Keivan G.; Agol, Eric; Allende Prieto, Carlos;
Barnes, Rory; Bizyaev, Dmitry; Cargile, Phillip; Chang, Liang; Da
Costa, Luiz N.; Porto De Mello, G. F.; Femenía, Bruno; Ferreira,
Leticia D.; Gary, Bruce; Hebb, Leslie; Holtzman, Jon; Liu, Jian;
Ma, Bo; Mack, Claude E.; Mahadevan, Suvrath; Maia, Marcio A. G.;
Nguyen, Duy Cuong; Ogando, Ricardo L. C.; Oravetz, Daniel J.; Paegert,
Martin; Pan, Kaike; Pepper, Joshua; Rebolo, Rafael; Santiago, Basilio;
Schneider, Donald P.; Shelden, Alaina C.; Simmons, Audrey; Tofflemire,
Benjamin M.; Wan, Xiaoke; Wang, Ji; Zhao, Bo
2012AJ....143..107W Altcode: 2012arXiv1202.4964W
TYC 4110-01037-1 has a low-mass stellar companion, whose small mass
ratio and short orbital period are atypical among binary systems
with solar-like (T <SUB>eff</SUB> <~ 6000 K) primary stars. Our
analysis of TYC 4110-01037-1 reveals it to be a moderately aged (lsim5
Gyr) solar-like star having a mass of 1.07 ± 0.08 M <SUB>⊙</SUB>
and radius of 0.99 ± 0.18 R <SUB>⊙</SUB>. We analyze 32 radial
velocity (RV) measurements from the SDSS-III MARVELS survey as well
as 6 supporting RV measurements from the SARG spectrograph on the
3.6 m Telescopio Nazionale Galileo telescope obtained over a period
of ~2 years. The best Keplerian orbital fit parameters were found
to have a period of 78.994 ± 0.012 days, an eccentricity of 0.1095
± 0.0023, and a semi-amplitude of 4199 ± 11 m s<SUP>-1</SUP>. We
determine the minimum companion mass (if sin i = 1) to be 97.7 ±
5.8 M <SUB>Jup</SUB>. The system's companion to host star mass ratio,
>=0.087 ± 0.003, places it at the lowest end of observed values for
short period stellar companions to solar-like (T <SUB>eff</SUB> <~
6000 K) stars. One possible way to create such a system would be if a
triple-component stellar multiple broke up into a short period, low q
binary during the cluster dispersal phase of its lifetime. A candidate
tertiary body has been identified in the system via single-epoch,
high contrast imagery. If this object is confirmed to be comoving,
we estimate it would be a dM4 star. We present these results in the
context of our larger-scale effort to constrain the statistics of
low-mass stellar and brown dwarf companions to FGK-type stars via the
MARVELS survey.
---------------------------------------------------------
Title: Insight into the Formation of the Milky Way through Cold Halo
Substructure. III. Statistical Chemical Tagging in the Smooth Halo
Authors: Schlaufman, Kevin C.; Rockosi, Constance M.; Lee, Young Sun;
Beers, Timothy C.; Allende Prieto, Carlos; Rashkov, Valery; Madau,
Piero; Bizyaev, Dmitry
2012ApJ...749...77S Altcode: 2012arXiv1202.2360S
We find that the relative contribution of satellite galaxies accreted
at high redshift to the stellar population of the Milky Way's smooth
halo increases with distance, becoming observable relative to the
classical smooth halo about 15 kpc from the Galactic center. In
particular, we determine line-of-sight-averaged [Fe/H] and [α/Fe]
in the metal-poor main-sequence turnoff (MPMSTO) population along
every Sloan Extension for Galactic Understanding and Exploration
(SEGUE) spectroscopic line of sight. Restricting our sample to those
lines of sight along which we do not detect elements of cold halo
substructure (ECHOS), we compile the largest spectroscopic sample of
stars in the smooth component of the halo ever observed in situ beyond
10 kpc. We find significant spatial autocorrelation in [Fe/H] in the
MPMSTO population in the distant half of our sample beyond about 15
kpc from the Galactic center. Inside of 15 kpc however, we find no
significant spatial autocorrelation in [Fe/H]. At the same time,
we perform SEGUE-like observations of N-body simulations of Milky
Way analog formation. While we find that halos formed entirely by
accreted satellite galaxies provide a poor match to our observations
of the halo within 15 kpc of the Galactic center, we do observe spatial
autocorrelation in [Fe/H] in the simulations at larger distances. This
observation is an example of statistical chemical tagging and indicates
that spatial autocorrelation in metallicity is a generic feature of
stellar halos formed from accreted satellite galaxies.
---------------------------------------------------------
Title: The Gaia-ESO Public Spectroscopic Survey
Authors: Gilmore, G.; Randich, S.; Asplund, M.; Binney, J.; Bonifacio,
P.; Drew, J.; Feltzing, S.; Ferguson, A.; Jeffries, R.; Micela, G.;
Negueruela, I.; Prusti, T.; Rix, H. -W.; Vallenari, A.; Alfaro, E.;
Allende-Prieto, C.; Babusiaux, C.; Bensby, T.; Blomme, R.; Bragaglia,
A.; Flaccomio, E.; François, P.; Irwin, M.; Koposov, S.; Korn, A.;
Lanzafame, A.; Pancino, E.; Paunzen, E.; Recio-Blanco, A.; Sacco,
G.; Smiljanic, R.; Van Eck, S.; Walton, N.; Aden, D.; Aerts, C.;
Affer, L.; Alcala, J. -M.; Altavilla, G.; Alves, J.; Antoja, T.;
Arenou, F.; Argiroffi, C.; Asensio Ramos, A.; Bailer-Jones, C.;
Balaguer-Nunez, L.; Bayo, A.; Barbuy, B.; Barisevicius, G.; Barrado
y Navascues, D.; Battistini, C.; Bellas Velidis, I.; Bellazzini, M.;
Belokurov, V.; Bergemann, M.; Bertelli, G.; Biazzo, K.; Bienayme, O.;
Bland-Hawthorn, J.; Boeche, C.; Bonito, S.; Boudreault, S.; Bouvier,
J.; Brandao, I.; Brown, A.; de Bruijne, J.; Burleigh, M.; Caballero,
J.; Caffau, E.; Calura, F.; Capuzzo-Dolcetta, R.; Caramazza, M.;
Carraro, G.; Casagrande, L.; Casewell, S.; Chapman, S.; Chiappini,
C.; Chorniy, Y.; Christlieb, N.; Cignoni, M.; Cocozza, G.; Colless,
M.; Collet, R.; Collins, M.; Correnti, M.; Covino, E.; Crnojevic,
D.; Cropper, M.; Cunha, M.; Damiani, F.; David, M.; Delgado, A.;
Duffau, S.; Edvardsson, B.; Eldridge, J.; Enke, H.; Eriksson, K.;
Evans, N. W.; Eyer, L.; Famaey, B.; Fellhauer, M.; Ferreras, I.;
Figueras, F.; Fiorentino, G.; Flynn, C.; Folha, D.; Franciosini,
E.; Frasca, A.; Freeman, K.; Fremat, Y.; Friel, E.; Gaensicke, B.;
Gameiro, J.; Garzon, F.; Geier, S.; Geisler, D.; Gerhard, O.; Gibson,
B.; Gomboc, A.; Gomez, A.; Gonzalez-Fernandez, C.; Gonzalez Hernandez,
J.; Gosset, E.; Grebel, E.; Greimel, R.; Groenewegen, M.; Grundahl,
F.; Guarcello, M.; Gustafsson, B.; Hadrava, P.; Hatzidimitriou, D.;
Hambly, N.; Hammersley, P.; Hansen, C.; Haywood, M.; Heber, U.; Heiter,
U.; Held, E.; Helmi, A.; Hensler, G.; Herrero, A.; Hill, V.; Hodgkin,
S.; Huelamo, N.; Huxor, A.; Ibata, R.; Jackson, R.; de Jong, R.;
Jonker, P.; Jordan, S.; Jordi, C.; Jorissen, A.; Katz, D.; Kawata,
D.; Keller, S.; Kharchenko, N.; Klement, R.; Klutsch, A.; Knude,
J.; Koch, A.; Kochukhov, O.; Kontizas, M.; Koubsky, P.; Lallement,
R.; de Laverny, P.; van Leeuwen, F.; Lemasle, B.; Lewis, G.; Lind,
K.; Lindstrom, H. P. E.; Lobel, A.; Lopez Santiago, J.; Lucas, P.;
Ludwig, H.; Lueftinger, T.; Magrini, L.; Maiz Apellaniz, J.; Maldonado,
J.; Marconi, G.; Marino, A.; Martayan, C.; Martinez-Valpuesta, I.;
Matijevic, G.; McMahon, R.; Messina, S.; Meyer, M.; Miglio, A.;
Mikolaitis, S.; Minchev, I.; Minniti, D.; Moitinho, A.; Momany, Y.;
Monaco, L.; Montalto, M.; Monteiro, M. J.; Monier, R.; Montes, D.;
Mora, A.; Moraux, E.; Morel, T.; Mowlavi, N.; Mucciarelli, A.; Munari,
U.; Napiwotzki, R.; Nardetto, N.; Naylor, T.; Naze, Y.; Nelemans, G.;
Okamoto, S.; Ortolani, S.; Pace, G.; Palla, F.; Palous, J.; Parker, R.;
Penarrubia, J.; Pillitteri, I.; Piotto, G.; Posbic, H.; Prisinzano,
L.; Puzeras, E.; Quirrenbach, A.; Ragaini, S.; Read, J.; Read, M.;
Reyle, C.; De Ridder, J.; Robichon, N.; Robin, A.; Roeser, S.; Romano,
D.; Royer, F.; Ruchti, G.; Ruzicka, A.; Ryan, S.; Ryde, N.; Santos,
N.; Sanz Forcada, J.; Sarro Baro, L. M.; Sbordone, L.; Schilbach, E.;
Schmeja, S.; Schnurr, O.; Schoenrich, R.; Scholz, R. -D.; Seabroke, G.;
Sharma, S.; De Silva, G.; Smith, M.; Solano, E.; Sordo, R.; Soubiran,
C.; Sousa, S.; Spagna, A.; Steffen, M.; Steinmetz, M.; Stelzer, B.;
Stempels, E.; Tabernero, H.; Tautvaisiene, G.; Thevenin, F.; Torra,
J.; Tosi, M.; Tolstoy, E.; Turon, C.; Walker, M.; Wambsganss, J.;
Worley, C.; Venn, K.; Vink, J.; Wyse, R.; Zaggia, S.; Zeilinger, W.;
Zoccali, M.; Zorec, J.; Zucker, D.; Zwitter, T.; Gaia-ESO Survey Team
2012Msngr.147...25G Altcode:
The Gaia-ESO Public Spectroscopic Survey has begun and will obtain high
quality spectroscopy of some 100000 Milky Way stars, in the field and
in open clusters, down to magnitude 19, systematically covering all the
major components of the Milky Way. This survey will provide the first
homogeneous overview of the distributions of kinematics and chemical
element abundances in the Galaxy. The motivation, organisation and
implementation of the Gaia-ESO Survey are described, emphasising the
complementarity with the ESA Gaia mission. Spectra from the very first
observing run of the survey are presented.
---------------------------------------------------------
Title: SDSS-III: Developments and Participation at the IAC
Authors: Allende Prieto, C.; Pérez Fournon, I.
2012iac..talk..369A Altcode: 2012iac..talk..287A
No abstract at ADS
---------------------------------------------------------
Title: HETDEX: A Magnitude-limited Spectroscopic Sample Of Stars In
The Galaxy Down To V 20
Authors: Allende-Prieto, Carlos; Shetrone, M.; Odewahn, S. C.;
Benedict, G.; Castanheira, B. G.; de Jong, R.; Lambert, D. L.;
MacQueen, P. J.; Marshall, J. L.; McArthur, B. E.; Sneden, C.;
HETDEX Collaboration
2012AAS...21942407A Altcode:
Spectroscopic surveys of stars in the Milky Way are growing rapidly in
size and scope, with the ambitious goals of unravelling the Galaxy's
formation and evolution, and finding out whether our galaxy fits
the current paradigm of hierarchical galaxy formation driven by cold
dark matter. These surveys follow target selection algorithms aimed
at extracting the most information out of a coarse sampling of the
stars in the Galaxy, and as result they are seriously biased. HETDEX
will be the first project to change that -- obtaining low-resolution
(R 750) spectra covering 350-550 nm that will render radial velocities
and overall metallicity for a flux-limited sample of > 100,000
stars down to V 20 over 60 square degrees. Questions that we hope to
address include: 1) the incidence of gross chemical peculiarities, 2)
the metallicity distributions of the main Galactic components, and 3)
the frequency of cold substructure over a range of scales. We show
simulated data and explore the performances of our preliminary data
analysis software.
---------------------------------------------------------
Title: Exploring The Sagittarius Dwarf Spheroidal Galaxy And Its
Tidal Tails With APOGEE
Authors: Majewski, Steven R.; Allende-Prieto, C.; Beers, T. C.;
Bizyaev, D. M.; Frinchaboy, P. M.; Garcia-Perez, A.; Holtzman, J.;
Ivans, I. I.; Law, D. R.; Nidever, D. L.; Schiavon, R. P.; Shetrone,
M.; Skrutskie, M. F.; Wilson, J. C.; Zasowski, G.
2012AAS...21941005M Altcode:
The Apache Point Observatory Galactic Evolution Experiment (APOGEE),
part of the Sloan Digital Sky Survey III, is exploring the stellar
populations of the Milky Way using the Sloan 2.5-m telescope
linked to a high resolution (R 22,500), near-infrared (1.51-1.68
microns) spectrograph with 300 optical fibers. For about 100,000,
predominantly red giant branch stars that APOGEE is targeting across
the Galactic bulge, disks and halo, the collected high S/N (>100 per
Nyquist-limit-sized pixel) spectra will provide accurate (+/-200 m/s)
radial velocities, stellar atmospheric parameters, and precise (+/-
0.1 dex) chemical abundances for about 15 chemical species. The APOGEE
survey targeting plan includes fields that have been specifically placed
on either the core or tails of the Sagittarius (Sgr) dSph galaxy. Some
of the target selection has relied on known or suspected giant star
members of Sgr identified in previous surveys. But other fields in the
path of the Sgr stream serendipitously uncover additional Sgr stars
through the normal APOGEE giant star targeting. We report on early
results from APOGEE commissioning data that include dozens of Sgr stars
spread over several distinct pointings on the Sgr core. In addition, we
report the discovery of Sgr stars found in several pointings directed at
the Galactic bulge and midplane. These data for Sgr stars lying behind
some of the dustiest parts of the Milky Way yield accurate velocities,
velocity dispersions and chemical information on stretches of the
Sagittarius stream never before explored. The results can be used to
refine models of the chemodynamical evolution of the Sgr system and
the shape of the gravitational potential of the Milky Way.
---------------------------------------------------------
Title: Stellar Cluster Abundances from APOGEE Commissioning Spectra
Authors: Shetrone, Matthew D.; Allende-Prieto, C.; Meszaros, Sz.;
Ivans, I.; Frinchaboy, P.; Bizyaev, D.; Schiavon, R.; Cunha, K.;
Smith, V.
2012AAS...21942803S Altcode:
The Apache Point Observatory Galactic Evolution Experiment (APOGEE)
will undertake an H-band (1.52-1.68 micron) spectroscopic survey of
1E5 red giant stars spanning the Galactic disk, bulge, and halo, with
typical limiting magnitude H 12.5. During the commissioning of APOGEE
a number of plates containing stellar clusters were observed. Some of
these star clusters are well-studied, such as M3, and others have few
literatureabundance references, such as NGC 5466. We exhibit sample
spectra from these clusters and give examples of the lines that can be
identified at different metallicities. Metallicities and abundances are
derived using a traditional equivalent width analysis with photometric
stellar parameters.
---------------------------------------------------------
Title: SDSS-III/APOGEE: Star Clusters From The APOGEE "First
Light” Field
Authors: Frinchaboy, Peter M.; Allende Prieto, C.; Beers, T. C.;
Bizyaev, D.; Holtzman, J.; Ivans, I.; Jackson, K. M.; Johnson, J. A.;
Majewski, S. R.; Nidever, D.; Garcia Perez, A.; Pinsonneault, M.;
Schiavon, R.; Shetrone, M.; Skrutskie, M.; Wilson, J. C.; Zasowski, G.
2012AAS...21942804F Altcode:
The Sloan Digital Sky Survey III/Apache Point Observatory Galactic
Evolution Experiment (SDSS-III/APOGEE) is a large-scale spectroscopic
survey of Galactic stars and star clusters. The SDSS-III/APOGEE
survey is designed to produce high-S/N, R = 22,500 spectra that cover
a wavelength range of 1.51 to 1.68 microns. By utilizing APOGEE's
excellent kinematics (velocity errors = 0.2 km/s) and abundances
(errors 0.1 dex). We can study star cluster kinematics and chemical
properties in detail. In this poster we present an analysis of 16
confirmed and candidate open clusters targeted in the APOGEE "first
light” field, in the constellation of Cygnus. The APOGEE data are
used to determine cluster membership and metallicities allowing for
improved or first determinations of basic cluster parameters (age,
chemistry, distance, reddening).
---------------------------------------------------------
Title: Apache Point Observatory Galactic Evolution Experiment
(APOGEE) Spectrograph
Authors: Wilson, John C.; Hearty, F.; Skrutskie, M. F.; Majewski,
S. R.; Schiavon, R.; Eisenstein, D.; Gunn, J.; Gillespie, B.; Weinberg,
D.; Blank, B.; Henderson, C.; Smee, S.; Barkhouser, R.; Harding,
A.; Hope, S.; Fitzgerald, G.; Stolberg, T.; Arns, J.; Nelson, M.;
Brunner, S.; Burton, A.; Walker, E.; Lam, C.; Maseman, P.; Barr, J.;
Leger, F.; Carey, L.; MacDonald, N.; Ebelke, G.; Beland, S.; Horne,
T.; Young, E.; Rieke, G.; Rieke, M.; O'Brien, T.; Crane, J.; Carr,
M.; Harrison, C.; Stoll, R.; Vernieri, M.; Holtzman, J.; Nidever,
D.; Shetrone, M.; Allende-Prieto, C.; Johnson, J.; Frinchaboy, P.;
Zasowski, G.; Garcia Perez, A.; Bizyaev, D.; Zhao, B.
2012AAS...21942802W Altcode:
The Apache Point Observatory Galactic Evolution Experiment (APOGEE)
will observe approximately 100,000 giant stars in the Milky Way with
a dedicated fiber-fed (300 fibers from the Sloan 2.5-m telescope)
near-infrared (1.5-1.7 micron) high resolution (R 22,500) spectrograph
as part of the Sloan Digital Sky Survey III (SDSS-III). By observing
in the near-infrared, APOGEE can uniformly sample all Milky Way
stellar populations (bulge, thin/thick disks and halo) in the same
survey to dramatically improve our understanding of the kinematical
and chemical enrichment history of our galaxy. The instrument design
includes several innovations: a novel fiber gang connector that allows
simultaneous optical connection of 300 fibers from the instrument into
swappable plug plate cartridges, the first deployed mosaic volume
phase holographic (VPH) grating, and a very large ( 0.4-m) aperture
six-element refractive camera incorporating crystalline silicon elements
to image 300 spectra onto three HAWAII-IIRG detectors simultaneously.
---------------------------------------------------------
Title: The ELM Survey. III. A Successful Targeted Survey for Extremely
Low Mass White Dwarfs
Authors: Brown, Warren R.; Kilic, Mukremin; Allende Prieto, Carlos;
Kenyon, Scott J.
2012ApJ...744..142B Altcode: 2011arXiv1111.6588B
Extremely low mass (ELM) white dwarfs (WDs) with masses < 0.25
M <SUB>⊙</SUB> are rare objects that result from compact binary
evolution. Here, we present a targeted spectroscopic survey of ELM
WD candidates selected by color. The survey is 71% complete and
has uncovered 18 new ELM WDs. Of the seven ELM WDs with follow-up
observations, six are short-period binaries and four have merger times
less than 5 Gyr. The most intriguing object, J1741+6526, likely has
either a pulsar companion or a massive WD companion making the system
a possible supernova Type Ia or an Ia progenitor. The overall ELM
survey has now identified 19 double degenerate binaries with <10 Gyr
merger times. The significant absence of short orbital period ELM WDs
at cool temperatures suggests that common envelope evolution creates
ELM WDs directly in short period systems. At least one-third of the
merging systems are halo objects, thus ELM WD binaries continue to form
and merge in both the disk and the halo. <P />Based on observations
obtained at the MMT Observatory, a joint facility of the Smithsonian
Institution and the University of Arizona.
---------------------------------------------------------
Title: VIRUS Parallel Observations with The Hobby-Eberly Telescope
Authors: Odewahn, Stephen C.; Drory, N.; Gebhardt, K.; de Jong, R.;
Allende Prieto, C.; Shetrone, M.; Tuttle, S.; HETDEX Collaboration
2012AAS...21942418O Altcode:
The VIRUS spectrograph will be installed on the upgraded Hobby-Eberly
Telescope (HET) in the Spring of 2012. This instrument will feature an
array of integral field units and will be used primarily to conduct a
survey for the HET Dark Energy Experiment (HETDEX). The VIRUS instrument
will be configured to allow parallel observations during the times when
the High-, Medium- and Low-Resolution Spectrographs are operating as
the primary instruments on HET. This parallel mode of observing will
be enabled long after HETDEX is completed and VIRUS becomes a service
instrument on HET. In an effort to explore various scientific uses for
such parallel data, we have taken the record of all HET observations
for the years 2003 through 2009 and estimated the sky coverage that
VIRUS parallel data would have provided. We have used the IFU footprint
of VIRUS as it is currently configured, and all observations with the
HET spectrographs that meet criteria such as length of exposure time,
sky brightness, galactic latitude; and positionally cross-matched these
data with various catalogs, such as USNOB2.0, to assess the number of
stars and galaxies that would have been detected in a VIRUS parallel
program. We review these results here and present plans for software
tools that will allow HET users to plan parallel programs.
---------------------------------------------------------
Title: SDSS-III/APOGEE: Main Survey and Star Cluster Target Selection
Authors: Jackson, Kelly; Zasowski, G.; Frinchaboy, P. M.; Johnson,
J. A.; Allende Prieto, C.; Beers, T. C.; Bizyaev, D.; Holtzman, J.;
Girardi, L.; Majewski, S. R.; Nidever, D.; Perez, A. G.; Pinto, H. R.;
Schiavon, R.; Shetrone, M.; Skrutskie, M.; Wilson, J. C.
2012AAS...21942801J Altcode:
The Sloan Digital Sky Survey III/Apache Point Observatory Galactic
Evolution Experiment (SDSS-III/APOGEE) is a high resolution H-band
(1.51-1.68 μ) spectroscopic survey covering all Galactic populations
within the Milky Way. During the survey's three-year lifetime,
we plan to target 100,000 Galactic stars, mostly red giants, from
within the disk, bulge, and halo. Target selection is primarily
based on near-infrared 2MASS data, and we use the RJCE method with
mid-infrared photometry from GLIMPSE and WISE to correct for the
effects of reddening and extinction. We also employ Washington+DDO51
photometry in selected fields to further reduce dwarf contamination
in the targeted sample. Open clusters falling serendipitously in the
targeted fields require a separate technique to most efficiently select
cluster candidate members, and we present the selection procedure used
for these targets.
---------------------------------------------------------
Title: Early APOGEE Chemical Results for the Milky Way Bulge
Authors: Garcia Perez, Ana Elia; Allende Prieto, C.; Bizyaev, D.;
Frinchaboy, P.; Holtzman, J.; Johnson, J.; Majewski, S. R.; Nidever,
D.; Schiavon, R.; Schultheis, M.; Shetrone, M. D.; Skrutskie, M.;
Wilson, J. C.; Zasowski, G.
2012AAS...21941004G Altcode: 2012AAS...21941004E
The stellar content of the bulge of the Galaxy is not well characterized
yet, in part due to the high extinction and, therefore, limited access
at optical wavelengths. The SDSS-III Apache Point Observatory Galaxy
Evolution Experiment (APOGEE) is an on-going near-infrared survey
acquiring very high quality spectra (S/N > 100 per pixel, R 22,500)
of 100,000 giant stars across the Galaxy. The APOGEE survey will enable
a detailed exploration of parts of the bulge that are not chemically
well known. We will show preliminary results of the composition of
bulge stars collected in the first months of the survey. Metallicity
distributions will be presented for different bulge fields and compared
with results from the literature, where available.
---------------------------------------------------------
Title: First APOGEE Results on Galactic Bulge Kinematics
Authors: Nidever, David L.; Allende Prieto, C.; Bizyaev, D.;
Frinchaboy, P. M.; Garcia Perez, A. E.; Holtzman, J.; Majewski, S. R.;
Schiavon, R.; Skrutskie, M. F.; Zasowski, G.
2012AAS...21941006N Altcode:
The SDSS-III Apache Point Observatory Galactic Evolution Experiment
(APOGEE) will obtain high resolution (R 22,500) and high S/N ( 100 per
pixel) H-band spectra of 100,000 giant stars in the Milky Way disk,
bulge and halo to study the chemical and kinematical evolution of
the Milky Way Galaxy. APOGEE will be able to probe deep into regions
of our galaxy that were previously hidden by a thick veil of dust. I
will present first APOGEE results on the Galactic bulge kinematics
using commissioning data in 18 fields. Our reduction pipeline currently
delivers radial velocites with accuracies of 0.2 km/s for the majority
of our target stars. These RVs are used to derive accurate rotation
curves and velocity dispersion profiles for our bulge fields, many of
them in regions not previously probed. We compare our results to other
surveys and to N-body models and confirm that the bulge is dominated
by a bar to large longitudes. We also find the first evidence for
kinematical substructure in our bulge fields.
---------------------------------------------------------
Title: Spectroscopic investigation of SDSS J100921.40 + 375233.9
selected from SDSS and GALEX photometry
Authors: Şahin, Timur; Lambert, David L.; Allende Prieto, Carlos
2012ASInC...6..265S Altcode: 2012arXiv1203.1461S; 2012ASInC...6..265C
In this study, we aim to reveal the nature of the Sloan Digital
Sky Survey (SDSS) star: SDSS J100921.40+375233.9, suspected to
have an extremely low metallicity We observed this star at high
spectral resolution and performed an abundance analysis. We derived
the spectroscopic parameters T_{eff} =5820±125 K, log g = 3.9±0.2,
and ξ_t = 1.1±0.5 km s^{-1}. The star is consistent with belonging
to the thick disk.
---------------------------------------------------------
Title: White Dwarf Stars in the HET Dark Energy Experiment
Authors: Castanheira, Barbara; Winget, D.; Gebhardt, K.; Allende
Prieto, C.; Shetrone, M.; Odewahn, S.; Montgomery, M. H.
2012AAS...21942408C Altcode:
In this poster, we present the project that will survey all white dwarf
stars observed in the Hobby-Eberly Telescope Dark Energy Experiment
(HETDEX) and the Visible Integral-field Replicable Unit Spectrograph
(VIRUS) observations in parallel mode. The final product will be a
unique magnitude-limited catalog of as many as 10,000 stars. Since we
will use data from an Integral-field Units, our survey will be free
of the selection biases that plagued preceding surveys, e.g. the Sloan
Digital Sky Survey (SDSS). The critical advantages of our program are
our ability to produce a white dwarf luminosity function five magnitudes
fainter than the one derived from the Palomar-Green survey and with
a similar number of faint stars as the one from SDSS. Our project
will help to derive a more precise age of the Galactic disk, and will
provide fundamental information about the white dwarf population and
the star formation history of the Milky Way, impacting the white dwarf
field and many other fields of astronomy.
---------------------------------------------------------
Title: Fundamental Parameters and Chemical Composition of Arcturus
Authors: Ramírez, I.; Allende Prieto, C.
2011ApJ...743..135R Altcode: 2011arXiv1109.4425R
We derive a self-consistent set of atmospheric parameters and abundances
of 17 elements for the red giant star Arcturus: T <SUB>eff</SUB> =
4286 ± 30 K, log g = 1.66 ± 0.05, and [Fe/H] = -0.52 ± 0.04. The
effective temperature was determined using model atmosphere fits
to the observed spectral energy distribution from the blue to the
mid-infrared (0.44 to 10 μm). The surface gravity was calculated using
the trigonometric parallax of the star and stellar evolution models. A
differential abundance analysis relative to the solar spectrum allowed
us to derive iron abundances from equivalent width measurements of
37 Fe I and 9 Fe II lines, unblended in the spectra of both Arcturus
and the Sun; the [Fe/H] value adopted is derived from Fe I lines. We
also determine the mass, radius, and age of Arcturus: M = 1.08 ±
0.06 M <SUB>⊙</SUB>, R = 25.4 ± 0.2 R <SUB>⊙</SUB>, and τ =
7.1<SUP>+1.5</SUP> <SUB>- 1.2</SUB> Gyr. Finally, abundances of the
following elements are measured from an equivalent width analysis of
atomic features: C, O, Na, Mg, Al, Si, K, Ca, Sc, Ti, V, Cr, Mn, Co,
Ni, and Zn. We find the chemical composition of Arcturus typical of
that of a local thick-disk star, consistent with its kinematics.
---------------------------------------------------------
Title: SDSS J163030.58+423305.8: a 40-min orbital period detached
white dwarf binary
Authors: Kilic, Mukremin; Brown, Warren R.; Hermes, J. J.; Allende
Prieto, Carlos; Kenyon, S. J.; Winget, D. E.; Winget, K. I.
2011MNRAS.418L.157K Altcode: 2011arXiv1109.6339K; 2011MNRAS.tmpL.352K
We report the discovery of a new detached, double white dwarf
(WD) system with an orbital period of 39.8 min. We targeted SDSS
J163030.58+423305.8 (hereafter J1630) as part of our radial velocity
programme to search for companions around low-mass WDs using the
6.5-m MMT. We detect peak-to-peak radial velocity variations of 576
km s<SUP>-1</SUP>. The mass function and optical photometry rule
out main-sequence companions. In addition, no millisecond pulsar
companions are detected in radio observations. Thus the invisible
companion is most likely another WD. Unlike the other 39-min
binary SDSS J010657.39-100003.3, follow-up high-speed photometric
observations of J1630 obtained at the McDonald 2.1-m telescope do
not show significant ellipsoidal variations, indicating a higher
primary mass and smaller radius. The absence of eclipses constrain
the inclination angle to i≤ 82°. J1630 contains a pair of WDs, 0.3
M<SUB>⊙</SUB> primary +≥0.3 M<SUB>⊙</SUB> invisible secondary,
at a separation of ≥0.32 R<SUB>⊙</SUB>. The two WDs will merge in
less than 31 Myr. Depending on the core composition of the companion,
the merger will form either a single core He-burning subdwarf star
or a rapidly rotating massive WD. The gravitational wave strain from
J1630 is detectable by instruments like the Laser Interferometer Space
Antenna (LISA) within the first year of operation. Based on observations
obtained at the MMT Observatory, a joint facility of the Smithsonian
Institution and the University of Arizona.
---------------------------------------------------------
Title: The science of EChO
Authors: Tinetti, Giovanna; Cho, James Y. -K.; Griffith, Caitlin A.;
Grasset, Olivier; Grenfell, Lee; Guillot, Tristan; Koskinen, Tommi T.;
Moses, Julianne I.; Pinfield, David; Tennyson, Jonathan; Tessenyi,
Marcell; Wordsworth, Robin; Aylward, Alan; van Boekel, Roy; Coradini,
Angioletta; Encrenaz, Therese; Snellen, Ignas; Zapatero-Osorio, Maria
R.; Bouwman, Jeroen; Coudé du Foresto, Vincent; Lopez-Morales,
Mercedes; Mueller-Wodarg, Ingo; Pallé, Enric; Selsis, Franck;
Sozzetti, Alessandro; Beaulieu, Jean-Philippe; Henning, Thomas; Meyer,
Michael; Micela, Giuseppina; Ribas, Ignasi; Stam, Daphne; Swain,
Mark; Krause, Oliver; Ollivier, Marc; Pace, Emanuele; Swinyard,
Bruce; Ade, Peter A. R.; Achilleos, Nick; Adriani, Alberto; Agnor,
Craig B.; Afonso, Cristina; Allende Prieto, Carlos; Bakos, Gaspar;
Barber, Robert J.; Barlow, Michael; Bernath, Peter; Bézard, Bruno;
Bordé, Pascal; Brown, Linda R.; Cassan, Arnaud; Cavarroc, Céline;
Ciaravella, Angela; Cockell, Charles; Coustenis, Athéna; Danielski,
Camilla; Decin, Leen; De Kok, Remco; Demangeon, Olivier; Deroo, Pieter;
Doel, Peter; Drossart, Pierre; Fletcher, Leigh N.; Focardi, Matteo;
Forget, Francois; Fossey, Steve; Fouqué, Pascal; Frith, James;
Galand, Marina; Gaulme, Patrick; González Hernández, Jonay I.;
Grassi, Davide; Griffin, Matt J.; Grözinger, Ulrich; Guedel, Manuel;
Guio, Pactrick; Hainaut, Olivier; Hargreaves, Robert; Hauschildt,
Peter H.; Heng, Kevin; Heyrovsky, David; Hueso, Ricardo; Irwin, Pat;
Kaltenegger, Lisa; Kervella, Patrick; Kipping, David; Kovacs, Geza; La
Barbera, Antonino; Lammer, Helmut; Lellouch, Emmanuel; Leto, Giuseppe;
Lopez Morales, Mercedes; Valverde, Lopez Miguel A.; Lopez-Puertas,
Manuel; Lovi, Christophe; Maggio, Antonio; Maillard, Jean-Pierre;
Prado, Jesus Maldonado; Marquette, Jean-Baptiste; Martin-Torres,
Francisco J.; Maxted, Pierre; Miller, Steve; Molinari, Sergio; Montes,
David; Moro-Martin, Amaya; Mousis, Olivier; Tuong, Napoléon Nguyen;
Nelson, Richard; Orton, Glenn S.; Pantin, Eric; Pascale, Enzo; Pezzuto,
Stefano; Poretti, Ennio; Prinja, Raman; Prisinzano, Loredana; Réess,
Jean-Michel; Reiners, Ansgar; Samuel, Benjamin; Sanz Forcada, Jorge;
Sasselov, Dimitar; Savini, Giorgio; Sicardy, Bruno; Smith, Alan;
Stixrude, Lars; Strazzulla, Giovanni; Vasisht, Gautam; Vinatier,
Sandrine; Viti, Serena; Waldmann, Ingo; White, Glenn J.; Widemann,
Thomas; Yelle, Roger; Yung, Yuk; Yurchenko, Sergey
2011IAUS..276..359T Altcode:
The science of extra-solar planets is one of the most rapidly
changing areas of astrophysics and since 1995 the number of
planets known has increased by almost two orders of magnitude. A
combination of ground-based surveys and dedicated space missions has
resulted in 560-plus planets being detected, and over 1200 that await
confirmation. NASA's Kepler mission has opened up the possibility of
discovering Earth-like planets in the habitable zone around some of the
100,000 stars it is surveying during its 3 to 4-year lifetime. The
new ESA's Gaia mission is expected to discover thousands of new
planets around stars within 200 parsecs of the Sun. The key challenge
now is moving on from discovery, important though that remains, to
characterisation: what are these planets actually like, and why are
they as they are? <P />In the past ten years, we have learned how to
obtain the first spectra of exoplanets using transit transmission and
emission spectroscopy. With the high stability of Spitzer, Hubble, and
large ground-based telescopes the spectra of bright close-in massive
planets can be obtained and species like water vapour, methane, carbon
monoxide and dioxide have been detected. With transit science came the
first tangible remote sensing of these planetary bodies and so one can
start to extrapolate from what has been learnt from Solar System probes
to what one might plan to learn about their faraway siblings. As we
learn more about the atmospheres, surfaces and near-surfaces of these
remote bodies, we will begin to build up a clearer picture of their
construction, history and suitability for life. <P />The Exoplanet
Characterisation Observatory, EChO, will be the first dedicated mission
to investigate the physics and chemistry of Exoplanetary Atmospheres. By
characterising spectroscopically more bodies in different environments
we will take detailed planetology out of the Solar System and into
the Galaxy as a whole. <P />EChO has now been selected by the European
Space Agency to be assessed as one of four M3 mission candidates.
---------------------------------------------------------
Title: V402 Lac, a mysterious eclipsing binary
Authors: Herrero, E.; Jordi, C.; Ribas, I.; Vilardell, F.;
Allende-Prieto, C.; Garcia-Melendo, E.; Naves, R.
2011hsa6.conf..532H Altcode:
Eclipsing binary (EB) systems showing double lines in their spectra
are excellent sources of knowledge about structure and evolution
of stars. The analysis of photometric and spectroscopic data in
such double systems provides very accurate values for the absolute
properties of both stars, as well as clues about their internal
structure, their formation process and the possible existence of
other bodies altering their motion. V402 Lac is a V=6.7 mag binary
system with two B9 type stars at a distance of 240 pc from the Sun,
classified as an Algol-type EB since Hipparcos observations. In our
work we are using light curves and radial velocity data in order to
obtain the parameters of the binary system through an analysis with the
Wilson-Devinney (WD) code. The first results, using independently the
two types of data, show a clear discrepancy in some orbital parameters,
which is also reproduced by new observations. Our study also revealed
the existence of apsidal movement in the system, and all the times
of minima are being used in order to characterize it through an O-C
diagram. We are dealing with a very interesting EB with no solution
for the moment. The photometric observations scheduled for late 2010
can be decisive to solve the orbit of the system and then be able to
obtain accurate values of the physical properties of the stars.
---------------------------------------------------------
Title: SDSS-III: Massive Spectroscopic Surveys of the Distant
Universe, the Milky Way, and Extra-Solar Planetary Systems
Authors: Eisenstein, Daniel J.; Weinberg, David H.; Agol, Eric; Aihara,
Hiroaki; Allende Prieto, Carlos; Anderson, Scott F.; Arns, James
A.; Aubourg, Éric; Bailey, Stephen; Balbinot, Eduardo; Barkhouser,
Robert; Beers, Timothy C.; Berlind, Andreas A.; Bickerton, Steven J.;
Bizyaev, Dmitry; Blanton, Michael R.; Bochanski, John J.; Bolton,
Adam S.; Bosman, Casey T.; Bovy, Jo; Brandt, W. N.; Breslauer, Ben;
Brewington, Howard J.; Brinkmann, J.; Brown, Peter J.; Brownstein,
Joel R.; Burger, Dan; Busca, Nicolas G.; Campbell, Heather; Cargile,
Phillip A.; Carithers, William C.; Carlberg, Joleen K.; Carr, Michael
A.; Chang, Liang; Chen, Yanmei; Chiappini, Cristina; Comparat, Johan;
Connolly, Natalia; Cortes, Marina; Croft, Rupert A. C.; Cunha, Katia;
da Costa, Luiz N.; Davenport, James R. A.; Dawson, Kyle; De Lee,
Nathan; Porto de Mello, Gustavo F.; de Simoni, Fernando; Dean, Janice;
Dhital, Saurav; Ealet, Anne; Ebelke, Garrett L.; Edmondson, Edward M.;
Eiting, Jacob M.; Escoffier, Stephanie; Esposito, Massimiliano; Evans,
Michael L.; Fan, Xiaohui; Femenía Castellá, Bruno; Dutra Ferreira,
Leticia; Fitzgerald, Greg; Fleming, Scott W.; Font-Ribera, Andreu;
Ford, Eric B.; Frinchaboy, Peter M.; García Pérez, Ana Elia; Gaudi,
B. Scott; Ge, Jian; Ghezzi, Luan; Gillespie, Bruce A.; Gilmore, G.;
Girardi, Léo; Gott, J. Richard; Gould, Andrew; Grebel, Eva K.; Gunn,
James E.; Hamilton, Jean-Christophe; Harding, Paul; Harris, David
W.; Hawley, Suzanne L.; Hearty, Frederick R.; Hennawi, Joseph F.;
González Hernández, Jonay I.; Ho, Shirley; Hogg, David W.; Holtzman,
Jon A.; Honscheid, Klaus; Inada, Naohisa; Ivans, Inese I.; Jiang,
Linhua; Jiang, Peng; Johnson, Jennifer A.; Jordan, Cathy; Jordan,
Wendell P.; Kauffmann, Guinevere; Kazin, Eyal; Kirkby, David; Klaene,
Mark A.; Knapp, G. R.; Kneib, Jean-Paul; Kochanek, C. S.; Koesterke,
Lars; Kollmeier, Juna A.; Kron, Richard G.; Lampeitl, Hubert; Lang,
Dustin; Lawler, James E.; Le Goff, Jean-Marc; Lee, Brian L.; Lee,
Young Sun; Leisenring, Jarron M.; Lin, Yen-Ting; Liu, Jian; Long,
Daniel C.; Loomis, Craig P.; Lucatello, Sara; Lundgren, Britt; Lupton,
Robert H.; Ma, Bo; Ma, Zhibo; MacDonald, Nicholas; Mack, Claude;
Mahadevan, Suvrath; Maia, Marcio A. G.; Majewski, Steven R.; Makler,
Martin; Malanushenko, Elena; Malanushenko, Viktor; Mandelbaum, Rachel;
Maraston, Claudia; Margala, Daniel; Maseman, Paul; Masters, Karen L.;
McBride, Cameron K.; McDonald, Patrick; McGreer, Ian D.; McMahon,
Richard G.; Mena Requejo, Olga; Ménard, Brice; Miralda-Escudé,
Jordi; Morrison, Heather L.; Mullally, Fergal; Muna, Demitri; Murayama,
Hitoshi; Myers, Adam D.; Naugle, Tracy; Neto, Angelo Fausti; Nguyen,
Duy Cuong; Nichol, Robert C.; Nidever, David L.; O'Connell, Robert
W.; Ogando, Ricardo L. C.; Olmstead, Matthew D.; Oravetz, Daniel J.;
Padmanabhan, Nikhil; Paegert, Martin; Palanque-Delabrouille, Nathalie;
Pan, Kaike; Pandey, Parul; Parejko, John K.; Pâris, Isabelle;
Pellegrini, Paulo; Pepper, Joshua; Percival, Will J.; Petitjean,
Patrick; Pfaffenberger, Robert; Pforr, Janine; Phleps, Stefanie;
Pichon, Christophe; Pieri, Matthew M.; Prada, Francisco; Price-Whelan,
Adrian M.; Raddick, M. Jordan; Ramos, Beatriz H. F.; Reid, I. Neill;
Reyle, Celine; Rich, James; Richards, Gordon T.; Rieke, George H.;
Rieke, Marcia J.; Rix, Hans-Walter; Robin, Annie C.; Rocha-Pinto,
Helio J.; Rockosi, Constance M.; Roe, Natalie A.; Rollinde, Emmanuel;
Ross, Ashley J.; Ross, Nicholas P.; Rossetto, Bruno; Sánchez, Ariel
G.; Santiago, Basilio; Sayres, Conor; Schiavon, Ricardo; Schlegel,
David J.; Schlesinger, Katharine J.; Schmidt, Sarah J.; Schneider,
Donald P.; Sellgren, Kris; Shelden, Alaina; Sheldon, Erin; Shetrone,
Matthew; Shu, Yiping; Silverman, John D.; Simmerer, Jennifer; Simmons,
Audrey E.; Sivarani, Thirupathi; Skrutskie, M. F.; Slosar, Anže; Smee,
Stephen; Smith, Verne V.; Snedden, Stephanie A.; Stassun, Keivan G.;
Steele, Oliver; Steinmetz, Matthias; Stockett, Mark H.; Stollberg,
Todd; Strauss, Michael A.; Szalay, Alexander S.; Tanaka, Masayuki;
Thakar, Aniruddha R.; Thomas, Daniel; Tinker, Jeremy L.; Tofflemire,
Benjamin M.; Tojeiro, Rita; Tremonti, Christy A.; Vargas Magaña,
Mariana; Verde, Licia; Vogt, Nicole P.; Wake, David A.; Wan, Xiaoke;
Wang, Ji; Weaver, Benjamin A.; White, Martin; White, Simon D. M.;
Wilson, John C.; Wisniewski, John P.; Wood-Vasey, W. Michael; Yanny,
Brian; Yasuda, Naoki; Yèche, Christophe; York, Donald G.; Young,
Erick; Zasowski, Gail; Zehavi, Idit; Zhao, Bo
2011AJ....142...72E Altcode: 2011arXiv1101.1529E
Building on the legacy of the Sloan Digital Sky Survey (SDSS-I
and II), SDSS-III is a program of four spectroscopic surveys on
three scientific themes: dark energy and cosmological parameters,
the history and structure of the Milky Way, and the population of
giant planets around other stars. In keeping with SDSS tradition,
SDSS-III will provide regular public releases of all its data,
beginning with SDSS Data Release 8 (DR8), which was made public
in 2011 January and includes SDSS-I and SDSS-II images and spectra
reprocessed with the latest pipelines and calibrations produced for the
SDSS-III investigations. This paper presents an overview of the four
surveys that comprise SDSS-III. The Baryon Oscillation Spectroscopic
Survey will measure redshifts of 1.5 million massive galaxies and
Lyα forest spectra of 150,000 quasars, using the baryon acoustic
oscillation feature of large-scale structure to obtain percent-level
determinations of the distance scale and Hubble expansion rate at z <
0.7 and at z ≈ 2.5. SEGUE-2, an already completed SDSS-III survey
that is the continuation of the SDSS-II Sloan Extension for Galactic
Understanding and Exploration (SEGUE), measured medium-resolution
(R = λ/Δλ ≈ 1800) optical spectra of 118,000 stars in a
variety of target categories, probing chemical evolution, stellar
kinematics and substructure, and the mass profile of the dark matter
halo from the solar neighborhood to distances of 100 kpc. APOGEE,
the Apache Point Observatory Galactic Evolution Experiment, will
obtain high-resolution (R ≈ 30,000), high signal-to-noise ratio
(S/N >= 100 per resolution element), H-band (1.51 μm < λ
< 1.70 μm) spectra of 10<SUP>5</SUP> evolved, late-type stars,
measuring separate abundances for ~15 elements per star and creating
the first high-precision spectroscopic survey of all Galactic stellar
populations (bulge, bar, disks, halo) with a uniform set of stellar
tracers and spectral diagnostics. The Multi-object APO Radial Velocity
Exoplanet Large-area Survey (MARVELS) will monitor radial velocities
of more than 8000 FGK stars with the sensitivity and cadence (10-40
m s<SUP>-1</SUP>, ~24 visits per star) needed to detect giant planets
with periods up to two years, providing an unprecedented data set for
understanding the formation and dynamical evolution of giant planet
systems. As of 2011 January, SDSS-III has obtained spectra of more
than 240,000 galaxies, 29,000 z >= 2.2 quasars, and 140,000 stars,
including 74,000 velocity measurements of 2580 stars for MARVELS.
