Author name code: allende-prieto ADS astronomy entries on 2022-09-14 author:"Allende Prieto, Carlos" ------------------------------------------------------------------------ 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. Bibcode: 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 ⊕, 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 H < -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. 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. Bibcode: 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 (Mp = 1.28 ± 0.17MJup, Teq = 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. 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. Bibcode: 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.
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.
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.
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⊙ and 2.13 ± 0.01 M⊙ and radii 1.87 ± 0.04 R⊙ and 1.85 ± 0.04 R⊙. 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⊙ stars. V402 Lac is composed of two stars with masses 2.80 ± 0.05 M⊙ and 2.78 ± 0.05 M⊙ and radii 2.38 ± 0.03 R⊙ and 2.36 ± 0.03 R⊙. 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. 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. Bibcode: 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. 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. Bibcode: 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. 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. Bibcode: 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 σA(C) < 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. 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 Bibcode: 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. 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 Bibcode: 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. 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. Bibcode: 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. 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 Bibcode: 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. Bibcode: 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 Bibcode: 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 Bibcode: 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. Bibcode: 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 Bibcode: 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 Bibcode: 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 Bibcode: 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. Bibcode: 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).

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).

(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. Bibcode: 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.

The principal changes from previous versions are summarized at http://www.sdss.org/dr16/whatsnew/

(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. Bibcode: 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 H2O and NH3 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.

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 Bibcode: 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 Universe1. Although a few hundred stars with metal content below 1,000th of the solar iron content are known in the Galaxy2-4, 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 universal5,6, 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 day7. 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. Bibcode: 2021yCat..36530160S Altcode: EDR3 status of high-velocity stars in the negative and positive tail of DR2's radial velocity distribution.

(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. Bibcode: 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−1) and long-term thermomechanical stability.
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.
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−1. 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.
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 (Prot = 34.99−0.53+0.58 days). We characterize the physical and orbital properties of the planet and find a minimum mass of 5.57−0.68+0.73 M⊕, 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⊕. We find no significant evidence for additional signals in the data with semi-amplitudes above 56 cm s−1 at 95% confidence.
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.

Full Table B.2 is only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/654/A60

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. Bibcode: 2021yCat..36540060L Altcode: Detection and characterization of the exoplanet HD 22496 b with ESPRESSO data.

(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 Bibcode: 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. Bibcode: 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 3.06−0.37+0.33 M⊕ and an orbital period of 12.796−0.019+0.020 days and report indications for the presence of a fifth nontransiting terrestrial planet. With a minimum mass of 2.46−0.82+0.66 M⊕ and an orbital period 23.15−0.17+0.60 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 3.6−1.5+1.4 and 4.57−0.85+0.77 g cm−3, 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 2.95−0.51+0.79 g cm−3 and despite a similar core mass fraction, up to 30% of the mass of L 98-59 d might be water.

Full Table B.1 is only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/653/A41

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. Bibcode: 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. Bibcode: 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.
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.
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.
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.
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 Teff, 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. Bibcode: 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 Teff, [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], Teff, 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. Bibcode: 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 Bibcode: 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 H2O 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 C2 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. Bibcode: 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 1.152−0.070+0.073 to 2.87−0.13+0.14 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 1.02−0.23+0.28 to 0.177−0.061+0.055 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. Bibcode: 2021yCat..36490026L Altcode: Raw and detrended data from CHEOPS, NGTS, SPECULOOS and TESS; raw data from ESPRESSO.

(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 Bibcode: 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 Bibcode: 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. Bibcode: 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. Bibcode: 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.

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 Bibcode: 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. Bibcode: 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 Bibcode: 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 Bibcode: 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-1. 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 10-6 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 Bibcode: 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 MGC,total = 9.6$^{+4.0}_{-2.6}\, \times$ 107 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. Bibcode: 2021A&A...646A.158T Altcode: 2020arXiv201112197T
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.
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.
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.
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.

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. Bibcode: 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. Bibcode: 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 Bibcode: 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. Bibcode: 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 × 108 M⊙, 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 Bibcode: 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. Bibcode: 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.
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.
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.
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-1 during a single night and 50 cm s-1 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-1. No difference has been measured across the UTs, neither in throughput nor RV precision.
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.

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. Bibcode: 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.
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.
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.
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 Rp 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 Rp and ~2 Rp, 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.