---------------------------------------------------------
Title: Erratum: "The Eighth Data Release of the Sloan
Digital Sky Survey: First Data from SDSS-III" <A
href="/abs/2011ApJS..193...29A">(2011, ApJS, 193, 29)</A>
Authors: Aihara, Hiroaki; Allende Prieto, Carlos; An, Deokkeun;
Anderson, Scott F.; Aubourg, Éric; Balbinot, Eduardo; Beers, Timothy
C.; Berlind, Andreas A.; Bickerton, Steven J.; Bizyaev, Dmitry;
Blanton, Michael R.; Bochanski, John J.; Bolton, Adam S.; Bovy, Jo;
Brandt, W. N.; Brinkmann, J.; Brown, Peter J.; Brownstein, Joel R.;
Busca, Nicolas G.; Campbell, Heather; Carr, Michael A.; Chen, Yanmei;
Chiappini, Cristina; Comparat, Johan; Connolly, Natalia; Cortes,
Marina; Croft, Rupert A. C.; Cuesta, Antonio J.; da Costa, Luiz N.;
Davenport, James R. A.; Dawson, Kyle; Dhital, Saurav; Ealet, Anne;
Ebelke, Garrett L.; Edmondson, Edward M.; Eisenstein, Daniel J.;
Escoffier, Stephanie; Esposito, Massimiliano; Evans, Michael L.; Fan,
Xiaohui; Femenía Castellá, Bruno; Font-Ribera, Andreu; Frinchaboy,
Peter M.; Ge, Jian; Gillespie, Bruce A.; Gilmore, G.; González
Hernández, Jonay I.; Gott, J. Richard; Gould, Andrew; Grebel, Eva
K.; Gunn, James E.; Hamilton, Jean-Christophe; Harding, Paul; Harris,
David W.; Hawley, Suzanne L.; Hearty, Frederick R.; Ho, Shirley; Hogg,
David W.; Holtzman, Jon A.; Honscheid, Klaus; Inada, Naohisa; Ivans,
Inese I.; Jiang, Linhua; Johnson, Jennifer A.; Jordan, Cathy; Jordan,
Wendell P.; Kazin, Eyal A.; Kirkby, David; Klaene, Mark A.; Knapp,
G. R.; Kneib, Jean-Paul; Kochanek, C. S.; Koesterke, Lars; Kollmeier,
Juna A.; Kron, Richard G.; Lampeitl, Hubert; Lang, Dustin; Le Goff,
Jean-Marc; Lee, Young Sun; Lin, Yen-Ting; Long, Daniel C.; Loomis,
Craig P.; Lucatello, Sara; Lundgren, Britt; Lupton, Robert H.; Ma,
Zhibo; MacDonald, Nicholas; Mahadevan, Suvrath; Maia, Marcio A. G.;
Makler, Martin; Malanushenko, Elena; Malanushenko, Viktor; Mandelbaum,
Rachel; Maraston, Claudia; Margala, Daniel; Masters, Karen L.; McBride,
Cameron K.; McGehee, Peregrine M.; McGreer, Ian D.; Ménard, Brice;
Miralda-Escudé, Jordi; Morrison, Heather L.; Mullally, F.; Muna,
Demitri; Munn, Jeffrey A.; Murayama, Hitoshi; Myers, Adam D.; Naugle,
Tracy; Neto, Angelo Fausti; Nguyen, Duy Cuong; Nichol, Robert C.;
O'Connell, Robert W.; Ogando, Ricardo L. C.; Olmstead, Matthew D.;
Oravetz, Daniel J.; Padmanabhan, Nikhil; Palanque-Delabrouille,
Nathalie; Pan, Kaike; Pandey, Parul; Pâris, Isabelle; Percival, Will
J.; Petitjean, Patrick; Pfaffenberger, Robert; Pforr, Janine; Phleps,
Stefanie; Pichon, Christophe; Pieri, Matthew M.; Prada, Francisco;
Price-Whelan, Adrian M.; Raddick, M. Jordan; Ramos, Beatriz H. F.;
Reylé, Céline; Rich, James; Richards, Gordon T.; Rix, Hans-Walter;
Robin, Annie C.; Rocha-Pinto, Helio J.; Rockosi, Constance M.; Roe,
Natalie A.; Rollinde, Emmanuel; Ross, Ashley J.; Ross, Nicholas P.;
Rossetto, Bruno M.; Sánchez, Ariel G.; Sayres, Conor; Schlegel,
David J.; Schlesinger, Katharine J.; Schmidt, Sarah J.; Schneider,
Donald P.; Sheldon, Erin; Shu, Yiping; Simmerer, Jennifer; Simmons,
Audrey E.; Sivarani, Thirupathi; Snedden, Stephanie A.; Sobeck,
Jennifer S.; Steinmetz, Matthias; Strauss, Michael A.; Szalay,
Alexander S.; Tanaka, Masayuki; Thakar, Aniruddha R.; Thomas, Daniel;
Tinker, Jeremy L.; Tofflemire, Benjamin M.; Tojeiro, Rita; Tremonti,
Christy A.; Vandenberg, Jan; Vargas Magaña, M.; Verde, Licia; Vogt,
Nicole P.; Wake, David A.; Wang, Ji; Weaver, Benjamin A.; Weinberg,
David H.; White, Martin; White, Simon D. M.; Yanny, Brian; Yasuda,
Naoki; Yeche, Christophe; Zehavi, Idit
2011ApJS..195...26A Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Circumstellar Material in Type Ia Supernovae via Sodium
Absorption Features
Authors: Sternberg, A.; Gal-Yam, A.; Simon, J. D.; Leonard, D. C.;
Quimby, R. M.; Phillips, M. M.; Morrell, N.; Thompson, I. B.; Ivans,
I.; Marshall, J. L.; Filippenko, A. V.; Marcy, G. W.; Bloom, J. S.;
Patat, F.; Foley, R. J.; Yong, D.; Penprase, B. E.; Beeler, D. J.;
Allende Prieto, C.; Stringfellow, G. S.
2011Sci...333..856S Altcode: 2011arXiv1108.3664S
Type Ia supernovae are key tools for measuring distances on a cosmic
scale. They are generally thought to be the thermonuclear explosion of
an accreting white dwarf in a close binary system. The nature of the
mass donor is still uncertain. In the single-degenerate model it is a
main-sequence star or an evolved star, whereas in the double-degenerate
model it is another white dwarf. We show that the velocity structure
of absorbing material along the line of sight to 35 type Ia supernovae
tends to be blueshifted. These structures are likely signatures of
gas outflows from the supernova progenitor systems. Thus, many type Ia
supernovae in nearby spiral galaxies may originate in single-degenerate
systems.
---------------------------------------------------------
Title: Metallicity gradients of disc stars for a cosmologically
simulated galaxy
Authors: Rahimi, Awat; Kawata, Daisuke; Allende Prieto, Carlos; Brook,
Chris B.; Gibson, Brad K.; Kiessling, Alina
2011MNRAS.415.1469R Altcode: 2011arXiv1103.6150R; 2011MNRAS.tmp..725R
We analyse for the first time the radial abundance gradients of the
disc stars of a disc galaxy simulated with our three-dimensional, fully
cosmological chemodynamical galaxy evolution code GCD+. We study how
[Fe/H], [N/O], [O/Fe], [Mg/Fe] and [Si/Fe] vary with galactocentric
radius. For the young stars of the disc, we found a negative slope
for [Fe/H] and [N/O] but a positive [O/Fe], [Mg/Fe] and [Si/Fe] slope
with radius. By analysing the star formation rate at different radii,
we found that the simulated disc contains a greater fraction of young
stars in the outer regions, while the old stars tend to be concentrated
in the inner parts of the disc. This can explain the positive [α/Fe]
gradient as well as the negative [N/O] gradient with radius. This
radial trend is a natural outcome of an inside-out formation of the
disc, regardless of its size and can thus explain the recently observed
positive [α/Fe] gradients in the Milky Way disc open clusters.
---------------------------------------------------------
Title: A 12 Minute Orbital Period Detached White Dwarf Eclipsing
Binary
Authors: Brown, Warren R.; Kilic, Mukremin; Hermes, J. J.; Allende
Prieto, Carlos; Kenyon, Scott J.; Winget, D. E.
2011ApJ...737L..23B Altcode: 2011arXiv1107.2389B
We have discovered a detached pair of white dwarfs (WDs) with a 12.75
minute orbital period and a 1315 km s<SUP>-1</SUP> radial velocity
amplitude. We measure the full orbital parameters of the system
using its light curve, which shows ellipsoidal variations, Doppler
boosting, and primary and secondary eclipses. The primary is a 0.25 M
<SUB>sun</SUB> tidally distorted helium WD, only the second tidally
distorted WD known. The unseen secondary is a 0.55 M <SUB>sun</SUB>
carbon-oxygen WD. The two WDs will come into contact in 0.9 Myr
due to loss of energy and angular momentum via gravitational wave
radiation. Upon contact the systems may merge (yielding a rapidly
spinning massive WD), form a stable interacting binary, or possibly
explode as an underluminous Type Ia supernova. The system currently has
a gravitational wave strain of 10<SUP>-22</SUP>, about 10,000 times
larger than the Hulse-Taylor pulsar; this system would be detected
by the proposed Laser Interferometer Space Antenna gravitational
wave mission in the first week of operation. This system's rapid
change in orbital period will provide a fundamental test of general
relativity. <P />Based on observations obtained at the MMT Observatory,
a joint facility of the Smithsonian Institution and the University of
Arizona, and on observations obtained at The McDonald Observatory of
The University of Texas at Austin.
---------------------------------------------------------
Title: The BigBOSS Experiment
Authors: Schlegel, D.; Abdalla, F.; Abraham, T.; Ahn, C.; Allende
Prieto, C.; Annis, J.; Aubourg, E.; Azzaro, M.; Baltay, S. Bailey. C.;
Baugh, C.; Bebek, C.; Becerril, S.; Blanton, M.; Bolton, A.; Bromley,
B.; Cahn, R.; Carton, P. -H.; Cervantes-Cota, J. L.; Chu, Y.; Cortes,
M.; Dawson, K.; Dey, A.; Dickinson, M.; Diehl, H. T.; Doel, P.; Ealet,
A.; Edelstein, J.; Eppelle, D.; Escoffier, S.; Evrard, A.; Faccioli,
L.; Frenk, C.; Geha, M.; Gerdes, D.; Gondolo, P.; Gonzalez-Arroyo,
A.; Grossan, B.; Heckman, T.; Heetderks, H.; Ho, S.; Honscheid, K.;
Huterer, D.; Ilbert, O.; Ivans, I.; Jelinsky, P.; Jing, Y.; Joyce,
D.; Kennedy, R.; Kent, S.; Kieda, D.; Kim, A.; Kim, C.; Kneib,
J. -P.; Kong, X.; Kosowsky, A.; Krishnan, K.; Lahav, O.; Lampton,
M.; LeBohec, S.; Le Brun, V.; Levi, M.; Li, C.; Liang, M.; Lim, H.;
Lin, W.; Linder, E.; Lorenzon, W.; de la Macorra, A.; Magneville,
Ch.; Malina, R.; Marinoni, C.; Martinez, V.; Majewski, S.; Matheson,
T.; McCloskey, R.; McDonald, P.; McKay, T.; McMahon, J.; Menard,
B.; Miralda-Escude, J.; Modjaz, M.; Montero-Dorta, A.; Morales, I.;
Mostek, N.; Newman, J.; Nichol, R.; Nugent, P.; Olsen, K.; Padmanabhan,
N.; Palanque-Delabrouille, N.; Park, I.; Peacock, J.; Percival, W.;
Perlmutter, S.; Peroux, C.; Petitjean, P.; Prada, F.; Prieto, E.;
Prochaska, J.; Reil, K.; Rockosi, C.; Roe, N.; Rollinde, E.; Roodman,
A.; Ross, N.; Rudnick, G.; Ruhlmann-Kleider, V.; Sanchez, J.; Sawyer,
D.; Schimd, C.; Schubnell, M.; Scoccimaro, R.; Seljak, U.; Seo, H.;
Sheldon, E.; Sholl, M.; Shulte-Ladbeck, R.; Slosar, A.; Smith, D. S.;
Smoot, G.; Springer, W.; Stril, A.; Szalay, A. S.; Tao, C.; Tarle,
G.; Taylor, E.; Tilquin, A.; Tinker, J.; Valdes, F.; Wang, J.; Wang,
T.; Weaver, B. A.; Weinberg, D.; White, M.; Wood-Vasey, M.; Yang,
J.; Yeche, X. Yang. Ch.; Zakamska, N.; Zentner, A.; Zhai, C.; Zhang, P.
2011arXiv1106.1706S Altcode:
BigBOSS is a Stage IV ground-based dark energy experiment to study
baryon acoustic oscillations (BAO) and the growth of structure with
a wide-area galaxy and quasar redshift survey over 14,000 square
degrees. It has been conditionally accepted by NOAO in response to a
call for major new instrumentation and a high-impact science program
for the 4-m Mayall telescope at Kitt Peak. The BigBOSS instrument is
a robotically-actuated, fiber-fed spectrograph capable of taking 5000
simultaneous spectra over a wavelength range from 340 nm to 1060 nm,
with a resolution R = 3000-4800. Using data from imaging surveys that
are already underway, spectroscopic targets are selected that trace the
underlying dark matter distribution. In particular, targets include
luminous red galaxies (LRGs) up to z = 1.0, extending the BOSS LRG
survey in both redshift and survey area. To probe the universe out to
even higher redshift, BigBOSS will target bright [OII] emission line
galaxies (ELGs) up to z = 1.7. In total, 20 million galaxy redshifts are
obtained to measure the BAO feature, trace the matter power spectrum
at smaller scales, and detect redshift space distortions. BigBOSS
will provide additional constraints on early dark energy and on the
curvature of the universe by measuring the Ly-alpha forest in the
spectra of over 600,000 2.2 < z < 3.5 quasars. BigBOSS galaxy
BAO measurements combined with an analysis of the broadband power,
including the Ly-alpha forest in BigBOSS quasar spectra, achieves a
FOM of 395 with Planck plus Stage III priors. This FOM is based on
conservative assumptions for the analysis of broad band power (kmax =
0.15), and could grow to over 600 if current work allows us to push
the analysis to higher wave numbers (kmax = 0.3). BigBOSS will also
place constraints on theories of modified gravity and inflation,
and will measure the sum of neutrino masses to 0.024 eV accuracy.
---------------------------------------------------------
Title: Insight into the Formation of the Milky Way through Cold Halo
Substructure. II. The Elemental Abundances of ECHOS
Authors: Schlaufman, Kevin C.; Rockosi, Constance M.; Lee, Young Sun;
Beers, Timothy C.; Allende Prieto, Carlos
2011ApJ...734...49S Altcode: 2011arXiv1104.1424S
We determine the average metallicities of the elements of cold halo
substructure (ECHOS) that we previously identified in the inner halo of
the Milky Way within 17.5 kpc of the Sun. As a population, we find that
stars kinematically associated with ECHOS are chemically distinct from
the background kinematically smooth inner halo stellar population along
the same Sloan Extension for Galactic Understanding and Exploration
(SEGUE) line of sight. ECHOS are systematically more iron-rich,
but less α-enhanced than the kinematically smooth component of the
inner halo. ECHOS are also chemically distinct from other Milky Way
components: more iron-poor than typical thick-disk stars and both more
iron-poor and α-enhanced than typical thin-disk stars. In addition,
the radial velocity dispersion distribution of ECHOS extends beyond
σ ~ 20 km s<SUP>-1</SUP>. Globular clusters are unlikely ECHOS
progenitors, as ECHOS have large velocity dispersions and are found in
a region of the Galaxy in which iron-rich globular clusters are very
rare. Likewise, the chemical composition of stars in ECHOS does not
match predictions for stars formed in the Milky Way and subsequently
scattered into the inner halo. Dwarf spheroidal (dSph) galaxies are
possible ECHOS progenitors, and if ECHOS are formed through the tidal
disruption of one or more dSph galaxies, the typical ECHOS [Fe/H] ~ -
1.0 and radial velocity dispersion σ ~ 20 km s<SUP>-1</SUP> implies a
dSph with M <SUB>tot</SUB> >~ 10<SUP>9</SUP> M <SUB>sun</SUB>. Our
observations confirm the predictions of theoretical models of Milky Way
halo formation that suggest that prominent substructures are likely to
be metal-rich, and our result implies that the most likely metallicity
for a recently accreted star currently in the inner halo is [Fe/H] ~
- 1.0.
---------------------------------------------------------
Title: VizieR Online Data Catalog: Halo streams in the SDSS-DR7
(Klement+, 2009)
Authors: Klement, R.; Rix, H. -W.; Flynn, C.; Fuchs, B.; Beers,
T. C.; Allende Prieto, C.; Bizyaev, D.; Brewington, H.; Lee, Y. S.;
Malanushenko, E.; Malanushenko, V.; Oravetz, D.; Pan, K.; Re Fiorentin,
P.; Simmons, A.; Snedden, S.
2011yCat..16980865K Altcode:
SDSS-I was an imaging and spectroscopic survey that began routine
operations in 2000 April and continued through 2005 June. The SDSS, and
its extensions, uses a dedicated 2.5m telescope located at the Apache
Point Observatory in New Mexico. <P />One of three subsurveys carried
out during the first extension of the SDSS, known as SDSS-II, the Sloan
Extension for Galactic Understanding and Exploration (SEGUE), ran from
2005 July to 2008 June. SEGUE obtained some 250000 medium-resolution
spectra of stars in the Galaxy. <P />(3 data files).
---------------------------------------------------------
Title: The shortest period detached binary white dwarf system
Authors: Kilic, Mukremin; Brown, Warren R.; Kenyon, S. J.; Allende
Prieto, Carlos; Andrews, J.; Kleinman, S. J.; Winget, K. I.; Winget,
D. E.; Hermes, J. J.
2011MNRAS.413L.101K Altcode: 2011arXiv1103.2354K
We identify SDSS J010657.39-100003.3 (hereafter J0106-1000) as the
shortest period detached binary white dwarf (WD) system currently
known. We targeted J0106-1000 as part of our radial velocity programme
to search for companions around known extremely low-mass (ELM; ∼0.2
M<SUB>⊙</SUB>) WDs using the 6.5-m Multiple Mirror Telescope. We
detect peak-to-peak radial velocity variations of 740 km s<SUP>-1</SUP>
with an orbital period of 39.1 min. The mass function and optical
photometry rule out a main-sequence star companion. Follow-up high-speed
photometric observations obtained at the McDonald 2.1-m telescope
reveal ellipsoidal variations from the distorted primary but no
eclipses. This is the first example of a tidally distorted WD. Modelling
the light curve, we constrain the inclination angle of the system to be
67°± 13°. J0106-1000 contains a pair of WDs (0.17 M<SUB>⊙</SUB>
primary + 0.43 M<SUB>⊙</SUB> invisible secondary) at a separation
of 0.32 R<SUB>⊙</SUB>. The two WDs will merge in 37 Myr and most
likely form a core He-burning single subdwarf star. J0106-1000 is the
shortest time-scale merger system currently known. The gravitational
wave strain from J0106-1000 is at the detection limit of the Laser
Interferometer Space Antenna (LISA). However, accurate ephemeris and
orbital period measurements may enable LISA to detect J0106-1000 above
the Galactic background noise. Based on observations obtained at the
Multiple Mirror Telescope (MMT) Observatory, a joint facility of the
Smithsonian Institution and the University of Arizona.
---------------------------------------------------------
Title: The ELM Survey: A Successful Targeted Survey for Extremely
Low Mass White Dwarfs
Authors: Brown, Warren R.; Kilic, M.; Allende Prieto, C.; Kenyon, S. J.
2011AAS...21832613B Altcode: 2011BAAS..43G32613B
We present the first targeted survey for Extremely Low Mass (ELM)
white dwarfs (WDs), helium core WDs with masses <0.3 M ⊙. Such low
mass WDs are the signature of extreme mass-loss stellar evolution. We
have discovered over a dozen new ELM WDs, most of which are compact
binary systems with <1 day orbital periods. We predict that at
least one of the systems is an eclipsing double-WD system that we
can use to place fundamental mass-radius constraints on helium-core
WD models. Intriguingly, the observed ELM WD systems are merging due
to gravitational wave radiation and will become gravitational wave
sources. We use our well-defined, non-kinematically-selected sample
to measure the space density of ELM WD systems; their merger rate is
comparable to the rate ofunderluminous supernovae, one model for which
is the detonation of 0.3 M ⊙ worth of helium.
---------------------------------------------------------
Title: The Eighth Data Release of the Sloan Digital Sky Survey:
First Data from SDSS-III
Authors: Aihara, Hiroaki; Allende Prieto, Carlos; An, Deokkeun;
Anderson, Scott F.; Aubourg, Éric; Balbinot, Eduardo; Beers, Timothy
C.; Berlind, Andreas A.; Bickerton, Steven J.; Bizyaev, Dmitry;
Blanton, Michael R.; Bochanski, John J.; Bolton, Adam S.; Bovy, Jo;
Brandt, W. N.; Brinkmann, J.; Brown, Peter J.; Brownstein, Joel R.;
Busca, Nicolas G.; Campbell, Heather; Carr, Michael A.; Chen, Yanmei;
Chiappini, Cristina; Comparat, Johan; Connolly, Natalia; Cortes,
Marina; Croft, Rupert A. C.; Cuesta, Antonio J.; da Costa, Luiz N.;
Davenport, James R. A.; Dawson, Kyle; Dhital, Saurav; Ealet, Anne;
Ebelke, Garrett L.; Edmondson, Edward M.; Eisenstein, Daniel J.;
Escoffier, Stephanie; Esposito, Massimiliano; Evans, Michael L.; Fan,
Xiaohui; Femenía Castellá, Bruno; Font-Ribera, Andreu; Frinchaboy,
Peter M.; Ge, Jian; Gillespie, Bruce A.; Gilmore, G.; González
Hernández, Jonay I.; Gott, J. Richard; Gould, Andrew; Grebel, Eva
K.; Gunn, James E.; Hamilton, Jean-Christophe; Harding, Paul; Harris,
David W.; Hawley, Suzanne L.; Hearty, Frederick R.; Ho, Shirley; Hogg,
David W.; Holtzman, Jon A.; Honscheid, Klaus; Inada, Naohisa; Ivans,
Inese I.; Jiang, Linhua; Johnson, Jennifer A.; Jordan, Cathy; Jordan,
Wendell P.; Kazin, Eyal A.; Kirkby, David; Klaene, Mark A.; Knapp,
G. R.; Kneib, Jean-Paul; Kochanek, C. S.; Koesterke, Lars; Kollmeier,
Juna A.; Kron, Richard G.; Lampeitl, Hubert; Lang, Dustin; Le Goff,
Jean-Marc; Lee, Young Sun; Lin, Yen-Ting; Long, Daniel C.; Loomis,
Craig P.; Lucatello, Sara; Lundgren, Britt; Lupton, Robert H.; Ma,
Zhibo; MacDonald, Nicholas; Mahadevan, Suvrath; Maia, Marcio A. G.;
Makler, Martin; Malanushenko, Elena; Malanushenko, Viktor; Mandelbaum,
Rachel; Maraston, Claudia; Margala, Daniel; Masters, Karen L.; McBride,
Cameron K.; McGehee, Peregrine M.; McGreer, Ian D.; Ménard, Brice;
Miralda-Escudé, Jordi; Morrison, Heather L.; Mullally, F.; Muna,
Demitri; Munn, Jeffrey A.; Murayama, Hitoshi; Myers, Adam D.; Naugle,
Tracy; Neto, Angelo Fausti; Nguyen, Duy Cuong; Nichol, Robert C.;
O'Connell, Robert W.; Ogando, Ricardo L. C.; Olmstead, Matthew D.;
Oravetz, Daniel J.; Padmanabhan, Nikhil; Palanque-Delabrouille,
Nathalie; Pan, Kaike; Pandey, Parul; Pâris, Isabelle; Percival, Will
J.; Petitjean, Patrick; Pfaffenberger, Robert; Pforr, Janine; Phleps,
Stefanie; Pichon, Christophe; Pieri, Matthew M.; Prada, Francisco;
Price-Whelan, Adrian M.; Raddick, M. Jordan; Ramos, Beatriz H. F.;
Reylé, Céline; Rich, James; Richards, Gordon T.; Rix, Hans-Walter;
Robin, Annie C.; Rocha-Pinto, Helio J.; Rockosi, Constance M.; Roe,
Natalie A.; Rollinde, Emmanuel; Ross, Ashley J.; Ross, Nicholas P.;
Rossetto, Bruno M.; Sánchez, Ariel G.; Sayres, Conor; Schlegel,
David J.; Schlesinger, Katharine J.; Schmidt, Sarah J.; Schneider,
Donald P.; Sheldon, Erin; Shu, Yiping; Simmerer, Jennifer; Simmons,
Audrey E.; Sivarani, Thirupathi; Snedden, Stephanie A.; Sobeck,
Jennifer S.; Steinmetz, Matthias; Strauss, Michael A.; Szalay,
Alexander S.; Tanaka, Masayuki; Thakar, Aniruddha R.; Thomas, Daniel;
Tinker, Jeremy L.; Tofflemire, Benjamin M.; Tojeiro, Rita; Tremonti,
Christy A.; Vandenberg, Jan; Vargas Magaña, M.; Verde, Licia; Vogt,
Nicole P.; Wake, David A.; Wang, Ji; Weaver, Benjamin A.; Weinberg,
David H.; White, Martin; White, Simon D. M.; Yanny, Brian; Yasuda,
Naoki; Yeche, Christophe; Zehavi, Idit
2011ApJS..193...29A Altcode: 2011arXiv1101.1559S
The Sloan Digital Sky Survey (SDSS) started a new phase in 2008 August,
with new instrumentation and new surveys focused on Galactic structure
and chemical evolution, measurements of the baryon oscillation feature
in the clustering of galaxies and the quasar Lyα forest, and a radial
velocity search for planets around ~8000 stars. This paper describes
the first data release of SDSS-III (and the eighth counting from the
beginning of the SDSS). The release includes five-band imaging of
roughly 5200 deg<SUP>2</SUP> in the southern Galactic cap, bringing
the total footprint of the SDSS imaging to 14,555 deg<SUP>2</SUP>,
or over a third of the Celestial Sphere. All the imaging data have
been reprocessed with an improved sky-subtraction algorithm and
a final, self-consistent photometric recalibration and flat-field
determination. This release also includes all data from the second
phase of the Sloan Extension for Galactic Understanding and Exploration
(SEGUE-2), consisting of spectroscopy of approximately 118,000 stars
at both high and low Galactic latitudes. All the more than half a
million stellar spectra obtained with the SDSS spectrograph have been
reprocessed through an improved stellar parameter pipeline, which has
better determination of metallicity for high-metallicity stars.
---------------------------------------------------------
Title: The SEGUE Stellar Parameter Pipeline. V. Estimation of
Alpha-element Abundance Ratios from Low-resolution SDSS/SEGUE
Stellar Spectra
Authors: Lee, Young Sun; Beers, Timothy C.; Allende Prieto, Carlos;
Lai, David K.; Rockosi, Constance M.; Morrison, Heather L.; Johnson,
Jennifer A.; An, Deokkeun; Sivarani, Thirupathi; Yanny, Brian
2011AJ....141...90L Altcode: 2010arXiv1010.2934L
We present a method for the determination of [α/Fe] ratios from
low-resolution (R = 2000) SDSS/SEGUE stellar spectra. By means
of a star-by-star comparison with degraded spectra from the ELODIE
spectral library and with a set of moderately high-resolution (R = 15,
000) and medium-resolution (R = 6000) spectra of SDSS/SEGUE stars, we
demonstrate that we are able to measure [α/Fe] from SDSS/SEGUE spectra
(with S/N>20/1) to a precision of better than 0.1 dex, for stars with
atmospheric parameters in the range T <SUB>eff</SUB> = [4500, 7000] K,
log g = [1.5, 5.0], and [Fe/H] = [-1.4, +0.3], over the range [α/Fe]
= [-0.1, +0.6]. For stars with [Fe/H] <-1.4, our method requires
spectra with slightly higher signal-to-noise to achieve this precision
(S/N>25/1). Over the full temperature range considered, the lowest
metallicity star for which a confident estimate of [α/Fe] can be
obtained from our approach is [Fe/H] ~-2.5 preliminary tests indicate
that a metallicity limit as low as [Fe/H] ~-3.0 may apply to cooler
stars. As a further validation of this approach, weighted averages of
[α/Fe] obtained for SEGUE spectra of likely member stars of Galactic
globular clusters (M15, M13, and M71) and open clusters (NGC 2420,
M67, and NGC 6791) exhibit good agreement with the values of [α/Fe]
from previous studies. The results of the comparison with NGC 6791
imply that the metallicity range for the method may extend to ~+0.5.
---------------------------------------------------------
Title: Bridging model and observed stellar spectra
Authors: Allende Prieto, C.
2011MNRAS.411..807A Altcode: 2010arXiv1009.3519A
Accurate model stellar fluxes are key for the analysis of observations
of individual stars or stellar populations. Model spectra differ from
real stellar spectra due to limitations of the input physical data
and adopted simplifications, but can be empirically calibrated to
maximize their resemblance to actual stellar spectra. We describe a
least-squares procedure of general use and test it on the MILES library.
---------------------------------------------------------
Title: The merger rate of extremely low mass white dwarf binaries:
links to the formation of AM CVn stars and underluminous supernovae
Authors: Brown, Warren R.; Kilic, Mukremin; Allende Prieto, Carlos;
Kenyon, Scott J.
2011MNRAS.411L..31B Altcode: 2010arXiv1011.3047B; 2010MNRAS.tmpL.180B
We study a complete, colour-selected sample of double-degenerate binary
systems containing extremely low mass (ELM) ≤0.25 M<SUB>⊙</SUB>
white dwarfs (WDs). We show, for the first time, that Milky Way disc
ELM WDs have a merger rate of approximately 4 × 10<SUP>-5</SUP>
yr<SUP>-1</SUP> due to gravitational wave radiation. The merger end
product depends on the mass ratio of the binary. The ELM WD systems
that undergo stable mass transfer can account for ≳3 per cent of
AM Canum Venaticorum (AM CVn) stars. More importantly, the ELM WD
systems that may detonate merge at a rate comparable to the estimated
rate of underluminous supernovae (SNe), rare explosions estimated
to produce only ∼0.2 M<SUB>⊙</SUB> worth of ejecta. At least 25
per cent of our ELM WD sample belong to the old thick disc and halo
components of the Milky Way. Thus, if merging ELM WD systems are the
progenitors of underluminous SNe, transient surveys must find them in
both elliptical and spiral galaxies. Based on observations obtained at
the MMT Observatory, a joint facility of the Smithsonian Institution
and the University of Arizona.
---------------------------------------------------------
Title: SDSS-III: news, data access, and activities at the IAC
Authors: Allende Prieto, C.; Pérez-Fournon, I.
2011iac..talk..244A Altcode: 2011iac..talk..193A
No abstract at ADS
---------------------------------------------------------
Title: Evidence for Circumstellar Material in Type Ia Supernovae
via Na I D Absorption Features
Authors: Sternberg, Assaf; Gal-Yam, A.; Simon, J. D.; Leonard,
D. C.; Quimby, R. M.; Phillips, M. M.; Morell, N. I.; Preston, G. W.;
Thompson, I. B.; Ivans, I. I.; Marshall, J. L.; Filippenko, A. V.;
Marcy, G. W.; Bloom, J. S.; Patat, F.; Yong, D.; Penprase, B. E.;
Toro Martinez, I.; Beeler, D. J.; Wheeler, J. C.; Allende Prieto,
C.; Stringfellow, G. S.
2011AAS...21743430S Altcode: 2011BAAS...4343430S
Type Ia Supernovae (SNe Ia) have high and homogeneous luminosities,
making them an essential tool for measuring distances on a cosmic scale,
useful to gauge the geometry and evolution of the Universe. However,
the nature of the progenitor system of these explosions is still
uncertain. The consensus view is that SNe Ia originate from an
accreting carbon-oxygen white dwarf (WD) in a binary system, that
undergoes a thermonuclear explosion as its mass approaches the critical
Chandrasekhar limit. In the single degenerate (SD) model the mass
donor is either a main sequence or an evolved star, while the double
degenerate (DD) model involves a second WD as the mass donor. In the
SD model non-accreted material blown away from the system prior to the
explosion would remain as circumstellar material (CSM). Detection of
such material in SN Ia spectra would support the SD model. Recently,
claims for such detections were reported for four SN Ia events
(SN2006X, SN2007le, SN 1999cl and SN2006dd), manifest as time variable
Na I D absorption features. We report the analysis of the largest high
resolution SN Ia spectra sample to date, consisting of 35 SN Ia events,
obtained using the Keck HIRES and Magellan MIKE spectrographs. 22
of these events exhibit significant Na I D absorption. We report a
statistical preference for blue-shifted absorption structures (similar
to those seen in SN 2006X and SN 2007le) that is incompatible with
observations of the Milky way absorption systems or an additional
core collapse SN sample. This apparent asymmetry suggests that most of
these features are intrinsic to the SNe themselves, supporting the SD
model for the progenitor system of a large fraction of SNe Ia in nearby
(z<0.06) spiral and lenticular galaxies.
---------------------------------------------------------
Title: The ELM Survey. II. Twelve Binary White Dwarf Merger Systems
Authors: Kilic, Mukremin; Brown, Warren R.; Allende Prieto, Carlos;
Agüeros, M. A.; Heinke, Craig; Kenyon, S. J.
2011ApJ...727....3K Altcode: 2010arXiv1011.4073K
We describe new radial velocity and X-ray observations of extremely
low-mass white dwarfs (ELM WDs, ~0.2 M <SUB>sun</SUB>) in the Sloan
Digital Sky Survey Data Release 4 and the MMT Hypervelocity Star
survey. We identify four new short period binaries, including two merger
systems. These observations bring the total number of short period
binary systems identified in our survey to 20. No main-sequence or
neutron star companions are visible in the available optical photometry,
radio, and X-ray data. Thus, the companions are most likely WDs. Twelve
of these systems will merge within a Hubble time due to gravitational
wave radiation. We have now tripled the number of known merging WD
systems. We discuss the characteristics of this merger sample and
potential links to underluminous supernovae, extreme helium stars, AM
CVn systems, and other merger products. We provide new observational
tests of the WD mass-period distribution and cooling models for ELM
WDs. We also find evidence for a new formation channel for single
low-mass WDs through binary mergers of two lower mass objects. <P
/>Based on observations obtained at the MMT Observatory, a joint
facility of the Smithsonian Institution and the University of Arizona.
---------------------------------------------------------
Title: Binary White Dwarf Mergers and Underluminous Supernovae
Authors: Kilic, Mukremin; Brown, W. R.; Kenyon, S. J.; Allende
Prieto, C.
2011AAS...21742302K Altcode: 2011BAAS...4342302K
Short period binary white dwarfs may merge within a Hubble time due
to gravitational wave radiation. We have begun a targeted survey to
find merging white dwarfs systems, and our first results have tripled
the number of known merging white dwarf systems. Our sample includes
systems with orbital periods as short as 1 hr and with merger times less
than 100 Myr. We will discuss the characteristics of <P />this merger
sample and potential links to Type Ia and underluminous supernovae.
---------------------------------------------------------
Title: Faint Near-ultraviolet/Far-ultraviolet Standards from
Swift/UVOT, GALEX, and SDSS Photometry
Authors: Siegel, Michael H.; Hoversten, Erik A.; Roming, Peter W. A.;
Landsman, Wayne B.; Allende Prieto, Carlos; Breeveld, Alice A.;
Brown, Peter; Holland, Stephen T.; Kuin, N. P. M.; Page, Mathew J.;
Vanden Berk, Daniel E.
2010ApJ...725.1215S Altcode: 2010arXiv1010.5219S
At present, the precision of deep ultraviolet photometry is somewhat
limited by the dearth of faint ultraviolet standard stars. In an
effort to improve this situation, we present a uniform catalog of
11 new faint (u ~ 17) ultraviolet standard stars. High-precision
photometry of these stars has been taken from the Sloan Digital Sky
Survey and Galaxy Evolution Explorer archives and combined with
new data from the Swift Ultraviolet Optical Telescope to provide
precise photometric measures extending from the near-infrared to the
far-ultraviolet. These stars were chosen because they are known to
be hot (20, 000 < T <SUB>eff</SUB> < 50, 000 K) DA white dwarfs
with published Sloan spectra that should be photometrically stable. This
careful selection allows us to compare the combined photometry and Sloan
spectroscopy to models of pure hydrogen atmospheres to both constrain
the underlying properties of the white dwarfs and test the ability of
white dwarf models to predict the photometric measures. We find that
the photometry provides good constraints on white dwarf temperatures,
which demonstrates the ability of Swift/UVOT to investigate the
properties of hot luminous stars. We further find that the models
reproduce the photometric measures in all 11 passbands to within
their systematic uncertainties. Within the limits of our photometry,
we find the standard stars to be photometrically stable. This success
indicates that the models can be used to calibrate additional filters
to our standard system, permitting easier comparison of photometry
from heterogeneous sources. The largest source of uncertainty in the
model fitting is the uncertainty in the foreground reddening curve,
a problem that is especially acute in the UV.
---------------------------------------------------------
Title: Granulation Signatures in the Spectrum of the Very Metal-poor
Red Giant HD 122563
Authors: Ramírez, I.; Collet, R.; Lambert, D. L.; Allende Prieto,
C.; Asplund, M.
2010ApJ...725L.223R Altcode: 2010arXiv1011.4077R
A very high resolution (R = λ/Δλ = 200, 000), high signal-to-noise
ratio (S/N ~= 340) blue-green spectrum of the very metal-poor ([Fe/H]
~= -2.6) red giant star HD 122563 has been obtained by us at McDonald
Observatory. We measure the asymmetries and core wavelengths of a set
of unblended Fe I lines covering a wide range of line strength. Line
bisectors exhibit the characteristic C-shape signature of surface
convection (granulation) and they span from about 100 m s<SUP>-1</SUP>
in the strongest Fe I features to 800 m s<SUP>-1</SUP> in the
weakest ones. Core wavelength shifts range from about -100 to -900
m s<SUP>-1</SUP>, depending on line strength. In general, larger
blueshifts are observed in weaker lines, but there is increasing
scatter with increasing residual flux. Assuming local thermodynamic
equilibrium (LTE), we synthesize the same set of spectral lines using
a state-of-the-art three-dimensional (3D) hydrodynamic simulation
for a stellar atmosphere of fundamental parameters similar to those
of HD 122563. We find good agreement between model predictions and
observations. This allows us to infer an absolute zero point for
the line shifts and radial velocity. Moreover, it indicates that
the structure and dynamics of the simulation are realistic, thus
providing support to previous claims of large 3D-LTE corrections to
elemental abundances and fundamental parameters of very metal-poor
red giant stars obtained with standard 1D-LTE spectroscopic analyses,
as suggested by the hydrodynamic model used here.
---------------------------------------------------------
Title: The ELM Survey. I. A Complete Sample of Extremely Low-mass
White Dwarfs
Authors: Brown, Warren R.; Kilic, Mukremin; Allende Prieto, Carlos;
Kenyon, Scott J.
2010ApJ...723.1072B Altcode: 2010arXiv1011.3050B
We analyze radial velocity observations of the 12 extremely low-mass
(ELM), with <=0.25 M <SUB>sun</SUB>, white dwarfs (WDs) in the MMT
Hypervelocity Star Survey. Eleven of the twelve WDs are binaries with
orbital periods shorter than 14 hr; the one non-variable WD is possibly
a pole-on system among our non-kinematically selected targets. Our
sample is unique: it is complete in a well-defined range of apparent
magnitude and color. The orbital mass functions imply that the unseen
companions are most likely other WDs, although neutron star companions
cannot be excluded. Six of the eleven systems with orbital solutions
will merge within a Hubble time due to the loss of angular momentum
through gravitational wave radiation. The quickest merger is J0923+3028,
a g = 15.7 ELM WD binary with a 1.08 hr orbital period and a <=130
Myr merger time. The chance of a supernova Ia event among our ELM WDs is
only 1%-7%, however. Three binary systems (J0755+4906, J1233+1602, and
J2119-0018) have extreme mass ratios and will most likely form stable
mass-transfer AM CVn systems. Two of these objects, SDSS J1233+1602 and
J2119-0018, are the lowest surface gravity WDs ever found; both show
Ca II absorption likely from accretion of circumbinary material. We
predict that at least one of our WDs is an eclipsing detached double WD
system, important for constraining helium core WD models. <P />Based
on observations obtained at the MMT Observatory, a joint facility of
the Smithsonian Institution and the University of Arizona.
---------------------------------------------------------
Title: Accurate Masses for the Primary and Secondary in the Eclipsing
White Dwarf Binary NLTT 11748
Authors: Kilic, Mukremin; Allende Prieto, Carlos; Brown, Warren R.;
Agüeros, M. A.; Kenyon, S. J.; Camilo, Fernando
2010ApJ...721L.158K Altcode: 2010arXiv1008.1069K
We measure the radial velocity curve of the eclipsing detached white
dwarf binary NLTT 11748. The primary exhibits velocity variations with
a semi-amplitude of 273 km s<SUP>-1</SUP> and an orbital period of
5.641 hr. We do not detect any spectral features from the secondary
star or any spectral changes during the secondary eclipse. We use our
composite spectrum to constrain the temperature and surface gravity of
the primary to be T <SUB>eff</SUB> = 8690 ± 140 K and log g = 6.54
± 0.05, which correspond to a mass of 0.18 M <SUB>sun</SUB>. For an
inclination angle of 89fdg9 derived from the eclipse modeling, the mass
function requires a 0.76 M <SUB>sun</SUB> companion. The merger time
for the system is 7.2 Gyr. However, due to the extreme mass ratio of
0.24, the binary will most likely create an AM CVn system instead of
a merger. <P />Based on observations obtained at the MMT Observatory,
a joint facility of the Smithsonian Institution and the University
of Arizona.
---------------------------------------------------------
Title: Spectroscopy from Photometry Using Sparsity: The SDSS Case
Study
Authors: Asensio Ramos, A.; Allende Prieto, C.
2010ApJ...719.1759A Altcode: 2010arXiv1006.5391A
We explore whether medium-resolution stellar spectra can be
reconstructed from photometric observations, taking advantage of the
highly compressible nature of the spectra. We formulate the spectral
reconstruction as a least-squares problem with a sparsity constraint. In
our test case using data from the Sloan Digital Sky Survey, only three
broadband filters are used as input. We demonstrate that reconstruction
using three principal components is feasible with these filters,
leading to median differences with respect to the original spectrum
smaller than 5%. We analyze the effect of uncertainties in the observed
magnitudes and find that the available high photometric precision
induces very small errors in the reconstruction. This process may
facilitate the extraction of purely spectroscopic quantities, such as
the overall metallicity, for hundreds of millions of stars for which
only photometric information is available, using standard analysis
techniques applied to the reconstructed spectra.
---------------------------------------------------------
Title: The Apache Point Observatory Galactic Evolution Experiment
(APOGEE) high-resolution near-infrared multi-object fiber spectrograph
Authors: Wilson, John C.; Hearty, Fred; Skrutskie, Michael F.;
Majewski, Steven; Schiavon, Ricardo; Eisenstein, Daniel; Gunn, Jim;
Blank, Basil; Henderson, Chuck; Smee, Stephen; Barkhouser, Robert;
Harding, Al; Fitzgerald, Greg; Stolberg, Todd; Arns, Jim; Nelson, Matt;
Brunner, Sophia; Burton, Adam; Walker, Eric; Lam, Charles; Maseman,
Paul; Barr, Jim; Leger, French; Carey, Larry; MacDonald, Nick; Horne,
Todd; Young, Erick; Rieke, George; Rieke, Marcia; O'Brien, Tom; Hope,
Steve; Krakula, John; Crane, Jeff; Zhao, Bo; Carr, Mike; Harrison,
Craig; Stoll, Robert; Vernieri, Mary A.; Holtzman, Jon; Shetrone,
Matt; Allende-Prieto, Carlos; Johnson, Jennifer; Frinchaboy, Peter;
Zasowski, Gail; Bizyaev, Dmitry; Gillespie, Bruce; Weinberg, David
2010SPIE.7735E..1CW Altcode: 2010SPIE.7735E..46W
The Apache Point Observatory Galactic Evolution Experiment (APOGEE) will
use a dedicated 300-fiber, narrow-band (1.5-1.7 micron), high resolution
(R~30,000), near-infrared spectrograph to survey approximately 100,000
giant stars across the Milky Way. This survey, conducted as part
of the Sloan Digital Sky Survey III (SDSS III), will revolutionize
our understanding of kinematical and chemical enrichment histories
of all Galactic stellar populations. The instrument, currently in
fabrication, will be housed in a separate building adjacent to the
2.5 m SDSS telescope and fed light via approximately 45-meter fiber
runs from the telescope. The instrument design includes numerous
technological challenges and innovations including a gang connector
that allows simultaneous connection of all fibers with a single plug to
a telescope cartridge that positions the fibers on the sky, numerous
places in the fiber train in which focal ratio degradation must be
minimized, a large (290 mm x 475 mm elliptically-shaped recorded area)
mosaic-VPH, an f/1.4 sixelement refractive camera featuring silicon
and fused silica elements with diameters as large as 393 mm, three
near-within a custom, LN2-cooled, stainless steel vacuum cryostat with
dimensions 1.4 m x 2.3 m x 1.3 m.
---------------------------------------------------------
Title: The Milky Way Tomography with SDSS. III. Stellar Kinematics
Authors: Bond, Nicholas A.; Ivezić, Željko; Sesar, Branimir; Jurić,
Mario; Munn, Jeffrey A.; Kowalski, Adam; Loebman, Sarah; Roškar,
Rok; Beers, Timothy C.; Dalcanton, Julianne; Rockosi, Constance M.;
Yanny, Brian; Newberg, Heidi J.; Allende Prieto, Carlos; Wilhelm, Ron;
Lee, Young Sun; Sivarani, Thirupathi; Majewski, Steven R.; Norris,
John E.; Bailer-Jones, Coryn A. L.; Re Fiorentin, Paola; Schlegel,
David; Uomoto, Alan; Lupton, Robert H.; Knapp, Gillian R.; Gunn,
James E.; Covey, Kevin R.; Allyn Smith, J.; Miknaitis, Gajus; Doi,
Mamoru; Tanaka, Masayuki; Fukugita, Masataka; Kent, Steve; Finkbeiner,
Douglas; Quinn, Tom R.; Hawley, Suzanne; Anderson, Scott; Kiuchi,
Furea; Chen, Alex; Bushong, James; Sohi, Harkirat; Haggard, Daryl;
Kimball, Amy; McGurk, Rosalie; Barentine, John; Brewington, Howard;
Harvanek, Mike; Kleinman, Scott; Krzesinski, Jurek; Long, Dan; Nitta,
Atsuko; Snedden, Stephanie; Lee, Brian; Pier, Jeffrey R.; Harris,
Hugh; Brinkmann, Jonathan; Schneider, Donald P.
2010ApJ...716....1B Altcode: 2009arXiv0909.0013B
We study Milky Way kinematics using a sample of 18.8 million
main-sequence stars with r < 20 and proper-motion measurements
derived from Sloan Digital Sky Survey (SDSS) and POSS astrometry,
including ~170,000 stars with radial-velocity measurements from the
SDSS spectroscopic survey. Distances to stars are determined using a
photometric-parallax relation, covering a distance range from ~100
pc to 10 kpc over a quarter of the sky at high Galactic latitudes
(|b|>20°). We find that in the region defined by 1 kpc <Z<
5 kpc and 3 kpc <R< 13 kpc, the rotational velocity for disk
stars smoothly decreases, and all three components of the velocity
dispersion increase, with distance from the Galactic plane. In contrast,
the velocity ellipsoid for halo stars is aligned with a spherical
coordinate system and appears to be spatially invariant within the
probed volume. The velocity distribution of nearby (Z < 1 kpc) K/M
stars is complex, and cannot be described by a standard Schwarzschild
ellipsoid. For stars in a distance-limited subsample of stars (<100
pc), we detect a multi-modal velocity distribution consistent with
that seen by HIPPARCOS. This strong non-Gaussianity significantly
affects the measurements of the velocity-ellipsoid tilt and vertex
deviation when using the Schwarzschild approximation. We develop and
test a simple descriptive model for the overall kinematic behavior
that captures these features over most of the probed volume, and can be
used to search for substructure in kinematic and metallicity space. We
use this model to predict further improvements in kinematic mapping of
the Galaxy expected from Gaia and the Large Synoptic Survey Telescope.
---------------------------------------------------------
Title: The Discovery of Binary White Dwarfs that will Merge Within
500 Myr
Authors: Kilic, Mukremin; Brown, Warren R.; Allende Prieto, Carlos;
Kenyon, S. J.; Panei, J. A.
2010ApJ...716..122K Altcode: 2009arXiv0911.1781K
We present radial velocity observations of four extremely low-mass (0.2
M <SUB>sun</SUB>) white dwarfs (WDs). All four stars show peak-to-peak
radial velocity variations of 540-710 km s<SUP>-1</SUP> with 1.0-5.9 hr
periods. The optical photometry rules out main-sequence companions. In
addition, no millisecond pulsar companions are detected in radio
observations. Thus, the invisible companions are most likely WDs. Two
of the systems are the shortest period binary WDs yet discovered. Due
to the loss of angular momentum through gravitational radiation, three
of the systems will merge within 500 Myr. The remaining system will
merge within a Hubble time. The mass functions for three of the systems
imply companions more massive than 0.46 M <SUB>sun</SUB>; thus, those
are carbon/oxygen core WDs. The unknown inclination angles prohibit a
definitive conclusion about the future of these systems. However, the
chance of a supernova Ia event is only 1%-5%. These systems are likely
to form single R Coronae Borealis stars, providing evidence for a WD +
WD merger mechanism for these unusual objects. One of the systems,
SDSS J105353.89+520031.0, has a 70% chance of having a low-mass WD
companion. This system will probably form a single helium-enriched
subdwarf O star. All four WD systems have unusual mass ratios of
<=0.2-0.8 that may also lead to the formation of AM CVn systems. <P
/>Based on observations obtained at the MMT Observatory, a joint
facility of the Smithsonian Institution and the University of Arizona.
---------------------------------------------------------
Title: Commission 36: Theory of Stellar Atmospheres
Authors: Asplund, Martin; Puls, Joachim; Landstreet, John; Allende
Prieto, Carlos; Ayres, Thomas; Berdyugina, Svetlana; Gustafsson,
Bengt; Hubeny, Ivan; Ludwig, Hans Günter; Mashonkina, Lyudmila;
Randich, Sofia
2010IAUTB..27..197A Altcode:
The members of the Commission 36 Organizing Committee attending the IAU
General Assembly in Rio de Janeiro met for a business session on August
7. Both members from the previous (2006-2009) and the new (2009-2012)
Organizing Committee partook in the discussions. Past president John
Landstreet described the work he had done over the past three years
in terms of supporting proposed conferences on the topic. He has
also spent significant amount of time establishing an updated mailing
list of all >350 members of the commission, which is unfortunately
not provided automatically by the IAU. Such a list is critical for a
rapid dissemination of information to the commission members and for
a correct and smooth running of elections of IAU officials. Everyone
present thanked John effusively for all of his hard work over the past
three years to stimulate a high level of activity within the discipline.
---------------------------------------------------------
Title: The Stellar Population of the Thin Disk
Authors: Allende Prieto, Carlos
2010IAUS..265..304A Altcode: 2010IAUS..265..304P; 2009arXiv0911.3598A
We discuss recent observations of stars located close to the symmetry
plane of the Milky Way, and examine them in the context of theories of
Galaxy formation and evolution. The kinematics, ages, and compositions
of thin disk stars in the solar neighborhood display complex patterns,
and interesting correlations. The Galactic disk does not seem to pose
any unsurmountable obstacles to hierarchical galaxy formation theories,
but a model of the Milky Way able to reproduce the complexity found
in the data will likely require a meticulous study of a significant
fraction of the stars in the Galaxy. Making such an observational
effort seems necessary in order to make a physics laboratory out of
our own galaxy, and ultimately ensure that the most relevant processes
are properly understood.
---------------------------------------------------------
Title: APOGEE: A high resolution SDSS-III H-band survey of the
Milky Way
Authors: Shetrone, M.; Lawler, J.; Schiavon, R.; Majewski, S.;
Hearty, F.; Wilson, J.; Allende Prieto, C.; Johnson, J.; Holtzman,
J.; Frinchaboy, P.
2010nuco.confE.109S Altcode: 2010PoS...100E.109S
No abstract at ADS
---------------------------------------------------------
Title: Searching for Signatures of Radial Mixing in The Chemically
Divided Galactic Disks
Authors: Lee, Young S.; Schonrich, R.; Beers, T. C.; Heather, M. L.;
An, D.; Allende Prieto, C.; Asplund, M.; Carollo, D.; Rockosi, C. M.
2010AAS...21541303L Altcode: 2010BAAS...42R.250L
The Milky Way's thick disk was originally identified by fitting
the vertical density distribution of stars to a double exponential
profile. Recent investigations have shown that, in addition to being
older, thick disk stars show chemical and kinematical properties
distinct from the thin disk. Most scenarios of thick disk formation
discussed to date emphasize mergers, e.g., heating of a pre-existing
thin disk, accretion of stars from disrupted <P />satellites, or in-situ
formation induced by infalling gas-rich systems. Recently, however,
growing observational and theoretical evidence has suggested that the
thick disk might be the result of the cumulative radial migration
of disk stars over the history of the Galaxy. According to these
models, disk stars move radially over their lifetimes, spreading the
chemical signatures associated with their birth place at a range of
galactocentric distances and giving rise to chemical and kinematical
signatures corresponding to the common thin and thick disk divisions. In
this study we search for observational signatures of radial mixing in
the disk populations based on a large sample of F-and G-type dwarfs
observed by SEGUE-1, divided into thin and thick disk populations
characterized by low (-0.1 <[α/Fe] < +0.2) and high (+0.3 <
[α/Fe] < +0.6) α-abundances, respectively. We also demonstrate
that we are able to determine [α/Fe] with an accuracy of < 0.1
dex down to S/N = 20/1 for the SEGUE stellar spectra. <P />This work
was supported in part by grants PHY 02-16783 and PHY <P />08-22648:
Physics Frontiers Center / Joint Institute for Nuclear <P />Astrophysics
(JINA), awarded by the U.S. National Science Foundation.
---------------------------------------------------------
Title: Spectrophotometric Standard Stars for the Dark Energy Survey
Authors: Allyn Smith, J.; Allam, S. S.; Burke, D. L.; Butner, M. J.;
Deustua, S. E.; Allende Prieto, C.; Tucker, D. L.; DES Collaboration
2010AAS...21547008A Altcode: 2010BAAS...42..514A
The Dark Energy Survey (DES) will cover some 5000 square degrees
in the southern hemisphere. The survey will use a set of filters
which are derived from the SDSS ugriz set, but are different enough
in their passbands to require new standard stars for use by non-DES
observers. This is especially true for the DES -z and -Y bands. <P
/>We present a strategy to develop hydrogen envelope (DA) white
dwarfs stars as potential calibrators for the DES. We will discuss
the observational and modeling effort required to have a set of
well-characterized DAs that span the DES footprint prior to the start
of survey operations. These stars will be used to establish and monitor
the color zero points for the DES photometric system and can be used
to search for systematic errors in the color zero points over the
area (ra, dec) of the survey. These stars will also be used as some
of the primary standards for the DES photometric system which will
allow nightly atmospheric monitoring during DES operations.
---------------------------------------------------------
Title: Gaia spectroscopy: processing, performances and scientific
returns
Authors: Katz, D.; Cropper, M.; Meynadier, F.; Jean-Antoine, A.;
Allende Prieto, C.; Baker, S.; Benson, K.; Berthier, J.; Bigot, L.;
Blomme, R.; Boudreault, S.; Chemin, L.; Crifo, F.; Damerdji, Y.; David,
M.; David, P.; Delle Luche, C.; Dolding, C.; Frémat, Y.; Gerbier,
N.; Gerssen, J.; Gómez, A.; Gosset, E.; Guerrier, A.; Guy, L.;
Hall, D.; Hestroffer, D.; Huckle, H.; Jasniewicz, G.; Ludwig, H. -G.;
Martayan, C.; Morel, T.; Nguyen, A. -T.; Ocvirk, P.; Parr, C.; Royer,
F.; Sartoretti, P.; Seabroke, G.; Simon, E.; Smith, M.; Soubiran, C.;
Steinmetz, M.; Thévenin, F.; Turon, C.; Udry, S.; Veltz, L.; Viala, Y.
2010EAS....45..189K Altcode: 2011EAS....45..189K
During the five years of the mission, the Gaia spectrograph, the Radial
Velocity Spectrometer (RVS) will repeatedly survey the celestial sphere
down to magnitude V ~ 17-18. This talk presents: (i) the system which
is currently developed within the Gaia Data Processing and Analysis
Consortium (DPAC) to reduce and calibrate the spectra and to derive the
radial and rotational velocities, (ii) the RVS expected performances
and (iii) scientific returns.
---------------------------------------------------------
Title: PHASES: a concept for a satellite-borne ultra-precise
spectrophotometer
Authors: del Burgo, C.; Allende Prieto, C.; Peacocke, T.
2010JInst...5.1006D Altcode: 2010arXiv1001.1879D; 2010JInst..01.1006D
The Planet Hunting and Asteroseismology Explorer Spectrophotometer,
PHASES, is a concept for a space-borne instrument to obtain flux
calibrated spectra and measure micro-magnitude photometric variations
of nearby stars. The science drivers are the determination of the
physical properties of stars and the characterisation of planets
orbiting them, to very high precision. PHASES, intended to be housed in
a micro-satellite, consists of a 20 cm aperture modified Baker telescope
feeding two detectors: the tracking detector, with a field of 1 degree
square, and the science detector for performing spectrophotometry. The
optical design has been developed with the primary goal of avoiding
stray light on the science detector, while providing spectra in the
wavelength range 370-960 nm with a resolving power that ranges from ~
900 at 370 nm to ~ 200 at 960 nm. The signal to noise per resolution
element obtained for a V = 10 magnitude star in a 1 minute integration
varies between ~ 35 and 140. An analysis of the light curve constrains
the radii of the planets relative to their parent stars' radii,
which are, in turn, tightly constrained by the combination of absolute
spectrophotometry and trigonometric parallaxes. The provisional optical
design satisfies all the scientific requirements, including a ~ 1%
rms flux calibration strategy based on observations of bright A-type
stars and model atmospheres, allowing the determination of stellar
angular diameters for nearby solar-like stars to 0.5%. This level of
accuracy will be propagated to the stellar radii for the nearest stars,
with highly reliable Hipparcos parallaxes, and more significantly,
to the planetary radii.
---------------------------------------------------------
Title: Insight into the Formation of the Milky Way Through Cold Halo
Substructure. I. The ECHOS of Milky Way Formation
Authors: Schlaufman, Kevin C.; Rockosi, Constance M.; Allende Prieto,
Carlos; Beers, Timothy C.; Bizyaev, Dmitry; Brewington, Howard; Lee,
Young Sun; Malanushenko, Viktor; Malanushenko, Elena; Oravetz, Dan;
Pan, Kaike; Simmons, Audrey; Snedden, Stephanie; Yanny, Brian
2009ApJ...703.2177S Altcode: 2009arXiv0908.2627S
We identify 10—seven for the first time—elements of cold halo
substructure (ECHOS) in the volume within 17.5 kpc of the Sun in the
inner halo of the Milky Way. Our result is based on the observed spatial
and radial velocity distribution of metal-poor main-sequence turnoff
(MPMSTO) stars in 137 Sloan Extension for Galactic Understanding and
Exploration lines of sight. We point out that the observed radial
velocity distribution is consistent with a smooth stellar component
of the Milky Way's inner halo overall, but disagrees significantly
at the radial velocities that correspond to our detections. We show
that all of our detections are statistically significant and that we
expect no false positives. These ECHOS represent the observable stellar
debris of ancient merger events in the stellar accretion history of
the Milky Way, and we use our detections and completeness estimates
to infer a formal upper limit of 0.34<SUP>+0.02</SUP> <SUB>-0.02</SUB>
on the fraction of the MPMSTO population in the inner halo that belong
to ECHOS. Our detections and completeness calculations also suggest
that there is a significant population of low fractional overdensity
ECHOS in the inner halo, and we predict that 1/3 of the inner halo
(by volume) harbors ECHOS with MPMSTO star number densities n ≈ 15
kpc<SUP>-3</SUP>. In addition, we estimate that there are of order
10<SUP>3</SUP> ECHOS in the entire inner halo. ECHOS are likely older
than known surface brightness substructure, so our detections provide
us with a direct measure of the accretion history of the Milky Way
in a region and time interval that has yet to be fully explored. In
concert with previous studies, our result suggests that the level
of merger activity has been roughly constant over the past few Gyr
and that there has been no accretion of single stellar systems more
massive than a few percent of a Milky Way mass in that interval.
---------------------------------------------------------
Title: Granulation in K-type dwarf stars. II. Hydrodynamic simulations
and 3D spectrum synthesis
Authors: Ramírez, I.; Allende Prieto, C.; Koesterke, L.; Lambert,
D. L.; Asplund, M.
2009A&A...501.1087R Altcode: 2009arXiv0905.3101R
Aims: To explore the impact of surface inhomogeneities on stellar
spectra, granulation models need to be computed. Ideally, the most
fundamental characteristics of these models should be carefully
tested before applying them to the study of more practical matters,
such as the derivation of photospheric abundances. Our goal is to
analyze the particular case of a K-dwarf. <BR />Methods: We construct a
three-dimensional radiative-hydrodynamic model atmosphere of parameters
T_eff=4820 K, log g=4.5, and solar chemical composition. Using this
model and 3D spectrum synthesis, we computed a number of Fe i and Fe
ii line profiles. The observations presented in the first paper of this
series were used to test the model predictions. The effects of stellar
rotation and instrumental imperfections are carefully taken into account
in the synthesis of spectral lines. <BR />Results: The theoretical
line profiles show the typical signatures of granulation: the lines
are asymmetric, with their bisectors having a characteristic C-shape
and their core wavelengths shifted with respect to their laboratory
values. The line bisectors span from about 10 to 250 m s<SUP>-1</SUP>,
depending on line strength, with the stronger features showing larger
span. The corresponding core wavelength shifts range from about -200 m
s<SUP>-1</SUP> for the weak Fe i lines to almost +100 m s<SUP>-1</SUP>
in the strong Fe i features. Based on observational results for the Sun,
we argue that there should be no core wavelength shift for Fe i lines
of EW≳100 mÅ. The cores of the strongest lines show contributions
from the uncertain top layers of the model, where non-LTE effects
and the presence of the chromosphere, which are important in real
stars, are not accounted for. The Fe ii lines suffer from stronger
granulation effects due to their deeper formation depth which makes them
experience stronger temperature and velocity contrasts. For example,
the core wavelength shifts of the weakest Fe ii lines are about -600
m s<SUP>-1</SUP>. The comparison of model predictions to observed Fe
i line bisectors and core wavelength shifts for our reference star,
HIP 86 400, shows excellent agreement, with the exception of the core
wavelength shifts of the strongest features, for which we suspect
inaccurate theoretical values. Since this limitation does not affect
the predicted line equivalent widths significantly, we consider our
3D model validated for photospheric abundance work.
---------------------------------------------------------
Title: Halo Streams in the Seventh Sloan Digital Sky Survey Data
Release
Authors: Klement, R.; Rix, H. -W.; Flynn, C.; Fuchs, B.; Beers,
T. C.; Allende Prieto, C.; Bizyaev, D.; Brewington, H.; Lee, Y. S.;
Malanushenko, E.; Malanushenko, V.; Oravetz, D.; Pan, K.; Re Fiorentin,
P.; Simmons, A.; Snedden, S.
2009ApJ...698..865K Altcode: 2009arXiv0904.1003K
We have detected stellar halo streams in the solar neighborhood
using data from the seventh public data release of the Sloan Digital
Sky Survey (SDSS), which includes the directed stellar program Sloan
Extension For Galactic Understanding and Exploration (SEGUE). In order
to derive distances to each star, we used the metallicity-dependent
photometric parallax relation from Ivezić et al. We examine and
quantify the accuracy of this relation by applying it to a set of
globular and open clusters observed by the SDSS/SEGUE and comparing
the resulting sequence to the fiducial cluster sequences obtained by
An et al. Our final sample consists of 22,321 nearby (d <= 2 kpc),
metal-poor ([Fe/H] <=-0.5) main-sequence stars with six-dimensional
estimates of position and space velocity (\vec{r},\vec{v}). We
characterize the orbits of these stars through suitable kinematic
proxies for their "effective" integrals of motion, angular momentum,
eccentricity, and orbital polar angle and compare the observed
distribution to expectations from a smooth distribution in four
[Fe/H] bins. The metallicities provide an additional dimension in
parameter space that is well suited to distinguish tidal streams from
those of dynamical origin. On this basis, we identify at least five
significant "phase-space overdensities" of stars on very similar orbits
in the solar neighborhood to which we can assign unambiguously peaked
[Fe/H] distributions. Three of them have been identified previously,
including the halo stream discovered by Helmi et al. at a significance
level of σ = 12.0. In addition, we find at least two new genuine halo
streams, judged by their kinematics and [Fe/H], at σ = 2.9 and 4.8,
respectively. For one stream the stars even show coherence in the
configuration space, matching a spatial overdensity of stars found by
Juric et al. at (R, z) ≈ (9.5, 0.8) kpc. Our results demonstrate
the practical power of our search method to detect substructure in
the phase-space distribution of nearby stars without making a priori
assumptions about the detailed form of the gravitational potential.
---------------------------------------------------------
Title: New faint optical spectrophotometric standards: hot white
dwarfs from the Sloan Digital Sky Survey
Authors: Allende Prieto, Carlos; Hubeny, Ivan; Smith, J. Allyn
2009MNRAS.396..759A Altcode: 2009arXiv0903.2420A; 2009MNRAS.tmp..646A
The spectral energy distributions for pure-hydrogen (DA) hot white
dwarfs can be accurately predicted by model atmospheres. This makes
it possible to define spectrophotometric calibrators by scaling the
theoretical spectral shapes with broad-band photometric observations -
a strategy successfully exploited for the spectrographs onboard the
Hubble Space Telescope (HST) using three primary DA standards. Absolute
fluxes for non-DA secondary standards, introduced to increase the
density of calibrators in the sky, need to be referred to the primary
standards, but a far better solution would be to employ a network
of DA stars scattered throughout the sky. We search for blue objects
in the sixth data release of the Sloan Digital Sky Survey (SDSS) and
fit DA model fluxes to identify suitable candidates. Reddening needs
to be considered in the analysis of many of these stars. We propose
a list of nine pure-hydrogen white dwarfs with absolute fluxes with
estimated uncertainties below 3 per cent, including four objects with
estimated errors <2 per cent, as candidates for spectrophotometric
standards in the range 14 < g < 18, and provide model-based
fluxes scaled to match the SDSS broad-band fluxes for each. We apply
the same method to the three HST DA standards, linking the zero point
of their absolute fluxes to ugr magnitudes transformed from photometry
obtained with the US Naval Observatory 1-m telescope. For these stars,
we estimate uncertainties of <1 per cent in the optical, finding
good consistency with the fluxes adopted for HST calibration.
---------------------------------------------------------
Title: The Seventh Data Release of the Sloan Digital Sky Survey
Authors: Abazajian, Kevork N.; Adelman-McCarthy, Jennifer K.; Agüeros,
Marcel A.; Allam, Sahar S.; Allende Prieto, Carlos; An, Deokkeun;
Anderson, Kurt S. J.; Anderson, Scott F.; Annis, James; Bahcall,
Neta A.; Bailer-Jones, C. A. L.; Barentine, J. C.; Bassett, Bruce
A.; Becker, Andrew C.; Beers, Timothy C.; Bell, Eric F.; Belokurov,
Vasily; Berlind, Andreas A.; Berman, Eileen F.; Bernardi, Mariangela;
Bickerton, Steven J.; Bizyaev, Dmitry; Blakeslee, John P.; Blanton,
Michael R.; Bochanski, John J.; Boroski, William N.; Brewington,
Howard J.; Brinchmann, Jarle; Brinkmann, J.; Brunner, Robert J.;
Budavári, Tamás; Carey, Larry N.; Carliles, Samuel; Carr, Michael
A.; Castander, Francisco J.; Cinabro, David; Connolly, A. J.; Csabai,
István; Cunha, Carlos E.; Czarapata, Paul C.; Davenport, James R. A.;
de Haas, Ernst; Dilday, Ben; Doi, Mamoru; Eisenstein, Daniel J.;
Evans, Michael L.; Evans, N. W.; Fan, Xiaohui; Friedman, Scott D.;
Frieman, Joshua A.; Fukugita, Masataka; Gänsicke, Boris T.; Gates,
Evalyn; Gillespie, Bruce; Gilmore, G.; Gonzalez, Belinda; Gonzalez,
Carlos F.; Grebel, Eva K.; Gunn, James E.; Györy, Zsuzsanna; Hall,
Patrick B.; Harding, Paul; Harris, Frederick H.; Harvanek, Michael;
Hawley, Suzanne L.; Hayes, Jeffrey J. E.; Heckman, Timothy M.; Hendry,
John S.; Hennessy, Gregory S.; Hindsley, Robert B.; Hoblitt, J.; Hogan,
Craig J.; Hogg, David W.; Holtzman, Jon A.; Hyde, Joseph B.; Ichikawa,
Shin-ichi; Ichikawa, Takashi; Im, Myungshin; Ivezić, Željko;
Jester, Sebastian; Jiang, Linhua; Johnson, Jennifer A.; Jorgensen,
Anders M.; Jurić, Mario; Kent, Stephen M.; Kessler, R.; Kleinman,
S. J.; Knapp, G. R.; Konishi, Kohki; Kron, Richard G.; Krzesinski,
Jurek; Kuropatkin, Nikolay; Lampeitl, Hubert; Lebedeva, Svetlana; Lee,
Myung Gyoon; Lee, Young Sun; French Leger, R.; Lépine, Sébastien;
Li, Nolan; Lima, Marcos; Lin, Huan; Long, Daniel C.; Loomis, Craig P.;
Loveday, Jon; Lupton, Robert H.; Magnier, Eugene; Malanushenko, Olena;
Malanushenko, Viktor; Mandelbaum, Rachel; Margon, Bruce; Marriner,
John P.; Martínez-Delgado, David; Matsubara, Takahiko; McGehee,
Peregrine M.; McKay, Timothy A.; Meiksin, Avery; Morrison, Heather
L.; Mullally, Fergal; Munn, Jeffrey A.; Murphy, Tara; Nash, Thomas;
Nebot, Ada; Neilsen, Eric H., Jr.; Newberg, Heidi Jo; Newman, Peter
R.; Nichol, Robert C.; Nicinski, Tom; Nieto-Santisteban, Maria; Nitta,
Atsuko; Okamura, Sadanori; Oravetz, Daniel J.; Ostriker, Jeremiah P.;
Owen, Russell; Padmanabhan, Nikhil; Pan, Kaike; Park, Changbom; Pauls,
George; Peoples, John, Jr.; Percival, Will J.; Pier, Jeffrey R.; Pope,
Adrian C.; Pourbaix, Dimitri; Price, Paul A.; Purger, Norbert; Quinn,
Thomas; Raddick, M. Jordan; Re Fiorentin, Paola; Richards, Gordon
T.; Richmond, Michael W.; Riess, Adam G.; Rix, Hans-Walter; Rockosi,
Constance M.; Sako, Masao; Schlegel, David J.; Schneider, Donald P.;
Scholz, Ralf-Dieter; Schreiber, Matthias R.; Schwope, Axel D.; Seljak,
Uroš; Sesar, Branimir; Sheldon, Erin; Shimasaku, Kazu; Sibley, Valena
C.; Simmons, A. E.; Sivarani, Thirupathi; Allyn Smith, J.; Smith,
Martin C.; Smolčić, Vernesa; Snedden, Stephanie A.; Stebbins, Albert;
Steinmetz, Matthias; Stoughton, Chris; Strauss, Michael A.; SubbaRao,
Mark; Suto, Yasushi; Szalay, Alexander S.; Szapudi, István; Szkody,
Paula; Tanaka, Masayuki; Tegmark, Max; Teodoro, Luis F. A.; Thakar,
Aniruddha R.; Tremonti, Christy A.; Tucker, Douglas L.; Uomoto, Alan;
Vanden Berk, Daniel E.; Vandenberg, Jan; Vidrih, S.; Vogeley, Michael
S.; Voges, Wolfgang; Vogt, Nicole P.; Wadadekar, Yogesh; Watters,
Shannon; Weinberg, David H.; West, Andrew A.; White, Simon D. M.;
Wilhite, Brian C.; Wonders, Alainna C.; Yanny, Brian; Yocum, D. R.;
York, Donald G.; Zehavi, Idit; Zibetti, Stefano; Zucker, Daniel B.
2009ApJS..182..543A Altcode: 2008arXiv0812.0649A
This paper describes the Seventh Data Release of the Sloan Digital
Sky Survey (SDSS), marking the completion of the original goals of
the SDSS and the end of the phase known as SDSS-II. It includes 11,663
deg<SUP>2</SUP> of imaging data, with most of the ~2000 deg<SUP>2</SUP>
increment over the previous data release lying in regions of low
Galactic latitude. The catalog contains five-band photometry for 357
million distinct objects. The survey also includes repeat photometry
on a 120° long, 2fdg5 wide stripe along the celestial equator in
the Southern Galactic Cap, with some regions covered by as many as
90 individual imaging runs. We include a co-addition of the best of
these data, going roughly 2 mag fainter than the main survey over
250 deg<SUP>2</SUP>. The survey has completed spectroscopy over
9380 deg<SUP>2</SUP> the spectroscopy is now complete over a large
contiguous area of the Northern Galactic Cap, closing the gap that
was present in previous data releases. There are over 1.6 million
spectra in total, including 930,000 galaxies, 120,000 quasars, and
460,000 stars. The data release includes improved stellar photometry
at low Galactic latitude. The astrometry has all been recalibrated
with the second version of the USNO CCD Astrograph Catalog, reducing
the rms statistical errors at the bright end to 45 milliarcseconds
per coordinate. We further quantify a systematic error in bright
galaxy photometry due to poor sky determination; this problem is less
severe than previously reported for the majority of galaxies. Finally,
we describe a series of improvements to the spectroscopic reductions,
including better flat fielding and improved wavelength calibration at
the blue end, better processing of objects with extremely strong narrow
emission lines, and an improved determination of stellar metallicities.
---------------------------------------------------------
Title: A Unique Star in the Outer Halo of the Milky Way
Authors: Lai, David K.; Rockosi, Constance M.; Bolte, Michael;
Johnson, Jennifer A.; Beers, Timothy C.; Lee, Young Sun; Allende
Prieto, Carlos; Yanny, Brian
2009ApJ...697L..63L Altcode: 2009arXiv0904.4693L
As part of a program to measure abundance ratios in stars beyond 15 kpc
from the Galactic center, we have discovered a metal-poor star in the
outer halo with a unique chemical signature. We originally identified
it in the Sloan Extension for Galactic Understanding and Exploration
survey as a distant metal-poor star. We obtained a follow-up spectrum
using the Echelle Spectrometer and Imager at the Keck 2 telescope, and
measure [Fe/H] =-3.17, [Mg/Fe] = -0.10, and [Ca/Fe] = +1.11. This is
one of the largest over-abundances of Ca measured in any star to date;
the extremely low value of [Mg/Ca] = -1.21 is entirely unique. To have
found such an unusual star in our small sample of 27 targets suggests
that there may be previously unobserved classes of stars yet to be
found in situ in the Galactic halo. <P />The data presented herein
were obtained at the W.M. Keck Observatory, which is operated as a
scientific partnership among the California Institute of Technology,
the University of California and the National Aeronautics and Space
Administration. The Observatory was made possible by the generous
financial support of the W.M. Keck Foundation.
---------------------------------------------------------
Title: SEGUE: A Spectroscopic Survey of 240,000 Stars with g = 14-20
Authors: Yanny, Brian; Rockosi, Constance; Newberg, Heidi Jo; Knapp,
Gillian R.; Adelman-McCarthy, Jennifer K.; Alcorn, Bonnie; Allam,
Sahar; Allende Prieto, Carlos; An, Deokkeun; Anderson, Kurt S. J.;
Anderson, Scott; Bailer-Jones, Coryn A. L.; Bastian, Steve; Beers,
Timothy C.; Bell, Eric; Belokurov, Vasily; Bizyaev, Dmitry; Blythe,
Norm; Bochanski, John J.; Boroski, William N.; Brinchmann, Jarle;
Brinkmann, J.; Brewington, Howard; Carey, Larry; Cudworth, Kyle
M.; Evans, Michael; Evans, N. W.; Gates, Evalyn; Gänsicke, B. T.;
Gillespie, Bruce; Gilmore, Gerald; Nebot Gomez-Moran, Ada; Grebel, Eva
K.; Greenwell, Jim; Gunn, James E.; Jordan, Cathy; Jordan, Wendell;
Harding, Paul; Harris, Hugh; Hendry, John S.; Holder, Diana; Ivans,
Inese I.; Ivezič, Željko; Jester, Sebastian; Johnson, Jennifer
A.; Kent, Stephen M.; Kleinman, Scot; Kniazev, Alexei; Krzesinski,
Jurek; Kron, Richard; Kuropatkin, Nikolay; Lebedeva, Svetlana; Lee,
Young Sun; French Leger, R.; Lépine, Sébastien; Levine, Steve; Lin,
Huan; Long, Daniel C.; Loomis, Craig; Lupton, Robert; Malanushenko,
Olena; Malanushenko, Viktor; Margon, Bruce; Martinez-Delgado, David;
McGehee, Peregrine; Monet, Dave; Morrison, Heather L.; Munn, Jeffrey
A.; Neilsen, Eric H., Jr.; Nitta, Atsuko; Norris, John E.; Oravetz,
Dan; Owen, Russell; Padmanabhan, Nikhil; Pan, Kaike; Peterson, R. S.;
Pier, Jeffrey R.; Platson, Jared; Re Fiorentin, Paola; Richards,
Gordon T.; Rix, Hans-Walter; Schlegel, David J.; Schneider, Donald P.;
Schreiber, Matthias R.; Schwope, Axel; Sibley, Valena; Simmons, Audrey;
Snedden, Stephanie A.; Allyn Smith, J.; Stark, Larry; Stauffer, Fritz;
Steinmetz, M.; Stoughton, C.; SubbaRao, Mark; Szalay, Alex; Szkody,
Paula; Thakar, Aniruddha R.; Sivarani, Thirupathi; Tucker, Douglas;
Uomoto, Alan; Vanden Berk, Dan; Vidrih, Simon; Wadadekar, Yogesh;
Watters, Shannon; Wilhelm, Ron; Wyse, Rosemary F. G.; Yarger, Jean;
Zucker, Dan
2009AJ....137.4377Y Altcode: 2009arXiv0902.1781T; 2009arXiv0902.1781Y
The Sloan Extension for Galactic Understanding and Exploration (SEGUE)
Survey obtained ≈240,000 moderate-resolution (R ~ 1800) spectra from
3900 Å to 9000 Å of fainter Milky Way stars (14.0 < g < 20.3)
of a wide variety of spectral types, both main-sequence and evolved
objects, with the goal of studying the kinematics and populations of our
Galaxy and its halo. The spectra are clustered in 212 regions spaced
over three quarters of the sky. Radial velocity accuracies for stars
are \sigma (RV) \sim 4 \:km\; s^{-1} at g < 18, degrading to \sigma
(RV) \sim 15\:km\; s^{-1} at g ~ 20. For stars with signal-to-noise
ratio >10 per resolution element, stellar atmospheric parameters
are estimated, including metallicity, surface gravity, and effective
temperature. SEGUE obtained 3500 deg<SUP>2</SUP> of additional
ugriz imaging (primarily at low Galactic latitudes) providing precise
multicolor photometry (σ(g, r, i) ~ 2%), (σ(u, z) ~ 3%) and astrometry
(≈0farcs1) for spectroscopic target selection. The stellar spectra,
imaging data, and derived parameter catalogs for this survey are
publicly available as part of Sloan Digital Sky Survey Data Release 7.
---------------------------------------------------------
Title: The Runaway White Dwarf LP400-22 has a Companion
Authors: Kilic, Mukremin; Brown, Warren R.; Allende Prieto, Carlos;
Swift, B.; Kenyon, S. J.; Liebert, J.; Agüeros, M. A.
2009ApJ...695L..92K Altcode: 2009arXiv0903.1843K
We report the detection of a radial velocity companion to the extremely
low-mass white dwarf (WD) LP400-22. The radial velocity of the WD
shows variations with a semiamplitude of 119 km s<SUP>-1</SUP> and a
0.98776 day period, which implies a companion mass of M >= 0.37
M <SUB>sun</SUB>. The optical photometry rules out a main-sequence
companion. Thus the invisible companion is another WD or a neutron
star. Using proper-motion measurements and the radial velocity of the
binary system, we find that it has an unusual Galactic orbit. LP400-22
is moving away from the Galactic center with a velocity of 396 ± 43
km s<SUP>-1</SUP>, which is very difficult to explain by supernova
runaway ejection mechanisms. Dynamical interactions with a massive
black hole like that in the Galactic center can in principle explain
its peculiar velocity, if the progenitor was a triple star system
comprised of a close binary and a distant tertiary companion. Until
better proper motions become available, we consider LP400-22 to be
most likely a halo star with a very unusual orbit.
---------------------------------------------------------
Title: Computing Solar Absolute Fluxes
Authors: Allende Prieto, C.
2009ASSP....7..199A Altcode: 2009nqsa.conf..199A
Computed color indices and spectral shapes for individual stars are
routinely compared with observations for essentially all spectral
types, but absolute fluxes are rarely tested. We can confront observed
irradiances with the predictions from model atmospheres for a few stars
with accurate angular diameter measurements, notably the Sun. Previous
calculations have been hampered by inconsistencies and the use of
outdated atomic data and abundances. I provide here a progress report
on our current efforts to compute absolute fluxes for solar model
photospheres. Uncertainties in the solar composition constitute a
significant source of error in computing solar radiative fluxes.
---------------------------------------------------------
Title: The Hobby-Eberly Telescope Chemical Abundances of Stars in
the Halo (CASH) Project
Authors: Shetrone, Matthew D.; Frebel, A.; Allende Prieto, C.; Krugler,
J.; Sneden, C.; Beers, T.; Rhee, J.; Roederer, I.; Cowan, J. J.
2009AAS...21340811S Altcode: 2009BAAS...41Q.207S
The chemical evolution of the Galaxy and the early Universe is a key
topic in modern astrophysics. The most metal-poor Galactic halo stars
are now frequently used in an attempt to reconstruct the onset of
the chemical and dynamical formation processes of the Galaxy. These
stars are an easily-accessible local equivalent of the high-redshift
Universe, and can thus be used to carry out near-field cosmology. <P
/>In order to identify large numbers of metal-poor stars we started the
Hobby-Eberly Telescope Chemical Abundances of Stars in the Halo (CASH)
Project. This University of Texas Long Term Project aims at discovering
metal-poor Galactic halo stars selected from various surveys. We present
the results of the first two years of HET observations: Thus far, 400
metal-poor star are observed with the high-resolution spectrograph
-- the largest data base for these objects so far. Data reduction,
stellar parameter determination, and our automated analysis procedure
are presented. We also report the abundances found in our stars with
which we aim to establish the frequencies of chemically distinct
subgroups of metal-poor stars in the halo.
---------------------------------------------------------
Title: Photometric Calibrations for 21st Century Science
Authors: Kent, Stephen; Kaiser, Mary Beth; Deustua, Susana E.; Smith,
J. Allyn; Adelman, Saul; Allam, Sahar; Baptista, Brian; Bohlin, Ralph
C.; Clem, James L.; Conley, Alex; Edelstein, Jerry; Elias, Jay; Glass,
Ian; Henden, Arne; Howell, Steve; Kimble, Randy A.; Kruk, Jeffrey W.;
Lampton, Michael; Magnier, Eugene A.; McCandliss, Stephan R.; Moos,
Warren; Mostek, Nick; Mufson, Stuart; Oswalt, Terry D.; Perlmutter,
Saul; Allende Prieto, Carlos; Rauscher, Bernard J.; Riess, Adam;
Saha, Abhijit; Sullivan, Mark; Suntzeff, Nicholas; Tokunaga, Alan;
Tucker, Douglas; Wing, Robert; Woodgate, Bruce; Wright, Edward L.
2009astro2010S.155K Altcode: 2009arXiv0903.2799K
The answers to fundamental science questions in astrophysics, ranging
from the history of the expansion of the universe to the sizes of nearby
stars, hinge on our ability to make precise measurements of diverse
astronomical objects. As our knowledge of the underlying physics of
objects improves along with advances in detectors and instrumentation,
the limits on our capability to extract science from measurements is
set, not by our lack of understanding of the nature of these objects,
but rather by the most mundane of all issues: the precision with
which we can calibrate observations in physical units. We stress the
need for a program to improve upon and expand the current networks of
spectrophotometrically calibrated stars to provide precise calibration
with an accuracy of equal to and better than 1% in the ultraviolet,
visible and near-infrared portions of the spectrum, with excellent
sky coverage and large dynamic range.
---------------------------------------------------------
Title: Granulation across the HR diagram
Authors: Ramírez, I.; Allende Prieto, C.; Lambert, D. L.; Koesterke,
L.; Asplund, M.
2009MmSAI..80..618R Altcode: 2009arXiv0908.4571R
We have obtained ultra-high quality spectra (R=180,000; S/N>300)
with unprecedented wavelength coverage (4400 to 7400 Å) for a
number of stars covering most of the HR diagram in order to test the
predictions of models of stellar surface convection. Line bisectors
and core wavelength shifts are both measured and modeled, allowing
us to validate and/or reveal the limitations of state-of-the-art
hydrodynamic model atmospheres of different stellar parameters. We
show the status of our project and preliminary results.
---------------------------------------------------------
Title: Accounting for convective blue-shifts in the determination
of absolute stellar radial velocities.
Authors: Allende Prieto, C.; Koesterke, L.; Ramírez, I.; Ludwig,
H. -G.; Asplund, M.
2009MmSAI..80..622A Altcode: 2009arXiv0909.0470A
For late-type non-active stars, gravitational redshifts and convective
blueshifts are the main source of biases in the determination of
radial velocities. If ignored, these effects can introduce systematic
errors of the order of ∼ 0.5 km s<SUP>-1</SUP>. We demonstrate that
three-dimensional hydrodynamical simulations of solar surface convection
can be used to predict the convective blue-shifts of weak spectral
lines in solar-like stars to ∼ 0.070 km s<SUP>-1</SUP>. Using accurate
trigonometric parallaxes and stellar evolution models, the gravitational
redshifts can be constrained with a similar uncertainty, leading to
absolute radial velocities accurate to ∼ 0.1 km s<SUP>-1</SUP>.
---------------------------------------------------------
Title: The Lowest Metallicity Stars from SDSS/SEGUE
Authors: Beers, Timothy C.; Lee, Y. S.; Peruta, C.; Sivarani, T.;
Allende Prieto, C.; Aoki, W.; Carollo, D.; SDSS
2009AAS...21341612B Altcode: 2009BAAS...41..228B
The first extension of the Sloan Digital Sky Survey (SDSS-II),
which included the program SEGUE: Sloan Extension for Galactic
Understanding and Exploration, ended in July, 2008. This effort has
already produced the largest sample of medium-resolution stellar spectra
yet obtained. These data are revolutionizing our understanding of the
nature of the stellar populations of the Milky Way, in particular
that of the halo populations. <P />The SEGUE Stellar Parameter
Pipeline (SSPP) has obtained estimates of the atmospheric parameters
(T<SUB>eff</SUB>, log g, [Fe/H]) for more than half of the spectra to
date, totaling in excess of 200,000 stars (not all stars observed in
SDSS/SEGUE have colors that are amenable to definitive determination
of their atmospheric parameters). Here we report on the distribution
of stellar metallicity, [Fe/H], for stars in the SDSS/SEGUE database
with [Fe/H] < -2. This sample now exceeds 15,000 stars, more than
triple the number of such stars discovered by all previous surveys
combined. We also comment on the prospects for further increases in this
sample in the near future, from the next extension of SDSS (SDSS-III),
now underway, which includes a full year of SEGUE operation from July
2008 to July 2009, and additional "piggy back” observations of stars
taken during subsequent years. <P />This work was supported in part by
grants PHY 02-16783 and PHY 08-22648: Physics Frontiers Center / Joint
Institute for Nuclear Astrophysics (JINA), awarded by the U.S. National
Science Foundation.
---------------------------------------------------------
Title: Spectroscopic Properties of Granulation in K-type Dwarf Stars
Authors: Ramirez, Ivan; Allende Prieto, C.; Asplund, M.; Koesterke,
L.; Lambert, D. L.
2009AAS...21340601R Altcode: 2009BAAS...41..198R
The presence of surface convection in K-type dwarfs is revealed in very
high quality spectra of nine bright stars. The observed asymmetries and
wavelength shifts of the Fe I absorption line profiles are mainly due
to granulation. The bisectors of the strongest Fe I lines have a span
of about 100 m/s and the central wavelengths of the weakest Fe I lines
are shifted by up to -200 m/s. The blueshifts decrease for stronger Fe
I lines, but they become independent of line strength for equivalent
widths larger than about 100 mA. The detection of this "plateau"
in the velocity shifts of the strongest Fe I lines is necessary to
remove the non-negligible uncertainty introduced by granulation in the
determination of absolute radial velocities. Line profiles computed
using a 3D model atmosphere accurately reproduce the observations, with
statistical tests showing an agreement at the 95 % confidence level,
which validates the 3D model for spectroscopic studies of abundances
and fundamental parameters of K-dwarfs. We find that 3D effects reduce
the difference in the iron abundance determined separately from Fe II
and Fe I lines, which is about 0.15 dex for 1D models, by two thirds,
thus alleviating significantly the iron ionization imbalance problem in
K-dwarfs. However, the 3D iron abundances from Fe I lines show a small
dependence with excitation potential, similar to the 1D case, possibly
due to non-LTE effects that have not been taken into account. We also
find that the 3D correction to the effective temperatures of solar
metallicity K-dwarfs derived with the infrared flux method is about +30
K. Finally, we show that the 3D spectrum synthesis of molecular bands
greatly improves the agreement with the observational data compared
to the 1D analysis, which overestimates the abundances derived from
molecular features by a factor of 2.