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 Bibcode: 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. Bibcode: 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 Pb = 5.3518 ± 0.0004 d and has a planet radius of $1.82^{+0.11}_{-0.09}$ R⊕ and a mass of $5.29^{+0.76}_{-0.77}$ M⊕, 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⊕. 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. Bibcode: 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. Bibcode: 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.
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.
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.
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.
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.

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 Bibcode: 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. Bibcode: 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.
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.
Methods: We used the Reloaded Rossiter-McLaughlin technique to measure the projected obliquity λ and the projected rotational velocity veq ṡsin(i*). 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.
Results: The planet is orbiting its slowly rotating host star (veq ṡsin(i*) = 0.53-0.05+0.07 km s-1) on a retrograde misaligned orbit (λ = -128.41-5.46+5.60 °). 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-1, and a full width at half maximum of 15.18 ± 1.75 km s-1. 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.
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.

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. Bibcode: 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-1, 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. Bibcode: 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) × 10-4, 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. Bibcode: 2020yCat..74995004M Altcode: tablerv.dat contains the radial velocities and activity indicators from K2-111 obtained by HARPS-N and ESPRESSO.

tablep1.dat contains the photometry for K2-111 from K-2, used for the transit fit.

tablep2.dat contains the photometry for K2-111 from WASP, and ASAS-SN, used to assess stellar variability.

(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. Bibcode: 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⊕ 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.
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.
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.
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-1) 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-1, 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⊕ 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 (ib =45.8-1.1+1.4 deg). This leads to the precise measurement of its absolute mass mb =14.1-0.4+0.5 MJup, indicating that π Men b can be classified as a brown dwarf.
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.

Tables B.1 and B.2 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/642/A31

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. Bibcode: 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.
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.
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.
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.
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.

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 Bibcode: 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 Bibcode: 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. Bibcode: 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.
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.
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 Pb = 4.01593 ± 0.00050 d and Pc = 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.
Results: Using ESPRESSO spectra, we derived the stellar parameters, Teff = 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⋆ = 1.03-0.02+0.04 M⊕ and R⋆ = 1.06-0.06+0.09 R⊕. We determine new values for the planetary properties of both planets. We characterize K2-38b as a super-Earth with RP = 1.54 ± 0.14 R⊕ and Mp = 7.3-1.0+1.1 M⊕, and K2-38c as a sub-Neptune with RP = 2.29 ± 0.26 R⊕ and Mp = 8.3-1.3+1.3 M⊕. Combining the radius and mass measurements, we derived a mean density of ρp = 11.0-2.8+4.1 g cm-3 for K2-38b and ρp = 3.8-1.1+1.8 g cm-3 for K2-38c, confirming K2-38b as one of the densest planets known to date.
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 MJ planet or stellar activity.

The ESPRESSO RVs used in this paper are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/641/A92

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. Bibcode: 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. Bibcode: 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.

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).

(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 Bibcode: 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 Bibcode: 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 Teff 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. Bibcode: 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 deg2 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. Bibcode: 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. Bibcode: 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.

Radial velocities extracted from ESPRESSO and CORALIE spectra, and spectroscopic stellar activity diagnostics from ESPRESSO.

(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. Bibcode: 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. Bibcode: 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.
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.
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-1. 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.
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⊕. In the combined dataset we measure a period of 11.18427 ± 0.00070 days with a minimum mass of 1.173 ± 0.086 M⊕. 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-1. If caused by a planetary companion, it would correspond to a minimum mass of 0.29 ± 0.08 M⊕. 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⊕ at periods shorter than 50 days.

The data used in this paper are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/639/A77

Based [in part] on Guaranteed Time Observations collected at the European Southern Observatory under ESO programme 1102.C-0744. by the ESPRESSO Consortium.

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 Bibcode: 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 ρT(R⊙)/ρt(R⊙) = 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 ρH(R⊙)/(ρT(R⊙) + ρt(R⊙)) = 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. Bibcode: 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 Bibcode: 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. Bibcode: 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.

(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. Bibcode: 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.

(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 Bibcode: 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. Bibcode: 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.

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.

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.

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.

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.

(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 Bibcode: 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-1. 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. Bibcode: 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.

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).

(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. Bibcode: 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.

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.

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.

(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 Bibcode: 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 RGC gradient of -0.068 ± 0.001 dex kpc-1 over the range of 6 < RGC < 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. Bibcode: 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.
Aims: We describe our multi-element (Na, Mg, K, and Ca) non-LTE (NLTE) calculations, which can be applied to the APOGEE survey.
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.
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.
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. Bibcode: 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).