---------------------------------------------------------
Title: Granulation in K-type dwarf stars. I. Spectroscopic
observations
Authors: Ramírez, I.; Allende Prieto, C.; Lambert, D. L.
2008A&A...492..841R Altcode: 2008arXiv0810.5247R
Aims: We seek to detect and quantify the effects of surface
convection (granulation) on the line spectra of K-dwarfs as a first
step towards a rigorous testing of hydrodynamic models for their
atmospheres. <BR />Methods: Very high-resolution (R≃160 000-210
000), high signal-to-noise ratio (S/N⪆300) spectra of nine bright
K-dwarfs were obtained with the 2dcoudé spectrograph on the 2.7 m
telescope at McDonald Observatory to determine wavelength shifts and
asymmetries of Fe i lines. Spectra of the same stars acquired with the
High Resolution Spectrograph (R≃120,000) on the 9.2 m Hobby Eberly
Telescope were used as radial velocity templates to calibrate the
wavelength scale of the 2dcoudé spectra. <BR />Results: The observed
shapes and positions of Fe i lines reveal asymmetries and wavelength
shifts that indicate the presence of granulation. In particular, line
bisectors show characteristic C-shapes while line core wavelengths are
blueshifted by an amount that increases with decreasing equivalent
width (EW). On average, Fe i line bisectors have a span that ranges
from nearly 0 for the weakest lines (residual core flux ⪆0.7) to
about 75 m s<SUP>-1</SUP> for the strongest lines (residual core flux
≃0.3), while wavelength shifts range from about -150 m s<SUP>-1</SUP>
in the weakest (EW≃10 mÅ) lines to 0 in the strongest (EW⪆100 mÅ)
features. A more detailed inspection of the bisectors and wavelength
shifts reveals star-to-star differences that are likely associated
with differences in stellar parameters, projected rotational velocity,
and stellar activity. While the first two are understood and confirmed
by our data, the relation to stellar activity, which is based on our
finding that the largest departures from the expected behavior are
seen in the most active stars, requires further investigation. For
the inactive, slow projected rotational velocity stars, we detect,
unequivocally, a plateau in the line-shifts at high EW values (EW⪆100
mÅ), a behavior that had been identified before only in the solar
spectrum. The detection of this plateau allows us to determine the
zero point of the convective blueshifts, which is useful to determine
absolute radial velocities. Thus, we are able to measure such velocities
with a mean uncertainty of about 60 m s<SUP>-1</SUP> for four of our
sample stars.
---------------------------------------------------------
Title: APOGEE: The Apache Point Observatory Galactic Evolution
Experiment
Authors: Allende Prieto, C.; Majewski, S. R.; Schiavon, R.; Cunha, K.;
Frinchaboy, P.; Holtzman, J.; Johnston, K.; Shetrone, M.; Skrutskie,
M.; Smith, V.; Wilson, J.
2008AN....329.1018A Altcode: 2008arXiv0809.2362A
APOGEE is a large-scale, NIR, high-resolution (R∼ 20 000)
spectroscopic survey of Galactic stars. It is one of the four
experiments in SDSS-III. Because APOGEE will observe in the H band,
where the extinction is six times smaller than in V, it will be
the first survey to pierce through Galactic dust and provide a vast,
uniform database of chemical abundances and radial velocities for stars
across all Galactic populations (bulge, disk, and halo). The survey
will be conducted with a dedicated, 300-fiber, cryogenic, spectrograph
that is being built at the University of Virginia, coupled to the
ARC 2.5-m telescope at Apache Point Observatory. APOGEE will use a
significant fraction of the SDSS-III bright time during a three-year
period to observe, at high signal-to-noise ratio (S/N> 100), about
100 000 giant stars selected directly from 2MASS down to a typical flux
limit of H<13. The main scientific objectives of APOGEE are: (1)
measuring unbiased metallicity distributions and abundance patterns for
the different Galactic stellar populations, (2) studying the processes
of star formation, feedback, and chemical mixing in the Milky Way, (3)
surveying the dynamics of the bulge and disk, placing constraints on
the nature and influence of the Galactic bar and spiral arms, and (4)
using extensive chemodynamical data, particularly in the inner Galaxy,
to unravel its formation and evolution.
---------------------------------------------------------
Title: Chemical abundances from the continuum
Authors: Allende Prieto, C.
2008PhST..133a4014A Altcode: 2008arXiv0809.2364A
The calculation of solar absolute fluxes in the near-UV is revisited,
discussing in some detail recent updates in theoretical calculations
of bound free opacity from metals. Modest changes in the abundances of
elements such as Mg and iron-peak elements have a significant impact
on atmospheric structure, and therefore self-consistent calculations
are necessary. With small adjustments to the solar photospheric
composition, we are able to reproduce fairly well the observed solar
fluxes between 200 and 270 nm, and between 300 and 420 nm, but find
too much absorption in the 270 290 nm window. A comparison between
our reference one-dimensional (1D) model and a 3D time-dependent
hydrodynamical simulation indicates that the continuum flux is only
weakly sensitive to 3D effects, with corrections reaching <10%
in the near-UV, and <2% in the optical.
---------------------------------------------------------
Title: Galactic Globular and Open Clusters in the Sloan Digital Sky
Survey. I. Crowded-Field Photometry and Cluster Fiducial Sequences
in ugriz
Authors: An, Deokkeun; Johnson, Jennifer A.; Clem, James L.; Yanny,
Brian; Rockosi, Constance M.; Morrison, Heather L.; Harding, Paul;
Gunn, James E.; Allende Prieto, Carlos; Beers, Timothy C.; Cudworth,
Kyle M.; Ivans, Inese I.; Ivezić, Željko; Lee, Young Sun; Lupton,
Robert H.; Bizyaev, Dmitry; Brewington, Howard; Malanushenko, Elena;
Malanushenko, Viktor; Oravetz, Dan; Pan, Kaike; Simmons, Audrey;
Snedden, Stephanie; Watters, Shannon; York, Donald G.
2008ApJS..179..326A Altcode: 2008arXiv0808.0001A
We present photometry for globular and open cluster stars observed
with the Sloan Digital Sky Survey (SDSS). In order to exploit the over
100 million stellar objects with r < 22.5 mag observed by SDSS,
we need to understand the characteristics of stars in the SDSS ugriz
filters. While star clusters provide important calibration samples
for stellar colors, the regions close to globular clusters, where
the fraction of field stars is smallest, are too crowded for the
standard SDSS photometric pipeline to process. To complement the
SDSS imaging survey, we reduce the SDSS imaging data for crowded
cluster fields using the DAOPHOT/ALLFRAME suite of programs and
present photometry for 17 globular clusters and three open clusters
in a SDSS value-added catalog. Our photometry and cluster fiducial
sequences are on the native SDSS 2.5 m ugriz photometric system, and
the fiducial sequences can be directly applied to the SDSS photometry
without relying on any transformations. Model photometry for red giant
branch and main-sequence stars obtained by Girardi et al. cannot be
matched simultaneously to fiducial sequences; their colors differ by
~0.02-0.05 mag. Good agreement (lesssim0.02 mag in colors) is found
with Clem et al. empirical fiducial sequences in u'g'r'i'z' when using
the transformation equations in Tucker et al.
---------------------------------------------------------
Title: Stellar Atmospheric Parameters: The Four-Step Program and
Gaia's Radial Velocity Spectrometer
Authors: Allende Prieto, Carlos
2008AIPC.1082...47A Altcode: 2008AIPC.1082...47P; 2008arXiv0810.4100A
The determination of atmospheric parameters is the first and most
fundamental step in the analysis of a stellar spectrum. Current and
forthcoming surveys involve samples of up to several million stars,
and therefore fully automated approaches are required to handle not
just data reduction but also the analysis, and in particular the
determination of atmospheric parameters. We propose that a successful
methodology needs, at the very least, to pass a series of consistency
tests that we dub the `four-step program'. This and related issues
are discussed in some detail in the context of the massive data set
to be obtained with the Radial Velocity Spectrometer onboard Gaia.
---------------------------------------------------------
Title: The SEGUE Stellar Parameter Pipeline. III. Comparison with
High-Resolution Spectroscopy of SDSS/SEGUE Field Stars
Authors: Allende Prieto, Carlos; Sivarani, Thirupathi; Beers,
Timothy C.; Lee, Young Sun; Koesterke, Lars; Shetrone, Matthew;
Sneden, Christopher; Lambert, David L.; Wilhelm, Ronald; Rockosi,
Constance M.; Lai, David K.; Yanny, Brian; Ivans, Inese I.; Johnson,
Jennifer A.; Aoki, Wako; Bailer-Jones, Coryn A. L.; Re Fiorentin, Paola
2008AJ....136.2070A Altcode: 2007arXiv0710.5780A
We report high-resolution spectroscopy of 125 field stars previously
observed as part of the Sloan Digital Sky Survey and its program for
Galactic studies, the Sloan Extension for Galactic Understanding
and Exploration (SEGUE). These spectra are used to measure radial
velocities and to derive atmospheric parameters, which we compare with
those reported by the SEGUE Stellar Parameter Pipeline (SSPP). The SSPP
obtains estimates of these quantities based on SDSS ugriz photometry and
low-resolution (R ~ 2000) spectroscopy. For F- and G-type stars observed
with high signal-to-noise ratios (S/Ns), we empirically determine
the typical random uncertainties in the radial velocities, effective
temperatures, surface gravities, and metallicities delivered by the SSPP
to be 2.4 km s<SUP>-1</SUP>, 130 K (2.2 %), 0.21 dex, and 0.11 dex,
respectively, with systematic uncertainties of a similar magnitude
in the effective temperatures and metallicities. We estimate random
errors for lower S/N based on numerical simulations. <P />Based on
observations obtained with the Hobby-Eberly Telescope (a joint project
of the University of Texas at Austin, Pennsylvania State University,
Stanford University, Ludwig-Maximilians-Universität München, and
Georg-August-Universität Göttingen), the W. M. Keck Observatory
(operated as a scientific partnership among the California Institute
of Technology, the University of California and NASA), and the Subaru
Telescope (operated by the National Astronomical Observatory of Japan).
---------------------------------------------------------
Title: Ground-Based Observations for Gaia (GBOG)
Authors: Soubiran, C.; Allende Prieto, C.; Altmann, M.; Bragaglia,
A.; Clementini, G.; Frémat, Y.; Heiter, U.; Joliet, E.; Pancino,
E.; Sartoretti, P.; Smart, R.; Thuillot, W.
2008sf2a.conf...35S Altcode:
This contribution gives an overview of the ground-based observing
efforts organized to collect the auxiliary data mandatory for the
calibrations and tests of the Gaia data processing.
---------------------------------------------------------
Title: The SEGUE Stellar Parameter Pipeline. I. Description and
Comparison of Individual Methods
Authors: Lee, Young Sun; Beers, Timothy C.; Sivarani, Thirupathi;
Allende Prieto, Carlos; Koesterke, Lars; Wilhelm, Ronald; Re Fiorentin,
Paola; Bailer-Jones, Coryn A. L.; Norris, John E.; Rockosi, Constance
M.; Yanny, Brian; Newberg, Heidi J.; Covey, Kevin R.; Zhang, Hao-Tong;
Luo, A. -Li
2008AJ....136.2022L Altcode: 2007arXiv0710.5645L
We describe the development and implementation of the Sloan Extension
for Galactic Exploration and Understanding (SEGUE) Stellar Parameter
Pipeline (SSPP). The SSPP is derived, using multiple techniques,
radial velocities, and the fundamental stellar atmospheric parameters
(effective temperature, surface gravity, and metallicity) for AFGK-type
stars, based on medium-resolution spectroscopy and ugriz photometry
obtained during the course of the original Sloan Digital Sky Survey
(SDSS-I) and its Galactic extension (SDSS-II/SEGUE). The SSPP also
provides spectral classification for a much wider range of stars,
including stars with temperatures outside the window where atmospheric
parameters can be estimated with the current approaches. This is Paper I
in a series of papers on the SSPP; it provides an overview of the SSPP,
and tests of its performance using several external data sets. Random
and systematic errors are critically examined for the current version
of the SSPP, which has been used for the sixth public data release of
the SDSS (DR-6).
---------------------------------------------------------
Title: The SEGUE Stellar Parameter Pipeline. II. Validation with
Galactic Globular and Open Clusters
Authors: Lee, Young Sun; Beers, Timothy C.; Sivarani, Thirupathi;
Johnson, Jennifer A.; An, Deokkeun; Wilhelm, Ronald; Allende Prieto,
Carlos; Koesterke, Lars; Re Fiorentin, Paola; Bailer-Jones, Coryn
A. L.; Norris, John E.; Yanny, Brian; Rockosi, Constance; Newberg,
Heidi J.; Cudworth, Kyle M.; Pan, Kaike
2008AJ....136.2050L Altcode: 2007arXiv0710.5778L
We validate the accuracy and precision of the current SEGUE (Sloan
Extension for Galactic Understanding and Exploration) Stellar Parameter
Pipeline (SSPP), which determines stellar atmospheric parameters
(effective temperature, surface gravity, and metallicity) and radial
velocities (RVs), by comparing these estimates for selected members of
three globular clusters (M 13, M 15, and M 2) and two open clusters
(NGC 2420 and M 67) to the literature values. Spectroscopic and
photometric data obtained during the course of the original Sloan
Digital Sky Survey (SDSS-I) and its first extension (SDSS-II/SEGUE)
are used to determine atmospheric parameter and RV estimates for stars
in these clusters. Based on the scatter in the metallicities derived
for the members of each cluster, we quantify the typical uncertainty
of the SSPP values, σ ([Fe/H]) = 0.13 dex for stars in the range of
-0.3 <= g - r <= 1.3 and 2.0 <= log g <= 5.0, at least over
the metallicity interval spanned by the clusters studied (-2.3 <=
[Fe/H] <= 0). The surface gravities and effective temperatures
derived by the SSPP are also compared with those estimated from the
comparison of color-magnitude diagrams with stellar evolution models;
we find satisfactory agreement (σ(T <SUB>eff</SUB>)< 200 K and
σ(log g) <= 0.4 dex).
---------------------------------------------------------
Title: The Variable Star One-shot Project, and its little child:
Wikimbad.
Authors: Foellmi, C.; Dall, T.; Pritchard, J.; Allende Prieto,
C.; Bruntt, H.; Amado, P. J.; Arentoft, T.; Baes, M.; Depagne, E.;
Fernandez, M.; Ivanov, V. D.; Koesterke, L.; Monaco, L.; O'Brien,
K.; Sarro, L. M.; Saviane, I.; Scharwaechter, J.; Schmidtobreick,
L.; Schütz, O.; Seifahrt, A.; Selman, F.; Stefanon, M.; Sterzik, M.
2008asvo.proc...15F Altcode: 2007arXiv0705.2136F
The Variable Star One-shot Project (VSOP) aimed at providing to
the world-wide stellar community the necessary one-shot spectrum of
unstudied variable stars, too often classified as such by an analysis
of photometric data only. The VSOP has established an new kind of
observational model, where all steps from observations to spectral
analysis, are automatized (or are underway to be fully automatized). The
project is centralized on a collaborative Wiki website. The VSOP
operational model is very successful, data are continuously flowing and
being analyzed, and VSOP is now a worldwide open collaboration of people
with very different and complementary skills and expertise. The idea of
a central Wiki website has been extended by one of us to propose a new
service to the whole astronomical community, called Wikimbad. Wikimbad
is an open Wiki website aimed at collecting, organizing and making
publicly available all kind of reduced and published astronomical
data. Its strengths and a comparison with the Virtual Observatory
are discussed.
---------------------------------------------------------
Title: Automated analysis of stellar spectra: application to the GAUDI
Authors: Solano, E.; Allende Prieto, C.
2008asvo.proc..109S Altcode:
In this paper we describe a methodology to be used for the automated
analysis of the spectroscopic contents of the GAUDI archive. We
perform chi-square minimisation in the 5000-5200 Å spectral
window to infer the atmospheric parameters and their random internal
uncertainties. Effective temperatures are anchored using a zero-point
correction into the scale defined by the method described in Ribas et
al. (2003). Surface gravities and metallicities were put in the scale
defined by nearby stars included in the S^{4}N archive. Comparison
with the Elodie.3 stellar library has shown excellent agreement. Our
final goal is to build a VO application, available from the Spanish
Virtual Observatory (SVO, http://svo.laeff.inta.es), to derive physical
parameters of large samples of stellar objects in an automated and
uniform way.
---------------------------------------------------------
Title: The Milky Way Tomography with SDSS. II. Stellar Metallicity
Authors: Ivezić, Željko; Sesar, Branimir; Jurić, Mario; Bond,
Nicholas; Dalcanton, Julianne; Rockosi, Constance M.; Yanny, Brian;
Newberg, Heidi J.; Beers, Timothy C.; Allende Prieto, Carlos;
Wilhelm, Ron; Lee, Young Sun; Sivarani, Thirupathi; Norris, John E.;
Bailer-Jones, Coryn A. L.; Re Fiorentin, Paola; Schlegel, David;
Uomoto, Alan; Lupton, Robert H.; Knapp, Gillian R.; Gunn, James E.;
Covey, Kevin R.; Allyn Smith, J.; Miknaitis, Gajus; Doi, Mamoru;
Tanaka, Masayuki; Fukugita, Masataka; Kent, Steve; Finkbeiner, Douglas;
Munn, Jeffrey A.; Pier, Jeffrey R.; Quinn, Tom; Hawley, Suzanne;
Anderson, Scott; Kiuchi, Furea; Chen, Alex; Bushong, James; Sohi,
Harkirat; Haggard, Daryl; Kimball, Amy; Barentine, John; Brewington,
Howard; Harvanek, Mike; Kleinman, Scott; Krzesinski, Jurek; Long,
Dan; Nitta, Atsuko; Snedden, Stephanie; Lee, Brian; Harris, Hugh;
Brinkmann, Jonathan; Schneider, Donald P.; York, Donald G.
2008ApJ...684..287I Altcode: 2008arXiv0804.3850I
Using effective temperature and metallicity derived from SDSS
spectra for ~60,000 F- and G-type main-sequence stars (0.2 <
g - r < 0.6), we develop polynomial models for estimating these
parameters from the SDSS u - g and g - r colors. These photometric
estimates have similar error properties as those determined from SDSS
spectra. We apply this method to SDSS photometric data for over 2
million F/G stars and measure the unbiased metallicity distribution
for a complete volume-limited sample of stars at distances between
500 pc and 8 kpc. The metallicity distribution can be exquisitely
modeled using two components with a spatially varying number ratio,
which correspond to disk and halo. The two components also possess
the kinematics expected for disk and halo stars. The metallicity
of the halo component is spatially invariant, while the median disk
metallicity smoothly decreases with distance from the Galactic plane
from -0.6 at 500 pc to -0.8 beyond several kiloparsecs. The absence of
a correlation between metallicity and kinematics for disk stars is in a
conflict with the traditional decomposition in terms of thin and thick
disks. We detect coherent substructures in the kinematics-metallicity
space, such as the Monoceros stream, which rotates faster than the LSR,
and has a median metallicity of [Fe/H] = -0.95, with an rms scatter of
only ~0.15 dex. We extrapolate our results to the performance expected
from the Large Synoptic Survey Telescope (LSST) and estimate that LSST
will obtain metallicity measurements accurate to 0.2 dex or better,
with proper-motion measurements accurate to ~0.5 mas yr<SUP>-1</SUP>,
for about 200 million F/G dwarf stars within a distance limit of ~100
kpc (g < 23.5).
---------------------------------------------------------
Title: VSOP: Fixing the variable sky with one-shot typing of
neglected variables
Authors: Dall, Thomas; Labrie, Kathleen; Nitta, Atsuko; Beers,
Tim; Koesterke, Lars; Bruntt, Hans; Kiss, Laszlo; Allende Prieto,
Carlos; Arentoft, Torben; Amado, Pedro; Baes, Maarten; Depagne, Eric;
Fernandez, Matilde; Foellmi, Cedric; Ivanov, Valentin; Lo Curto,
Gaspare; Monaco, Lorenzo; O'Brien, Kieran; Pritchard, John; Sarro,
Luis Manuel; Saviane, Ivo; Scharwaechter, Julia; Schmidtobreick, Linda;
Schuetz, Oliver; Seifahrt, Andreas; Selman, Fernando; Stefanon, Mauro;
Sterzik, Michael
2008noao.prop...95D Altcode:
Stellar variability types are assigned on the basis of lightcurve
appearance, which often remains unchallenged without further
observational evidence. VSOP (Variable Star One-shot Project) is a large
international collaboration, which has so far obtained spectra of more
than 800 stars during the past two years. Operationally this program
is a completely new concept, perfectly suited for a modern, efficient
observatory, providing Gemini with a large pool of filler observations,
and we ask specifically to be placed in Band 3. Scientifically, our
aims are: (1) obtain first spectroscopy of all unstudied variable
stars in both hemispheres, (2) provide data products to the public
in a fast and automatic way, (3) generate an influx of serendipitous
discoveries across all fields of astrophysics.
---------------------------------------------------------
Title: The Hobby-Eberly Telescope Chemical Abundances of Stars in
the Halo CASH Project I. Observations of the First Year
Authors: Frebel, A.; Allende Prieto, C.; Roederer, I. U.; Shetrone,
M.; Rhee, J.; Sneden, C.; Beers, T. C.; Cowan, J. J.
2008ASPC..393..203F Altcode:
We present preliminary results obtained from the first year of
observations of a new, long-term project of the University of Texas,
the Hobby-Eberly Telescope Chemical Abundances of Stars in the Halo
(CASH) Project.
---------------------------------------------------------
Title: The Hobby-Eberly Telescope Chemical Abundances of Stars in
the Halo (CASH) Project III. Abundance Analysis of Three Bright
Hamburg/ESO Survey Stars
Authors: Davies, L. A.; Frebel, A.; Cowan, J. J.; Allende Prieto,
C.; Sneden, C.
2008ASPC..393..187D Altcode:
We present an abundance analysis of three newly discovered stars from
the Hamburg/ESO survey for which HET observations have been obtained
as part of the CASH project. Light elemental abundances of all three
stars agree with those of other metal-poor stars. This means that
they likely formed from well-mixed gas. Upper limits on the heavier
neutron-capture abundances have not eliminated the possibility that
these stars are r-process enhanced. However, the measured barium
abundances are rather low.
---------------------------------------------------------
Title: The Hobby-Eberly Telescope Chemical Abundances of Stars in
the Halo CASH Project II. The Li-, r- and s-Enhanced Metal-Poor
Giant ligiant
Authors: Frebel, A.; Roederer, I. U.; Shetrone, M.; Allende Prieto,
C.; Rhee, J.; Gallino, R.; Bisterzo, S.; Sneden, C.; Beers, T. C.;
Cowan, J. J.
2008ASPC..393..207F Altcode:
We present the first detailed abundance analysis of the metal-poor
giant ligiant. This star was observed as part of the University of Texas
Long-Term Chemical Abundances of Stars in the Halo (CASH) Project. We
find that this metal-poor ([Fe/H] =-2.2) star has an unusually high
lithium abundance (log ɛ (Li)= +2.1), mild carbon ([C/Fe] =+0.7) and
sodium ([Na/Fe] =+0.6) enhancement, as well as enhancement of both
spro ([Ba/Fe] =+0.8) and rpro ([Eu/Fe] =+0.5) material. The high Li
abundance can be explained by self-enrichment through extra mixing
mechanisms. If so, ligiant is the most metal-poor star in which this
short-lived phase of Li enrichment has been observed. The r- and spro
material was not produced in this star but was either present in the
gas from which ligiant formed or was transferred to it from a more
massive binary companion. Despite the current non-detection of radial
velocity variations (over a time span of ∼180 days), it is possible
that ligiant is in a long-period binary system, similar to other stars
with both r and s enrichment.
---------------------------------------------------------
Title: Signatures of Granulation in the Spectra of K-Dwarfs
Authors: Ramírez, I.; Allende Prieto, C.; Lambert, D. L.; Asplund, M.
2008ASPC..393..255R Altcode: 2007arXiv0712.0387R
Very high resolution (R>150,000) spectra of a small sample of
nearby K-dwarfs have been acquired to measure the line asymmetries
and central wavelength shifts caused by convective motions present
in stellar photospheres. This phenomenon of granulation is modeled
by 3D hydrodynamical simulations but they need to be confronted with
accurate observations to test their realism before they are used in
stellar abundance studies. We find that the line profiles computed
with a 3D model agree reasonably well with the observations. The line
bisectors and central wavelength shifts on K-dwarf spectra have a
maximum amplitude of only about 200 m s<SUP>-1</SUP> and we have been
able to resolve these granulation effects with a very careful observing
strategy. By computing a number of iron lines with 1D and 3D models
(assuming local thermodynamic equilibrium), we find that the impact of
3D-LTE effects on classical iron abundance determinations is negligible.
---------------------------------------------------------
Title: The Hobby-Eberly Telescope Chemical Abundances of Stars in the
Halo (CASH) Project. I. The Lithium-, s-, and r-enhanced Metal-poor
Giant HKII 17435-00532
Authors: Roederer, Ian U.; Frebel, Anna; Shetrone, Matthew D.;
Allende Prieto, Carlos; Rhee, Jaehyon; Gallino, Roberto; Bisterzo,
Sara; Sneden, Christopher; Beers, Timothy C.; Cowan, John J.
2008ApJ...679.1549R Altcode: 2008arXiv0802.3701R
We present the first detailed abundance analysis of the metal-poor giant
HKII 17435-00532. This star was observed as part of the University
of Texas long-term project Chemical Abundances of Stars in the Halo
(CASH). A spectrum was obtained with the High Resolution Spectrograph
(HRS) on the Hobby-Eberly Telescope with a resolving power of R ~
15,000. Our analysis reveals that this star may be located on the
red giant branch, red horizontal branch, or early asymptotic giant
branch. We find that this metal-poor ([Fe/H] = - 2.2) star has an
unusually high lithium abundance [log ɛ (Li) = + 2.1], mild carbon
([C/Fe] = + 0.7) and sodium ([Na/Fe] = + 0.6) enhancement, as well
as enhancement of both s-process ([Ba/Fe] = + 0.8) and r-process
([Eu/Fe] = + 0.5) material. The high Li abundance can be explained
by self-enrichment through extra mixing that connects the convective
envelope with the outer regions of the H-burning shell. If so, HKII
17435-00532 is the most metal-poor star in which this short-lived phase
of Li enrichment has been observed. The Na and n-capture enrichment
can be explained by mass transfer from a companion that passed through
the thermally pulsing AGB phase of evolution with only a small initial
enrichment of r-process material present in the birth cloud. Despite
the current nondetection of radial velocity variations (over ~180
days), it is possible that HKII 17435-00532 is in a long-period or
highly inclined binary system, similar to other stars with similar
n-capture enrichment patterns. <P />Based on observations obtained
with the Hobby-Eberly Telescope, which is a joint project of the
University of Texas at Austin, the Pennsylvania State University,
Stanford University, Ludwig-Maximilians-Universität München, and
Georg-August-Universität Göttingen.
---------------------------------------------------------
Title: Center-to-Limb Variation of Solar Three-dimensional
Hydrodynamical Simulations
Authors: Koesterke, L.; Allende Prieto, C.; Lambert, D. L.
2008ApJ...680..764K Altcode: 2008arXiv0802.2177K
We examine closely the solar center-to-limb variation of continua
and lines and compare observations with predictions from both a
three-dimensional (3D) hydrodynamic simulation of the solar surface
(provided by M. Asplund and collaborators) and one-dimensional (1D)
model atmospheres. Intensities from the 3D time series are derived by
means of the new synthesis code ASSepsilonT, which overcomes limitations
of previously available codes by including a consistent treatment of
scattering and allowing for arbitrarily complex line and continuum
opacities. In the continuum, we find very similar discrepancies between
synthesis and observation for both types of model atmospheres. This
is in contrast to previous studies that used a "horizontal" and
time-averaged representation of the 3D model and found a significantly
larger disagreement with observations. The presence of temperature and
velocity fields in the 3D simulation provides a significant advantage
when it comes to reproducing solar spectral line shapes. Nonetheless,
a comparison of observed and synthetic equivalent widths reveals that
the 3D model also predicts more uniform abundances as a function
of position angle on the disk. We conclude that the 3D simulation
provides not only a more realistic description of the gas dynamics,
but despite its simplified treatment of the radiation transport, it
also predicts reasonably well the observed center-to-limb variation,
which is indicative of a thermal structure free from significant
systematic errors.
---------------------------------------------------------
Title: The Abundances of Oxygen and Carbon in the Solar Photosphere
Authors: Allende Prieto, C.
2008ASPC..384...39A Altcode: 2008csss...14...39P; 2007astro.ph..2429A
A series of recent studies has placed the best estimates of the
photospheric abundances of carbon and oxygen at log ɛ =8.39
and 8.66, respectively. These values are ∼ 40 % lower than
earlier estimates. A coalition of corrections due to the adoption
of an improved model atmosphere, updated atomic data and non-LTE
corrections, and a reevaluation of the effect of blending features,
is responsible for the change. The adopted hydrodynamical model of
the solar surface is an important element to the update, but using a
theoretical 1D model atmosphere leads to an average oxygen abundance
modestly increased by 0.09 dex, and a carbon abundance only 0.02 dex
higher. Considering a state-of-the-art 3D hydrodynamical model of the
solar surface yields consistent results from different sets of atomic
and molecular lines. Systematic errors are likely to dominate the final
uncertainties, but the available information indicates they are limited
to <0.1 dex. The new abundances are closer to expectations based on
the compositions of other nearby objects, although a fully consistent
picture, considering galactic chemical evolution and diffusion at the
bottom of the solar convection zone, is still lacking.
---------------------------------------------------------
Title: The Lithium-, r- and s-Enhanced Metal-Poor Giant HK-II
17435-00532
Authors: Roederer, Ian U.; Frebel, Anna; Shetrone, Matthew; Allende
Prieto, Carlos; Rhee, Jaehyon; Gallino, Roberto; Bisterzo, Sara;
Sneden, Christopher; Beers, Timothy C.; Cowan, John J.
2008AIPC.1001..169R Altcode:
We present the first detailed abundance analysis of the metal-poor
giant HK-II 17435-00532. This star was observed as part of the
University of Texas Long-Term Chemical Abundances of Stars in the Halo
(CASH) Project. A spectrum was obtained with the High Resolution
Spectrograph (HRS) on the Hobby-Eberly Telescope with a resolving
power of R~15000. Our analysis reveals that this star may be located
on the red giant branch, red horizontal branch, or early asymptotic
giant branch. We find that this metal-poor ([Fe/H] = -2.2) star has an
unusually high lithium abundance (logɛ(Li) = +2.1), mild carbon ([C/Fe]
= +0.7) and sodium ([Na/Fe] = +0.6) enhancement, as well as enhancement
of both s-process ([Ba/Fe] = +0.8) and r-process ([Eu/Fe] = +0.5)
material. The high Li abundance can be explained by self-enrichment
through extra mixing mechanisms that connect the convective envelope
with the outer regions of the H-burning shell. If so, HK-II 17435-00532
is the most metal-poor starin which this short-lived phase of Li
enrichment has been observed. The r- and s-process material was not
produced in this star but was either present in the gas from which
HK-II 17435-00532 formed or was transferred to it from a more massive
binary companion. Despite the current non-detection of radial velocity
variations (over a time span of ~180 days), it is possible that HK-II
17435-00532 is in a long-period binary system, similar to other stars
with both r and s enrichment.
---------------------------------------------------------
Title: The Sixth Data Release of the Sloan Digital Sky Survey
Authors: Adelman-McCarthy, Jennifer K.; Agüeros, Marcel A.; Allam,
Sahar S.; Allende Prieto, Carlos; Anderson, Kurt S. J.; Anderson,
Scott F.; Annis, James; Bahcall, Neta A.; Bailer-Jones, C. A. L.;
Baldry, Ivan K.; Barentine, J. C.; Bassett, Bruce A.; Becker, Andrew
C.; Beers, Timothy C.; Bell, Eric F.; Berlind, Andreas A.; Bernardi,
Mariangela; Blanton, Michael R.; Bochanski, John J.; Boroski,
William N.; Brinchmann, Jarle; Brinkmann, J.; Brunner, Robert J.;
Budavári, Tamás; Carliles, Samuel; Carr, Michael A.; Castander,
Francisco J.; Cinabro, David; Cool, R. J.; Covey, Kevin R.; Csabai,
István; Cunha, Carlos E.; Davenport, James R. A.; Dilday, Ben; Doi,
Mamoru; Eisenstein, Daniel J.; Evans, Michael L.; Fan, Xiaohui;
Finkbeiner, Douglas P.; Friedman, Scott D.; Frieman, Joshua A.;
Fukugita, Masataka; Gänsicke, Boris T.; Gates, Evalyn; Gillespie,
Bruce; Glazebrook, Karl; Gray, Jim; Grebel, Eva K.; Gunn, James
E.; Gurbani, Vijay K.; Hall, Patrick B.; Harding, Paul; Harvanek,
Michael; Hawley, Suzanne L.; Hayes, Jeffrey; Heckman, Timothy M.;
Hendry, John S.; Hindsley, Robert B.; Hirata, Christopher M.; Hogan,
Craig J.; Hogg, David W.; Hyde, Joseph B.; Ichikawa, Shin-ichi;
Ivezić, Željko; Jester, Sebastian; Johnson, Jennifer A.; Jorgensen,
Anders M.; Jurić, Mario; Kent, Stephen M.; Kessler, R.; Kleinman,
S. J.; Knapp, G. R.; Kron, Richard G.; Krzesinski, Jurek; Kuropatkin,
Nikolay; Lamb, Donald Q.; Lampeitl, Hubert; Lebedeva, Svetlana; Lee,
Young Sun; French Leger, R.; Lépine, Sébastien; Lima, Marcos; Lin,
Huan; Long, Daniel C.; Loomis, Craig P.; Loveday, Jon; Lupton, Robert
H.; Malanushenko, Olena; Malanushenko, Viktor; Mandelbaum, Rachel;
Margon, Bruce; Marriner, John P.; Martínez-Delgado, David; Matsubara,
Takahiko; McGehee, Peregrine M.; McKay, Timothy A.; Meiksin, Avery;
Morrison, Heather L.; Munn, Jeffrey A.; Nakajima, Reiko; Neilsen,
Eric H., Jr.; Newberg, Heidi Jo; Nichol, Robert C.; Nicinski, Tom;
Nieto-Santisteban, Maria; Nitta, Atsuko; Okamura, Sadanori; Owen,
Russell; Oyaizu, Hiroaki; Padmanabhan, Nikhil; Pan, Kaike; Park,
Changbom; Peoples, John, Jr.; Pier, Jeffrey R.; Pope, Adrian C.;
Purger, Norbert; Raddick, M. Jordan; Re Fiorentin, Paola; Richards,
Gordon T.; Richmond, Michael W.; Riess, Adam G.; Rix, Hans-Walter;
Rockosi, Constance M.; Sako, Masao; Schlegel, David J.; Schneider,
Donald P.; Schreiber, Matthias R.; Schwope, Axel D.; Seljak, Uroš;
Sesar, Branimir; Sheldon, Erin; Shimasaku, Kazu; Sivarani, Thirupathi;
Allyn Smith, J.; Snedden, Stephanie A.; Steinmetz, Matthias; Strauss,
Michael A.; SubbaRao, Mark; Suto, Yasushi; Szalay, Alexander S.;
Szapudi, István; Szkody, Paula; Tegmark, Max; Thakar, Aniruddha R.;
Tremonti, Christy A.; Tucker, Douglas L.; Uomoto, Alan; Vanden Berk,
Daniel E.; Vandenberg, Jan; Vidrih, S.; Vogeley, Michael S.; Voges,
Wolfgang; Vogt, Nicole P.; Wadadekar, Yogesh; Weinberg, David H.;
West, Andrew A.; White, Simon D. M.; Wilhite, Brian C.; Yanny, Brian;
Yocum, D. R.; York, Donald G.; Zehavi, Idit; Zucker, Daniel B.
2008ApJS..175..297A Altcode: 2007arXiv0707.3413A
This paper describes the Sixth Data Release of the Sloan Digital Sky
Survey. With this data release, the imaging of the northern Galactic cap
is now complete. The survey contains images and parameters of roughly
287 million objects over 9583 deg<SUP>2</SUP>, including scans over
a large range of Galactic latitudes and longitudes. The survey also
includes 1.27 million spectra of stars, galaxies, quasars, and blank
sky (for sky subtraction) selected over 7425 deg<SUP>2</SUP>. This
release includes much more stellar spectroscopy than was available in
previous data releases and also includes detailed estimates of stellar
temperatures, gravities, and metallicities. The results of improved
photometric calibration are now available, with uncertainties of
roughly 1% in g, r, i, and z, and 2% in u, substantially better than
the uncertainties in previous data releases. The spectra in this data
release have improved wavelength and flux calibration, especially
in the extreme blue and extreme red, leading to the qualitatively
better determination of stellar types and radial velocities. The
spectrophotometric fluxes are now tied to point-spread function
magnitudes of stars rather than fiber magnitudes. This gives more robust
results in the presence of seeing variations, but also implies a change
in the spectrophotometric scale, which is now brighter by roughly 0.35
mag. Systematic errors in the velocity dispersions of galaxies have
been fixed, and the results of two independent codes for determining
spectral classifications and redshifts are made available. Additional
spectral outputs are made available, including calibrated spectra from
individual 15 minute exposures and the sky spectrum subtracted from
each exposure. We also quantify a recently recognized underestimation
of the brightnesses of galaxies of large angular extent due to poor sky
subtraction; the bias can exceed 0.2 mag for galaxies brighter than r =
14 mag.
---------------------------------------------------------
Title: Revised Parameter Estimates For The Most Metal-Poor Candidates
In SDSS-I And SEGUE
Authors: Krugler, Julie A.; Beers, T. C.; Lee, Y. S.; Sivarani, T.;
Marsteller, B.; Wilhelm, R.; Allende Prieto, C.; Frebel, A.; Norris,
J. E.; Johnson, J.; Ivans, I.; Yanny, B.; Rockosi, C.; Morrison, H.;
Newberg, H. J.; Knapp, J.
2008AIPC..990..151K Altcode:
There are several hundred thousand R = 2000 stellar spectra reported in
the final public release of the Sloan Digital Sky Survey (SDSS-I) and
the continuing project SEGUE (Sloan Extension for Galactic Exploration
and Understanding), which has completed roughly half of its scheduled
set of observations to date. <P />The stars in this sample were
targeted for a wide variety of reasons, and hence do not represent a
sample from which an unbiased metallicity distribution function (MDF)
of stars in the halo or thick-disk populations may be drawn. However,
there exist over 6500 stars with estimated metallicities [Fe/H]<-2.0
and effective temperatures in the range 4500 K<Teff<7000 K among
this sample, based on application of the SDSS/SEGUE spectroscopic
parameter analysis pipeline. We have continued to refine estimates of
the stellar parameters for these stars, using an automated synthetic
spectrum approach, autoMOOG. This technique produces estimates of
[Fe/H] as well as [C/Fe] (or upper limits on these quantities) based
on MOOG syntheses of the region of spectrum around the CaII K line
and the CH G band, respectively. <P />This sample represents, by a
factor of more than three, the largest database of very metal-poor
stars yet assembled. A least 1000 of these stars have g<16.5,
and hence are amenable to high-resolution spectroscopic studies with
presently available large-aperture telescopes.
---------------------------------------------------------
Title: The Century Survey Galactic Halo Project III: A Complete
4300 DEG<SUP>2</SUP> Survey of Blue Horizontal Branch Stars in the
Metal-Weak Thick Disk and Inner Halo
Authors: Brown, Warren R.; Beers, Timothy C.; Wilhelm, Ronald;
Allende Prieto, Carlos; Geller, Margaret J.; Kenyon, Scott J.; Kurtz,
Michael J.
2008AJ....135..564B Altcode: 2007arXiv0711.2886B
We present a complete spectroscopic survey of 2414 2MASS-selected blue
horizontal branch (BHB) candidates selected over 4300 deg<SUP>2</SUP>
of the sky. We identify 655 BHB stars in this non-kinematically
selected sample. We calculate the luminosity function of field BHB
stars, and find evidence for very few hot BHB stars in the field. The
BHB stars located at a distance from the Galactic plane |Z| <
4 kpc trace what is clearly a metal-weak thick disk population, with
a mean metallicity of [Fe/H] = -1.7, a rotation velocity gradient of
dv<SUB>rot</SUB>/d|Z| = -28 ± 3.4 km s<SUP>-1</SUP> in the region |Z|
< 6 kpc, and a density scale height of h<SUB>Z</SUB> = 1.26 ± 0.1
kpc. The BHB stars located at 5 < |Z| < 9 kpc are a predominantly
inner-halo population, with a mean metallicity of [Fe/H] = -2.0 and
a mean Galactic rotation of -4 ± 31 km s<SUP>-1</SUP>. We infer the
density of halo and thick disk BHB stars is 104 ± 37 kpc<SUP>-3</SUP>
near the Sun, and the relative normalization of halo to thick-disk
BHB stars is 4 ± 1% near the Sun.
---------------------------------------------------------
Title: A dedicated northern search for the first stars
Authors: Beers, Timothy; Norris, John; Allende Prieto, Carlos;
Aoki, Wako; Asplund, Martin; Bessell, Michael; Christlieb, Norbert;
Frebel, Anna; Johnson, Jennifer; Melendez, Jorge; Sneden, Christopher;
Yong, David
2008noao.prop..179B Altcode:
We propose to continue a northern sky program using high resolution,
moderate S/N spectra to discover the chemically oldest stars - ultra
metal-poor dwarfs and giants drawn from the Hamburg/ESO and SEGUE
surveys. With these data we seek to (1) discover more stars with [Fe/H]
< -4.0 (only three of which are known and all of which our group
has discovered) to constrain the nature of the first stars; (2) measure
the Li abundance for more stars with [Fe/H] < -4.0, to investigate
further the non-detection on this element in the subgiant HE1327-2326
([Fe/H] = -5.4) and its implication for Big Bang Nucleosynthesis;
and (3) discover further r-process enhanced metal-poor stars with
detectable Th and U, for cosmo-chronometric age determinations.
---------------------------------------------------------
Title: VSOP: Fixing the variable sky with one-shot typing of
neglected variables
Authors: Dall, Thomas; Labrie, Kathleen; Nitta, Atsuko; Beers,
Tim; Allende Prieto, Carlos; Koesterke, Lars; Bruntt, Hans; Kiss,
Laszlo; Arentoft, Torben; Amado, Pedro; Baes, Maarten; Depagne, Eric;
Fernandez, Matilde; Foellmi, Cedric; Ivanov, Valentin; Lo Curto,
Gaspare; Monaco, Lorenzo; O'Brien, Kieran; Pritchard, John; Sarro,
Luis Manuel; Saviane, Ivo; Scharwaechter, Julia; Schmidtobreick, Linda;
Schuetz, Oliver; Seifahrt, Andreas; Selman, Fernando; Stefanon, Mauro;
Sterzik, Michael
2008noao.prop..151D Altcode:
Stellar variability types are assigned on the basis of lightcurve
appearance, which often remains unchallenged without further
observational evidence. VSOP (Variable Star One-shot Project) is a
large international collaboration, which has so far obtained spectra of
more than 500 stars during the past year. Operationally this program
is a completely new concept, perfectly suited for a modern, efficient
observatory, providing Gemini with a large pool of filler observations,
and we ask specifically to be placed in Band 3. Scientifically, our
aims are: (1) obtain first spectroscopy of all unstudied variable
stars in both hemispheres, (2) provide data products to the public
in a fast and automatic way, (3) generate an influx of serendipitous
discoveries across all fields of astrophysics.
---------------------------------------------------------
Title: The initial-final mass relationship from white dwarfs in
common proper motion pairs
Authors: Catalán, S.; Isern, J.; García-Berro, E.; Ribas, I.;
Allende Prieto, C.; Bonanos, A. Z.
2008A&A...477..213C Altcode: 2007arXiv0710.1542C
Context: The initial-final mass relationship of white dwarfs, which
is poorly constrained, is of paramount importance for different
aspects of modern astrophysics. From an observational perspective,
most of the studies up to now have been done using white dwarfs in
open clusters. <BR />Aims: In order to improve the initial-final mass
relationship, we explore the possibility of deriving a semi-empirical
relation studying white dwarfs in common proper motion pairs. If
these systems are comprised of a white dwarf and a FGK star, the total
age and the metallicity of the progenitor of the white dwarf can be
inferred from the detailed analysis of the companion. <BR />Methods:
We have performed an exhaustive search for common proper motion
pairs containing a DA white dwarf and a FGK star using the available
literature and crossing the SIMBAD database with the Villanova White
Dwarf Catalog. We have acquired long-slit spectra of the white dwarf
members of the selected common proper motion pairs, as well as high
resolution spectra of their companions. From these observations, a full
analysis of the two members of each common proper motion pair leads
to the initial and final masses of the white dwarfs. <BR />Results:
These observations have allowed us to provide updated information
for the white dwarfs, since some of them were misclassified. In the
case of the DA white dwarfs, their atmospheric parameters, masses,
and cooling times have been derived using appropriate white dwarf
models and cooling sequences. From a detailed analysis of the FGK
star spectra we have inferred the metallicity. Then, using either
isochrones or X-ray luminosities we have obtained the main-sequence
lifetime of the progenitors, and subsequently their initial masses. <BR
/>Conclusions: This work is the first one using common proper motion
pairs to improve the initial-final mass relationship, and has also
allowed us to cover the poorly explored low-mass domain. As in the case
of studies based on white dwarfs in open clusters, the distribution of
the semi-empirical data presents a large scatter, which is higher than
the expected uncertainties in the derived values. This suggests that the
initial-final mass relationship may not be a single-valued function. <P
/>Based on observations obtained at: Calar Alto Observatory, Almería,
Spain, el Roque de los Muchachos, Canary Islands, Spain, McDonald
Observatory, Texas, USA, and Las Campanas Observatory, Chile. Tables
[see full textsee full textsee full text], [see full textsee full
textsee full text] and [see full textsee full textsee full text]
are only available in electronic form at http://www.aanda.org
---------------------------------------------------------
Title: An abundance survey of the Galactic thick disk
Authors: Reddy, B. E.; Lambert, D. L.; Allende Prieto, C.