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).

(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. Bibcode: 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.

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.

(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. Bibcode: 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.

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).

(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. Bibcode: 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).

(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 Bibcode: 2020Natur.580..597E Altcode: 2020arXiv200305528E Ultrahot giant exoplanets receive thousands of times Earth's insolation1,2. Their high-temperature atmospheres (greater than 2,000 kelvin) are ideal laboratories for studying extreme planetary climates and chemistry3-5. Daysides are predicted to be cloud-free, dominated by atomic species6 and much hotter than nightsides5,7,8. Atoms are expected to recombine into molecules over the nightside9, resulting in different day and night chemistries. Although metallic elements and a large temperature contrast have been observed10-14, 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 transit4,7,15. 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 dayside16. 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. Bibcode: 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 Bibcode: 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.

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.

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).

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 Bibcode: 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 Bibcode: 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 H2O and FeH molecular line lists. Our sample range in Teff 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⊙. 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 Bibcode: 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. Bibcode: 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⊙ and a massive stellar black hole (BH) of 70 M⊙. This finding challenges our current theories of massive star evolution and formation of BHs at solar metallicity.
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.
Methods: We use the non-LTE stellar atmosphere code FASTWIND to analyze new and archival high-resolution data.
Results: We determine (Teff, 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+2.1-1.9 M⊙ and an evolutionary mass, assuming single star evolution, of 5.2+0.3-0.6 M⊙. We determine an upper limit of 8 km s-1 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 Teff and log g and a consistent distance around 2 kpc.
Conclusions: We propose that the B-type star is a slightly evolved main sequence star of 3-5 M⊙ 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⊙, the mass of the dark companion would be 4-5 M⊙, 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 Bibcode: 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 μℓ 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 Bibcode: 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 Bibcode: 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. Bibcode: 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.
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.
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.
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.
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.

Tables 1 and 2 are also available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.http://u-strasbg.fr/viz-bin/cat/J/A+A/633/A129 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 Bibcode: 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⊙ 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 Bibcode: 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-1 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-1 using magnesium abundances and at 0.04 ± 0.01 dex Gyr-1 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. Bibcode: 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.

(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. Bibcode: 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 Bibcode: 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. Bibcode: 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-1. 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 Bibcode: 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 Bibcode: 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.
Aims: We explore the possibility of using unsupervised clustering algorithms to separate stellar populations with distinct chemical patterns.
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.
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.

The list of stars is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/629/A34 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. Bibcode: 2019yCat..36290034G Altcode: Initial list of stars used in the article.

(1 data file). Title: The Challenges of Observing, Calibrating, and Modeling Stellar Spectral Energy Distributions Authors: Allende Prieto, Carlos Bibcode: 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. Bibcode: 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. C24668 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 C2 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 Bibcode: 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 108 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. Bibcode: 2019yCat.113380686C Altcode: Atmospheric parameters and radial velocities for 27 stars and detailed abundances for 23 stars.

(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 Bibcode: 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 7Li production.

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. Bibcode: 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.
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.
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.
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 Bibcode: 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 χ2 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. Bibcode: 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.

(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 Bibcode: 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 Bibcode: 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 apo ∼ 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. Bibcode: 2019A&A...622A.191M Altcode: 2018arXiv181208817M
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.
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.
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.
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.

Full Table 2 is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/622/A191 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. Bibcode: 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.

(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. Bibcode: 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 deg2 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 deg2 of J-PLUS data, containing about 4.3 million stars and 3.0 million galaxies at r < 21 mag. With a goal of 8500 deg2 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. Bibcode: 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 GRVS = 12 mag.
Aims: This paper describes the validation and properties of the median radial velocities published in Gaia DR2.
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.
Results: Gaia DR2 contains median radial velocities for 7 224 631 stars, with Teff 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-1. In addition, the Gaia radial velocities show a positive trend as a function of magnitude, which starts around GRVS 9 mag and reaches about + 500 m s-1 at GRVS = 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-1. The radial velocity precision is a function of many parameters, in particular, the magnitude and effective temperature. For bright stars, GRVS ∈ [4, 8] mag, the precision, estimated using the full dataset, is in the range 220-350 m s-1, which is about three to five times more precise than the pre-launch specification of 1 km s-1. At the faint end, GRVS = 11.75 mag, the precisions for Teff = 5000 and 6500 K are 1.4 and 3.7 km s-1, 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. Bibcode: 2019AJ....157...26L Altcode: 2019arXiv190101300L We measure the mean Galactocentric radial component of the velocity of stars (v R ) 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 R at R ≈ 9-13 kpc, reaching a maximum of ≈6 km s-1, and a decrease at large values of R, reaching a negative (contraction) value of ≈-10 km s-1 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 R , 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. Bibcode: 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 108.5 ≲ M* ≲ 109 M⊙. 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. Bibcode: 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.
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.
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.
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-1, with a dispersion of 5.8 km s-1, 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 Teff 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. Bibcode: 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-1 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 Bibcode: 2018ApJ...866...42F Altcode: 2018arXiv180408622W; 2018arXiv180408622F We present a search for new members of the 300 km s-1 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}-0.09+0.12 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 × 103 L ⊙. 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. Bibcode: 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.