2008mru..conf...69R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Solar chemical peculiarities?
Authors: Allende Prieto, C.
2008mru..conf...30A Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The Hobby-Eberly Telescope "Chemical Abundances Of Stars
In The Halo" (CASH) Project. I. The Lithium-, r-, and s-enhanced
Metal-poor Giant HK-II 17435-00532
Authors: Roederer, Ian U.; Frebel, A.; Shetrone, M.; Allende Prieto,
C.; Rhee, J.; Gallino, R.; Bisterzo, S.; Sneden, C.; Beers, T. C.;
Cowan, J. J.
2007AAS...21113103R Altcode: 2007BAAS...39..959R
We present the first detailed abundance analysis of the metal-poor giant
HK-II 17435-00532. This star was observed as part of the University
of Texas Long-Term "Chemical Abundances of Stars in the Halo" (CASH)
Project. A spectrum was obtained with the High Resolution Spectrograph
(HRS) on the Hobby-Eberly Telescope with a resolving power of R
15,000. Our analysis reveals that this star may be located on the
red giant branch, red horizontal branch, or early asymptotic giant
branch. We find that this metal-poor ([Fe/H]=-2.2) star has an unusually
high lithium abundance (log ɛ (Li)=+2.1), mild carbon ([C/Fe]=+0.7)
and sodium ([Na/Fe]=+0.6) enhancement, as well as enhancement of both
s-process ([Ba/Fe]=+0.8) and r-process ([Eu/Fe]=+0.5) material. The
high Li abundance can be explained by self-enrichment through
extra mixing mechanisms that connect the convective envelope with
the outer regions of the H-burning shell. If so, HK-II 17435-00532
is the most metal-poor star in which this short-lived phase of Li
enrichment has been observed. The r- and s-process material was not
produced in this star but was either present in the gas from which
HK-II 17435-00532 formed or was transferred to it from a more massive
binary companion. Despite the current non-detection of radial velocity
variations (over a time span of 180 days), it is possible that HK-II
17435-00532 is in a long-period binary system, similar to other stars
with both r and s enrichment. <P />We acknowledge support from the
W.J. McDonald Fellowship of McDonald Observatory (to A.F), NASA's AAS
Small Research Grant Program and the GALEX GI grant 05-GALEX05-27
(to J.R.), the Italian MIUR-PRIN06 Project "Late phases of Stellar
Evolution: Nucleosynthesis in Supernovae, AGB Stars, Planetary Nebulae"
(to R.G.), and the U.S. National Science Foundation (grants AST06-07708
to C.S., AST04-06784, AST07-07776 and PHY02-15783 to T.C.B., and AST
07-07447 to J.J.C.).
---------------------------------------------------------
Title: The Metallicity Distribution of the Milky Way's Stellar Halo
Authors: Allende Prieto, Carlos
2007AAS...21114804A Altcode: 2007BAAS...39.1001A
SDSS DR6 includes about 300,000 stellar spectra, and a significant
fraction of them belong to members of the halo. We make use of
these data to examine closely the shape of the halo metallicity
distribution. Does it have a single peak? Is it bimodal? Does it offer
any clues on its formation and evolution?
---------------------------------------------------------
Title: Constraints on Circumstellar Material around the Type Ia
Supernova 2007af
Authors: Simon, Joshua D.; Gal-Yam, Avishay; Penprase, Bryan E.; Li,
Weidong; Quimby, Robert M.; Silverman, Jeffrey M.; Allende Prieto,
Carlos; Wheeler, J. Craig; Filippenko, Alexei V.; Martinez, Irene T.;
Beeler, Daniel J.; Patat, Ferdinando
2007ApJ...671L..25S Altcode: 2007arXiv0709.1472S
Patat et al. recently inferred the existence of circumstellar material
around a normal Type Ia supernova (SN Ia) for the first time, finding
time-variable Na I D absorption lines in the spectrum of SN 2006X. We
present high-resolution spectroscopy of the bright SN Ia 2007af at
three epochs and search for variability in any of the Na D absorption
components. Over the time range from 4 days before to 24 days after
maximum light, we find that the host-galaxy Na D lines appear to be
of interstellar rather than circumstellar origin and do not vary
down to the level of 18 mÅ (column density of 2×10<SUP>11</SUP>
cm<SUP>-2</SUP>). We limit any circumstellar absorption lines to be
weaker than ~10 mÅ (6×10<SUP>10</SUP> cm<SUP>-2</SUP>). For the
case of material distributed in spherically symmetric shells of radius
~10<SUP>16</SUP> cm surrounding the progenitor system, we place an upper
limit on the shell mass of ~(3×10<SUP>-8</SUP>)/X M<SUB>solar</SUB>,
where X is the Na ionization fraction. We also show that SN 2007af is
a photometrically and spectroscopically normal SN Ia. Assuming that
the variable Na D lines in SN 2006X came from circumstellar matter, we
therefore conclude that either there is a preferred geometry for the
detection of variable absorption components in SNe Ia, or SN 2007af
and SN 2006X had different types of progenitor systems. <P />Some of
the data presented herein were obtained at the W. M. Keck Observatory,
which is operated as a scientific partnership among the California
Institute of Technology, the University of California, and NASA. The
Observatory was made possible by the generous financial support of the
W. M. Keck Foundation. <P />Based in part on observations obtained
with the Hobby-Eberly Telescope, which is a joint project of the
University of Texas at Austin, the Pennsylvania State University,
Stanford University, Ludwig-Maximilians-Universität München, and
Georg-August-Universität Göttingen.
---------------------------------------------------------
Title: The Apache Point Observatory Galactic Evolution Experiment
(APOGEE)
Authors: Majewski, Steven R.; Skrutskie, M. F.; Schiavon, R. P.;
Wilson, J. C.; O'Connell, R. W.; Smith, V. V.; Shetrone, M.; Cunha,
K.; Frinchaboy, P. M.; Reid, I. N.; Allende Prieto, C.; Eisenstein,
D.; Indebetouw, R.; Nelson, M. J.; Patterson, R. J.; Rood, R. T.;
Beers, T.; Bullock, J.; Crane, J. D.; Geisler, D.; Hawley, S. L.;
Holtzman, J.; Johnston, K. V.; McWilliam, A.; Munn, J. A.; Spergel,
D. N.; Weinberg, D.; Weinberg, M.
2007AAS...21113208M Altcode: 2007BAAS...39..962M
APOGEE is a large-scale, NIR, high-resolution (R 20,000) spectroscopic
survey of Galactic stars, and is one of the four experiments in
the SDSS-III suite. APOGEE will provide, by orders of magnitude,
the largest uniform database of chemical abundances, spectroscopic
parallaxes and kinematics for Galactic stars across the bulge, disk,
and halo. The survey will be conducted with a dedicated, 300-fiber,
cryogenic, spectrograph operating in the H-band, to be built at the
University of Virginia. APOGEE will use approximately half of the time
on 150 bright nights each year during a three-year period to observe,
at high S/N, of order 100,000 giant stars selected directly from 2MASS
down to a flux limit of H 13.5. Many of the targets will be located
in the inner Galaxy, towards the Galactic bulge/bar and disk, often in
regions never accessed by optical observations. With its high resolution
and S/N, APOGEE will determine, for a vast sample, accurate abundance
patterns, spanning numerous chemical species, and precision radial
velocities, with better than 0.5 km/s accuracy. Some of the scientific
objectives of this survey are to (1) provide extensive chemodynamical
data on the inner Galaxy (thin/thick disk, bar/bulge, low latitude
halo substructure) sufficient to constrain formation/evolution models,
(2) place constraints on the first stars from unbiased metallicity
distribution functions of these stellar populations, (3) constrain
and understand physical processes of star formation, feedback, mixing
in the formation of the Galaxy, (4) survey the dynamics of the bulge
and disk, and place constraints on the nature and influence of the
Galactic bar and spiral arms, (5) attempt to isolate what portion of
the disk and bulge come from accretion versus formation in situ.
---------------------------------------------------------
Title: The Hobby-Eberly Telescope Chemical Abundances of Stars in
the Halo (CASH) Project. First Year Results
Authors: Frebel, Anna; Allende Prieto, C.; Davies, L. A.; Roederer,
I.; Shetrone, M.; Sneden, C.; Rhee, J.; Beers, T. C.; Cowan, J. J.
2007AAS...21113104F Altcode: 2007BAAS...39..959F
We introduce the The Hobby-Eberly Telescope Chemical Abundances of
Stars in the Halo (CASH) Project. This University of Texas Long
Term Project aims at discovering metal-poor Galactic halo stars
selected from various surveys. We present the results of the first
year of HET observations: Thus far, 200 objects are observed with the
high-resolution spectrograph. Data reduction and stellar parameter
determination, as well as our automated analysis procedure are
described. A handful of stars with [Fe/H]<-3.0 were found. We also
report an individual abundance analysis of three metal-poor program
stars that confirm our automated analysis techniques.
---------------------------------------------------------
Title: Velocities from Cross-Correlation: A Guide for Self-Improvement
Authors: Allende Prieto, Carlos
2007AJ....134.1843A Altcode: 2007arXiv0707.2764A
The measurement of Doppler velocity shifts in spectra is a ubiquitous
theme in astronomy, usually handled by computing the cross-correlation
of the signals and finding the location of its maximum. This
paper addresses the problem of the determination of wavelength or
velocity shifts among multiple spectra of the same, or very similar,
objects. We implement the classical cross-correlation method and
experiment with several simple models to determine the location of the
maximum of the cross-correlation function. We propose a new technique,
self-improvement, to refine the derived solutions by requiring that
the relative velocity for any given pair of spectra be consistent with
all others. By exploiting all available information, spectroscopic
surveys involving large numbers of similar objects may improve their
precision significantly. As an example, we simulate the analysis
of a survey of G-type stars with the SDSS instrumentation. Applying
self-improvement refines relative radial velocities by more than 50%
at low signal-to-noise ratios. The concept is equally applicable to the
problem of combining a series of spectroscopic observations of the same
object, each with a different Doppler velocity or instrument-related
offset, into a single spectrum with an enhanced signal-to-noise ratio.
---------------------------------------------------------
Title: The Initial--Final Mass Relationship of White Dwarfs in Common
Proper Motion Pairs
Authors: Catalán, S.; Ribas, I.; Isern, J.; García-Berro, E.;
Allende Prieto, C.
2007ASPC..372...69C Altcode:
A promising approach to decrease the uncertainties in the initial--final
mass relationship, which is still poorly constrained, is to study white
dwarfs for which external constraints are available, for instance, white
dwarfs in common proper motion pairs (CPMPs). Important information
of the white dwarf can be inferred from the study of the companion,
since they were born at the same time and with the same initial chemical
composition. In this contribution, we report new results obtained from
spectroscopic observations of both members of several CPMPs composed
of a F, G or K type star and a DA white dwarf.
---------------------------------------------------------
Title: Computing Solar Absolute Fluxes
Authors: Allende Prieto, Carlos
2007arXiv0709.2194A Altcode:
Computed color indices and spectral shapes for individual stars are
routinely compared with observations for essentially all spectral
types, but absolute fluxes are rarely tested. We can confront observed
irradiances with the predictions from model atmospheres for a few stars
with accurate angular diameter measurements, notably the Sun. Previous
calculations have been hampered by inconsistencies and the use of
outdated atomic data and abundances. I provide here a progress report
on our current efforts to compute absolute fluxes for solar model
photospheres. Uncertainties in the solar composition constitute a
significant source of error in computing solar radiative fluxes.
---------------------------------------------------------
Title: VSOP: the variable star one-shot project. I. Project
presentation and first data release
Authors: Dall, T. H.; Foellmi, C.; Pritchard, J.; Lo Curto, G.; Allende
Prieto, C.; Bruntt, H.; Amado, P. J.; Arentoft, T.; Baes, M.; Depagne,
E.; Fernandez, M.; Ivanov, V.; Koesterke, L.; Monaco, L.; O'Brien,
K.; Sarro, L. M.; Saviane, I.; Scharwächter, J.; Schmidtobreick,
L.; Schütz, O.; Seifahrt, A.; Selman, F.; Stefanon, M.; Sterzik, M.
2007A&A...470.1201D Altcode: 2007arXiv0705.4195D
Context: About 500 new variable stars enter the General Catalogue
of Variable Stars (GCVS) every year. Most of them however lack
spectroscopic observations, which remains critical for a correct
assignement of the variability type and for the understanding of
the object. <BR />Aims: The Variable Star One-shot Project (VSOP)
is aimed at (1) providing the variability type and spectral type of
all unstudied variable stars, (2) process, publish, and make the data
available as automatically as possible, and (3) generate serendipitous
discoveries. This first paper describes the project itself, the
acquisition of the data, the dataflow, the spectroscopic analysis and
the on-line availability of the fully calibrated and reduced data. We
also present the results on the 221 stars observed during the first
semester of the project. <BR />Methods: We used the high-resolution
echelle spectrographs HARPS and FEROS in the ESO La Silla Observatory
(Chile) to survey known variable stars. Once reduced by the dedicated
pipelines, the radial velocities are determined from cross correlation
with synthetic template spectra, and the spectral types are determined
by an automatic minimum distance matching to synthetic spectra, with
traditional manual spectral typing cross-checks. The variability types
are determined by manually evaluating the available light curves
and the spectroscopy. In the future, a new automatic classifier,
currently being developed by members of the VSOP team, based on these
spectroscopic data and on the photometric classifier developed for the
COROT and Gaia space missions, will be used. <BR />Results: We confirm
or revise spectral types of 221 variable stars from the GCVS. We
identify 26 previously unknown multiple systems, among them several
visual binaries with spectroscopic binary individual components. We
present new individual results for the multiple systems <ASTROBJ>V349
Vel</ASTROBJ> and <ASTROBJ>BC Gru</ASTROBJ>, for the composite spectrum
star <ASTROBJ>V4385 Sgr</ASTROBJ>, for the T Tauri star <ASTROBJ>V1045
Sco</ASTROBJ>, and for <ASTROBJ>DM Boo</ASTROBJ> which we re-classify
as a BY Draconis variable. The complete data release can be accessed
via the VSOP web site. <P />Based on data obtained at the La Silla
Observatory, European Southern Observatory, under program ID 077.D-0085.
---------------------------------------------------------
Title: The Initial-Final Mass Relationship of White Dwarfs in Common
Proper Motion Pairs and Open Clusters
Authors: Catalán, S.; Ribas, I.; Isern, J.; García-Berro, E.;
Allende Prieto, C.
2007IAUS..240..380C Altcode: 2006IAUS..240E.204C
The initial-to-final mass relationship is the connection between
the mass of a white dwarf and the mass of its progenitor in the main
sequence. This function is of paramount importance to aspects such as
determining ages and distances of globular clusters, constraining the
chemical evolution in galaxies, and also understanding the properties
of the galactic population of white dwarfs. Despite its relevance,
this relation is still poorly constrained. A promising approach to
diminish the uncertainties is to study white dwarfs for which external
constraints are available. This is the case of white dwarfs in common
proper motion pairs. Important information of the white dwarf member
can be inferred from the study of the companion, since they were born
at the same time and with the same chemical composition. We report
new results obtained from spectroscopic observations of both members
of several common proper motion pairs composed of a main sequence star
(F, G or K type) and a white dwarf. From the fitting of the absorption
lines to theoretical models we obtain the effective temperature and
the surface gravity of the white dwarf member and, consequently,
its mass and cooling time. The determination of the metallicity of
the main sequence companion helps us to infer the metallicity of the
progenitor of the white dwarf. This procedure allows us to estimate the
main sequence lifetime of the white dwarf, and hence, to determine the
total age of the system. At that point, we will be able to derive the
mass of the main sequence progenitor of the white dwarf and to better
establish the initial-to-final mass relationship.
---------------------------------------------------------
Title: The Discovery of a Companion to the Lowest Mass White Dwarf
Authors: Kilic, Mukremin; Brown, Warren R.; Allende Prieto, Carlos;
Pinsonneault, M. H.; Kenyon, S. J.
2007ApJ...664.1088K Altcode: 2007arXiv0704.1813K
We report the detection of a radial velocity companion to SDSS
J091709.55+463821.8, the lowest mass white dwarf currently known,
with M~0.17 M<SUB>solar</SUB>. The radial velocity of the white dwarf
shows variations with a semi-amplitude of 148.8+/-6.9 km s<SUP>-1</SUP>
and a period of 7.5936+/-0.0024 hr, which implies a companion mass
of M>=0.28 M<SUB>solar</SUB>. The lack of evidence of a companion
in the optical photometry forces any main-sequence companion to be
smaller than 0.1 M<SUB>solar</SUB>, hence a low-mass main-sequence
star companion is ruled out for this system. The companion is most
likely another white dwarf, and we present tentative evidence for an
evolutionary scenario that could have produced it. However, a neutron
star companion cannot be ruled out, and follow-up radio observations are
required to search for a pulsar companion. <P />Observations reported
here were obtained at the MMT Observatory, a joint facility of the
Smithsonian Institution and the University of Arizona.
---------------------------------------------------------
Title: VSOP: Fixing the variable sky with one-shot typing of
neglected variables
Authors: Dall, Thomas; Nitta, Atsuko; Labrie, Kathleen; Beers,
Tim; Allende Prieto, Carlos; Koesterke, Lars; Bruntt, Hans; Kiss,
Laszlo; Arentoft, Torben; Amado, Pedro; Baes, Maarten; Depagne, Eric;
Fernandez, Matilde; Foellmi, Cedric; Ivanov, Valentin; Lo Curto,
Gaspare; Monaco, Lorenzo; O'Brien, Kieran; Pritchard, John; Sarro,
Luis Manuel; Saviane, Ivo; Scharwaechter, Julia; Schmidtobreick, Linda;
Schuetz, Oliver; Seifahrt, Andreas; Selman, Fernando; Stefanon, Mauro;
Sterzik, Michael
2007noao.prop...64D Altcode:
Stellar variability types are assigned on the basis of lightcurve
appearance, which often remains unchallenged without further
observational evidence. VSOP (Variable Star One-shot Project) is a
large international collaboration, which has so far obtained spectra of
more than 400 stars during the past year. Operationally this program
is a completely new concept, perfectly suited for a modern, efficient
observatory, providing Gemini with a large pool of filler observations,
and we ask specifically to be placed in Band 3. Scientifically, our
aims are: (1) obtain first spectroscopy of all unstudied variable
stars in both hemispheres, (2) provide data products to the public
in a fast and automatic way, (3) generate an influx of serendipitous
discoveries across all fields of astrophysics.
---------------------------------------------------------
Title: HS 1857+5144: a hot and young pre-cataclysmic variable
Authors: Aungwerojwit, A.; Gänsicke, B. T.; Rodríguez-Gil, P.;
Hagen, H. -J.; Giannakis, O.; Papadimitriou, C.; Allende Prieto, C.;
Engels, D.
2007A&A...469..297A Altcode: 2007arXiv0704.1780A
Aims:We report the discovery of a new white dwarf/M dwarf binary,
HS 1857+5144, identified in the Hamburg Quasar Survey (HQS). <BR
/>Methods: Time-resolved optical spectroscopy and photometry were
carried out to determine the properties of this new cataclysmic variable
progenitor (pre-CV). <BR />Results: The light curves of HS 1857+5144
display a sinusoidal variation with a period of P_orb = 383.52 min
and peak-to-peak amplitudes of 0.7 mag and 1.1 mag in the B-band and
R-band, respectively. The large amplitude of the brightness variation
results from a reflection effect on the heated inner hemisphere of
the companion star, suggesting a very high temperature of the white
dwarf. Our radial velocity study confirms the photometric period
as the orbital period of the system. A model atmosphere fit to the
spectrum of the white dwarf obtained at minimum light provides limits
to its mass and temperature of M_wd≃ 0.6-1.0 {M}<SUB>⊙</SUB> and
T_wd≃ 70 000-100 000 K, respectively. The detection of He II 4686
absorption classifies the primary star of HS 1857+5144 as a DAO white
dwarf. Combining the results from our spectroscopy and photometry, we
estimate the mass of the companion star and the binary inclination
to be M_sec≃ 0.15-0.30 {M}<SUB>⊙</SUB> and i≃ 45°-55°,
respectively. <BR />Conclusions: We classify HS 1857+5144 as one
of the youngest pre-CV known to date. The cooling age of the white
dwarf suggests that the present system has just emerged from a common
envelope phase 10<SUP>5</SUP> yr ago. HS 1857+5144 will start mass
transfer within or below the 2-3 h period gap.
---------------------------------------------------------
Title: SWSextantis stars: the dominant population of cataclysmic
variables with orbital periods between 3 and 4h
Authors: Rodríguez-Gil, P.; Gänsicke, B. T.; Hagen, H. -J.;
Araujo-Betancor, S.; Aungwerojwit, A.; Allende Prieto, C.; Boyd, D.;
Casares, J.; Engels, D.; Giannakis, O.; Harlaftis, E. T.; Kube, J.;
Lehto, H.; Martínez-Pais, I. G.; Schwarz, R.; Skidmore, W.; Staude,
A.; Torres, M. A. P.
2007MNRAS.377.1747R Altcode: 2007MNRAS.tmp..348R; 2007arXiv0704.1129R
We present time-series optical photometry of five new cataclysmic
variables (CVs) identified by the Hamburg Quasar Survey (HQS). The
deep eclipses observed in HS 0129+2933 (= TT Tri), HS 0220+0603 and HS
0455+8315 provided very accurate orbital periods of 3.35129827(65),
3.58098501(34) and 3.56937674(26) h, respectively. HS 0805+3822
shows grazing eclipses and has a likely orbital period of 3.2169(2)
h. Time-resolved optical spectroscopy of the new CVs (with the exception
of HS 0805+3822) is also presented. Radial velocity studies of the
Balmer emission lines provided an orbital period of 3.55 h for HS
1813+6122, which allowed us to identify the observed photometric signal
at 3.39 h as a negative superhump wave. The spectroscopic behaviour
exhibited by all the systems clearly identifies them as new SW Sextantis
(SW Sex) stars. HS 0220+0603 shows unusual NII and SiII emission lines
suggesting that the donor star may have experienced nuclear evolution
via the CNO cycle. <P />These five new additions to the class increase
the number of known SW Sex stars to 35. Almost 40 per cent of the total
SW Sex population do not show eclipses, invalidating the requirement
of eclipses as a defining characteristic of the class and the models
based on a high orbital inclination geometry alone. On the other hand,
as more SW Sex stars are identified, the predominance of orbital periods
in the narrow 3-4.5 h range is becoming more pronounced. In fact,
almost half the CVs which populate the 3-4.5 h period interval are
definite members of the class. The dominance of SW Sex stars is even
stronger in the 2-3 h period gap, where they make up 55 per cent of
all known gap CVs. These statistics are confirmed by our results from
the HQS CVs. Remarkably, 54 per cent of the Hamburg nova-like variables
have been identified as SW Sex stars with orbital periods in the 3-4.5
h range. The observation of this pile-up of systems close to the upper
boundary of the period gap is difficult to reconcile with the standard
theory of CV evolution, as the SW Sex stars are believed to have the
highest mass-transfer rates among CVs. <P />Finally, we review the
full range of common properties that the SW Sex stars exhibit. Only a
comprehensive study of this rich phenomenology will prompt to a full
understanding of the phenomenon and its impact on the evolution of
CVs and the accretion processes in compact binaries in general.
---------------------------------------------------------
Title: Estimation of stellar atmospheric parameters from SDSS/SEGUE
spectra
Authors: Re Fiorentin, P.; Bailer-Jones, C. A. L.; Lee, Y. S.; Beers,
T. C.; Sivarani, T.; Wilhelm, R.; Allende Prieto, C.; Norris, J. E.
2007A&A...467.1373R Altcode: 2007astro.ph..3309R
We present techniques for the estimation of stellar atmospheric
parameters (T_eff, log~g, [Fe/H]) for stars from the SDSS/SEGUE
survey. The atmospheric parameters are derived from the observed
medium-resolution (R = 2000) stellar spectra using non-linear regression
models trained either on (1) pre-classified observed data or (2)
synthetic stellar spectra. In the first case we use our models to
automate and generalize parametrization produced by a preliminary
version of the SDSS/SEGUE Spectroscopic Parameter Pipeline (SSPP). In
the second case we directly model the mapping between synthetic spectra
(derived from Kurucz model atmospheres) and the atmospheric parameters,
independently of any intermediate estimates. After training, we apply
our models to various samples of SDSS spectra to derive atmospheric
parameters, and compare our results with those obtained previously
by the SSPP for the same samples. We obtain consistency between the
two approaches, with RMS deviations on the order of 150 K in T_eff,
0.35 dex in log~g, and 0.22 dex in [Fe/H]. The models are applied to
pre-processed spectra, either via Principal Component Analysis (PCA) or
a Wavelength Range Selection (WRS) method, which employs a subset of the
full 3850-9000Å spectral range. This is both for computational reasons
(robustness and speed), and because it delivers higher accuracy (better
generalization of what the models have learned). Broadly speaking, the
PCA is demonstrated to deliver more accurate atmospheric parameters when
the training data are the actual SDSS spectra with previously estimated
parameters, whereas WRS appears superior for the estimation of log~g via
synthetic templates, especially for lower signal-to-noise spectra. From
a subsample of some 19 000 stars with previous determinations of
the atmospheric parameters, the accuracies of our predictions (mean
absolute errors) for each parameter are T_eff to 170/170 K, log~g
to 0.36/0.45 dex, and [Fe/H] to 0.19/0.26 dex, for methods (1) and
(2), respectively. We measure the intrinsic errors of our models by
training on synthetic spectra and evaluating their performance on an
independent set of synthetic spectra. This yields RMS accuracies of 50
K, 0.02 dex, and 0.03 dex on T_eff, log~g, and [Fe/H], respectively. Our
approach can be readily deployed in an automated analysis pipeline,
and can easily be retrained as improved stellar models and synthetic
spectra become available. We nonetheless emphasise that this approach
relies on an accurate calibration and pre-processing of the data
(to minimize mismatch between the real and synthetic data), as well
as sensible choices concerning feature selection. From an analysis of
cluster candidates with available SDSS spectroscopy (M 15, M 13, M 2,
and NGC 2420), and assuming the age, metallicity, and distances given
in the literature are correct, we find evidence for small systematic
offsets in T_eff and/or log~g for the parameter estimates from the
model trained on real data with the SSPP. Thus, this model turns out
to derive more precise, but less accurate, atmospheric parameters than
the model trained on synthetic data.
---------------------------------------------------------
Title: Revised Parameter Estimates For The Most Metal-poor Candidates
In SDSS-I And SEGUE
Authors: Krugler, Julie A.; Beers, T. C.; Lee, Y.; Sivarani, T.;
Marsteller, B.; Wilhelm, R.; Allende Prieto, C.; Frebel, A.; Norris,
J. E.; Johnson, J.; Ivans, I.; Yanny, B.; Rockosi, C.; Morrison, H.;
Newberg, H. J.; Knapp, J.
2007AAS...210.7402K Altcode: 2007BAAS...39..180K
There are several hundred thousand R = 2000 stellar spectra reported
in the final public release of the Sloan Digital Sky Survey (SDSS-I)
and the continuation project SEGUE (Sloan Extension for Galactic
Exploration and Understanding), which has completed roughly half of
its scheduled set of observations to date. <P />The stars in this
sample were targeted for a wide variety of reasons, and hence do not
represent a sample from which an unbiased metallicity distribution
function (MDF) of stars in the halo or thick-disk populations may be
drawn. However, there exist over 9000 stars with estimated metallicities
[Fe/H]>-2.0 and effective temperatures in the range 5000K < Teff
< 7000K among this sample, based on application of the SDSS/SEGUE
spectroscopic parameter analysis pipeline. We have continued to refine
estimates of the stellar parameters for these stars, using an automated
synthetic spectrum approach. This technique produces estimates of [Fe/H]
as well as [C/Fe] (or upper limits on these quantitites) based on MOOG
syntheses of the region of spectrum around the CaII K line and the CH
G band, respectively. This sample represents, by a factor of more than
three, the largest database of very metal-poor stars yet assembled. A
least 1000 of these stars have g < 16.5, and hence are amenable
to high-resolution spectroscopic studies with presently available
large-aperture telescopes. We report on the catalog of these stars,
and consider the shape of the low-metallicity tail of the halo MDF
derived from these data. <P />Funding for the SDSS and SDSS-II has
been provided by the Alfred P. Sloan Foundation, the Participating
Institutions, the National Science Foundation, the U.S. Department of
Energy, the National Aeronautics and Space Administration, the Japanese
Monbukagakusho, the Max Planck Society, and the Higher Education
Funding Council for England. The SDSS Web Site is http://www.sdss.org/.
---------------------------------------------------------
Title: The Lowest Mass White Dwarf
Authors: Kilic, Mukremin; Allende Prieto, Carlos; Brown, Warren R.;
Koester, D.
2007ApJ...660.1451K Altcode: 2006astro.ph.11498K
Extremely low mass white dwarfs are very rare objects likely formed
in compact binary systems. We present MMT optical spectroscopy of
42 low-mass white dwarf candidates serendipitously discovered in a
survey for hypervelocity B-type stars. One of these objects, SDSS
J0917+46, has T<SUB>eff</SUB>=11,288+/-72 K and logg=5.48+/-0.03
with an estimated mass of 0.17 M<SUB>solar</SUB>, it is the lowest
gravity/mass white dwarf currently known. However, 40 of the low-mass
candidates are normal DA white dwarfs with apparently inaccurate SDSS
g magnitudes. We revisit the identification of low-mass white dwarf
candidates previously found in the SDSS and conclude that four objects
have M<0.2 M<SUB>solar</SUB>. None of these white dwarfs show excess
emission from a binary companion, and radial velocity searches will
be necessary to constrain the nature of the unseen companions.
---------------------------------------------------------
Title: Oxygen abundances in nearby stars. Clues to the formation
and evolution of the Galactic disk
Authors: Ramírez, I.; Allende Prieto, C.; Lambert, D. L.
2007A&A...465..271R Altcode: 2007astro.ph..1362R
The abundances of iron and oxygen are homogeneously determined in
a sample of 523 nearby (d<150 pc) FGK disk and halo stars with
metallicities in the range -1.5<[Fe/H]<0.5. Iron abundances were
obtained from an LTE analysis of a large set of Fe I and Fe II lines
with reliable atomic data. Oxygen abundances were inferred from a
restricted non-LTE analysis of the 777 nm O I triplet. We adopted the
infrared flux method temperature scale and surface gravities based
on Hipparcos trigonometric parallaxes. Within this framework, the
ionization balance of iron lines is not satisfied: the mean abundances
from the Fe I lines are systematically lower by 0.06 dex than those
from the Fe II lines for dwarf stars of T<SUB>eff</SUB>>5500 K and
[Fe/H]<0.0, and giant stars of all temperatures and metallicities
covered by our sample. The discrepancy worsens for cooler and metal-rich
main-sequence stars. We use the stellar kinematics to compute the
probabilities of our sample stars to be members of the thin disk,
thick disk, or halo of the Galaxy. We find that the majority of the
kinematically-selected thick-disk stars show larger [O/Fe] ratios
compared to thin-disk stars while the rest show thin-disk abundances,
which suggests that the latter are thin-disk members with unusual
(hotter) kinematics. A close examination of this pattern for disk stars
with ambiguous probabilities shows that an intermediate population with
properties between those of the thin and thick disks does not exist,
at least in the solar neighborhood. Excluding the stars with unusual
kinematics, we find that thick-disk stars show slowly decreasing
[O/Fe] ratios from about 0.5 to 0.4 in the -0.8<[Fe/H]<-0.3
range. Using a simple model for the chemical evolution of the thick
disk we show that this trend results directly from the metallicity
dependence of the Type II supernova yields. At [Fe/H]>-0.3, we find
no obvious indication of a sudden decrease (i.e., a "knee") in the
[O/Fe] vs. [Fe/H] pattern of thick-disk stars that would connect the
thick and thin disk trends at a high metallicity. We conclude that Type
Ia supernovae (SN Ia) did not contribute significantly to the chemical
enrichment of the thick disk. In the -0.8<[Fe/H]<+0.3 range,
thin-disk stars show decreasing [O/Fe] ratios from about 0.4 to 0.0
that require a SN Ia contribution. The implications of these results
for studies of the formation and evolution of the Galactic disk are
discussed. <P />Tables 4-6 are only available in electronic form at
the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/465/271 Partially based
on observations obtained with the Hobby-Eberly Telescope, which is a
joint project of the University of Texas at Austin, the Pennsylvania
State University, Stanford University, Ludwig-Maximilians-Universität
München, and Georg-August-Universität Göttingen; and data from the
UVES Paranal Observatory Project (ESO DDT Program ID 266.D-5655).
---------------------------------------------------------
Title: VizieR Online Data Catalog: Oxygen abundances in nearby stars
(Ramirez+, 2007)
Authors: Ramirez, I.; Allende Prieto, C.; Lambert, D. L.
2007yCat..34650271R Altcode:
We provide in Table 4 basic (HIP and HD numbers, V magnitude and
parallax) and kinematic (radial velocities and heliocentric space
velocity) data for our sample stars. The kinematic probabilities of
being a thin-disk, thick-disk, and halo member are also given. Table 5
contains the line data used in our abundance computations as well as the
equivalent widths of the lines measured in the solar spectrum. Stellar
parameters and abundances are given in Table 6. Effective temperatures
were derived using color calibrations based on the infrared flux
method temperature scale while surface gravities were determined from
the Hipparcos parallaxes and estimates of the stellar masses based on
theoretical isochrones. We provide the mean abundance of iron determined
from Fe I and Fe II lines separately and a mean [Fe/H] value obtained
after applying our empirical re-scaling of the Fe I abundances. LTE
and non-LTE oxygen abundances derived from the 777nm OI triplet are
also given. The last three columns of Table 6, if available, provide
our estimates of the stellar ages. <P />(3 data files).
---------------------------------------------------------
Title: A Search for Evidence of an Abundance Gradient in the Galactic
Halo Based on Stars from SDSS-I DR-5
Authors: Carollo, Daniela; Beers, T. C.; Lee, Y. S.; Sivarani, T.;
Allende Prieto, C.; Norris, J.; Munn, J. A.; Chiba, M.
2006AAS...20916809C Altcode: 2006BAAS...38.1139C
One of the classical tests of the early dynamical evolution of the
Milky Way is the prediction of the monolithic collapse model (e.g.,
Eggen, Lynden-Bell, & Sandage 1962) of a decline in the mean stellar
abundance of the halo population as one proceeds to stars at greater
distances, or equivalently, with higher local space velocities in the
solar neighborhood. This stands in contrast to the prediction of galaxy
formation within the Cold Dark Matter paradigm, where assembly from
multiple fragments (e.g., Searle & Zinn 1978) would not be expected
to produce an abundance gradient in the halo. Although several attempts
have been made in the past to test this idea, all such efforts have
been limited by small sample sizes, concerns about selection biases,
or both. We are presently analyzing a very large sample of over 24,000
stars selected as calibration objects (used for providing checks on
the spectrophotometric flux and reddening corrections) from SDSS-I
DR-5. These stars are primarily F (and early G-type) turnoff stars
in the thick-disk and halo populations of the Galaxy. The color-based
selection ensures that an adequate number (several thousand) of very
low-metallicity ([Fe/H] < -2.0) stars exist in order to search for
the presence (or not) of a halo abundance gradient. Accurate estimates
of radial velocity, metallicity, temperature, surface gravity, and
distance are obtained for all of these stars by application of the
(still evolving) SDSS/SEGUE spectroscopic analysis pipeline discussed
in other contributions at this meeting. This information is combined
with proper motions derived from the recalibrated USNOB-2 catalog,
as discussed by Munn et al. (2004), in order to obtain estimates of
their full space motions. Results on the search for a halo abundance
gradient, based on these data, will be reported.
---------------------------------------------------------
Title: The SDSS-II/SEGUE Spectroscopic Parameter Pipeline
Authors: Lee, Young S.; Beers, T. C.; Sivarani, T.; Wilhelm, R.;
Allende Prieto, C.; Norris, J. E.; Fiorentin, P. R.; Bailer-Jones,
C. A.; SEGUE Calibration Team
2006AAS...20916815L Altcode: 2006BAAS...38.1140L
The Sloan Extension for Galactic Understanding and Exploration (SEGUE)
is one of three key projects in SDSS-II. SEGUE is in the process of
obtaining ugriz imaging of some 3500 square degrees of sky outside
of the SDSS-I footprint, with special attention being given to scans
of lower galactic latitudes in order to better probe the disk/halo
interface in the Galaxy. Over one-third of the imaging has already
been completed. SEGUE is also obtaining R = 2000 sectroscopy over the
wavelenth range 380 900 nm for 250,000 stars in 200 selected areas over
the sky available from Apache Point, New Mexico. The spectroscopic
candidates are selected on the basis of ugriz photometry to populate
some 16 target categories of stars chosen to explore the nature of the
stellar populations in the Galaxy as a function of distance from the Sun
(from 0.5 kpc to over 100 kpc). <P />The SEGUE data clearly require
automated analysis tools in order to extract the maximum amount of
useful information. In this contribution we describe the development
and execution of the SEGUE spectroscopic analysis pipeline, which
makes use of multiple approaches (including spectral matching, neural
network analysis, line index calculations, etc.) in order to estimate
the fundamental stellar atmospheric parameters (effective temperature,
surface gravity, and [Fe/H]). These approaches are in the process of
being extended to include determinations of other elemental abundances
(e.g., C, Na, Mg) that the SDSS spectra probe. <P />Funding for the
SDSS and SDSS-II has been provided by the Alfred P. Sloan Foundation,
the Participating Institutions, the National Science Foundation,
the U.S. Department of Energy, the National Aeronautics and Space
Administration, the Japanese Monbukagakusho, the Max Planck Society,
and the Higher Education Funding Council for England. The SDSS Web
Site is http://www.sdss.org/.
---------------------------------------------------------
Title: Solar Chemical Peculiarities?
Authors: Allende Prieto, Carlos
2006astro.ph.12200A Altcode:
Several investigations of FGK stars in the solar neighborhood have
suggested that thin-disk stars with an iron abundance similar to
the Sun appear to show higher abundances of other elements, such
as silicon, titanium, or nickel. Offsets could arise if the samples
contain stars with ages, mean galactocentric distances, or kinematics,
that differ on average from the solar values. They could also arise
due to systematic errors in the abundance determinations, if the
samples contain stars that are different from the Sun regarding their
atmospheric parameters. We re-examine this issue by studying a sample
of 80 nearby stars with solar-like colors and luminosities. Among these
solar "analogs", the objects with solar iron abundances exhibit solar
abundances of carbon, silicon, calcium, titanium and nickel.
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Title: The Most Metal-Poor Candidates in SDSS-I DR-5
Authors: Beers, Timothy C.; Lee, Y.; Sivarani, T.; Marsteller, B.;
Krugler, J.; Wilhelm, R.; Allende Prieto, C.; Norris, J.; Johnson,
J.; Ivans, I.; Yanny, B.; Rockosi, C.; Morrison, H.; Newberg, H. J.;
Knapp, J.
2006AAS...20916808B Altcode: 2006BAAS...38.1139B
There are some 194,000 R = 2000 stellar spectra reported in the
final public release of the Sloan Digital Sky Survey (SDSS-I), known
as DR-5. Setting aside the stars observed during the course of early
tests for the Sloan Extension for Galactic Understanding and Exploration
(SEGUE), which will be considered in the future, this leaves a total of
about 168,000 stellar spectra. The stars in this sample were targeted
for a wide variety of reasons, and hence do not represent a <P />sample
from which an unbiased metallicity distribution function (MDF) of
stars in the halo or thick-disk populations may be drawn. However,
there exist some 6500 stars with estimated metallicities [Fe/H] <
-2.0 and effective temperatures in the range 5000K < Teff <
7000K among this sample, based on application of the SDSS/SEGUE
spectroscopic analysis pipeline described in other contributions at
this meeting. <P />This sample represents, by a factor of more than
three, the largest database of very metal-poor stars yet assembled. A
least 1000 of these stars have g < 16.5, and hence are amenable
to high-resolution spectroscopic studies with presently available
large-aperture telescopes. We report on the catalog of these stars,
and consider the shape of the low-metallicity tail of the halo MDF
derived from these data. <P />Funding for the SDSS and SDSS-II has
been provided by the Alfred P. Sloan Foundation, the Participating
Institutions, the National Science Foundation, the U.S. Department of
Energy, the National Aeronautics and Space Administration, the Japanese
Monbukagakusho, the Max Planck Society, and the Higher Education
Funding Council for England. The SDSS Web Site is http://www.sdss.org/.
---------------------------------------------------------
Title: High-Resolution Calibration of the SDSS/SEGUE Spectroscopic
Analysis Pipeline
Authors: Sivarani, T.; Beers, T. C.; Lee, Y.; Krugler, J.; Wilhelm,
R.; Allende Prieto, C.; Sneden, C.; Lambert, D. L.; Shetrone, M.;
Johnson, J.; Ivans, I.; Rockosi, C.; Lai, D.; Morrison, H.; Aoki, W.
2006AAS...20916810S Altcode: 2006BAAS...38.1139S
We present a discussion of efforts to obtain external validation of the
estimated atmospheric parameters (Teff, log g, [Fe/H]) obtained from
medium-resolution (R = 2000) SDSS spectroscopy and ugriz photometry,
which are being employed for both the completed SDSS-I and the
ongoing SEGUE survey. The SDSS/SEGUE spectroscopic pipeline makes
use of a number of methods for the estimation of each parameter, with
estimated internal errors on the order of σ(Teff) = 150 K, σ(log g)
= 0.4 dex, and σ([Fe/H]) = 0.3 dex. Over the course of the past two
years, we have obtained over 100 high-resolution optical spectra of
SDSS/SEGUE stars using the HET, KECK and SUBARU telescopes. For the
KECK/HIRES spectra, which have R = 40000, we have performed standard
high-resolution analyses to estimate the stellar parameters. For the
HET and KECK-ESI data, which have R = 15000 and R = 5000, respectively,
we have performed synthetic spectra matching in order to to estimate
the stellar parameters. We find that the derived stellar parameters
agree well with the SDSS/SEGUE pipeline estimates for the temperature
range 5000 K < Teff < 6500K; the errors are of the order of the
internal errors expected from the SDSS/SEGUE pipeline. For effective
temperatures in the range 4000 K to 5000 K the estimated parameters
from the high-resolution spectroscopy exhibit offsets relative to the
SDSS/SEGUE pipeline values on the order of ΔTeff = 200 K, Δlogg =
0.8 dex, and Δ[Fe/H] = 0.4 dex. Similar offsets exist for stars with T
> 6500 K. The main reason for these offsets appears to arise due to
varying microturbulence, for which the medium-resolution SDSS spectra
are not sensitive. We also have performed external checks on pipline
radial velocities. We find that the errors in radial velocities are
on the order of 7 km/s for stars, which is at the expected level.
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Title: Fundamental parameters and abundances of metal-poor stars:
the SDSS standard BD +17 4708
Authors: Ramírez, I.; Allende Prieto, C.; Redfield, S.; Lambert, D. L.
2006A&A...459..613R Altcode: 2006astro.ph..8559R
The atmospheric parameters and iron abundance of the Sloan Digital
Sky Survey (SDSS) spectrophotometric standard star BD +17 4708
are critically examined using up-to-date Kurucz model atmospheres,
LTE line formation calculations, and reliable atomic data. We find
T<SUB>eff</SUB>=6141 ± 50 K, log g=3.87 ± 0.08, and [Fe/H]=-1.74
± 0.09. The line-of-sight interstellar reddening, bolometric flux,
limb-darkened angular diameter, stellar mass, and the abundances
of Mg, Si, and Ca are also obtained: E(B-V)=0.010 ± 0.003,
f<SUB>bol</SUB>=(4.89±0.10) × 10<SUP>-9</SUP> erg cm<SUP>-2</SUP>
s<SUP>-1</SUP>, θ=0.1016 ± 0.0023 mas, M=0.91 ± 0.06~M_⊙,
[Mg/Fe]=0.40 ± 0.10, [Si/Fe]=0.35 ± 0.11, [Ca/Fe]=0.36 ± 0.11. This
star is a unique example of a moderately metal-poor star for which the
effective temperature (T<SUB>eff</SUB>) can be accurately constrained
from the observed spectral energy distribution (corrected for
reddening). Such analysis leads to a value that is higher than most
spectroscopic results previously reported in the literature (~5950
K). Interstellar reddening was estimated using various prescriptions,
including an analysis of interstellar lines. The surface gravity of the
star was inferred from the fitting of the wings of the Mg I b lines. We
used transition probabilities measured in the laboratory and reliable
damping constants for unblended Fe lines to derive the iron abundance
using both Fe I and Fe II lines. We find that the ionization balance
of Fe lines is satisfied only if a low T<SUB>eff</SUB> (~5950 K)
is adopted. The mean iron abundance we obtain from the Fe II lines
corresponds to A_Fe=5.77 ± 0.09 ([Fe/H]=-1.74 for our derived
A<SUB>Fe,⊙</SUB>=7.51) while that from the Fe I lines is A_Fe=5.92
± 0.11, and therefore with our preferred T<SUB>eff</SUB> (6141 K),
the discrepancy between the mean iron abundance from Fe I and Fe II
lines cannot be explained by overionization by UV photons as the main
non-LTE effect. Interestingly, the Fe I excitation balance is satisfied
with a T<SUB>eff</SUB> only slightly warmer than our preferred solution
and not with the lower value of 5950 K. We also comment on non-LTE
effects and the importance of inelastic collisions with neutral H
atoms in the determination of oxygen abundances in metal-poor stars
from the 7774 Å O I triplet.