(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. Bibcode: 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.
Aims: We provide a comprehensive and homogeneous collection of synthetic spectra for a wide range of atmospheric parameters and chemical compositions.
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.
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.

Data files are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/618/A25 Title: Testing models of stellar structure and evolution - I. Comparison with detached eclipsing binaries Authors: del Burgo, C.; Allende Prieto, C. Bibcode: 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⊙, 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 Bibcode: 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. Bibcode: 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).

(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 Bibcode: 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. Bibcode: 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.
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.
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.
Results: The spectroscopic processing pipeline produced median radial velocities for Gaia stars with narrow-band near-IR magnitude GRVS ≤ 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 (Teff ≥ 7000 K) and coolest (Teff ≤ 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-1, and the overall precision is ~1 km s-1; it reaches ~200 m s-1 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. Bibcode: 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.
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.
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.
Results: We demonstrate the effectiveness of our offset non-uniformity models in mitigating the effects in Gaia data.
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. Bibcode: 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 Bibcode: 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 Bibcode: 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. Bibcode: 2018yCat..36180025A Altcode: The following text describes the data files available from ftp://carlos:allende@ftp.ll.iac.es/collection

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).

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.

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.

for the nsc files and 0.2-2.5um for the ns files.

nsc ('coarse' grids): [Fe/H], Teff, logg

size filename Teff range R

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

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

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

ns ('large' grids): [Fe/H], [alpha/Fe], log(micro), Teff, logg

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

(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. Bibcode: 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. Bibcode: 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).

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.

(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 Bibcode: 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.
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.
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.
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).
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.

Full Tables B.1-B.4 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/612/A98 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 Bibcode: 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 (www.sdss.org) 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 Bibcode: 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. Bibcode: 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.
Aims: Here, we aim to spectroscopically confirm the presence of the disk stars up to much larger distances.
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.
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: 12C/13C 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 Bibcode: 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 12C/13C. Values of the 12C/13C ratio were obtained from a spectrum synthesis analysis. The derived 12C/13C 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 12C/13C, 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. Bibcode: 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.

(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 Bibcode: 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}{crit}={8.3}-4.1+0.1 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}{eff} 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 Bibcode: 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 (ΔRVmax) for APOGEE targets is a strong function of log g, with MS stars showing ΔRVmax as high as ∼300 {km} {{{s}}}-1, and steadily dropping down to ∼30 {km} {{{s}}}-1 for log g ∼ 0, as stars climb up the red giant branch (RGB). Red clump stars show a distribution of ΔRVmax values comparable to that of stars at the tip of the RGB, implying they have similar multiplicity characteristics. The observed attrition of high ΔRVmax 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 ΔRVmax 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 Bibcode: 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}⊙ ∼ -5. In our quest to push down the metallicity threshold we have identified SDSS J0023+0307, a primitive star with T eff = 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.

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 Bibcode: 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. Bibcode: 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.

(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 Bibcode: 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}{eff}=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.

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 Bibcode: 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. Bibcode: 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 Bibcode: 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 up) 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 Bibcode: 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. Bibcode: 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. Bibcode: 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 Bibcode: 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, http://www.sdss.org, 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. Bibcode: 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 deg2 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]SEGUE < -3.0 stars among [Fe/H]Pristine < -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 Bibcode: 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⊙ to M < 0.3 M⊙ 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. Bibcode: 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 Bibcode: 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. Bibcode: 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 α2000 = 00h22m and δ2000 = +64°23΄. By parameterizing the stellar density with a King profile, we have obtained a central density of ρ0 = 6.5 ± 0.2 star arcmin-2 and a core radius of rcore = 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)o = 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 <Vr> = -53.1 ± 3.1 km s-1. 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. Bibcode: 2017A&A...605A..40A Altcode: 2017arXiv170509233A
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.
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.
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.
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.