---------------------------------------------------------
Title: VizieR Online Data Catalog: Elemental abundances for 176 stars
(Reddy+, 2006)
Authors: Reddy, B. E.; Lambert, D. L.; Allende Prieto, C.
2006yCat..73671329R Altcode:
High-resolution spectra of the program stars were obtained during the
period 2002 December-2004 June at the Harlan J. Smith 2.7-m telescope
of the W.J. McDonald Observatory, using the 2dcoude echelle spectrometer
with a 2048x2048 Tektronix CCD as detector. <P />(2 data files).
---------------------------------------------------------
Title: Stellar Abundances: Recent and Foreseeable Trends
Authors: Allende Prieto, C.
2006ASPC..352..105A Altcode: 2006astro.ph..1352A
The determination of chemical abundances from stellar spectra is
considered a mature field of astrophysics. Digital spectra of stars
are recorded and processed with standard techniques, much like samples
in the biological sciences. Nevertheless, uncertainties typically
exceed 20% and are dominated by systematic errors. The first part of
this paper addresses what is being done to reduce measurement errors,
and what is not being done, but should be. The second part focuses on
some of the most exciting applications of stellar spectroscopy in the
arenas of galactic structure and evolution, the origin of the chemical
elements, and cosmology.
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Title: The SDSS-I Value Added Catalog of Stellar Parameters and the
SEGUE Pipeline
Authors: Beers, T. C.; Lee, Y.; Sivarani, T.; Allende Prieto, C.;
Wilhelm, R.; Re Fiorentin, P.; Bailer-Jones, C.
2006IAUJD..13E..26B Altcode:
We report on the development, calibration, and refinement of the
SDSS-I Value Added Catalog (VAC) of stellar abundances, temperatures,
and surface gravities. This catalog is based on observations of several
hundred thousand stars obtained during the course of the original Sloan
Digital Sky Survey, now known as SDSS-I. A spectroscopic pipeline has
been developed that obtains estimates of [Fe/H], T[eff], and logg
based on medium-resolution (R = 2000) spectra and ugriz photometry
obtained with the ARC 2.5m telescope. This same pipeline is being
used for estimation of stellar parameters for the ongoing SEGUE: Sloan
Extension for Galactic Understanding and Evolution project. We discuss
the methods explored for development of the VAC, as well as tests of
the calibration based on high-resolution spectroscopy obtained with the
Hobby-Eberly Telescope, the Keck telescopes, and the Subaru telescope
---------------------------------------------------------
Title: Teff, logg, [Fe/H] and alpha-abundance of SDSS stars from an
automated determination algorithm: TGMETalpha.
Authors: Girard, P.; Allende Prieto, C.; Soubiran, C.
2006IAUJD..13E..46G Altcode:
We have developed TGMETalpha in order to determine T[eff], logg,
[Fe/H] and [alpha/Fe] for large samples of FGK stars observed at
various spectral resolutions. Tests on several hundred echelle
spectra of reference stars degraded at low resolution (R=1.000)
have provided typical rms precisions of sigma_ T [eff]~150 K,
sigma_logg~0.44, sigma_[Fe/H]~0.15 and sigma_[alpha/ Fe]~0.06. We
have used TGMETalpha to determine atmospheric parameters and alpha
abundances from ~15000 SDSS stellar spectra. Thanks to this very large
sample we have investigated the spatial distribution of [alpha/Fe]
perpendicular to the galactic disk.
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Title: First Results from ROTES: The ROtse Telescope Eclipsing-binary
Survey
Authors: Ribas, I.; Morales, J. C.; Allende Prieto, C.; Jordi, C.;
Bradstreet, D. H.; Sanders, S. J.
2006Ap&SS.304..231R Altcode: 2006Ap&SS.tmp..104R
Detached eclipsing binaries (EBs) provide a unique opportunity to
carry out stringent tests on stellar evolution models. The value of
EBs is enhanced by their membership in open clusters, but the number of
known systems is still very scarce. We have started a systematic search
for late-type EBs in the nearest open clusters with the fully robotic
ROTSE3b telescope at McDonald Observatory in West Texas. On our first
campaigns on the Hyades and Collinder 359, we have identified a number
of previously unknown eclipsing binary candidates. Some of these stars
have been selected for spectroscopic and photometric follow-up. Here
we present details of the observing and reduction strategy as well as
the first results of this ongoing survey.
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Title: "StarDate: The Solar System" And "StarDate: Beyond The
Solar System"
Authors: Hemenway, Mary Kay; Benningfield, D.; Trafton, L. M.; Allende
Prieto, C.; Barnes, T. G., III; Johnson, R. A.; Jones, T. M.; Preston,
S. L.
2006AAS...208.1804H Altcode: 2006BAAS...38...99H
Two recent published guides help educators and the general public
journey to the universe. The writers and editors of StarDate and
astronomers from the University of Texas at Austin produced each of
the forty-page guides. "The Solar System" includes the sun, planets,
and minor bodies of the solar system. "Beyond the Solar System"
includes stars, extrasolar planets, galaxies, cosmology, and some
tools of astronomers. Both guides include activities for families
and/or teachers. In addition to the printed guides, the content and
related resources appear on-line at stardate.org. Spanish translations
of the content are being prepared for radiouniverso.org. The McDonald
Observatory Educator Advisory Board is performing evaluation of the
guides for use by K-12 teachers.Support from the National Aeronautics
and Space Administration under Education and Public Outreach supplements
to Grant/Contract/Agreement No. NNG04G131G and NAG5-13147 issued
through the Office of Space Science is gratefully acknowledged.
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Title: Elemental abundance survey of the Galactic thick disc
Authors: Reddy, Bacham E.; Lambert, David L.; Allende Prieto, Carlos
2006MNRAS.367.1329R Altcode: 2006MNRAS.tmp..343R; 2005astro.ph.12505R
We have performed an abundance analysis for F- and G- dwarfs of the
Galactic thick-disc component. A sample of 176 nearby (d<= 150pc)
thick-disc candidate stars was chosen from the Hipparcos catalogue and
subjected to a high-resolution spectroscopic analysis. Using accurate
radial velocities combined with the Hipparcos astrometry, kinematics
(U, V and W) and Galactic orbital parameters were computed. We
estimate the probability for a star to belong to the thin disc,
the thick disc or the halo. With a probability P>= 70 per cent
taken as certain membership, we assigned 95 stars to the thick disc,
13 to the thin disc, and 20 to the halo. The remaining 48 stars in the
sample cannot be assigned with reasonable certainty to one of the three
components. <P />Abundances of C, O, Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr,
Mn, Fe, Co, Ni, Cu, Zn, Y, Ba, Ce, Nd and Eu have been obtained. The
abundances for the thick-disc stars are compared with those for the
thin-disc members from Reddy et al. The ratios of α-elements (O, Mg,
Si, Ca and Ti) to iron for thick-disc stars show a clear enhancement
compared to thin-disc members in the range -0.3 < [Fe/H] <
-1.2. There are also other elements - Al, Sc, V, Co, and possibly Zn -
which show enhanced ratios to iron in the thick disc relative to the
thin disc. The abundances of Na, Cr, Mn, Ni and Cu (relative to Fe) are
very similar for thin- and thick-disc stars. The dispersion in abundance
ratios [X/Fe] at given [Fe/H] for thick-disc stars is consistent with
the expected scatter due to measurement errors, suggesting a lack of
`cosmic' scatter. <P />A few stars classified as members of the thick
disc by our kinematic criteria show thin-disc abundances. These stars,
which appear older than most thin-disc stars, are also, on average,
younger than the thick-disc population. They may have originated early
in the thin-disc history, and been subsequently scattered to hotter
orbits by collisions. The thick disc may not include stars with [Fe/H]
> -0.3. The observed compositions of the thin and thick discs seem
to be consistent with the models of galaxy formation by hierarchical
clustering in a Lambda cold dark matter (ΛCDM) universe.
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Title: Spot patterns and differential rotation in the eclipsing
pre-cataclysmic variable binary, V471 Tau
Authors: Hussain, G. A. J.; Allende Prieto, C.; Saar, S. H.; Still, M.
2006MNRAS.367.1699H Altcode: 2006astro.ph..2562H; 2006MNRAS.tmp..295H
We present surface spot maps of the K2V primary star in the
pre-cataclysmic variable binary system, V471 Tau. The spot maps show the
presence of large high-latitude spots located at the sub-white dwarf
longitude region. By tracking the relative movement of spot groups
over the course of four nights (eight rotation cycles), we measure
the surface differential rotation rate of the system. Our results
reveal that the star is rotating rigidly with a surface shear rate,
dΩ= 1.6 +/- 6mradd<SUP>-1</SUP>. The single active star AB Dor has
a similar spectral type, rotation period and activity level as the K
star in V471 Tau, but displays much stronger surface shear (46 <
dΩ < 58mradd<SUP>-1</SUP>). Our results suggest that tidal locking
may inhibit differential rotation; this reduced shear, however, does
not affect the overall magnetic activity levels in active K dwarfs.
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Title: SDSS J103913.70+533029.7: A Super Star Cluster in the Outskirts
of a Galaxy Merger
Authors: Knapp, Gillian R.; Tremonti, Christy A.; Rockosi, Constance
M.; Schlegel, David J.; Yanny, Brian; Beers, Timothy C.; Allende
Prieto, Carlos; Wilhelm, Ron; Lupton, Robert H.; Gunn, James E.;
Niederste-Ostholt, Martin; Schneider, Donald P.; Covey, Kevin;
Seth, Anil; Ivezić, Željko; Eisenstein, Daniel J.; Helmboldt,
Joe; Finkbeiner, Douglas P.; Padmanabhan, Nikhil; Kleinman, Scot J.;
Long, Dan; Snedden, Stephanie A.; Nitta, Atsuko; Harvanek, Michael;
Krzesinski, Jurek; Brewington, Howard J.; Barentine, John C.; Newman,
Peter R.; Nielsen, Eric H., Jr.; Fukugita, Masataka; Brinkmann, J.
2006AJ....131..859K Altcode: 2005astro.ph.11010K
We describe the serendipitous discovery in the spectroscopic data of the
Sloan Digital Sky Survey of a starlike object, SDSS J103913.70+533029.7,
at a heliocentric radial velocity of +1012 km s<SUP>-1</SUP>. Its
proximity in position and velocity to the spiral galaxy NGC 3310
suggests an association with the galaxy. At this distance, SDSS
J103913.70+533029.7 has the luminosity of a super star cluster and
a projected distance of 17 kpc from NGC 3310. Its spectroscopic
and photometric properties imply a mass of >10<SUP>6</SUP>
M<SUB>solar</SUB> and an age close to that of the tidal shells seen
around NGC 3310, suggesting that it formed in the event that formed
the shells.
---------------------------------------------------------
Title: The SDSS-I Value-Added Catalog of stellar parameters and the
SEGUE pipeline.
Authors: Beers, T. C.; Lee, Y.; Sivarani, T.; Allende Prieto, C.;
Wilhelm, R.; Fiorentin, P. Re; Bailer-Jones, C.; Norris, J. E.;
SEGUE Calibration Team
2006MmSAI..77.1171B Altcode:
We report on the development, calibration, and refinement of the
SDSS-I Value Added Catalog (VAC) of stellar abundances, temperatures,
and surface gravities. This catalog is based on observations of several
hundred thousand stars obtained during the course of the original Sloan
Digital Sky Survey, now known as SDSS-I. A spectroscopic pipeline
has been developed that obtains estimates of [Fe/H], T_eff, and log
g based on medium-resolution (R = 2000) spectra and ugriz photometry
obtained with the ARC 2.5m telescope. This same pipeline is being used
for estimation of stellar parameters for the ongoing SEGUE: Sloan
Extension for Galactic Understanding and Exploration project. We
discuss the methods explored for development of the VAC, as well
as tests of the calibration based on high-resolution spectroscopy
obtained with the Hobby-Eberly Telescope, the Keck telescopes, and
the Subaru telescope. Based on the existing high-resolution data,
the offsets and scatter of the atmospheric parameters obtained from
the present pipeline are, respectively - [Fe/H]: +0.04 ± 0.18 dex,
T_eff: +17.0 ± 114 K, and log g: +0.03 ± 0.33 dex. These results,
which are quite encouraging, may degrade somewhat as the parameter
space for which high-resolution data presently exists is expanded to
include stars of higher and lower effective temperatures.
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Title: A Spectroscopic Study of the Ancient Milky Way: F- and G-Type
Stars in the Third Data Release of the Sloan Digital Sky Survey
Authors: Allende Prieto, Carlos; Beers, Timothy C.; Wilhelm, Ronald;
Newberg, Heidi Jo; Rockosi, Constance M.; Yanny, Brian; Lee, Young Sun
2006ApJ...636..804A Altcode: 2005astro.ph..9812A
We perform an analysis of spectra and photometry for 22,770 stars
included in the third data release (DR3) of the Sloan Digital Sky
Survey (SDSS). We derive atmospheric parameters and distances. Our
analysis procedures are throughly checked using three recently published
spectroscopic libraries of nearby stars and alternative methods. The
SDSS sample covers a range in stellar brightness of 14<V<22,
primarily at intermediate Galactic latitudes, and comprises large
numbers of F- and G-type stars from the thick-disk and halo populations,
therefore including some of the oldest stars in the Milky Way. We
find that halo stars exhibit a broad range of iron abundances, with a
peak at [Fe/H]~=-1.4. This population exhibits essentially no Galactic
rotation. Thick-disk G-dwarf stars at distances from the Galactic plane
in the range 1<|z|<3 kpc show a much more compact metallicity
distribution, with a maximum at [Fe/H]~=-0.7, and a median Galactic
rotation lagging the local standard of rest by 63 km s<SUP>-1</SUP>. A
comparison of color indices and metal abundances with isochrones
indicates that no significant star formation has taken place in the
halo in the last ~11 Gyr, but there are thick-disk stars that are at
least 2 Gyr younger. We find the metallicities of thick-disk stars
to be nearly independent of Galactocentric distance between 5 and 14
kpc from the Galactic center, in contrast with the marked gradients
found in the literature for the thin disk. No vertical metallicity
gradient is apparent for the thick disk, but we detect a gradient in
its rotational velocity of -16+/-4 km s<SUP>-1</SUP> kpc<SUP>-1</SUP>
between 1 and 3 kpc from the plane. We estimate that among the stars
in our sample there are over 2000 with an iron abundance [Fe/H]<-2,
and over 150 stars with an iron abundance [Fe/H]<-3.
---------------------------------------------------------
Title: SDSS spectroscopic survey of stars.
Authors: Ivezić, Ž.; Schlegel, D.; Uomoto, A.; Bond, N.; Beers, T.;
Allende Prieto, C.; Wilhelm, R.; Lee, Y. Sun; Sivarani, T.; Jurić,
M.; Lupton, R.; Rockosi, C.; Knapp, G.; Gunn, J.; Yanny, B.; Jester,
S.; Kent, S.; Pier, J.; Munn, J.; Richards, G.; Newberg, H.; Blanton,
M.; Eisenstein, D.; Hawley, S.; Anderson, S.; Harris, H.; Kiuchi, F.;
Chen, A.; Bushong, J.; Sohi, H.; Haggard, D.; Kimball, A.; Barentine,
J.; Brewington, H.; Harvanek, M.; Kleinman, S.; Krzesinski, J.; Long,
D.; Nitta, A.; Snedden, S.; SDSS Collaboration
2006MmSAI..77.1057I Altcode: 2007astro.ph..1509I
In addition to optical photometry of unprecedented quality, the Sloan
Digital Sky Survey (SDSS) is also producing a massive spectroscopic
database. We discuss determination of stellar parameters, such as
effective temperature, gravity and metallicity from SDSS spectra,
describe correlations between kinematics and metallicity, and study
their variation as a function of the position in the Galaxy. We show
that stellar parameter estimates by Beers et al. show a good correlation
with the position of a star in the g-r vs. u-g color-color diagram,
thereby demonstrating their robustness as well as a potential for
photometric parameter estimation methods. Using Beers et al. parameters,
we find that the metallicity distribution of the Milky Way stars at
a few kpc from the galactic plane is bimodal with a local minimum at
[Z/Z_⊙] ∼ -1.3. The median metallicity for the low-metallicity
[Z/Z_⊙]< -1.3 subsample is nearly independent of Galactic
cylindrical coordinates R and z, while it decreases with z for the
high-metallicity [Z/Z_⊙]> -1.3 sample. We also find that the
low-metallicity sample has ∼2.5 times larger velocity dispersion and
that it does not rotate (at the ∼10 km/s level), while the rotational
velocity of the high-metallicity sample decreases smoothly with the
height above the galactic plane.
---------------------------------------------------------
Title: Chemical abundances in the ancient Milky Way: G-type SDSS
stars. Automated determination of T_{eff}, log g, [Fe/H] and
[alpha /F]
Authors: Girard, P.; Allende Prieto, C.; Soubiran, C.
2006MmSAI..77.1173G Altcode:
We have developed TGMETalpha in order to determine T_{eff}, log g,
[Fe/H] and [alpha /Fe] for large samples of FGK stars observed at
various spectral resolutions. Tests on several hundred echelle spectra
of reference stars degraded to low resolution (R=1.000) indicate
typical rms precisions of sigma (T_{eff})∼150 K, sigma (logg)∼0.44,
sigma ([Fe/H])∼0.15 and sigma ([alpha /Fe])∼0.06. We have used
TGMETalpha to determine atmospheric parameters and alpha -abundances
from ∼15000 SDSS stellar spectra. Thanks to this very large sample
we have investigated the vertical, radial and rotational properties as
well as the abundance ratio of alpha elements to iron, [alpha /Fe],
of samples representative of the thick disk and the halo. Results
presented in the poster, provide new constraints on galactic thick
disk formation models. We find evidence for a strong negative radial
gradient in [alpha /Fe] with a lack or small one in [Fe/H] in the
thick disk. Moreover, there is a lack of vertical gradient in both
[Fe/H] and [alpha /Fe]. These features have to be reconciled with the
timescale of the thick disk formation as well as with the SFR, IMF,
infall of gas or accreted satellite debris.
---------------------------------------------------------
Title: Low Metallicity Stars in SDSS and SEGUE
Authors: Beers, T. C.; Allende Prieto, C.; Wilhelm, R.; Norris, J. E.;
Yanny, B.; Newberg, H. J.; Rockosi, C.; Sivarani, T.; Lee, Y.
2005AAS...20714704B Altcode: 2005BAAS...37.1405B
Over the past half century, astronomers have identified on the order
of 2000 Very Metal Poor (VMP) stars with [Fe/H] < -2.0, and a
few hundred Extremely Metal Poor (EMP) stars with [Fe/H] < -3.0,
primarily from two large objective prism surveys, the HK survey of
Beers and collaborators and the Hamburg/ESO Survey of Christlieb and
colleagues. High-resolution spectroscopic follow-up of a subset of these
stars has resulted in the discovery of interesting, but rare, individual
stars that display characteristic elemental abundance patterns that are
constraining models of the nature of first-generation stars, the initial
mass function at low metallicity, the yields of early supernovae,
and the operation and astrophysical sites(s) of the r-process and
s-process. <P />Application of a newly developed spectroscopic pipeline
for SEGUE has already revealed the presence of at least 2500 VMP stars
and several hundred EMP stars in the public SDSS archive (through
DR-4). The color selection algorithm that is being used for SEGUE is
discussed, and the efficiency of the identification of VMP stars in
SEGUE is presented. Based on the early SEGUE test data, we estimate
that some 20,000 VMP stars will be identified by this survey within the
next three years. We also discuss current plans for the calibration and
refinement of the SEGUE spectroscopic pipeline and for obtaining rapid
high-resolution follow-up of the most interesting stars. <P />T.C.B.,
S.T., and Y.L. acknowledge partial support from grant AST 04-06784,
as well as from grant PHY 02-16783, Physics Frontier Center/Joint
Institute for Nuclear Astrophysics (JINA), awarded by the US National
Science Foundation. H.J.N acknowledges partial support from NSF grant
AST 03-07571. J.E.N. acknowledges partial support from Australian
Research Council Grant DP0342613.
---------------------------------------------------------
Title: Calibration of the SDSS/SEGUE Spectroscopic Pipeline
Authors: Sivarani, T.; Beers, T. C.; Lee, Y.; Rockosi, C.; Lai, D.;
Yanny, B.; Tucker, D.; Smith, J. A.; Wilhelm, R.; Allende Prieto ,
C.; Norris, J.; Morrison, H.; Plez, B.
2005AAS...20713113S Altcode: 2005BAAS...37S1379S
We describe an ongoing effort to validate the estimated atmospheric
parameters (Teff, log g, [Fe/H]) obtained from SDSS spectroscopy
(R = 2000) and ugriz photometry, which are being employed for both
the previous SDSS-I and the ongoing SEGUE surveys. The spectroscopic
pipeline makes use of a number of methods for the estimation of each
parameter, with estimated internal errors in the order of σ (Teff)
= 150 K, σ (log g) = 0.4 dex, and σ ([Fe/H]) = 0.3 dex. However,
several of these methods rely on an uncertain transformation of g-r
colors to B-V, and there does not presently exist an external validation
of the derived parameters based on high-resolution spectroscopy. In
order to address these deficiencies, we have generated two new grids
of synthetic spectra and ugriz colors (based on both Kurucz NEWODF
models with no covective overshoot and MARCS models) for stellar
atmospheric parameters covering the ranges 3500 K ≤ Teff ≤ 10000
K, 0.0 ≤ log g ≤ 5.0, and -5.0 ≤ [Fe/H] ≤ 0.0. The two grids
will provide a useful internal check on the dependence of the derived
parameters on the adopted stellar models. In addition to these
grids, we have also generated a carbon-enriched subgrid, covering
the entire parameter space for various values of carbon enhancement
([C/Fe] = 0.5,1.0,1.5,2.0). This subgrid makes use of carbon-enhanced
MARCS models instead of scaled solar models, since the atmospheric
structures themselves can be altered by enhanced carbon, especially
at cooler temperatures. The synthetic colors will be calibrated
using a selection of standard stars and open and globular cluster
stars covering a wide range of stellar atmospheric parameters. We
have already obtained a small number of the high-resolution spectra
for SDSS stars needed to calibrate the spectroscopic pipeline;
much larger samples of high-resolution data are presently being
acquired. Preliminarycomparisons of the estimated atmospheric
parameters based on the SDSS/SEGUE spectroscopic pipeline with those
derived from the high-resolution specta will be reported. <P />T.S.,
Y.L., and T.C.B. acknowledge partial support from grant AST 04-06784,
as well as from grant PHY 02-16783, Physics Frontier Center/Joint
Institute for Nuclear Astrophysics (JINA), awarded by the US National
Science Foundation.
---------------------------------------------------------
Title: Properties of the Warm Star Sample from SDSS-Data Release 4
Authors: Wilhelm, R.; Beers, T. C.; Allende Prieto, C.; Rockosi, C.;
Yanny, B.; Newberg, H. J.; Sivarani, T.; Lee, Y.
2005AAS...20713112W Altcode: 2005BAAS...37.1379W
The warm star sample (7000 < Teff < 10,000 K) in SDSS is comprised
of field horizontal branch (FHB) stars and a large number of blue
straggler (BS) stars. Because these stars have a higher intrinsic
luminosity than their cooler, turnoff and main-sequence counterparts,
they are an ideal sample for probing both the global properties of the
thick disk and halo of the Galaxy and the properties of distant halo
structures such as the Sagittarius and Monoceros streams. <P />We have
determined stellar parameters of Teff, log g and [Fe/H] for a large
sample (N = 5060) of SDSS stars using a combination of photometric color
indices and spectroscopic line analysis. In addition we have identified
1110 stars that have significant deviations between the color indices
and hydrogen line strength, of which a subsample appear to be RR Lyrae
variables with photometry and spectroscopy observations taken out of
phase. We present the results of our stellar parameter analysis along
with a new distance calibration for the FHB and BS samples and report
on metallicity trends as a function of distance out to 60 kiloparsecs
from the Sun. In addition we compare the kinematic properties of the
halo and thick disk populations and present metal abundances for the
old population stars in the Sagittarius and Monoceros streams. Finally,
we present evidence that a surprisingly large fraction of the BS sample
occupy the Hertzsprung Gap, a result that is consistent with recently
published findings for BS stars in globular clusters. <P />T.C.B.,
S.T., and Y.L. acknowledge partial support from grant AST 04-06784,
as well as from grant PHY 02-16783, Physics Frontier Center/Joint
Institute for Nuclear Astrophysics (JINA), awarded by the US National
Science Foundation. H.J.N acknowledges partial support from NSF grant
AST 03-07571.
---------------------------------------------------------
Title: SEGUE Target Selection, Kinematics and Distribution of Blue
Horizontal Branch Stars in the Galactic Halo
Authors: Nevils, G. K.; Newberg, H. N.; Allende Prieto, C.; Beers,
T. B.; Lee, Y. L.; Sivarani, T.; Wilhelm, R. W.; Yanny, B. Y.
2005AAS...20713105N Altcode: 2005BAAS...37.1378N
Using a sample of 654 objects selected from the Sloan Digital Sky
Survey (SEGUE) plates, we evaluated and adjusted the SDSS target
algorithm for Blue Horizontal Branch (BHB) stars. We then tested the
spectroscopically determined surface gravity for these stars against the
Lenz et al. 1998 photometric “v-parameter" = 0.283(u-g) - 0.354(g-r) +
0.455(r-i) + 0.766(i-z). Spectroscopic and photometric determinations
of the surface gravity agreed within 0.35 dex. Using surface gravity
and g-r color, we estimated the distance from the center of the Galaxy
and the height off of the Galactic plane for each star. We compare the
galactocentric radial velocities of our star sample with known radial
velocity models of the Galactic Halo. The 76 objects located at galactic
latitudes (b) of -20° and galactic longitude (l) of 110° match in
coordinates, distance from the Sun and radial velocity the model of the
Monoceros tidal stream. <P />G.K.N. was supported by an REU program at
Rensselaer Polytechnic Institute, NSF grant PHYS 04-53231. H.J.N and
G.K.N. acknowledge support from NSF grant AST 03-07571. T.C.B., S.T.,
and Y.L. acknowledge support from NSF grant AST 04-06784, as well as
from NSF grant PHY 02-16783, Physics Frontier Center/Joint Institute
for Nuclear Astrophysics (JINA).
---------------------------------------------------------
Title: Metallicity of the Monoceros Stream from A/F-type Stars
Authors: Wilhelm, R.; Beers, T. C.; Allende Prieto, C.; Newberg,
H. J.; Yanny, B.
2005ASPC..336..371W Altcode:
We have obtained metallicity estimates for a sample of A/F-type
stars that appear to be members of the recently discovered Monoceros
Stream. This sample of candidate main-sequence turn-off stars was
chosen from the Sloan Digitized Sky Survey southern program spectra. The
average metallicity, <[Fe/H]> = -1.37 ± 0.04, is consistent with
the abundance of six suspected Monoceros Stream globular clusters and
with that of the metal-weak thick disk. There is some suggestion that
the Monoceros turn-off stars are younger than the oldest population
of stream globular clusters.
---------------------------------------------------------
Title: The Milky Way as Seen from Apache Point
Authors: Allende Prieto, C.; Beers, T. C.; Wilhelm, R.; Newberg,
H. J.; Yanny, B.
2005ASPC..336..301A Altcode:
We present the results of the analysis of spectra and photometry for
more than 14,000 stars which are part of the second public data release
of the Sloan Digital Sky Survey. We discuss the inferred metallicities
and distances, which suggest that the formation of the Galactic thick
disk took place over a short period of time.
---------------------------------------------------------
Title: The Revised Solar Abundance of Oxygen
Authors: Allende Prieto, C.; Lambert, D. L.
2005LPICo1278....9A Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The Century Survey Galactic Halo Project. II. Global Properties
and the Luminosity Function of Field Blue Horizontal Branch Stars
Authors: Brown, Warren R.; Geller, Margaret J.; Kenyon, Scott J.;
Kurtz, Michael J.; Allende Prieto, Carlos; Beers, Timothy C.;
Wilhelm, Ronald
2005AJ....130.1097B Altcode: 2005astro.ph..5328B
We discuss a 175 deg<SUP>2</SUP> spectroscopic survey for blue
horizontal branch (BHB) stars in the Galactic halo. We use the Two
Micron All Sky Survey (2MASS) and the Sloan Digital Sky Survey (SDSS)
to select BHB candidates, and we find that the 2MASS and SDSS color
selection is 38% and 50% efficient, respectively, for BHB stars. Our
samples include one likely runaway B7 star 6 kpc below the Galactic
plane. The global properties of the BHB samples are consistent
with membership in the halo population: the median metallicity is
[Fe/H]=-1.7, the velocity dispersion is 108 km s<SUP>-1</SUP>, and
the mean Galactic rotation of the BHB stars 3 kpc<|z|<15 kpc
is -4+/-30 km s<SUP>-1</SUP>. We discuss the theoretical basis of the
Preston, Shectman, and Beers M<SUB>V</SUB>-color relation for BHB stars
and conclude that the intrinsic shape of the BHB M<SUB>V</SUB>-color
relation results from the physics of stars on the horizontal branch. We
calculate the luminosity function for the field BHB star samples
using the maximum likelihood method of Efstathiou and coworkers,
which is unbiased by density variations. The field BHB luminosity
function exhibits a steep rise at bright luminosities, a peak between
0.8<M<SUB>V</SUB><1.0, and a tail at faint luminosities. We
compare the field BHB luminosity functions with the luminosity functions
derived from 16 different globular cluster BHBs. Kolmogorov-Smirnov
tests suggest that field BHB stars and BHB stars in globular clusters
share a common distribution of luminosities, with the exception of
globular clusters with extended BHBs.
---------------------------------------------------------
Title: Orbital parameters of the microquasar LS I +61 303
Authors: Casares, J.; Ribas, I.; Paredes, J. M.; Martí, J.; Allende
Prieto, C.
2005MNRAS.360.1105C Altcode: 2005astro.ph..4332C; 2005MNRAS.tmp..483C
New optical spectroscopy of the high-mass X-ray binary microquasar LS
I +61 303 is presented. Eccentric orbital fits to our radial velocity
measurements yield updated orbital parameters in good agreement with
previous work. Our orbital solution indicates that the periastron
passage occurs at radio phase 0.23 and the X-ray/radio outbursts are
triggered 2.5-4 d after the compact star passage. The spectrum of the
optical star is consistent with a B0 V spectral type and contributes
~65 per cent of the total light, the remainder being the result
of emission by a circumstellar disc. We also measure the projected
rotational velocity to be v sini~= 113 km s<SUP>-1</SUP>.
---------------------------------------------------------
Title: Line formation in solar granulation. IV. [O I], O I and OH
lines and the photospheric O abundance
Authors: Asplund, M.; Grevesse, N.; Sauval, A. J.; Allende Prieto,
C.; Kiselman, D.
2005A&A...435..339A Altcode:
A&A, 417, 751-768 (2004), DOI:10.1051/0004-6361:20034328
---------------------------------------------------------
Title: B-type supergiants in the SMC: Chemical compositions and
comparison of static and unified models
Authors: Dufton, P. L.; Ryans, R. S. I.; Trundle, C.; Lennon, D. J.;
Hubeny, I.; Lanz, T.; Allende Prieto, C.
2005A&A...434.1125D Altcode: 2004astro.ph.12367D
High-resolution UCLES/AAT spectra are presented for nine B-type
supergiants in the SMC, chosen on the basis that they may show
varying amounts of nuclear-synthetically processed material mixed to
their surface. These spectra have been analysed using a new grid of
approximately 12 000 non-LTE line blanketed tlusty model atmospheres
to estimate atmospheric parameters and chemical composition. The
abundance estimates for O, Mg and Si are in excellent agreement with
those deduced from other studies, whilst the low estimate for C may
reflect the use of the C II doublet at 4267 Å. The N estimates
are approximately an order of magnitude greater than those found
in unevolved B-type stars or H II regions but are consistent with
the other estimates in AB-type supergiants. These results have been
combined with results from a unified model atmosphere analysis of
UVES/VLT spectra of B-type supergiants (Trundle et al. 2004, A&A,
417, 217) to discuss the evolutionary status of these objects. For
two stars that are in common with those discussed by Trundle et al.,
we have undertaken a careful comparison in order to try to understand
the relative importance of the different uncertainties present in
such analyses, including observational errors and the use of static
or unified models. We find that even for these relatively luminous
supergiants, tlusty models yield atmospheric parameters and chemical
compositions similar to those deduced from the unified code fastwind.
---------------------------------------------------------
Title: A Study of the Near-Ultraviolet Spectrum of Vega
Authors: García-Gil, Alejandro; García López, Ramón J.; Allende
Prieto, Carlos; Hubeny, Ivan
2005ApJ...623..460G Altcode: 2005astro.ph..1213G
UV, optical, and near-IR spectra of Vega have been combined to test
our understanding of stellar atmospheric opacities and to examine the
possibility of constraining chemical abundances from low-resolution
UV fluxes. We have carried out a detailed analysis assuming local
thermodynamic equilibrium (LTE) to identify the most important
contributors to the UV continuous opacity: H, H<SUP>-</SUP>, C I, and
Si II. Our analysis also assumes that Vega is spherically symmetric
and that its atmosphere is well described with the plane-parallel
approximation. By comparing observations and computed fluxes, we have
been able to discriminate between two different flux scales that have
been proposed, the IUE-INES and the HST scales; we favor the latter. The
effective temperature and angular diameter derived from the analysis
of observed optical and near-UV spectra are in very good agreement
with previous determinations based on different techniques. The silicon
abundance is poorly constrained by the UV observations of the continuum
and strong lines, but the situation is more favorable for carbon, and
the abundances inferred from the UV continuum and optical absorption
lines are in good agreement. Some spectral intervals in the UV spectrum
of Vega poorly reproduced by the calculations are likely affected
by deviations from LTE, but we conclude that our understanding of UV
atmospheric opacities is fairly complete for early A-type stars.
---------------------------------------------------------
Title: Oxygen, sodium and iron abundances in the Hyades
Authors: Allende Prieto, C.; Yong, D.; Lambert, D. L.
2005ESASP.560..389A Altcode: 2005csss...13..389A
No abstract at ADS
---------------------------------------------------------
Title: VizieR Online Data Catalog: Center-to-limb variation of quiet
Sun (Allende+, 2004)
Authors: Allende Prieto, C.; Asplund, M.; Fabiani Bendicho, P.
2005yCat..34231109A Altcode:
Solar observations of the center-to-limb variation of several spectral
lines were carried out in October 22-23, 1997, with the Gregory Coude
Telescope (GCT) and its Czerny-Turner echelle spectrograph at the
Observatorio del Teide (Tenerife, Spain). <P />We secured spectra
for 8 spectral setups in 6 different positions across the solar
disk, as summarized in Table 1. <P />Positions #1 to #5 were always
at heliocentric angles theta = 0, 15, 30, 45, and 60 degrees (mu =
cos(theta) = 1.00, 0.97, 0.87, 0.71, and 0.50) along a straight line
crossing the center of the solar disk. Position #6 was also selected
along the same direction, sometimes at theta = 75 degrees and others
at 80 degrees (mu = 0.26 or 0.17). <P />(2 data files).
---------------------------------------------------------
Title: Line formation in solar granulation. VI. [C I], C I, CH and
C<SUB>2</SUB> lines and the photospheric C abundance
Authors: Asplund, M.; Grevesse, N.; Sauval, A. J.; Allende Prieto,
C.; Blomme, R.
2005A&A...431..693A Altcode: 2004astro.ph.10681A
The solar photospheric carbon abundance has been determined from [C
I], C I, CH vibration-rotation, CH A-X electronic and C<SUB>2</SUB>
Swan electronic lines by means of a time-dependent, 3D, hydrodynamical
model of the solar atmosphere. Departures from LTE have been considered
for the C I lines. These turned out to be of increasing importance for
stronger lines and are crucial to remove a trend in LTE abundances
with the strengths of the lines. Very gratifying agreement is found
among all the atomic and molecular abundance diagnostics in spite of
their widely different line formation sensitivities. The mean value
of the solar carbon abundance based on the four primary abundance
indicators ([C I], C I, CH vibration-rotation, C<SUB>2</SUB> Swan)
is log ɛ<SUB>C</SUB> = 8.39 ± 0.05, including our best estimate of
possible systematic errors. Consistent results also come from the CH
electronic lines, which we have relegated to a supporting role due
to their sensitivity to the line broadening. The new 3D based solar C
abundance is significantly lower than previously estimated in studies
using 1D model atmospheres.
---------------------------------------------------------
Title: VizieR Online Data Catalog: B-type Supergiants in the SMC
(Dufton+, 2005)
Authors: Dufton, P. L.; Ryans, R. S. I.; Trundle, C.; Lennon, D. J.;
Hubeny, I.; Lanz, T.; Allende Prieto, C.
2005yCat..34341125D Altcode:
Table 4 contains the adopted atomic data, equivalent widths and
abundance estimates for all the metal lines observed in the SMC
supergiants. It also contains data for the SMC near main sequence
star AzV 304, which has been used in a differential analysis. <P />(2
data files).
---------------------------------------------------------
Title: The Metallicity Distribution Function of the Halo of the
Milky Way
Authors: Beers, Timothy C.; Christlieb, Norbert; Norris, John E.;
Bessell, Michael S.; Wilhelm, Ronald; Allende Prieto, Carlos; Yanny,
Brian; Rockosi, Constance; Newberg, Heidi Jo; Rossi, Silvia; Lee,
Young Sun
2005IAUS..228..175B Altcode: 2005astro.ph..8423B
We report on the distribution of metallicities, [Fe/H], for very
metal-poor stars in the halo of the Galaxy. Although the primary
information on the nature of the Metallicity Distribution Function
(MDF) is obtained from the two major recent surveys for metal-poor
stars, the HK survey of Beers and collaborators, and the Hamburg/ESO
Survey of Christlieb and collaborators, we also discuss the MDF derived
from the publicly available database of stellar spectra and photometry
contained in the third data release of the Sloan Digital Sky Survey
(SDSS DR-3). Even though the SDSS was not originally planned as a
stellar survey, significant numbers of stars have been observed to date
- DR-3 contains spectroscopy for over 70,000 stars, at least half of
which are suitable for abundance determinations. There are as many
very metal-poor ([Fe/H] ) stars in DR-3 as have been obtained from
all previous survey efforts combined. We also discuss prospects for
significant expansion of the list of metal-poor stars to be obtained
from the recently funded extension of the SDSS, which includes the
project SEGUE: Sloan Extension for Galactic Understanding and Evolution.
---------------------------------------------------------
Title: Oxygen in galactic disk stars: non-LTE abundances from the
777 nm O I triplet
Authors: Ramirez, Ivan; Allende Prieto, Carlos; Lambert, David L.
2005IAUS..228..271R Altcode: 2005astro.ph..6744R
Oxygen abundances for a large sample of dwarf and giant stars
kinematically selected to be part of the Galactic thin and thick disks
have been determined from a non-LTE analysis of the O I triplet lines
at 777 nm. The abundance analysis was performed using the infrared
flux method temperature scale, trigonometric surface gravities, and
accurate atomic data. Within this framework, the ionization balance of
iron lines could not be satisfied and so we adopted the iron abundances
from Fe II lines only given that they are relatively less sensitive
to changes in the atmospheric parameters. We show the resulting [O/Fe]
vs. [Fe/H] relationship and briefly discuss its implications.
---------------------------------------------------------
Title: Stellar Kinematics and Chemical Abundances at the
Thick-Disk/Halo Interface
Authors: Rockosi, C. M.; Beers, T. C.; Allende-Prieto, C.; Wilhelm,
R.; Munn, J. A.
2004AAS...20514210R Altcode: 2004BAAS...36.1582R
The old stellar populations of the Milky Way carry the signature of
their formation environment and dynamical history in their kinematics
and chemical abundances. In particular, the dynamically hot thick disk
and halo contain the oldest stars in the Galaxy, and are remnants
of its more chaotic past. We present a study of the high-latitude
thick disk and halo based on a uniformly-selected sample of over 3000
stars with available medium-resolution (2.3 Å) stellar spectra and
ugriz photometry from the Sloan Digital Sky Survey. The stars occupy
the main-sequence turnoff region of old populations and are selected
without any kinematic or metallicity criteria, hence they provide an
unbiased sample of the underlying stellar populations. This is the first
one-third of a sample that will soon include on the order of 10,000 such
stars. <P />We use radial velocities, proper motions, and estimates of
[Fe/H], T<SUB>eff</SUB>, and log g to examine the rotation velocity,
chemical abundance patterns, and velocity dispersions as a function of
distance and position in the Galaxy. Based on these data, we examine the
properties of the thick disk as a function of height above the Galactic
plane and obtain a new estimate of the relative normalization of the
thick disk and halo populations in the Galaxy. <P />This work received
partial funding support from grant NASA grant HST-HF-01143.01-A and PHY
02-16783, Physics Frontier Centers/JINA: Joint Institute for Nuclear
Astrophysics, awarded by the US National Science Foundation.
---------------------------------------------------------
Title: A Value Added Catalog of Stellar Atmospheric Parameters for
SDSS DR-3
Authors: Beers, T. C.; Lee, Y.; Allende Prieto, C.; Wilhelm, R.;
Yanny, B.; Rockosi, C.; Newberg, H. J.; Munn, J.
2004AAS...205.2108B Altcode: 2004BAAS...36R1377B
We report atmospheric parameter estimates (T<SUB>eff</SUB>, log g,
[Fe/H]) and other information (radial velocities, proper motions,
distance estimates) for roughly 40,000 stars (out of a total of
some 75,000) from the third public release of the Sloan Digital Sky
Survey (SDSS), DR-3. As part of this exercise, we have compiled a
set of spectral templates that might prove useful as examples of the
kinds of stars that will be found in the SEGUE (Sloan Extension for
Galactic Understanding and Evolution) project, which is part of the
proposed SDSS-II extension. <P />This work received partial funding
support from grant PHY 02-16783, Physics Frontier Centers/JINA: Joint
Institute for Nuclear Astrophysics, awarded by the US National Science
Foundation. C.R. acknowldeges support from NASA grant HST-HF-01143.01-A.
---------------------------------------------------------
Title: Fundamental Stellar Parameters Derived From High-Resolution
High Signal-To-Noise Spectra of Stars Within 15pc of the Sun
Authors: Olgin, J. G.; Smith, V. V.; Cunha, K.; Allende-Prieto, C.
2004AAS...205.5208O Altcode: 2004BAAS...36.1424O
High-resolution spectra of a sample of all known stars more
luminous than MV=+6.5 and closer than 15 parsecs are being analyzed
spectroscopically in order to derive their effective temperatures
and surface gravities. These spectra are taken from the database of
"A Spectroscopic Survey of Stars in the Solar Neighborhood". The
analysis utilizes a sample of Fe I and Fe II lines. The stellar
parameters derived from this analysis are compared to previously
published values from various studies. A comparison of the different
temperature scales will be discussed as well as the impact these
differences have on chemical abundance studies of cool stars. This
research is supported in part by the National Science Foundation
(AST03-07534 and AST03-07532),NASA (NAG5-13175), and JPL.
---------------------------------------------------------
Title: High-Resolution Spectroscopy of the Transiting Planet Host
Star TrES-1
Authors: Sozzetti, Alessandro; Yong, David; Torres, Guillermo;
Charbonneau, David; Latham, David W.; Allende Prieto, Carlos; Brown,
Timothy M.; Carney, Bruce W.; Laird, John B.
2004ApJ...616L.167S Altcode: 2004astro.ph.10483S
We report on a spectroscopic determination of the stellar parameters
and chemical abundances for the parent star of the transiting planet
TrES-1. Based on a detailed analysis of iron lines in our Keck and
Hobby-Eberly Telescope spectra, we derive T<SUB>eff</SUB>=5250+/-75
K, logg=4.6+/-0.2, and [Fe/H]=0.00+/-0.09. By measuring the Ca
II activity indicator and by putting useful upper limits on the
Li abundance, we constrain the age of TrES-1 to be 2.5+/-1.5
Gyr. By comparing theoretical stellar evolution models with the
observational parameters, we obtain M<SUB>*</SUB>=0.89+/-0.05
M<SUB>solar</SUB> and R<SUB>*</SUB>=0.83+/-0.05 R<SUB>solar</SUB>. Our
improved estimates of the stellar parameters are utilized in
a new analysis of the transit photometry of TrES-1 to derive
a mass M<SUB>p</SUB>=(0.76+/-0.05)M<SUB>J</SUB>, a radius
R<SUB>p</SUB>=1.04<SUP>+0.08</SUP><SUB>-0.05</SUB>R<SUB>J</SUB>, and
an inclination i=89.5<SUP>+0.5</SUP><SUB>-1.3</SUB> deg. The improved
planetary mass and radius estimates provide the grounds for new crucial
tests of theoretical models of evolution and evaporation of irradiated
extrasolar giant planets.
---------------------------------------------------------
Title: The McDonald Observatory Planet Search Projects
Authors: Endl, M.; Cochran, W. D.; McArthur, B.; Allende Prieto, C.;
Hatzes, A. P.; Paulson, D. B.
2004ASPC..321..105E Altcode:
Presently every telescope at McDonald Observatory is utilized for the
search for extrasolar planets. Here we give an overview of the precision
Doppler surveys currently in progress at the 9.2 m Hobby-Eberly Telscope
(HET) and the Harlan J. Smith 2.7 m telescope. Other planet search
programs at McDonald Observatory include a transit search at the 0.8 m
telescope (Baliber & Cochran 2003) and a project to detect planets
orbiting stable pulsating white dwarfs (Mullally et al. 2003).
---------------------------------------------------------
Title: SDSS ugriz Color-Magnitude Diagrams and Spectroscopy of
Galactic Globular Clusters
Authors: Lee, Y.; De Lee, N.; Beers, T. C.; Smith, H.; Wilhelm, R.;
Allende Prieto, C.; Yanny, B.; Rockosi, C.; Newberg, H. J.
2004AAS...205.2302L Altcode: 2004BAAS...36.1381L
The Sloan Digitized Sky Survey (SDSS) and the proposed Sloan Extension
for Galactic Understanding and Evolution (SEGUE) offer a unprecedented
stellar database with which to explore the properties of the thin disk,
thick disk, and halo of the Galaxy. To make full use of the information
contained in the available spectra and photometry, we require external
checks on determinations of radial velocity, temperature, surface
gravity, and metal abundance for stars in the SDSS/SEGUE database. One
useful approach is to make use of the large number of globular cluster
stars that have been (or will be) observed in SDSS/SEGUE. <P />As
examples, we present color-magnitude diagrams, in the SDSS ugriz system,
for four galactic globular clusters, M 2, M 13, M 15, and NGC 2419,
based on photometry reported in the third SDSS public data release,
DR-3. These data are compared with recent isochrones suitable for old,
metal-poor clusters of the halo population. <P />In addition, as part
of tests being conducted for SEGUE, we have obtained medium-resolution
(2.3 Å ) spectra for some 30 likely members of the cluster M 15. These
data are used to provide an independent check on the accuracy with
which we can estimate the radial velocities and atmospheric parameters
(T<SUB>eff</SUB>, log g, [Fe/H]) for SDSS stars that will be obtained
during the course of SEGUE. <P />This work received partial funding
support from grant PHY 02-16783, Physics Frontier Centers/JINA: Joint
Institute for Nuclear Astrophysics, awarded by the US National Science
Foundation. C.R. acknowledges support from NASA grant HST-HF-01143.01-A.
---------------------------------------------------------
Title: Oxygen In The Galactic Disk: Non-LTE Abundances From The 777
nm O I Triplet
Authors: Ramirez, I.; Allende Prieto, C.; Lambert, D. L.
2004AAS...205.5212R Altcode: 2004BAAS...36.1424R
Oxygen abundances for a large sample of dwarf stars in the Galactic thin
and thick disks are determined from a non-LTE analysis of the oxygen
triplet lines at 777 nm. Kinematic criteria are employed to determine
whether a star belongs to the thin or thick disk. Temperatures are
obtained from photometric calibrations based on the infrared flux
method and surface gravities from Hipparcos parallaxes and stellar
evolution calculations. High resolution spectra from the HET and the
2.7 m telescopes at McDonald Observatory, and the VLTI-UVES archive are
used. Metallicities are derived from relatively unblended Fe I and Fe
II lines for which reliable laboratory gf values are available. Oxygen
abundances are obtained from the triplet lines at 777 nm and a
restricted non-LTE analysis, i.e. spectrum synthesis was performed
with non-LTE level populations on an LTE atmospheric structure. We
confirm previous studies that suggest higher oxygen abundances in
the thick disk than in the thin disk although our preliminary results
favor a smooth transition instead of two completely separate trends,
i.e. thick disk stars with intermediate and relatively lower oxygen
abundances are also found.
---------------------------------------------------------
Title: Automated analysis of stellar spectra
Authors: Allende Prieto, C.
2004AN....325..604A Altcode:
Classical model-atmosphere analyses of stellar spectra usually begin by
measuring equivalent widths, and then proceed into a loop in which 1)
model spectra are calculated for a set of abundances and atmospheric
parameters, and 2) observed and computed spectra are compared and
corrections to the abundances and parameters are inferred. Automated
techniques have been developed to automate the measurement of equivalent
widths, and some or all parts in the analysis loop. However, in order
to tackle the massive datasets provided by the new spectroscopic
surveys with dedicated telescopes, it is necessary to make some
radical changes. It is argued that future analyses of stellar spectra
should abandon the use of equivalent widths, and rely on tables of
synthetic spectra that can be either interpolated extremely fast in
minimum-distance optimization methods or used for training genetic
algorithms. Examples of ongoing projects involving high-dispersion
stellar spectra for a small sample and low-dispersion spectra for a
sample of tens of thousands of stars are described.
---------------------------------------------------------
Title: Center-to-limb variation of solar line profiles as a test of
NLTE line formation calculations
Authors: Allende Prieto, C.; Asplund, M.; Fabiani Bendicho, P.
2004A&A...423.1109A Altcode: 2004astro.ph..5154A; 2004astro.ph..5154P
We present new observations of the center-to-limb variation
of spectral lines in the quiet Sun. Our long-slit spectra are
corrected for scattered light, which amounts to 4-8% of the continuum
intensity, by comparison with a Fourier transform spectrum of the disk
center. Different spectral lines exhibit different behaviors, depending
on their sensitivity to the physical conditions in the photosphere and
the range of depths they probe as a function of the observing angle,
providing a rich database to test models of the solar photosphere and
line formation. We examine the effect of inelastic collisions with
neutral hydrogen in NLTE line formation calculations of the oxygen
infrared triplet, and the Na I λ6160.8 line. Adopting a classical
one-dimensional theoretical model atmosphere, we find that the sodium
transition, formed in higher layers, is more effectively thermalized
by hydrogen collisions than the high-excitation oxygen lines. This
result appears as a simple consequence of the decrease of the ratio
N<SUB>H</SUB>/N<SUB>e</SUB> with depth in the solar photosphere. The
center-to-limb variation of the selected lines is studied both under
LTE and NLTE conditions. In the NLTE analysis, inelastic collisions
with hydrogen atoms are considered with a simple approximation or
neglected, in an attempt to test the validity of such approximation. For
the sodium line studied, the best agreement between theory and
observation happens when NLTE is considered and inelastic collisions
with hydrogen are neglected in the rate equations. The analysis of
the oxygen triplet benefits from a very detailed calculation using an
LTE three-dimensional model atmosphere and NLTE line formation. The
χ<SUP>2</SUP> statistics favors including hydrogen collisions with
the approximation adopted, but the oxygen abundance derived in that
case is significantly higher than the value derived from OH infrared
transitions. <P />GCT spectra are only available in electronic form
at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5)
or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/423/1109
---------------------------------------------------------
Title: HD 137510: An Oasis in the Brown Dwarf Desert
Authors: Endl, Michael; Hatzes, Artie P.; Cochran, William D.;
McArthur, Barbara; Allende Prieto, Carlos; Paulson, Diane B.; Guenther,
Eike; Bedalov, Ana
2004ApJ...611.1121E Altcode: 2004astro.ph..4584E
Since the beginning of precise Doppler surveys, which have had
stunning success in detecting extrasolar planetary companions, one
surprising enigma has emerged: the relative paucity of spectroscopic
binaries where the secondary mass lies in between the stellar and
planetary mass regime. This gap in the mass function for close-in
(a<3-4 AU) companions to solar-type stars is generally referred
to as the “brown dwarf desert.” Here we report the detection of a
companion to HD 137510 (G0 IV), with a minimum mass of 26M<SUB>J</SUB>,
moving in an eccentric orbit (e=0.4) with a period of 798 days and an
orbital semimajor axis of 1.85 AU. The detection is based on precise
differential radial velocity data obtained by the McDonald Observatory
and Thüringer Landessternwarte Tautenburg planet search programs. <P
/>Based on observations made at McDonald Observatory and the Thüringer
Landessternwarte Tautenburg.
---------------------------------------------------------
Title: The Mass of the Galaxy from Large Samples of Field
Horizontal-Branch Stars in the SDSS Early Data Release
Authors: Beers, T. C.; Chiba, M.; Sakamoto, T.; Wilhelm, R.; Allende
Prieto, C.; Sommer-Larsen, J.; Newberg, H. J.; Yanny, B.; Marsteller,
B.; Pier, J. R.
2004IAUS..220..195B Altcode:
We present a new estimate of the mass of the Milky Way, making use of a
large sample of 955 field horizontal-branch (FHB) stars from the Early
Data Release of the Sloan Digital Sky Survey. This sample of stars
has been classified on the basis of an automated analysis approach,
in combination with other methods, in order to obtain estimates of the
physical parameters of the stars, i.e., T_eff, log g, [Fe/H], and should
be relatively free of contamination from halo blue stragglers. The
stars all have measured radial velocities and photometric distance
estimates, and the sample includes objects as distant as ∼ 75 kpc
from the Galactic center. Application of a Bayesian likelihood method,
for a specific model of the Galaxy, indicates that the total mass of the
Galaxy lies in the range 1.5-4.0 x 10<SUP>12</SUP> M<SUB>⊙</SUB>. Our
sample appears to reveal a clear signature of a dual halo population of
FHB stars, with the boundary between the inner and outer halo around
20 kpc, and the possibility of rather striking differences in the
rotational properties of the Galaxy at low metallicity.
---------------------------------------------------------
Title: S<SUP>4</SUP>N: A spectroscopic survey of stars in the solar
neighborhood. The Nearest 15 pc
Authors: Allende Prieto, C.; Barklem, P. S.; Lambert, D. L.; Cunha, K.
2004A&A...420..183A Altcode: 2004astro.ph..3108P; 2004astro.ph..3108A
We report the results of a high-resolution spectroscopic survey of all
the stars more luminous than M_V = 6.5 mag within 14.5 pc from the
Sun. The Hipparcos catalog's completeness limits guarantee that our
survey is comprehensive and free from some of the selection effects in
other samples of nearby stars. The resulting spectroscopic database,
which we have made publicly available, includes spectra for 118 stars
obtained with a resolving power of R ≃ 50 000, continuous spectral
coverage between ∼ 362-921 nm, and typical signal-to-noise ratios
in the range 150-600. We derive stellar parameters and perform a
preliminary abundance and kinematic analysis of the F-G-K stars
in the sample. The inferred metallicity ([Fe/H]) distribution is
centered at about -0.1 dex, and shows a standard deviation of 0.2
dex. A comparison with larger samples of Hipparcos stars, some of
which have been part of previous abundance studies, suggests that
our limited sample is representative of a larger volume of the local
thin disk. We identify a number of metal-rich K-type stars which
appear to be very old, confirming the claims for the existence of
such stars in the solar neighborhood. With atmospheric effective
temperatures and gravities derived independently of the spectra, we
find that our classical LTE model-atmosphere analysis of metal-rich
(and mainly K-type) stars provides discrepant abundances from neutral
and ionized lines of several metals. This ionization imbalance could
be a sign of departures from LTE or inhomogeneous structure, which
are ignored in the interpretation of the spectra. Alternatively,
but seemingly unlikely, the mismatch could be explained by systematic
errors in the scale of effective temperatures. Based on transitions of
majority species, we discuss abundances of 16 chemical elements. In
agreement with earlier studies we find that the abundance ratios to
iron of Si, Sc, Ti, Co, and Zn become smaller as the iron abundance
increases until approaching the solar values, but the trends reverse
for higher iron abundances. At any given metallicity, stars with a low
galactic rotational velocity tend to have high abundances of Mg, Si,
Ca, Sc, Ti, Co, Zn, and Eu, but low abundances of Ba, Ce, and Nd. The
Sun appears deficient by roughly 0.1 dex in O, Si, Ca, Sc, Ti, Y,
Ce, Nd, and Eu, compared to its immediate neighbors with similar iron
abundances. <P />Based on observations made with the 2.7 m telescope at
the McDonald Observatory of the University of Texas at Austin (Texas),
and the 1.52 m telescope at the European Southern Observatory (La
Silla, Chile) under the agreement with the CNPq/Observatorio Nacional
(Brazil). <P />Tables 3-5 are only available in electronic form at
the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or
via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/420/183
---------------------------------------------------------
Title: Line formation in solar granulation. IV. [O I], O I and OH
lines and the photospheric O abundance
Authors: Asplund, M.; Grevesse, N.; Sauval, A. J.; Allende Prieto,
C.; Kiselman, D.
2004A&A...417..751A Altcode: 2003astro.ph.12290A
The solar photospheric oxygen abundance has been determined from
[O I], O I, OH vibration-rotation and OH pure rotation lines by
means of a realistic time-dependent, 3D, hydrodynamical model of
the solar atmosphere. In the case of the O I lines, 3D non-LTE
calculations have been performed, revealing significant departures
from LTE as a result of photon losses in the lines. We derive a solar
oxygen abundance of log ɛ<SUB>O</SUB> = 8.66 ± 0.05. All oxygen
diagnostics yield highly consistent abundances, in sharp contrast
with the results of classical 1D model atmospheres. This low value
is in good agreement with measurements of the local interstellar
medium and nearby B stars. This low abundance is also supported by
the excellent correspondence between lines of very different line
formation sensitivities, and between the observed and predicted line
shapes and center-to-limb variations. Together with the corresponding
down-ward revisions of the solar carbon, nitrogen and neon abundances,
the resulting significant decrease in solar metal mass fraction to Z =
0.0126 can, however, potentially spoil the impressive agreement between
predicted and observed sound speed in the solar interior determined
from helioseismology.
---------------------------------------------------------
Title: Magnesium Isotope Ratios in Hyades Stars
Authors: Yong, David; Lambert, David L.; Allende Prieto, Carlos;
Paulson, Diane B.
2004ApJ...603..697Y Altcode: 2003astro.ph.12054Y
Using classical model atmospheres and an LTE analysis, Mg
isotope ratios <SUP>24</SUP>Mg:<SUP>25</SUP>Mg:<SUP>26</SUP>Mg
are measured in 32 Hyades dwarfs covering effective temperatures
4000K<=T<SUB>eff</SUB><=5000K. We find no significant trend
in any isotope ratio versus T<SUB>eff</SUB>, and the mean isotope
ratio is in excellent agreement with the solar value. We determine
stellar parameters and Fe abundances for 56 Hyades dwarfs covering
4000K<=T<SUB>eff</SUB><=6200K. For stars warmer than 4700 K,
we derive a cluster mean value of [Fe/H]=0.16+/-0.02 (σ=0.1),
in good agreement with previous studies. For stars cooler than
4700 K, we find that the abundance of Fe from ionized lines
exceeds the abundance of Fe from neutral lines. At 4700 K,
[Fe/H]<SUB>II</SUB>-[Fe/H]<SUB>I</SUB>~=0.3dex, while at 4000 K
[Fe/H]<SUB>II</SUB>-[Fe/H]<SUB>I</SUB>~=1.2dex. This discrepancy
between the Fe abundance from neutral and ionized lines likely reflects
inadequacies in the model atmospheres and the presence of non-LTE or
other effects. Despite the inability of the models to reproduce the
ionization equilibrium for Fe, the Mg isotope ratios appear immune to
these problems and remain a powerful tool for studying Galactic chemical
evolution. <P />Data presented here were obtained at the W. M. Keck
Observatory, which is operated as a scientific partnership among the
California Institute of Technology, the University of California,
and the National Aeronautics and Space Administration. The Observatory
was made possible by the generous financial support of the W. M. Keck
Foundation.
---------------------------------------------------------
Title: VizieR Online Data Catalog: Spectroscopic survey in solar
neighborhood (Allende Prieto+ 2004)
Authors: Allende Prieto, C.; Barklem, P. S.; Lambert, D. L.; Cunha, K.
2004yCat..34200183A Altcode:
Tables with kinematic data and chemical abundances for the sample. The
atomic line data are also provided. The data in FITS are available
in the internet from the project site S4N (Spectrsocopic Survey of
Stars in the Solar Neighborhood) at http://hebe.as.utexas.edu/s4n/
and at its mirror http://www.astro.uu.se/~s4n/ <P />(5 data files).
---------------------------------------------------------
Title: New Resources to Explore the Old Galaxy: Mining the SDSS
Authors: Allende Prieto, C.; Beers, T. C.; Li, Y.; Newberg, H. J.;
Wilhelm, R.; Yanny, B.
2004oee..sympE...1A Altcode: 2003astro.ph..4352A; 2003astro.ph..4352P
The Sloan Digital Sky Survey (SDSS) is collecting photometry and
intermediate resolution spectra for ∼10<SUP>5</SUP> stars in
the thick-disk and stellar halo of the Milky Way. This massive
dataset can be used to infer the properties of the stars that make
up these structures, and considerably deepen our vision of the old
components of the Galaxy. We devise tools for automatic analysis of
the SDSS photometric and spectroscopic data based on plane-parallel
line-blanketed LTE model atmospheres and fast optimization algorithms. A
preliminary study of about 5000 stars in the Early Data Release gives
a hint of the vast amount of information that the SDSS stellar sample
contains.
---------------------------------------------------------
Title: Physical Parameters of SDSS Stars, the Nature of the SDSS
`Ring around the Galaxy', and the SEGUE Project
Authors: Beers, Timothy C.; Allende Prieto, Carlos; Wilhelm, Ronald;
Yanny, Brian; Newberg, Heidi
2004PASA...21..207B Altcode:
Although the Sloan Digital Sky Survey (SDSS) was primarily envisioned as
a tool for understanding the nature of the `high redshift' universe,
significant discoveries have already been made at lower redshift,
z~0, through studies of stars in the Milky Way galaxy. We have begun
to explore the nature of the Milky Way by detailed investigation
of the publicly accessible SDSS archive, using spectroscopically
targeted stars of special interest (e.g. field horizontal-branch stars,
carbon-enhanced stars, and F- and G-type turnoff stars), as well as the
stars originally selected as photometric and reddening standards. The
first step is to use the SDSS data (which includes independently
calibrated five-band photometry and spectrophotometry of individual
stars) to derive reliable estimates of the stellar physical parameters,
such as T<SUB> eff</SUB>, logg, and [Fe/H], for stars that have been
observed to date. Of particular interest, at present, are the stars
that are apparently associated with the Monoceros Stream (also known
as the SDSS `Ring around the Galaxy'), for which we report derived
metallicities. The techniques we have developed for derivation of the
physical parameters for these stars are presently being applied to other
stars in the SDSS database, including the Early Data Release (EDR),
as well as the first official public database, DR-1. Here we report
on the progress made to date, and comment on what might be explored in
the near future from a dedicated extension of the SDSS survey (SEGUE)
that specifically targets stars in the Milky Way.
---------------------------------------------------------
Title: Elemental Abundances in the Galactic Disk
Authors: Reddy, B. E.; Tomkin, J.; Lambert, D. L.; Allende Prieto, C.
2004oee..sympE..49R Altcode:
Here, we discussed our recent results of elemental abundance survey
of Galactic disk based on 181 F- and G-type dwarfs (published by
Reddy et al. 2003, MNRAS, 340, 304). Using high-resolution and high
signal-to-noise spectra we obtained quantitative abundances for 27
elements: C, N, O, Na, Mg, Al, Si, S, K, Ca, Sc, Ti, V, Cr, Mn, Co,
Ni, Cu, Zn, Sr, Y, Zr, Ba, Ce, Nd, and Eu. For the entire sample we
have determined kinematic (U,V,W) and the orbital parameters (peri-
and apo- Galactic distances). <P />The alpha-elements -- O, Mg,
Si, Ca, and Ti -- show [α/Fe] to increase slightly with decreasing
[Fe/H]. Heavy elements with dominant contributions at solar metallicity
from the s-process show [s/Fe] to decrease slightly with decreasing
[Fe/H]. Scatter in [X/Fe] at a fixed [Fe/H] is entirely attributable
to the small measurement errors, after excluding the few thick disk
stars and the s-process enriched CH subgiants. Tight limits are set on
`cosmic' scatter. If a weak trend with [Fe/H] is taken into account,
the composition of a thin disk star expressed as [X/Fe] is independent
of the star's age and birthplace for elements contributed in different
proportions by massive stars (Type II SN), exploding white dwarfs
(Type Ia SN), and asymptotic red giant branch stars. <P />By combining
our sample with published studies, we deduced properties of thin and
thick disk stars. Thick disk stars are primarily identified by their
V<SUB>LSR</SUB> in the range - 40 to -100 km s<SUP>-1</SUP>. These
are very old stars with origins in the inner Galaxy and metallicities
[Fe/H] <∼-0.4. At the same [Fe/H], the sampled thin disk stars
have V<SUB>LSR</SUB> ∼0 km s<SUP>-1</SUP>, and are generally younger
with a birthplace at about the Sun's Galactocentric distance. In the
range -0.35 ≥ [Fe/H] ≥ -0.70, well represented by present thin
and thick disk samples, [X/Fe] of the thick disk stars is greater
than that of thin disk stars for Mg, Al, Si, Ca, Ti, and Eu. [X/Fe]
is very similar for the thin and thick disk for -- notably -- Na, and
iron-group elements. Barium ([Ba/Fe]) may be underabundant in thick
relative to thin disk stars. These results extend previous ideas about
composition differences between the thin and thick disk.
---------------------------------------------------------
Title: A Large, “Fair", Sample of Halo and Thick Disk Stars from
the SDSS
Authors: Rockosi, C. M.; Beers, T. C.; Allende Prieto, C.; Wilhelm,
R.; Sloan Digital Sky Survey Collaboration
2003AAS...20311210R Altcode: 2003BAAS...35.1385R
The structure and evolution of the Milky Way is imprinted on the
kinematics, chemical abundances, and spatial distribution of its
constituent stars. In the past, samples of stars in the halo and
thick disk have primarily been selected either on the basis of their
kinematics (e.g., proper-motion selection), their distinct abundances
(e.g., objective-prism selection of metal-poor stars), or their unusual
colors (e.g., via δ (U-B)). As a result, it has been difficult to
confidently infer a unbiased picture of the underlying chemo-dynamical
properties of the of these populations. <P />We present an analysis
of the kinematics of the thick disk and the halo based on a sample of
1200 stars from two high-latitude fields for which we have measured
radial velocities, proper motions, chemical abundances, and derived
estimates of T<SUB>eff</SUB> and log(g), based on flux-calibrated
medium-resolution spectroscopy and five-band ugriz photometry obtained
from the Sloan Digital Sky Survey (SDSS). The stars are randomly chosen
in the range g-r < 0.8, r < 19.15, and lie near the main-sequence
turnoff of ancient stellar populations at distances between 1 and 10
kpc from the sun. They are selected without regard to their kinematics
or chemical composition, and so represent a fair sample of the stellar
populations from which they are drawn. We use this nearly ideal dataset
to examine the correlation between kinematics, chemical abundance,
and position in the Galaxy along these lines of sight. We compare the
velocity and chemical abundance information with the global properties
of the thick disk and halo as traced by the main-sequence turnoff color
in the SDSS photometry, and with models for the thick disk and halo fit
to SDSS color magnitude diagrams. <P />These data represent the first
10% of a much larger sample we are in the process of assembling. Future
surveys of Galactic stars, such as might be obtained by the proposed
SEGUE extension to SDSS, will enable unprecedented knowledge of the
nature of the thick-disk, and the inner and outer halo populations of
the Milky Way. <P />This work has received partial support from NSF
grants AST 00-98508 and AST 00-98549 and NASA grant HST-HF-01143.01-A.
---------------------------------------------------------
Title: The Kinematic Signature of the Sagittarius Dwarf Galaxy Tidal
Debris from SDSS-DR1
Authors: Wilhelm, R.; Beers, T. C.; Allende Prieto, C.; Newberg, H.;
Yanny, B.
2003AAS...20311201W Altcode: 2003BAAS...35.1383W
Recent results from the Sloan Digital Sky Survey (SDSS) and the
2MASS All-Sky Survey have clearly revealed the extent of the spatial
distribution of stars affiliated with the tidal debris tail of
the Sagittarius Dwarf Galaxy (Sgr). Although these surveys help to
constrain the shape of the Sgr orbit, kinematics of the tidal tail
stars are crucial in order to fully characterize the structure and
dynamics of this component of our Galactic halo, and to allow a better
determination of the shape of the Milky Way dark matter halo. <P />We
present kinematic results for a sample of horizontal-branch stars from
the SDSS-DR1 spectroscopic data. SDSS photometry and spectroscopy
were used to determine the stellar parameters (T<SUB>eff</SUB>, log
g, [Fe/H]) and subsequent luminosity classification. Distances and
radial velocities for a sample of blue horizontal-branch stars were
analyzed in the direction of the leading Northern tidal arm located
at (b,l) ∼ (350, 50) and the trailing southern arc at (b, l) ∼
(157, -58). There exists clear evidence of kinematic substructure
in both directions. The data match quite well the distribution of
carbon stars and model predictions of Ibata et. al (2001 ApJ 551,
2941). This includes the velocity dispersion in the northern arm,
where we find σ = 55 km/s, and evidence for a bi-modal distribution
in the southern arc field, with the dominant component having a very
small velocity dispersion, σ = 30 km/s. These results are consistent
with a more spherical dark matter halo (q<SUB>m</SUB> = 0.9) as found
by Ibata et. al. <P />Partial support has been received for this work
from NSF grants AST 00-98508 and AST 00-98549.
---------------------------------------------------------
Title: A Search for Kinematic Evidence of Tidal Tails in Globular
Clusters
Authors: Lauchner, A.; Wilhelm, R.; Beers, T. C.; Allende Prieto, C.
2003AAS...20311226L Altcode: 2003BAAS...35.1388L
Recent star count surveys of areas around globular star clusters
have shown strong evidence of tidal tails stretching out many
degrees beyond the cluster tidal radius. These tails are believed
to be cluster stars which have escaped due to tidal shocking after
passages through the disk of the Galaxy. Although the statistical
star counts indicate and overdensity of stars around the clusters,
to date, there is little kinematic verification for any tidal tail
stars. <P />We present results of a kinematic search for evidence of
tidal tails using the Sloan Digital Sky Survey (SDSS), Data Release-1
(DR1). This search was conducted using thirteen globular star clusters
which were found to be within three degrees of the DR1 strips. Using
stars from the DR1 spectroscopy database, we have determined radial
velocities, distances and metal abundance for the large number of
the SDSS stars. The SDSS stars include horizontal branch stars, blue
stragglers and main sequence turn-off stars, most of which reach to
the distances of the clusters. Comparing these parameters to that of
a given globular cluster, we search for stars which match the cluster
parameters to within the uncertainty of our derived parameters. Along
with the candidate findings for this project, we will also including
a comparison of candidate tidal star positions to that of published
tidal tails from star counts, and discuss future refinements and
follow-up observations.
---------------------------------------------------------
Title: S<SUP>4</SUP>N: A Spectroscopic Survey of Stars in the Solar
Neighborhood
Authors: Lambert, D. L.; Allende Prieto, C.; Cunha, K.
2003csss...12..875L Altcode:
We are using the McDonald 2.7m and ESO 1.52m telescopes <P />to
obtain spectra of nearby stars at high-resolution, high S/N, and
with complete optical coverage. The sample includes all stars in the
Hipparcos catalog brighter than M<SUB>V</SUB> = 6.5 (∼ K2 V) within
a 12770 pc<SUP>3</SUP> sphere centered at the Sun. The survey is 78 %
complete. The database will be publicly released in approximately 1
year. We plan to: 1) Provide homogeneous radial velocities with the
accuracy required to exploiting in full the accurate proper motions
and parallaxes determined by Hipparcos (0.1 < σ (v) < 1.0 km
s<SUP>-1</SUP>); 2) Provide homogeneous chemical abundances for a
large (> 30) number of elements with an accuracy of 0.04 dex; 3)
Determine the fundamental stellar parameters for the sample using an
array of different methods. We discuss potential applications.
---------------------------------------------------------
Title: The Century Survey Galactic Halo Project. I. Stellar Spectral
Analysis
Authors: Brown, Warren R.; Allende Prieto, Carlos; Beers, Timothy
C.; Wilhelm, Ronald; Geller, Margaret J.; Kenyon, Scott J.; Kurtz,
Michael J.
2003AJ....126.1362B Altcode: 2003astro.ph..5406B
The Century Survey Galactic Halo Project is a photometric and
spectroscopic survey from which we select relatively blue stars
(V-R<0.30 mag) as probes of the Milky Way halo. The survey strip
spans the range of Galactic latitude 35°<b<88°, allowing us to
study the nature of populations of stars and their systematic motions as
a function of Galactic latitude. One of our primary goals is to use blue
horizontal-branch stars to trace potential star streams in the halo, and
to test the hierarchical model for the formation of the Galaxy. In this
paper we discuss spectroscopy and multipassband photometry for a sample
of 764 blue stars in the Century Survey region. Our sample consists
predominantly of A- and F-type stars. We describe our techniques
for determination of radial velocities, effective temperatures,
metallicities, and surface gravities. Based on these measurements,
we derive distance estimates by comparison with a set of calibrated
isochrones. We devote special attention to the classification of blue
horizontal-branch stars, and compare the results obtained from the
application of the techniques of Kinman et al., Wilhelm et al., and
Clewley et al. We identify 55 blue horizontal-branch stars. Our large
sample of stars also uncovers a number of unusual objects, including
three carbon-enhanced stars, a late B-type star located 0.8 kpc above
the Galactic plane, and a DZ white dwarf.
---------------------------------------------------------
Title: Non-LTE Model Atmospheres for Late-Type Stars. I. A Collection
of Data for Light Neutral and Singly Ionized Atoms
Authors: Allende Prieto, Carlos; Lambert, David L.; Hubeny, Ivan;
Lanz, Thierry
2003ApJS..147..363A Altcode: 2003astro.ph..3559A; 2003astro.ph..3559P
With the goal of producing a reliable set of model atoms and singly
ionized ions for use in building NLTE model atmospheres, we have
combined measured energy levels, critically compiled line transition
probabilities, and resonance-averaged calculations of photoionization
cross sections. <P />A majority of the elements from Li to Ca are
considered, covering most of the important species in late-type
atmospheres. These include elements that contribute free electrons
and/or continuous opacity in the ultraviolet (e.g., Mg and Si), as well
as trace elements whose abundance determinations rely on ultraviolet
lines (e.g., B from B I lines). The new data complement and, for the
species in common, supersede a previous collection of model atoms
originally designed for use in studies of early-type stars.
---------------------------------------------------------
Title: Non-LTE Model Atmospheres for Late-Type Stars. II. Restricted
Non-LTE Calculations for a Solar-like Atmosphere
Authors: Allende Prieto, Carlos; Hubeny, Ivan; Lambert, David L.
2003ApJ...591.1192A Altcode: 2003astro.ph..3560A; 2003astro.ph..3560P
We test our knowledge of the atomic opacity in the solar UV
spectrum. Using the atomic data compiled in the first paper in
this series from modern, publicly available databases, we perform
calculations that are compared with space-based observations of
the Sun. At wavelengths longer than about 2600 Å, LTE modeling can
reproduce quite closely the observed fluxes; uncertainties in the atomic
line data account fully for the differences between calculated and
observed fluxes. At shorter wavelengths, departures from LTE appear
to be important, since our LTE and restricted non-LTE calculations
differ. Analysis of visible/near-IR Na I and O I lines, two species
that produce a negligible absorption in the UV, shows that observed
departures from LTE for these species can be reproduced very accurately
with restricted (fixed atmospheric structure) non-LTE calculations.
---------------------------------------------------------
Title: VizieR Online Data Catalog: [X/Fe] of Galactic disc F and G
dwarfs (Reddy+, 2003)
Authors: Reddy, B. E.; Tomkin, J.; Lambert, D. L.; Allende Prieto, C.
2003yCat..73400304R Altcode:
All the observations were made at the Harlan J. Smith 2.7-m telescope
at McDonald Observatory, using the 2dcoude echelle spectrometer
(Tull et al., 1995PASP..107..251T) with a 2048x2048 pixel Tektronix
charge-coupled device (CCD) as detector. <P />(3 data files).
---------------------------------------------------------
Title: V471 Tau: mapping magnetic activity in a pre-CV binary system.
Authors: Hussain, G. A. J.; Allende Prieto, C.; Saar, S. H.; Collier
Cameron, A.; Still, M. D.
2003AAS...202.0804H Altcode: 2003BAAS...35..708H; 2003AAS...202..804H
The technique of Doppler imaging enables us to map starspots at the
surfaces of rapidly rotating cool stars. Starspots are probes of
magnetic activity, thus the locations of these spots also indicate
where the strongest magnetic fields tend to emerge. We present surface
spot maps of the K2V component of V471 Tau from 2001-2002. Our spot
maps can be used (a) to show that magnetic activity is confined to
high latitude regions in the K2V component, (b) to measure surface
differential rotation of this component and (c) to evaluate spot
lifetimes in rapid rotators. We conclude that the K2V component of
V471 Tau shows a similar equator-pole lap-time as the Sun and that
its surface spots last on the order of months.
---------------------------------------------------------
Title: An automated system to classify stellar spectra - I
Authors: Allende Prieto, Carlos
2003MNRAS.339.1111A Altcode: 2002astro.ph.12138A; 2002astro.ph.12138P
Analyses of stellar spectra often begin with the determination of a
number of parameters that define a model atmosphere. This work presents
a prototype for an automated spectral classification system that uses a
150-Å-wide region around Hβ, and applies to stars of spectral types
A-K with normal (scaled solar) chemical composition. The new tool
exploits synthetic spectra based on plane-parallel flux-constant model
atmospheres. The input data are high signal-to-noise ratio spectra with
a resolution greater than approximately 1 Å. The output parameters
are forced to agree with an external scale of effective temperatures,
based on the infrared flux method. The system is fast - a spectrum is
classified in a few seconds - and well suited for implementation on
a web server. We estimate upper limits to the 1σ random error in the
retrieved effective temperatures, surface gravities and metallicities
as 100 K, 0.3 and 0.1 dex, respectively.
---------------------------------------------------------
Title: The chemical compositions of Galactic disc F and G dwarfs
Authors: Reddy, Bacham E.; Tomkin, Jocelyn; Lambert, David L.;
Allende Prieto, Carlos
2003MNRAS.340..304R Altcode: 2002astro.ph.11551R
Photospheric abundances are presented for 27 elements from carbon to
europium in 181 F and G dwarfs from a differential local thermodynamic
equilibrium (LTE) analysis of high-resolution and high signal-to-noise
ratio spectra. Stellar effective temperatures (T<SUB>eff</SUB>)
were adopted from an infrared flux method calibration of Strömgren
photometry. Stellar surface gravities (g) were calculated from Hipparcos
parallaxes and stellar evolutionary tracks. Adopted T<SUB>eff</SUB> and
g values are in good agreement with spectroscopic estimates. Stellar
ages were determined from evolutionary tracks. Stellar space motions
(U, V, W) and a Galactic potential were used to estimate Galactic
orbital parameters. These show that the vast majority of the stars
belong to the Galactic thin disc. <P />Relative abundances expressed
as [X/Fe] generally confirm previously published results. We give
results for C, N, O, Na, Mg, Al, Si, S, K, Ca, Sc, Ti, V, Cr, Mn,
Co, Ni, Cu, Zn, Sr, Y, Zr, Ba, Ce, Nd and Eu. The α elements - O,
Mg, Si, Ca and Ti - show [α/Fe] to increase slightly with decreasing
[Fe/H]. Heavy elements with dominant contributions at solar metallicity
from the s-process show [s/Fe] to decrease slightly with decreasing
[Fe/H]. Scatter in [X/Fe] at a fixed [Fe/H] is entirely attributable
to the small measurement errors, after excluding the few thick disc
stars and the s-process-enriched CH subgiants. Tight limits are set on
`cosmic' scatter. If a weak trend with [Fe/H] is taken into account,
the composition of a thin disc star expressed as [X/Fe] is independent
of the star's age and birthplace for elements contributed in different
proportions by massive stars (Type II supernovae), exploding white
dwarfs (Type Ia supernovae) and asymptotic red giant branch stars. <P
/>By combining our sample with various published studies, comparisons
between thin and thick disc stars are made. In this composite sample,
thick disc stars are primarily identified by their V<SUB>LSR</SUB>
in the range -40 to -100 km s<SUP>-1</SUP>. These are very old stars
with origins in the inner Galaxy and metallicities [Fe/H]<=-0.4. At
the same [Fe/H], the sampled thin disc stars have V<SUB>LSR</SUB>~ 0 km
s<SUP>-1</SUP>, and are generally younger with a birthplace at about the
Sun's Galactocentric distance. In the range -0.35 >=[Fe/H]>=-0.70,
well represented by present thin and thick disc samples, [X/Fe] of
the thick disc stars is greater than that of thin disc stars for Mg,
Al, Si, Ca, Ti and Eu. [X/Fe] is very similar for the thin and thick
disc for - notably - Na and iron-group elements. Barium ([Ba/Fe]) may
be underabundant in thick relative to thin disc stars. These results
extend previous ideas about composition differences between the thin
and thick disc.
---------------------------------------------------------
Title: Comparisons between Observed and Computed Visible and Near-UV
Spectra of Vega
Authors: García-Gil, A.; Allende Prieto, C.; García López, R. J.;
Hubeny, I.
2003ASPC..288..145G Altcode: 2003sam..conf..145G
By using the Synspec program with different LTE and NLTE atmospheric
models of Alpha Lyrae (Vega, spectral type A0V), we obtain different
emitted fluxes. Taking into account the distance from Hipparcos, it
is obtained the spectrum that would be observed from Earth for each
model. This spectrum is compared with UV calibrations from the IUE
and UARS satellites and visible ground-based observations. Absolute
fluxes from the SOLSTICE experiment onboard UARS provide an independent
source to assess the quality of the available data. The main goal
of this work is to better understand and solve the controversy about
the missing opacity problem in the UV. This is just the first step in
that direction.
---------------------------------------------------------
Title: NLTE Line Formation in Late-Type Stellar Atmospheres
Authors: Allende Prieto, C.; Hubeny, I.; Lambert, D. L.; Lanz, T.
2003IAUS..210P.A24A Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Automated Stellar Spectral Classification and Parameter-Ization
for the Masses
Authors: von Hippel, Ted; Allende Prieto, Carlos; Sneden, Chris
2003gafe.conf..147V Altcode: 2002astro.ph..8185V
Stellar spectroscopic classification has been successfully automated by
a number of groups. Automated classification and parameterization work
best when applied to a homogeneous data set, and thus these techniques
primarily have been developed for and applied to large surveys. While
most ongoing large spectroscopic surveys target extragalactic objects,
many stellar spectra have been and will be obtained. We briefly
summarize past work on automated classification and parameterization,
with emphasis on the work done in our group. Accurate automated
classification in the spectral type domain and parameterization
in the temperature domain have been relatively easy. Automated
parameterization in the metallicity domain, formally outside the MK
system, has also been effective. Due to the subtle effects on the
spectrum, automated classification in the luminosity domain has been
somewhat more difficult, but still successful. In order to extend
the use of automated techniques beyond a few surveys, we present our
current efforts at building a web-based automated stellar spectroscopic
classification and parameterization machine. Our proposed machinery
would provide users with MK classifications as well as the astrophysical
parameters of effective temperature, surface gravity, mean abundance,
abundance anomalies, and microturbulence.
---------------------------------------------------------
Title: Estimation of Elemental Abundances, Temperatures, and Surface
Gravities for SDSS Stellar Spectra
Authors: Li, Y.; Beers, T. C.; Allende Prieto, C.; Wilhelm, R.; Yanny,
B.; Newberg, H.
2002AAS...201.1613L Altcode: 2002BAAS...34.1126L
Discovery of the true nature of the halo of the Galaxy has long
been limited by the number of stars with available spectroscopy and
photometry. This constraint will soon be lifted. While undertaking a
thorough spectroscopic follow-up of ~ 1,000,000 extragalactic sources,
the Sloan Digital Sky Survey (SDSS) will ALSO obtain spectra of as many
as ~ 100,000 Galactic sources (30,000 of which will be available with
DR-1, the first data release from SDSS). With a bright limit of V ~
14, the SDSS stellar sample will be, by far, the largest spectroscopic
survey of the Galactic halo and the thick disk yet obtained. The
spectral coverage of SDSS is 3900--9100 Å, with a resolving power δ
λ /λ ~ 2000. These data can potentially provide radial velocities,
temperatures, and gravities, as well as measured abundances of Fe, Ca,
Na, Mg, and C, for stars with spectral types in the range A to K. The
spectra are flux-calibrated, and 5-band photometry is available for
all targets, allowing for reasonably accurate distance estimates. The
limited -- and highly variable -- signal-to-noise ratios of the spectra,
together with the large sample size, require the development of fast
and robust automated methods of analysis. As a first step, we have
calculated a grid of synthetic fluxes based on LTE model atmospheres and
spectral syntheses. We are currently exploring different algorithms to
optimally extract the information in the spectra from the comparison
with the synthetic spectra. Preliminary results exploiting a genetic
algorithm are presented for about 4000 stars in the Early Data Release.
---------------------------------------------------------
Title: Analysis of Stellar Spectra from the Century Survey
Authors: Beers, T. C.; Allende Prieto, C.; Wilhelm, R.; Brown, W.;
Geller, M. J.; Kenyon, S.; Kurtz, M.
2002AAS...20111502B Altcode: 2002BAAS...34.1290B
We describe new methods of analysis that have been developed in order to
make optimal use of the stellar spectral data obtained during the course
of follow-up medium-resolution observations of color-selected stars from
the “Century Survey.” The initial selection of stars in the stellar
component of the Century Survey is based on broadband V and R photometry
covering a strip of 1<SUP>o</SUP> x 64<SUP>o</SUP> degrees over the
range 8h5 <= R.A. <= 13h5 . We have endeavored to identify stars
of spectral type A, in particular those stars which are likely to be
field horizontal-branch (FHB) stars, as well as those at or near the
main-sequence turnoff of the halo and thick-disk populations. Once the
candidates are identified, we obtain medium-resolution spectroscopy of
the sample using the FAST spectrograph on the Tillinghast 60" telescope
on Mount Hopkins. These data are supplemented, where available, with
JHK photometry obtained from early release 2MASS data. The spectra are
analyzed with LTE model atmospheres to determine effective temperatures,
metallicities, and gravities for the sample. In addition, we obtain
estimates of C/Fe and Mg/Fe ratios from the strength of the CH G-band
and the Mb I triplet. As the spectra are flux calibrated, we used the
best-matching synthetic spectra and stellar evolutionary calculations
to estimate distances to dwarfs and giants. Three different methods
have been used to identify FHB stars, and to distinguish them from
their higher surface gravity counterparts of similar temperature
(many of which are likely to be blue stragglers). Distances to FHB
stars are obtained using previously published relationships between
their luminosity, temperature, and metal abundance. These data are
then used to perform kinematic analyses of the sample, as described
in a separate abstract.
---------------------------------------------------------
Title: The Century Survey Galactic Halo Project
Authors: Brown, W. R.; Geller, M. J.; Kenyon, S.; Kurtz, M.; Beers,
T.; Allende Prieto, C.; Wilhelm, R.
2002AAS...20110503B Altcode: 2002BAAS...34R1273B
The Century Survey is a photometric survey strip from which we
select blue stars to probe the Milky Way halo. We obtain S/N=30
spectra for every star with (V-R)<0.25 and V<16.5 mag in the
1<SUP>o</SUP> x 64<SUP>o</SUP> Century Survey strip, and for every
star with (J-H)<0.15 and J<15 mag in an adjacent 1<SUP>o</SUP>
x 64<SUP>o</SUP> 2MASS region. The Century Survey is placed along a
roughly constant line of galactic longitude and spans 35<SUP>o</SUP>
< b < 88<SUP>o</SUP>. This placement allows us to measure
populations of stars and their systematic motions as a function of
galactic latitude. One of our primary goals is to use blue horizontal
branch stars to trace potential star streams in the halo and test
the hierarchal picture for the formation of the Galaxy. We present
a sample of 764 stars from the Century Survey. We measure radial
velocities, abundances, effective temperatures,surface gravities,
and other physical parameters from the spectra. Approximately half
of the stars are F-types located in the thick disk. The other half
of the stars are A-types with a +/- 105 km s<SUP>-1</SUP> velocity
dispersion consistent with a halo population. We use three methods
to distinguish blue horizontal branch from higher surface gravity
A-type stars, and identify 54 blue horizontal branch stars to r=15
kpc in our sample. We look for associations in velocity, abundance,
and position. In addition, we find a small number of unusual objects
in the Century Survey, including white dwarfs, quasars, and B-type
stars at modest distances above the Galactic plane.
---------------------------------------------------------
Title: The isotopic mixture of barium in the metal-poor subgiant
HD 140283
Authors: Lambert, David L.; Allende Prieto, Carlos
2002MNRAS.335..325L Altcode: 2002astro.ph..5376L
Analyses of the abundances of neutron-capture elements have led to the
belief that these elements in metal-poor stars are r-process products
with relative abundances closely resembling those found in the Solar
system. This picture was challenged by Magain, who found that a pure
r-process mix of the barium isotopes was inconsistent with the mix of
odd to even barium isotopes derived from analysis of the BaII line
at 4554 Å in the spectrum of the metal-poor subgiant HD 140283. In
this paper, we address Magain's challenge using new high-resolution
high signal-to-noise spectra of HD 140283, and find, in contrast to
his result, that a solar-like r-process isotopic mixture provides a
fair fit to the observed 4554-Å profile.