The model spectra are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/605/A40 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. Bibcode: 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).
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 (MV-[Fe/H]) relations for the RR Lyrae stars, with zero points based on TGAS.
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 σϖ/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 σϖ/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 σϖ/ϖ< 0.5). The new relations were computed using multi-band (V,I,J,Ks) 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 MV- [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.
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.
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.

Full Tables A.1-A.3 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/605/A79 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. Bibcode: 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 Bibcode: 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 Bibcode: 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. Bibcode: 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 Bibcode: 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. Bibcode: 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.
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.
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.
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.

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. Bibcode: 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 Bibcode: 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. Bibcode: 2017MNRAS.468..239C Altcode: 2017arXiv170203343C We report the discovery of four massive (M > 0.8 M⊙) ZZ Ceti white dwarfs, including an ultramassive 1.16 M⊙ 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⊙, hydrogen and helium envelope masses of MH = 5.8 × 10-7 M⊙ and MHe = 4.5 × 10-4 M⊙ 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⊙ 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⊙, 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. Bibcode: 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.

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 Bibcode: 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 Bibcode: 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. Bibcode: 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.

ferre.pdf file contains the FERRE uses's guide.

The code can be obtained from http://hebe.as.utexas.edu/ferre

Example :

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,

It is the grid used for the paper.

(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. Bibcode: 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 ML,YREC ∼ 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. Bibcode: 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.
Aims: We investigate the scientific potential and limitations of the TGAS component by means of the astrometric data for open clusters.
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.
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.
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.

Tables D.1 to D.19 are also available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/601/A19 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. Bibcode: 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.
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.
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.
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.
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 Bibcode: 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. Bibcode: 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.

(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. Bibcode: 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. Bibcode: 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.

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 http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/598/A5 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 Bibcode: 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. Bibcode: 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 H2O 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]Kepler-138 = -0.09 ± 0.09 dex and [Fe/H]Kepler-186 = -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. Bibcode: 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 Bibcode: 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. Bibcode: 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 <RGal< 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.

The data described in Table B.1 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/597/A30 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. Bibcode: 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-1), 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 Re, the radial trend of [Na/Fe] is similar to [α/Fe] and [C/Fe], being constant out to ∼0.5 Re, and decreasing by ∼0.2-0.3 dex at ∼0.8 Re, 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 Bibcode: 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 Bibcode: 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 Bibcode: 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.

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 Bibcode: 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.

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 Bibcode: 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. Bibcode: 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⋆ = 1.20 ± 0.05 R⊙ 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 Rp = 1.41 ± 0.06 RJ 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, Teff = 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⋆ = 1.20 ± 0.06 R⊙ and Teff = 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 Bibcode: 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 }r2 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-1. 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 Bibcode: 2016A&A...596A..98A Altcode: 2016arXiv160907821A
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.
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.
Results: We find dV/ d [Fe/H] = -18 ± 2 km s-1 dex-1 for stars in the thin disk and dV/ d [Fe/H] = +23 ± 10 km s-1 dex-1 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-1 dex-1. 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.
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. Bibcode: 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.

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).

(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 Bibcode: 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.

(1 data file). Title: Learning about stars from their colors Authors: Allende Prieto, C. Bibcode: 2016A&A...595A.129A Altcode: 2016arXiv160908557A
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.
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.
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.
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. Bibcode: 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.
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. Bibcode: 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.

http://www.cosmos.esa.int/gaia 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. Bibcode: 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.
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.
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.
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-1 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-1. 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.
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. Bibcode: 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 Bibcode: 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. Bibcode: 2016A&A...594A..68D Altcode: 2016arXiv160705954D
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.
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 (Teff, 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.
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 Grvs < 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.
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. Bibcode: 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 12C and 14N 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 Bibcode: 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. Bibcode: 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.

(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 Bibcode: 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 Bibcode: 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. Bibcode: 2016A&A...593A..28F Altcode: 2016arXiv160604811F
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.
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.
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.

Tables 4-6 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/593/A28 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. Bibcode: 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-1 for the α-elements [O/H], [Ca/H], [Si/H], and [Mg/H], and -0.035 dex kpc-1 and -0.040 dex kpc-1 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. Bibcode: 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. Bibcode: 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.

(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 Bibcode: 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. Bibcode: 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.
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.
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.
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.

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 http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/593/A10 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. Bibcode: 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. Bibcode: 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 7deg2 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).

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)0<1.3, 0.5<(u-g)0<3.5, and proper motions smaller than 11mas/yr.

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).

(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. Bibcode: 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. Bibcode: 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.

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}2 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.

Table3 gives the weights as a function of wavelength, for the 15 APOGEE chemical elements.

(1 data file). Title: Solar and stellar photospheric abundances Authors: Allende Prieto, Carlos Bibcode: 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. Bibcode: 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 Bibcode: 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 χ2 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. Bibcode: 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.
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.
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 KIC 3241581 (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.
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 Teff = 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.
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.

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 http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/589/A27 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. Bibcode: 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.

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.

(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. Bibcode: 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. Bibcode: 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 Bibcode: 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-1, 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}{Jup}. 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. Bibcode: 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 Bibcode: 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⊙ mean and 0.25 M⊙ 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.

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. Bibcode: 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).

(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. Bibcode: 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 GRVS~ 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.
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.
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 10-2.5 to 10+ 0.5 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.
Results: For all the stellar types we considered, stars brighter than GRVS~ 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 Teff, 0.10 dex in log(g), 0.04 dex in [M/H], and 0.03 dex in [α/Fe] at GRVS = 10.3. They degrade to 155 K in Teff, 0.15 dex in log(g), 0.10 dex in [M/H], and 0.1 dex in [α/Fe] at GRVS~ 12. Similar accuracies in Teff 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 GRVS = 12.6 and 13.4, respectively). For the faintest stars, with GRVS≳ 13-14, a Teff input from the spectrophotometric-derived parameters will allow the final GSP-Spec parametrization to be improved.
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 Bibcode: 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 MJup), 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. Bibcode: 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 10-4 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 m2 is sufficiently large to achieve the necessary spectro-photometric precision: for the Phase A study a 1.13 m2 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. Bibcode: 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. Bibcode: 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. Bibcode: 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-1) 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 Bibcode: 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}{eff}, {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}{eff} \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. Bibcode: 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.

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. Bibcode: 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.
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.
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.
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.
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-1, dependent on instrumental configuration.

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 http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/580/A75 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 Bibcode: 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. Bibcode: 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 (Teff ≃ 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 Bibcode: 2015ApJ...807...82T Altcode: 2015arXiv150503536T We investigate the occurrence rate of rapidly rotating (v{sin}i >10 km s-1), 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-1 < v{sin}i < 10 km s-1 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-1) 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 Bibcode: 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 deg2 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 deg2 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 deg2; 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. Bibcode: 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.

(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. Bibcode: 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}eff}) 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}eff} = 3500-8000 K) and MARCS/Turbospectrum ({{T}eff} = 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-1), 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. Bibcode: 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. Bibcode: 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.

The Kepler space telescope has observed ~196400 stars (Huber et al., 2014ApJS..211....2H, Cat. J/ApJS/211/2) in a field of 105deg2 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).

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);

JHKs from 2MASS (Cutri et al., 2003, Cat. II/246; Skrutskie et al., 2006, Cat. VII/233);

the Kepler magnitude, Kp, as derived from a combination of the griz magnitudes (Brown et al., 2011, Cat. J/AJ/142/112);

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).

(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. Bibcode: 2015A&A...577A..81F Altcode: 2015arXiv150304362F
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 ≤ Teff ≤ 6300 K, and distances from the Milky Way plane in excess of 5 kpc, and determine their abundances of Fe, Ca, and Mg.
Methods: We followed the same methodology as in the previous paper in this series, deriving atmospheric parameters by χ2 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.
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.

Table 1 and beginning of Tables 2 and 3 are available in electronic form at http://www.aanda.orgFull Tables 2 and 3 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/577/A81 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 Bibcode: 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 28Si 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 Bibcode: 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-1. 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-1 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 (Teff, 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. Bibcode: 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.

Appendix A is available in electronic form at http://www.aanda.org 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. Bibcode: 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.
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.
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.
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 ρ Oph, Cha I, NGC 2264, γ Vel, and NGC 2547 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 Teff, ≈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. Bibcode: 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 12C/13C, 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 12C/13C 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. Bibcode: 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.