---------------------------------------------------------
Title: Spectrophotometry of Procyon A: Testing Metal Opacities
Authors: Allende-Prieto, Carlos
2002hst..prop.9368A Altcode: 2002hst..prop.5721A
Metal opacity shapes the near-UV spectrum of late-type stars,
which dominate intermediate and old stellar populations. Learning
the details of how metal opacity blocks the light in this spectral
region is of capital importance to understanding the energy balance
in the atmosphere of these stars and, ultimately, building reliable
models to interpret observed fluxes. The model atmospheres most
used in spectroscopic analyses of individual stars and at the core of
population synthesis codes are based on calculations of photoionization
cross-sections from the 70's, when better data have been available for
a long time. We implement modern cross-sections in our calculations
of synthetic fluxes and model atmospheres, but the models need to
be confronted with observations. Detailed absolute fluxes for stars
of known effective temperatures and angular diameters can constrain
the opacities directly from observations. So far, such high-quality
UV observations are available only for the Sun, and this leaves some
room for ambiguity between line and continuum opacity. Observations
with identical quality are possible with STIS for a second nearby
late-type star: Procyon A. This star is indeed the only relatively
unevolved late-type star for which an extremely precise determination
of its angular diameter is available.
---------------------------------------------------------
Title: A Reappraisal of the Solar Photospheric C/O Ratio
Authors: Allende Prieto, Carlos; Lambert, David L.; Asplund, Martin
2002ApJ...573L.137A Altcode: 2002astro.ph..6089A; 2002astro.ph..6089P
An accurate determination of photospheric solar abundances requires
detailed modeling of the solar granulation and accounting for departures
from local thermodynamical equilibrium (LTE). We argue that the
forbidden C I line at 8727 Å is largely immune to departures from
LTE and can be realistically modeled using LTE radiative transfer
in a time-dependent three-dimensional simulation of solar surface
convection. We analyze the [C I] line in the solar flux spectrum to
derive the abundance logɛ(C)=8.39+/-0.04 dex. Combining this result
with our parallel analysis of [O I] λ6300, we find C/O=0.50+/-0.07,
in agreement with the ratios measured in the solar corona from gamma-ray
spectroscopy and solar energetic particles.
---------------------------------------------------------
Title: Detailed analysis of Balmer lines in cool dwarf stars
Authors: Barklem, P. S.; Stempels, H. C.; Allende Prieto, C.;
Kochukhov, O. P.; Piskunov, N.; O'Mara, B. J.
2002A&A...385..951B Altcode: 2002astro.ph..1537B
An analysis of Hα and Hβ spectra in a sample of 30 cool dwarf and
subgiant stars is presented using MARCS model atmospheres based on the
most recent calculations of the line opacities. A detailed quantitative
comparison of the solar flux spectra with model spectra shows that
Balmer line profile shapes, and therefore the temperature structure
in the line formation region, are best represented under the mixing
length theory by any combination of a low mixing-length parameter alpha
and a low convective structure parameter y. A slightly lower effective
temperature is obtained for the sun than the accepted value, which we
attribute to errors in models and line opacities. The programme stars
span temperatures from 4800 to 7100 K and include a small number of
population II stars. Effective temperatures have been derived using
a quantitative fitting method with a detailed error analysis. Our
temperatures find good agreement with those from the Infrared Flux
Method (IRFM) near solar metallicity but show differences at low
metallicity where the two available IRFM determinations themselves are
in disagreement. Comparison with recent temperature determinations
using Balmer lines by Fuhrmann (\cite{fuhrmann98, fuhrmann00}),
who employed a different description of the wing absorption due
to self-broadening, does not show the large differences predicted
by Barklem et al. (\cite{bpo:hyd}). In fact, perhaps fortuitously,
reasonable agreement is found near solar metallicity, while we find
significantly cooler temperatures for low metallicity stars of around
solar temperature. Based on observations collected at the Isaac Newton
Telescope, La Palma, Spain, and McDonald Observatory, Texas, USA.
---------------------------------------------------------
Title: Signatures of Convection in the Spectrum of Procyon:
Fundamental Parameters and Iron Abundance
Authors: Allende Prieto, Carlos; Asplund, Martin; García López,
Ramón J.; Lambert, David L.
2002ApJ...567..544A Altcode: 2001astro.ph.11055A; 2001astro.ph.11055P
We have observed the spectrum of Procyon A (F5 IV) from 4559 to 5780
Å with a signal-to-noise ratio of ~10<SUP>3</SUP> and a resolving
power of 2×10<SUP>5</SUP>. We have measured the line bisectors
and relative line shifts of a large number of Fe I and Fe II lines,
comparing them to those found in the solar spectrum. A three-dimensional
hydrodynamical model atmosphere has been computed and is tested against
observations. The model reproduces in detail most of the features
observed, although we identify some room for improvement. At all levels,
the comparison of the three-dimensional time-dependent calculations
with the observed spectral lines shows a much better agreement than for
classical homogeneous models, making it possible to refine previous
estimates of the iron abundance, the projected rotational velocity,
the limb darkening, and the systemic velocity of the Procyon binary
system. The difference between the iron abundance determined with
the three-dimensional model and its one-dimensional counterpart is
<~0.05 dex. We find consistency between the iron abundance derived
from Fe I and Fe II lines, suggesting that departures from LTE in the
formation of the studied lines are relatively small. The scatter in
the iron abundance determined from different lines still exceeds the
expectations from the uncertainties in the atomic data, pointing out
that one or more components in the modeling can be refined further.
---------------------------------------------------------
Title: Lithium and Hα in stars and brown dwarfs of sigma Orionis.
Authors: Zapatero Osorio, M. R.; Béjar, V. J. S.; Pavlenko, Ya.;
Rebolo, R.; Allende Prieto, C.; Martín, E. L.; García López, R. J.
2002A&A...384..937Z Altcode: 2002astro.ph..2147O; 2002astro.ph..2147Z
We present intermediate- and low-resolution optical spectra around Hα
and Li I lambda 6708 Åfor a sample of 25 low mass stars and 2 brown
dwarfs with confirmed membership in the pre-main sequence stellar sigma
Orionis cluster. Our observations are intended to investigate the age
of the cluster. The spectral types derived for our target sample are
found to be in the range K6-M8.5, which corresponds to a mass interval
of roughly 1.2-0.02 M<SUB>sun</SUB> on the basis of state-of-the-art
evolutionary models. Radial velocities (except for one object) are
found to be consistent with membership in the Orion complex. All cluster
members show considerable Hα emission and the Li I resonance doublet
in absorption, which is typical of very young ages. We find that our
pseudo-equivalent widths of Hα and Li I (measured relative to the
observed local pseudo-continuum formed by molecular absorptions) appear
rather dispersed (and intense in the case of Hα ) for objects cooler
than M3.5 spectral class, occurring at the approximate mass where low
mass stars are expected to become fully convective. The least massive
brown dwarf in our sample, S Ori 45 (M8.5, ~ 0.02 M<SUB>sun</SUB>),
displays variable Hα emission and a radial velocity that differs from
the cluster mean velocity. Tentative detection of forbidden lines in
emission indicates that this brown dwarf may be accreting mass from a
surrounding disk. We also present recent computations of Li I lambda
6708 Åcurves of growth for low gravities and for the temperature
interval (about 4000-2600 K) of our sample. The comparison of our
observations to these computations allows us to infer that no lithium
depletion has yet taken place in sigma Orionis, and that the observed
pseudo-equivalent widths are consistent with a cluster initial lithium
abundance close to the cosmic value. Hence, the upper limit to the sigma
Orionis cluster age can be set at 8 Myr, with a most likely value around
2-4 Myr. Based on observations made with the following telescopes:
3.5-m telescope at the Spanish-German Calar Alto Observatory (Spain)
operated by the Max-Planck-Institut für Astronomie in Heidelberg
(Germany); 2.5-m Isaac Newton telescope operated on the island of La
Palma by the Isaac Newton Group in the Spanish Observatorio del Roque
de Los Muchachos of the Instituto de Astrofísica de Canarias; 2.1-m
Otto Struve telescope at McDonald Observatory (USA); and the 10-m Keck
II telescope of the W. M. Keck Observatory, which is operated as a
scientific partnership among the California Institute of Technology,
the University of California and the National Aeronautics and Space
Administration (the Observatory was made possible by the generous
financial support of the W. M. Keck Foundation).
---------------------------------------------------------
Title: Convective Wavelength Shifts in the Spectra of Late-Type Stars
Authors: Allende Prieto, Carlos; Lambert, David L.; Tull, Robert G.;
MacQueen, Phillip J.
2002ApJ...566L..93A Altcode: 2002astro.ph..1355P; 2002astro.ph..1355A
We present ultrahigh-resolution spectra for a set of nearby F-G-K
stars on, or close to, the main sequence. The wavelength shifts of
stellar lines relative to their laboratory wavelengths are measured for
more than a thousand Fe I lines per star, finding a clear correlation
with line depth. The observed patterns are interpreted as convective
blueshifts that become more prominent for weaker lines, which are formed
in deeper atmospheric layers. A morphological sequence with spectral
type or effective temperature is apparent. Two K giant stars have also
been studied. The velocity span between weak and strong lines for these
stars is larger than for the dwarfs and subgiants of similar spectral
types. Our results show that convective wavelength shifts may seriously
compromise the accuracy of absolute spectroscopic radial velocities
but that an empirical correction may be applied to measured velocities.
---------------------------------------------------------
Title: The Spectrum of the Th-Ar Hollow-Cathode Lamp Used with the
2dcoude Spectrograph
Authors: Allende Prieto, Carlos
2001astro.ph.11172A Altcode: 2001astro.ph.11172P
We have produced an atlas of the Th-Ar hollow-cathode lamp used with
the 2dcoude spectrograph at McDonald Observatory. The atlas covers from
3611.9 to 10596.4 A at a resolving power of 52,000. We have determined
the wavelenghts of 1483 emission lines in the spectrum with a median
precision of 0.00023 A. A web-based interface is offered for interactive
visualization of segments of the atlas or spectral orders.
---------------------------------------------------------
Title: Three-dimensional Spectral Classification of Low-Metallicity
Stars Using Artificial Neural Networks
Authors: Snider, Shawn; Allende Prieto, Carlos; von Hippel, Ted;
Beers, Timothy C.; Sneden, Christopher; Qu, Yuan; Rossi, Silvia
2001ApJ...562..528S Altcode: 2001astro.ph..7409S
We explore the application of artificial neural networks (ANNs)
for the estimation of atmospheric parameters (T<SUB>eff</SUB>, logg,
and [Fe/H]) for Galactic F- and G-type stars. The ANNs are fed with
medium-resolution (Δλ~1-2 Å) non-flux-calibrated spectroscopic
observations. From a sample of 279 stars with previous high-resolution
determinations of metallicity and a set of (external) estimates
of temperature and surface gravity, our ANNs are able to predict
T<SUB>eff</SUB> with an accuracy of σ(T<SUB>eff</SUB>)=135-150 K over
the range 4250<=T<SUB>eff</SUB><=6500 K, logg with an accuracy
of σ(logg)=0.25-0.30 dex over the range 1.0<=logg<=5.0 dex,
and [Fe/H] with an accuracy σ([Fe/H])=0.15-0.20 dex over the range
-4.0<=[Fe/H]<=0.3. Such accuracies are competitive with the
results obtained by fine analysis of high-resolution spectra. It is
noteworthy that the ANNs are able to obtain these results without
consideration of photometric information for these stars. We have
also explored the impact of the signal-to-noise ratio (S/N) on the
behavior of ANNs and conclude that, when analyzed with ANNs trained
on spectra of commensurate S/N, it is possible to extract physical
parameter estimates of similar accuracy with stellar spectra having
S/N as low as 13. Taken together, these results indicate that the ANN
approach should be of primary importance for use in present and future
large-scale spectroscopic surveys.
---------------------------------------------------------
Title: Chemical Abundances from Inversions of Stellar Spectra:
Analysis of Solar-Type Stars with Homogeneous and Static Model
Atmospheres
Authors: Allende Prieto, Carlos; Barklem, Paul S.; Asplund, Martin;
Ruiz Cobo, Basilio
2001ApJ...558..830A Altcode: 2001astro.ph..5262P; 2001astro.ph..5262A
Spectra of late-type stars are usually analyzed with static model
atmospheres in local thermodynamic equilibrium (LTE) and a homogeneous
plane-parallel or spherically symmetric geometry. The energy balance
requires particular attention, as two elements that are particularly
difficult to model play an important role: line blanketing and
convection. Inversion techniques are able to bypass the difficulties
of a detailed description of the energy balance. Assuming that the
atmosphere is in hydrostatic equilibrium and LTE, it is possible
to constrain its structure from spectroscopic observations. Among
the most serious approximations still implicit in the method is a
static and homogeneous geometry. In this paper, we take advantage of a
realistic three-dimensional radiative hydrodynamical simulation of the
solar surface to check the systematic errors incurred by an inversion
assuming a plane-parallel horizontally-homogeneous atmosphere. The
thermal structure recovered resembles the spatial and time average
of the three-dimensional atmosphere. Furthermore, the abundances
retrieved are typically within 10% (0.04 dex) of the abundances used
to construct the simulation. The application to a fairly complete data
set from the solar spectrum provides further confidence in previous
analyses of the solar composition. There is only a narrow range of
one-dimensional thermal structures able to fit the absorption lines in
the spectrum of the Sun. With our carefully selected data set, random
errors are about a factor of 2 smaller than systematic errors. A small
number of strong metal lines can provide very reliable results. We
foresee no major difficulties in applying the technique to other
similar stars, and obtaining similar accuracies, using spectra with
λ/δλ~5×10<SUP>4</SUP> and a signal-to-noise ratio as low as 30.
---------------------------------------------------------
Title: The Forbidden Abundance of Oxygen in the Sun
Authors: Allende Prieto, Carlos; Lambert, David L.; Asplund, Martin
2001ApJ...556L..63A Altcode: 2001astro.ph..6360P; 2001astro.ph..6360A
We reexamine closely the solar photospheric line at 6300 Å, which is
attributed to a forbidden line of neutral oxygen and is widely used
in analyses of other late-type stars. We use a three-dimensional
time-dependent hydrodynamical model solar atmosphere that has been
tested successfully against observed granulation patterns and an array
of absorption lines. We show that the solar line is a blend with a
Ni I line, as previously suggested but oftentimes neglected. Thanks
to accurate atomic data on the [O I] and Ni I lines, we are able to
derive an accurate oxygen abundance for the Sun: logɛ(O)=8.69+/-0.05
dex, a value at the lower end of the distribution of previously
published abundances but in good agreement with estimates for the
local interstellar medium and hot stars in the solar neighborhood. We
conclude by discussing the implication of the Ni I blend on oxygen
abundances derived from [O I] λ6300 in disk and halo stars.
---------------------------------------------------------
Title: Hipparcos, IUE, and the Stellar Content of the Solar
Neighbourhood
Authors: Allende Prieto, C.
2001RMxAC..10..205A Altcode: 2000astro.ph..5600A; 2000astro.ph..5600P
The spectroscopic parallaxes in the Hipparcos catalogue can be used
to translate absolute stellar fluxes observed at Earth to the fluxes
emerging at the stellar surface for nearby stars. The comparison of
these fluxes with the predictions of theoretical model atmospheres
allows us to determine the effective temperature and the metallicity
of the stars. It is suggested that it is possible to study the stellar
content of the solar neighbourhood making use of the large number of
ultraviolet spectra in the archive of the IUE satellite.
---------------------------------------------------------
Title: An Empirical Procedure to Estimate Distances to Stellar
Clusters
Authors: Allende Prieto, Carlos
2001ApJ...547..200A Altcode: 2000astro.ph..9421P; 2000astro.ph..9421A
A most desirable feature of a standard candle to estimate astronomical
distances is robustness against changes in metallicity and age. It is
argued that the radii of main-sequence stars with spectral types from
solar to A0 show predictable changes with metallicity and detectable
changes with evolution. Such stars populate the solar neighborhood
and therefore benefit from measurements of angular diameters. Also,
reliable determinations of their masses and radii are available from
observations of eclipsing binaries. Three empirical relationships are
defined and suggested for estimating distances to dwarfs from only BVK
photometry. Comparison with Hipparcos trigonometric parallaxes shows
that the method provides errors of about 15% for a particular star,
which can be reduced to roughly 1.5% when applied to young clusters
(age <~1-2 Gyr) with ~100 stars of the appropriate spectral
types. If reddening is unknown, main-sequence stars with effective
temperatures close to 8000 K can constrain it, although an estimate
of R≡A(V)/E(B-V) is required.
---------------------------------------------------------
Title: An empirical method to derive distance to stellar clusters
Authors: Allende Prieto, C.
2001hsa..conf..153A Altcode:
No abstract at ADS
---------------------------------------------------------
Title: (T<SUB>eff</SUB>, log g, [Fe/H]) Classification of
Low-Resolution Stellar Spectra using Artificial Neural Networks
(CD-ROM Directory: contribs/snider)
Authors: Snider, S.; Qu, Y.; Allende Prieto, C.; von Hippel, T.;
Beers, T. C.; Sneden, C.; Lambert, D. L.; Rossi, S.
2001ASPC..223.1344S Altcode: 2001csss...11.1344S
No abstract at ADS
---------------------------------------------------------
Title: R200,000 Spectroscopic Observations of Procyon. The Surface
Convection and Radial Velocity (CD-ROM Directory: contribs/allende2)
Authors: Allende Prieto, C.; Asplund, M.; García López, R. J.;
Lambert, D. L.; Nordlund, Å.
2001ASPC..223..760A Altcode: 2001csss...11..760A
No abstract at ADS
---------------------------------------------------------
Title: From Brightness and Colour to Size and Temperature (CD-ROM
Directory: contribs/lambert2)
Authors: Lambert, D. L.; Allende Prieto, C.
2001ASPC..223..821L Altcode: 2001csss...11..821L
No abstract at ADS
---------------------------------------------------------
Title: Comparing Absolute Near-UV Fluxes of Late-Type Stars with the
Predictions of Model Atmospheres (CD-ROM Directory: contribs/allende1)
Authors: Allende Prieto, C.
2001ASPC..223..754A Altcode: 2001csss...11..754A
No abstract at ADS
---------------------------------------------------------
Title: The INT Search for Metal-Poor Stars: Spectroscopic Observations
and Classification via Artificial Neural Networks
Authors: Allende Prieto, Carlos; Rebolo, Rafael; García López,
Ramón J.; Serra-Ricart, Miquel; Beers, Timothy C.; Rossi, Silvia;
Bonifacio, Piercarlo; Molaro, Paolo
2000AJ....120.1516A Altcode: 2000astro.ph..5598A; 2000astro.ph..5598P
With the dual aims of enlarging the list of extremely metal-poor
stars identified in the Galaxy and boosting the numbers of moderately
metal-deficient stars in directions that sample the rotational
properties of the thick disk, we have used the 2.5 m Isaac Newton
Telescope and the Intermediate Dispersion Spectrograph to carry out a
survey of brighter (primarily northern hemisphere) metal-poor candidates
selected from the HK objective-prism-interference-filter survey of
Beers and collaborators. Over the course of only three observing runs
(15 nights) we have obtained medium-resolution (λ/δλ~=2000) spectra
for 1203 objects (V~=11-15). Spectral absorption-line indices and radial
velocities have been measured for all the candidates. Metallicities,
quantified by [Fe/H], and intrinsic (B-V)<SUB>0</SUB> colors have been
estimated for 731 stars with effective temperatures cooler than roughly
6500 K by using artificial neural networks (ANNs) trained with spectral
indices. We show that this method performs as well as a previously
explored Ca II K calibration technique, yet it presents some practical
advantages. Among the candidates in our sample we identify 195 stars
with [Fe/H]<=-1.0, 67 stars with [Fe/H]<=-2.0, and 12 new stars
with [Fe/H]<=-3.0. Although the effective yield of metal-poor stars
in our sample is not as large as that in previous HK survey follow-up
programs, the rate of discovery per unit of telescope time is quite
high. Further development of the ANN technique, with the networks
being fed the entire spectrum, rather than just the spectral indices,
holds the promise to produce fast, accurate, multidimensional spectral
classifications (with the associated physical parameter estimates),
as is required to process the large data flow provided by present and
future instrumentation. Based on observations made with the Isaac Newton
Telescope operated on the island of La Palma by the Isaac Newton Group
in the Spanish Observatorio del Roque de los Muchachos of the Instituto
de Astrofisica de Canarias.
---------------------------------------------------------
Title: Line formation in solar granulation. I. Fe line shapes,
shifts and asymmetries
Authors: Asplund, M.; Nordlund, Å.; Trampedach, R.; Allende Prieto,
C.; Stein, R. F.
2000A&A...359..729A Altcode: 2000astro.ph..5320A
Realistic ab-initio 3D, radiative-hydrodynamical convection simulations
of the solar granulation have been applied to Fe i and Fe ii line
formation. In contrast to classical analyses based on hydrostatic 1D
model atmospheres the procedure contains no adjustable free parameters
but the treatment of the numerical viscosity in the construction
of the 3D, time-dependent, inhomogeneous model atmosphere and the
elemental abundance in the 3D spectral synthesis. However, the numerical
viscosity is introduced purely for numerical stability purposes and is
determined from standard hydrodynamical test cases with no adjustments
allowed to improve the agreement with the observational constraints
from the solar granulation. The non-thermal line broadening is mainly
provided by the Doppler shifts arising from the convective flows in
the solar photosphere and the solar oscillations. The almost perfect
agreement between the predicted temporally and spatially averaged
line profiles for weak Fe lines with the observed profiles and the
absence of trends in derived abundances with line strengths, seem to
imply that the micro- and macroturbulence concepts are obsolete in
these 3D analyses. Furthermore, the theoretical line asymmetries and
shifts show a very satisfactory agreement with observations with an
accuracy of typically 50-100 m s<SUP>-1</SUP> on an absolute velocity
scale. The remaining minor discrepancies point to how the convection
simulations can be refined further.
---------------------------------------------------------
Title: The Near-Ultraviolet Continuum of Late-Type Stars
Authors: Allende Prieto, Carlos; Lambert, David L.
2000AJ....119.2445A Altcode: 2000astro.ph..1508P; 2000astro.ph..1508A
Analyses of the near-ultraviolet continuum of late-type stars have led
to controversial results regarding the performance of state-of-the-art
model atmospheres. The release of the homogeneous International
Ultraviolet Explorer (IUE) final archive and the availability of the
high-accuracy Hipparcos parallaxes provide an opportunity to revisit
this issue, as accurate stellar distances make it possible to compare
observed absolute fluxes with the predictions of model atmospheres. The
near-UV continuum is highly sensitive to T<SUB>eff</SUB> and [Fe/H],
and once the gravity is constrained from the parallax, these parameters
may be derived from the analysis of low-dispersion, long-wavelength
(2000-3000 Å) IUE spectra for stars previously studied by Alonso,
Arribas, & Martínez-Roger using the Infrared Flux Method (IRFM). A
second comparison is carried out against the stars spectroscopically
investigated by Gratton, Carretta, & Castelli. It is shown that
there is a good agreement between T<SUB>eff</SUB> values obtained
from the IRFM and those from the near-UV continuum, and a remarkable
correspondence between observed and synthetic fluxes for stars with 4000
K<=T<SUB>eff</SUB><=6000 K of any metallicity and gravity. These
facts suggest that model atmospheres provide an adequate description
of the near-UV continuum forming region and that the opacities involved
are essentially understood.
---------------------------------------------------------
Title: Model Photospheres for Late-Type Stars from the Inversion
of High-Resolution Spectroscopic Observations: Groombridge 1830 and
ɛ Eridani
Authors: Allende Prieto, Carlos; García López, Ramón J.; Lambert,
David L.; Ruiz Cobo, Basilio
2000ApJ...528..885A Altcode: 1999astro.ph..7368P; 1999astro.ph..7368A
An inversion technique to recover LTE one-dimensional model photospheres
for late-type stars, which was previously applied to the Sun by Allende
Prieto et al. in 1998, is now employed to reconstruct, semiempirically,
the photospheres of cooler dwarfs: the metal-poor Groombridge 1830 and
the active star of solar metallicity ɛ Eridani. The model atmospheres
we find reproduce satisfactorily all the considered weak-to-moderate
neutral lines of metals, satisfying in detail the excitation equilibrium
of iron, the wings of strong lines, and the slope of the optical
continuum. The retrieved models show a slightly steeper temperature
gradient than flux-constant model atmospheres in the layers where
logτ<=-0.5. We argue that these differences should reflect missing
ingredients in the flux-constant models and point to granular-like
inhomogeneities as the best candidate. The iron ionization equilibrium
is well satisfied by the model for Gmb 1830, but not for ɛ Eri, for
which a discrepancy of 0.2 dex between the logarithmic iron abundance
derived from neutral and singly ionized lines may signal departures from
LTE. The chemical abundances of calcium, titanium, chromium, and iron
derived with the empirical models from neutral lines do not differ much
from previous analyses based on flux-constant atmospheric structures.
---------------------------------------------------------
Title: Results of Observational Campaigns Carried Out During the
Impact of Lunar Prospector into a Permanently Shadowed Crater near
the South Pole of the Moon
Authors: Barker, E. S.; Allende Prieto, C.; Farnham, T. L.; Goldstein,
D. B.; Nerem, R. S.; Austin, J. V.; Shim, J. Y.; Storrs, A. B.; Stern,
S. A.; Binder, A. B.; Bida, T.; Morgan, T.; Larson, S. M.; Sprague,
A. L.; Hunten, D. M.; Hill, R. E.; Kozlowski, R. W. H.; Ludwig, B.;
Rubinson, S.; Baumgardner, J.; Mendillo, M.; Wilson, J.; Wroten, J.;
Verani, S.; Benn, C. R.; Garcia Lopez, R. J.; Gates, E.; Talent,
D. L.; Alday, A.; Pozar, A.; Witte, D.; Africano, B.; Villanneva,
B.; Anderson, R.; Kervin, P.; Rossano, G. S.; Walker, R. W.; Hoss,
S.; Anderson, C. M.; Offutt, W.; Lunar Prospector Team
1999DPS....31.5903B Altcode: 1999BAAS...31R1583B
On July 31, 1999 the Lunar Prospector (LP) spacecraft was commanded
to deorbit and thus impact into the floor of a permanently shadowed
crater at -88.7S, 42E (Goldstein, et al. 1999, GRL 26, pp1653-1656 and
paper 38.06 at this conference). Coordinated observational program
(spectroscopy and imaging) were carried out at HST, SWAS, Keck,
McDonald, WIRO, Mt.Lemmon, Mt. Bigelow, McMath-Pierce, WIYN, Lick, IRTF,
JCMT, AMOS, AEOS, WHT, OVRO, Palomar, WBO. The LP navigation team is
confident the impact occurred as predicted, but observational teams
did not detect any evidence of the impact. No debris or dust plumes
were detected in the visible or IR. No water vapor, OH, C<SUB>2</SUB>
or HCN molecular emissions were detected. Scattered light from
the bright lunar limb limited the accuracy and detectability of
several investigations. Upper limits for the production of OH will
be presented. Four different observing groups saw no change in the
Na abundance. We are grateful to observatory directors for target of
opportunity time, to observatory staffs for critical observing support,
and for funding support from the Planetary Astronomy program (NASA HQ),
NASA grant NAG5-8704, the Research Corp. and GO-08539.01-97A from STScI.
---------------------------------------------------------
Title: (Teff,log g,[Fe/H]) Classification of Low-Resolution Stellar
Spectra using Artificial Neural Networks
Authors: Snider, Shawn; Qu, Yuan; Allende Prieto, Carlos; von Hippel,
Ted; Beers, Timothy C.; Sneden, Chistopher; Lambert, David L.
1999astro.ph.12404S Altcode:
New generation large-aperture telescopes, multi-object spectrographs,
and large format detectors are making it possible to acquire very
large samples of stellar spectra rapidly. In this context, traditional
star-by-star spectroscopic analysis are no longer practical. New
tools are required that are capable of extracting quickly and with
reasonable accuracy important basic stellar parameters coded in the
spectra. Recent analyses of Artificial Neural Networks (ANNs) applied to
the classification of astronomical spectra have demonstrated the ability
of this concept to derive estimates of temperature and luminosity. We
have adapted the back-propagation ANN technique developed by von
Hippel et al. (1994) to predict effective temperatures, gravities
and overall metallicities from spectra with resolving power ~ 2000
and low signal-to-noise ratio. We show that ANN techniques are very
effective in executing a three-parameter (Teff,log g,[Fe/H]) stellar
classification. The preliminary results show that the technique is
even capable of identifying outliers from the training sample.
---------------------------------------------------------
Title: Spectroscopic Observations of Convective Patterns in the
Atmospheres of Metal-poor Stars
Authors: Allende Prieto, Carlos; García López, Ramón J.; Lambert,
David L.; Gustafsson, Bengt
1999ApJ...526..991A Altcode: 1999astro.ph..7046A; 1999astro.ph..7046P
Convective line asymmetries in the optical spectrum of two metal-poor
stars, Gmb 1830 and HD 140283, are compared to those observed for solar
metallicity stars. The line bisectors of the most metal-poor star, the
subgiant HD 140283, show a significantly larger velocity span that the
expectations for a solar-metallicity star of the same spectral type
and luminosity class. The enhanced line asymmetries are interpreted
as the signature of the lower metal content, and therefore opacity,
in the convective photospheric patterns. These findings point out the
importance of the three-dimensional convective velocity fields in the
interpretation of the observed line asymmetries in metal-poor stars and,
in particular, urge caution when deriving isotopic ratios from observed
line shapes and shifts using one-dimensional model atmospheres. The
mean line bisector of the photospheric atomic lines is compared with
those measured for the strong Mg I b<SUB>1</SUB> and b<SUB>2</SUB>
features. The upper parts of the bisectors are similar, and-assuming
they overlap-the bottom ends of the stronger lines, which are formed
higher in the atmosphere, go much farther to the red. This is in
agreement with the expected decreasing of the convective blueshifts
in upper atmospheric layers, and is compatible with the high-velocity
redshifts observed in the chromosphere, transition region, and corona
in late-type stars.
---------------------------------------------------------
Title: A Consistency Test of Spectroscopic Gravities for Late-Type
Stars
Authors: Allende Prieto, Carlos; García López, Ramón J.; Lambert,
David L.; Gustafsson, Bengt
1999ApJ...527..879A Altcode: 1999astro.ph..7155P; 1999astro.ph..7155A
Chemical analyses of late-type stars are usually carried out
following the classical recipe: LTE line formation and homogeneous,
plane-parallel, flux-constant, and LTE model atmospheres. We review
different results in the literature that have suggested significant
inconsistencies in the spectroscopic analyses, pointing out the
difficulties in deriving independent estimates of the stellar
fundamental parameters and hence, detecting systematic errors. The
trigonometric parallaxes measured by the Hipparcos mission provide
accurate appraisals of the stellar surface gravity for nearby
stars, which are used here to check the gravities obtained from the
photospheric iron ionization balance. We find an approximate agreement
for stars in the metallicity range -1.0<=[Fe/H]<=0, but the
comparison shows that the differences between the spectroscopic and
trigonometric gravities decrease toward lower metallicities for more
metal-deficient dwarfs (-2.5<=[Fe/H]<=-1.0), which casts a shadow
upon the abundance analyses for extreme metal-poor stars that make use
of the ionization equilibrium to constrain the gravity. The comparison
with the strong-line gravities derived by Edvardsson and Fuhrmann
confirms that this method provide systematically larger gravities than
the ionization balance. The strong-line gravities get closer to the
physical ones for the stars analyzed by Fuhrmann, but they are even
further away than the iron ionization gravities for the stars of lower
gravities in Edvardsson's sample. The confrontation of the deviations
of the iron ionization gravities in metal-poor stars, reported here
with departures from the excitation balance found in the literature,
show that they are likely to be induced by the same physical mechanism.
---------------------------------------------------------
Title: Fundamental parameters of nearby stars from the comparison with
evolutionary calculations: masses, radii and effective temperatures
Authors: Allende Prieto, C.; Lambert, D. L.
1999A&A...352..555A Altcode: 1999astro.ph.11002P; 1999astro.ph.11002A
The Hipparcos mission has made it possible to constrain the positions
of nearby field stars in the colour-magnitude diagram with very
high accuracy. These positions can be compared with the predictions
of stellar evolutionary calculations to provide information on the
basic parameters of the stars: masses, radii, effective temperatures,
ages, and chemical composition. The degeneracy between mass, age,
and metallicity is not so large as to prevent a reliable estimate of
masses, radii and effective temperatures, at least for stars of solar
metallicity. The evolutionary models of Bertelli et al. (1994) predict
those parameters finely, and furthermore, the applied transformation
from the theoretical (log g- T_eff) to the observational (M_v-B-V)
plane is precise enough to derive radii with an uncertainty of ~ 6%,
masses within 8%, and T_effs within ~ 2% for a certain range of the
stellar parameters. This is demonstrated by means of comparison with
the measurements in eclipsing binaries and the InfraRed Flux Method. The
application of the interpolation procedure in the theoretical isochrones
to the stars within 100 pc from the Sun observed with Hipparcos
provides estimates for 17,219 stars. Table~1 is only available in
electronic form at the CDS via anonymous ftp to: cdsarc.u-strasbg.fr
(130.79.128.5) or via http://cdsweb.u-strasbg.fr/Abstract.html
---------------------------------------------------------
Title: VizieR Online Data Catalog: Fundamental parameters of stars
(Allende Prieto+, 1999)
Authors: Allende Prieto, C.; Lambert, D. L.
1999yCat..33520555A Altcode:
The Hipparcos mission has made it possible to constrain the positions
of nearby field stars in the colour-magnitude diagram with very
high accuracy. These positions can be compared with the predictions
of stellar evolutionary calculations to provide information on the
basic parameters of the stars: masses, radii, effective temperatures,
ages, and chemical composition. The degeneracy between mass, age,
and metallicity is not so large as to prevent a reliable estimate
of masses, radii and effective temperatures, at least for stars of
solar metallicity. The evolutionary models of Bertelli et al. (1994,
Cat. <J/A+AS/106/275>) predict those parameters finely,
and furthermore, the applied transformation from the theoretical
log(g)-T<SUB>eff</SUB> to the observational M<SUB>v</SUB>-B-V plane
is precise enough to derive radii with an uncertainty of ~6%, masses
within 8%, and Teffs within ~2% for a certain range of the stellar
parameters. This is demonstrated by means of comparison with the
measurements in eclipsing binaries and the InfraRed Flux Method. The
application of the interpolation procedure in the theoretical isochrones
to the stars within 100pc from the Sun observed with Hipparcos provides
estimates for 17,219 stars included in this Table. (1 data file).
---------------------------------------------------------
Title: Surface Inhomogeneities and Semiempirical Modeling of
Metal-poor Stellar Photospheres
Authors: Allende Prieto, Carlos
1999PASP..111..522A Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Convection in Metal-Poor Stars as Traced from Spectral Line
Asymmetries
Authors: Allende Prieto, C.; Asplund, M.; García López, R. J.;
Gustafsson, B.; Lambert, D. L.
1999ASPC..173..205A Altcode: 1999sstt.conf..205A
No abstract at ADS
---------------------------------------------------------
Title: Surface Inhomogeneities and Semi-Empirical Modeling of
Metal-Poor Stellar Photospheres
Authors: Allende Prieto, C.
1998AAS...193.2202A Altcode: 1998BAAS...30.1282A
The interpretation of detailed spectroscopic observations of different
stars reveals inconsistencies, due likely to inadequacies of the
underlying hypothesis. The high accuracy of the parallaxes measured
by the Hipparcos satellite established a firm reference frame that is
used here to test theoretical classical model atmospheres for cool
stars. Previously suspected errors in the ionization balance are
clearly confirmed, pointing towards important departures from local
thermodynamic equilibrium for low-gravity stars. We propose a method of
semi-empirical modeling of stellar atmospheres, as an alternative to the
use of flux-constant one-dimensional model atmospheres. The new method
is carried out via an inversion procedure that uses normalized line
profiles as input data. The procedure is applied to the Sun, showing its
effectiveness through comparison with spatially resolved observations
and absolute flux measurements. The application to other stars, in
particular the metal-poor star Groombridge 1830, and the solar-like
metallicity and active star Eps Eridani, yields semi-empirical model
photospheres that succeed in reproducing all the considered spectral
features. The very high-resolution spectra of Groombridge 1830 and
the extremely metal deficient sub-giant HD140283 allow us to detect
line asymmetries that are interpreted as the signature of convective
patterns that, at least in HD140283, appear significantly enhanced
due to the low atmospheric opacity. Finally, a survey for very metal
poor stars in the Galaxy was conducted from the Isaac Newton Telescope
at the Roque de los Muchachos Observatory in La Palma. In parallel,
we develop a new method of classification of stellar spectra based on
artificial neural networks, demonstrating its abilities and advantages
against previously used schemes.
---------------------------------------------------------
Title: A catalogue of accurate wavelengths in the optical spectrum
of the Sun
Authors: Allende Prieto, C.; Garcia Lopez, R. J.
1998A&AS..131..431A Altcode: 1998astro.ph..3262P; 1998astro.ph..3262A
We present accurate measurements of the central wavelengths of
4947 atomic absorption lines in the solar optical spectrum. The
wavelengths, precise to a level ~ 50-150 m s(-1) , are given for
both flux and disc-centre spectra, as measured in relatively recent
FTS solar atlases. This catalogue modernizes existing sources based
on photographic measurements and provides a benchmark to test
and perform wavelength calibrations of astronomical spectra. It
will also permit observers to improve the absolute wavelength
calibration of solar optical spectra when lamps are not available
at the telescope. Table 1 is only available in electronic form at
CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/Abstract.html
---------------------------------------------------------
Title: Model Photospheres for Late-Type Stars from the Inversion of
High-Resolution Spectroscopic Observations: The Sun
Authors: Allende Prieto, Carlos; Ruiz Cobo, Basilio; García López, J.
1998ApJ...502..951A Altcode: 1998astro.ph..2353P; 1998astro.ph..2353A
An inversion technique has been developed to recover LTE,
one-dimensional, model photospheres for late-type stars from very high
resolution, high signal-to-noise ratio stellar line profiles. It is
successfully applied to the Sun by using a set of clean Ti I, Ca I,
Cr I, and Fe I normalized line profiles with accurate transition
probabilities, taking advantage of the well-understood collisional
enhancement of the wings of the Ca I line at 6162 Å. Line and
continuum center-to-limb variations, continuum flux, and wings of
strong metal lines are synthesized by means of the model obtained
and are compared with solar observations, as well as with predictions
from other well-known theoretical and empirical solar models, showing
the reliability of the inversion procedure. The prospects for and
limitations of the application of this method to other late-type stars
are discussed.
---------------------------------------------------------
Title: Fe i line shifts in the optical spectrum of the Sun
Authors: Allende Prieto, C.; Garcia Lopez, R. J.
1998A&AS..129...41A Altcode: 1997astro.ph.10066A; 1997astro.ph.10066P
New improvements in the measurement of both the optical solar spectrum
and laboratory wavelengths for lines of neutral iron are combined
to extract central wavelength shifts for 1446 lines observed in
the Sun. This provides the largest available database of accurate
solar wavelengths useful as a reference for comparison with other
solar-type stars. It is shown how the velocity shifts correlate
with line strength, approaching a constant value, close to zero,
for lines with equivalent widths larger than 200 m Angstroms. Table
1 is available in electronic form only via the CDS ftp 130.79.128.5
or http://cdsweb.u-strasbg.fr/Abstract.html
---------------------------------------------------------
Title: VizieR Online Data Catalog: Accurate wavelengths in the Sun
spectrum (Allende Prieto+ 1998)
Authors: Allende Prieto, C.; Garcia Lopez, R. J.
1998yCat..41310431A Altcode:
Central line wavelengths in the spectrum of the Sun observed at the
centre of the disc, and in the flux spectrum, line identification and
solar log(gf). (1 data file).
---------------------------------------------------------
Title: An Inversion Technique to Derive Model Photospheres in
Late-Type Stars from High-Resolution Spectroscopy: The Sun
Authors: Allende Prieto, Carlos; Ruiz Cobo, Basilio; Garcia Lopez,
Ramon J.
1998ASPC..154..813A Altcode: 1998csss...10..813A; 1997astro.ph.10067A; 1997astro.ph.10067P
An inversion technique has been developed to recover LTE one-dimensional
model photospheres for late-type stars from very high-resolution high
signal-to-noise stellar line profiles. It is successfully applied
to the Sun using a set of unblended Ti 1, Ca 1, Cr 1 and Fe 1 lines
with accurate transition probabilities. Temperature stratification,
continuum flux, center-to-limb variation and wings of strong metal
lines obtained from the resulting model are compared with those from
other well-known theoretical and empirical solar models and show the
reliability of the procedure.
---------------------------------------------------------
Title: Surface inhomogeneitites and semi-empirical modeling of
metal-poor stellar atmospheres
Authors: Allende Prieto, Carlos
1998PhDT........16A Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Beryllium, Lithium and Oxygen Abundances in F-type Stars
Authors: Garcia Lopez, R. J.; Dominguez Herrera, M. C.; Perez de Taoro,
M. R.; Casares, C.; Rasilla, J. L.; Rebolo, R.; Allende Prieto, C.
1998ASPC..154..924G Altcode: 1998csss...10..924G; 1997astro.ph.10065G; 1997astro.ph.10065L
Beryllium and oxygen abundances have been derived in a sample of F-type
field stars for which lithium abundances had been measured previously,
with the aim of obtaining observational constraints to discriminate
between the different mixing mechanisms proposed. Mixing associated
with the transport of angular momentum in the stellar interior and
internal gravity waves within the framework of rotating evolutionary
models, appear to be promising ways to explain the observations.
---------------------------------------------------------
Title: VizieR Online Data Catalog: Fe I line shifts in the Sun
(Allende Prieto+ 1998)
Authors: Allende Prieto, C.; Garcia Lopez, J. R.
1997yCat..41290041A Altcode:
Central wavelengths measured in the FTS disc-centre spectrum, in the
FTS flux spectrum, rest wavelengths, excitation potentials, transition
probabilities (log(gfs)) and line equivalent widths at the centre of the
disc when available (from Moore et al. 1966 (The Solar Spectrum 2935Å
to 8770Å, National Bureau of Standards Monograph 61) and compiled by
A. D. Wittmann, private communication). An asterisk in the equivalent
width means that the line has a blend. <P />(1 data file).
---------------------------------------------------------
Title: The Limited Influence of Pressure Gradients on Late-Type
Stellar Line Asymmetries
Authors: Allende Prieto, Carlos; García López, Ramón J.; Trujillo
Bueno, Javier
1997ApJ...483..941A Altcode: 1997astro.ph..1061P; 1997astro.ph..1061A
Line asymmetries and shifts are powerful tools for studying velocity
fields in the stellar photospheres. Other effects, however, could
also generate asymmetries, blurring the information of the velocity
patterns. We have studied the shifts and asymmetries induced in the
profiles of spectral lines by pressure effects. The best theoretical and
experimental data on line broadening and shifts caused by collisions
with atomic hydrogen were used to analyze the Na I D and three Ca I
lines. Line bisectors of synthetic spectra computed with accurate data
for the Na I and Ca I lines are compared with very high resolution,
high signal-to-noise ratio solar spectra and indicate that pressure
broadening reproduces the wings of the observed lines, but pressure
shifts introduce neither asymmetries nor shifts comparable to the
observed ones.
---------------------------------------------------------
Title: The Optical Spectral Line List of RR Telescopii
Authors: McKenna, F. C.; Keenan, F. P.; Hambly, N. C.; Allende Prieto,
C.; Rolleston, W. R. J.; Aller, L. H.; Feibelman, W. A.
1997ApJS..109..225M Altcode:
The symbiotic nova RR Telescopii has been observed with the 1.5
m telescope of the Cerro Tololo Inter-American Observatory (CTIO),
using the 1.5 m bench-mounted echelle spectrograph in conjunction with
a Tektronix CCD. It displays a rich emission-line spectrum, ranging in
excitation from O I to [Ni VIII]. We present a list of 491 measured
lines, with their suggested identifications, covering a wavelength
range from 3430 to 9320 Å. Of these, only nine are unidentified, and
70 lines are cataloged that were not given in the original line list of
Thackeray. Absolute line intensities are also given, which have been
derived by comparing the high-resolution data with a flux-calibrated
low-resolution spectrum taken with the Cassegrain spectrograph on the
1.0 m telescope at CTIO.
---------------------------------------------------------
Title: New Line Identifications in the Optical Spectrum of the Slow
Nova RR Telescopii
Authors: McKenna, F. C.; Keenan, F. P.; Hambly, N. C.; Allende Prieto,
C.; Aller, L. H.; Feibelman, W. A.
1996IrAJ...23..157M Altcode:
The symbiotic nova RR~Telescopii has been observed with the 1.5m
telescope of the Cerro Tololo Inter-American Observatory (CTIO),
using the 1.5m Bench-Mounted Echelle Spectrograph (BME) in conjunction
with a Tek CCD. It displays a rich emission line spectrum, ranging
in excitation from O I to [Ni VIII]. The result is a list of 483
measured lines, with their suggested identifications, covering a
range from 3430 A to 9320 A. Of these, only nine are unidentified,
and 70 lines are catalogued that were not given in the original line
list of Thackeray. We have also obtained absolute line intensities,
which have been derived by comparing the high-resolution data with
a flux calibrated low-resolution spectrum taken with the Cassegrain
Spectrograph on the 1.0m at the CTIO.
---------------------------------------------------------
Title: Line asymmetries in the metal-poor star HD 140283
Authors: Allende Prieto, C.; García López, R. J.; Lambert, D. L.;
Gustafsson, B.
1995IAUS..176P.107A Altcode:
No abstract at ADS