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 http://www.aanda.org 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. Bibcode: 2015A&A...574L...7S Altcode: 2015arXiv150101330S The nearby (distance ~ 350-400 pc), rich Vela OB2 association, includes γ2 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 γ2 Velorum. Here we analyse the results of Gaia-ESO survey observations of NGC 2547, a 35 Myr cluster located two degrees south of γ2 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 γ2 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 γ2 Velorum that expanded after gas expulsion or formed in a less dense environment that is spread over the whole Vela OB2 region.

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 http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/574/L7 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. Bibcode: 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.

(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. Bibcode: 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.

(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. Bibcode: 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).

(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 Bibcode: 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 Bibcode: 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 105 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 Bibcode: 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. Bibcode: 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. Bibcode: 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 105 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.

Full Table 3 is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/573/A115Based 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. Bibcode: 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 eff ~ 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. Bibcode: 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 Bibcode: 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 Bibcode: 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 Bibcode: 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 Bibcode: 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 ≥ 12o), and the metal-poor components become very weak at low latitude (|b| < 4o). 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. Bibcode: 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. Bibcode: 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. Bibcode: 2014A&A...572A..33M Altcode: 2014arXiv1408.6687M
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).
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).
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 RGC 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.

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 http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/572/A33 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. Bibcode: 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 Bibcode: 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 Bibcode: 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 eff, 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 eff 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 eff 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. Bibcode: 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.

(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. Bibcode: 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 × 10-10 yr-1, 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-1) 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. Bibcode: 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.

(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. Bibcode: 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.

(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. Bibcode: 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 105 stars and high-resolution UVES spectra for about 5000 stars. With UVES, the Survey has already observed 1447 FGK-type stars.
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.
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.
Results: The recommended results successfully reproduce the atmospheric parameters of the benchmark stars and the expected Teff-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 Teff, 0.13 dex for log g and 0.07 dex for [Fe/H]. Systematic biases are estimated to be between 50-100 K for Teff, 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.
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.

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 http://www.aanda.org 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. Bibcode: 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. Bibcode: 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-1 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⊙ primary and a ≥0.14 M⊙ secondary, at a separation of ≥0.19 R⊙. 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. Bibcode: 2014yCat..35720033M Altcode: 2014yCat..35729033M Table2 contains chemical abundances of 1916 stars from GES DR1.

(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. Bibcode: 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 Bibcode: 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+0.039-0.053 dex kpc-1 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 Bibcode: 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 kpc3 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. Bibcode: 2014A&A...568A...7A Altcode: 2014arXiv1406.4997A
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).
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.
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.

Full Table 1 is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/568/A7 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. Bibcode: 2014A&A...567A...5R Altcode: 2014arXiv1403.7568R
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.
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.
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 Vφ 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-1 dex-1. 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-1 and a very small positive [α/Fe] gradient. For the thick disc, flat gradients in [M/H] and [α/Fe] are derived.
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.

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 http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/567/A5 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 Bibcode: 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 Bibcode: 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 Bibcode: 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. Bibcode: 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 Bibcode: 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. Bibcode: 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.

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.

(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. Bibcode: 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 105 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-1 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-1) and to the radial velocities of the standard stars (~0.5 km s-1) 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.

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. Bibcode: 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.

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 Bibcode: 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 Bibcode: 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)0 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. Bibcode: 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).
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).
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).
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].

Appendix A is available in electronic form at http://www.aanda.org 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 Bibcode: 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 deg2. 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. Bibcode: 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. Bibcode: 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" (2014, ApJ, 780, 7) Authors: Palladino, Lauren E.; Schlesinger, Katharine J.; Holley-Bockelmann, Kelly; Allende Prieto, Carlos; Beers, Timothy C.; Lee, Young Sun; Schneider, Donald P. Bibcode: 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. Bibcode: 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 Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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-1 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. Bibcode: 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 Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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 < Teff < 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. Bibcode: 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. Bibcode: 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-1 and a measurement floor at vsin i = 4 km s-1. This survey significantly increases the number of M dwarfs studied for rotational velocities and radial velocity variability (at ~100-200 m s-1), 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-1 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. Bibcode: 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. Bibcode: 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 105 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 Bibcode: 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 deg2 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-1 for radii >0.°8 from center to a dynamical cold point of 8 km s-1 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. Bibcode: 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 GC <= 14.5 kpc, but [M/H] does show a gradient for R GC < 10 kpc and a significant flattening beyond R GC = 10 kpc. In particular, whereas fitting a single linear trend yields an [M/H] gradient of -0.09 ± 0.03 dex kpc-1—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 GC <= 10) than previously found (-0.20 ± 0.08 dex kpc-1) and a nearly flat trend beyond 10 kpc (-0.02 ± 0.09 dex kpc-1). 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. Bibcode: 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 ~105 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. Bibcode: 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. Bibcode: 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-1 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 Bibcode: 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-1. Using additional high-resolution spectroscopy, we find the host star has an effective temperature T eff = 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 ⊙ and 0.92 ± 0.19 R ⊙. The minimum mass of MARVELS-5b is 65.0 ± 2.9M Jup, 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 ⊙ 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. Bibcode: 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.

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.

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.

(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 Bibcode: 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 Jup 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 ⊙, 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-1. Moderate resolution spectroscopy of the host star has determined the following parameters: T eff = 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 * = 1.11 ± 0.11 M ⊙ and R * = 1.06 ± 0.23 R ⊙ 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. Bibcode: 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 ⊙ 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.

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. Bibcode: 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.
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.
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.
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.

Tables 2, 4, 5, and reduced spectra are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/553/A95 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. Bibcode: 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 Jup) 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-1 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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.

(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. Bibcode: 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 12C, 13C, 14N, and 16O, 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 12C synthesized during 4He-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 Bibcode: 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. Bibcode: 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.

(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. Bibcode: 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.
Aims: We provide theoretical corrections for the net velocity shifts due to convection expected for the measurements from the Gaia Radial Velocity Spectrometer (RVS).
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.
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-1 for late-K-type stars, and they increase with stellar mass, reaching about 0.3 km s-1 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-1 and dominate convective blueshifts for dwarfs, but become much weaker for giants.

Appendix A is available in electronic form at http://www.aanda.orgModel spectra from the 1D and 3D calculations are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr130.79.128.5 or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/550/A103 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. Bibcode: 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 1), thick-disk (P 2), and halo (P 3) members. We confirm previous findings of enhanced [O/Fe] in thick-disk (P 2 > 0.5) relative to thin-disk (P 1 > 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 1 < 0.7, P 2 < 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 3 > 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-1 halo stars with V > -200 km s-1 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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 (RGC) 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 < RGC < 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 Bibcode: 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 eff = 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-1, period P = 9.0090 ± 0.0004 days, and eccentricity e = 0.226 ± 0.011. Adopting a mass of 1.16 ± 0.11 M ⊙ for the subgiant host star, we infer that the companion has a minimum mass of 40.0 ± 2.5 M Jup. 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 ⊙ 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 rotsin i, but unusual for a subgiant of this T eff. 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. Bibcode: 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. Bibcode: 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 eff < 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. Bibcode: 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).

(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 Bibcode: 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 R ≈ 35 km s-1). We determine the local value of the circular velocity to be Vc (R 0) = 218 ± 6 km s-1 and find that the rotation curve is approximately flat with a local derivative between -3.0 km s-1 kpc-1 and 0.4 km s-1 kpc-1. 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 0 < 9 kpc, radial velocity V R, ⊙ = -10 ± 1 km s-1, and rotational velocity V phi, ⊙ = 242+10 - 3 km s-1, 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-1 in Vc . Marginalizing over all the systematics that we consider, we find that Vc (R 0) < 235 km s-1 at >99 % confidence. We find an offset between the Sun's rotational velocity and the local circular velocity of 26 ± 3 km s-1, which is larger than the locally measured solar motion of 12 km s-1. This larger offset reconciles our value for Vc with recent claims that Vc >~ 240 km s-1. Combining our results with other data, we find that the Milky Way's dark-halo mass within the virial radius is ~8 × 1011 M ⊙. 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. Bibcode: 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 eq up to 2,000 K, to those of a few Earth masses, with T eq 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. Bibcode: 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 H2O 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. Bibcode: 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) × 10-12 s s-1 (or -0.31 ± 0.09 ms yr-1). We revise the system parameters based on our new photometric and spectroscopic observations: J0651 contains two WDs with M 1 = 0.26 ± 0.04 M ⊙ and M 2 = 0.50 ± 0.04 M ⊙. General relativity predicts orbital decay due to gravitational wave radiation of (- 8.2 ± 1.7) × 10-12 s s-1 (or -0.26 ± 0.05 ms yr-1). 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 Bibcode: 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 eff = 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 1 = 1.21 ± 0.08 M ⊙ and R 1 = 1.09+0.15 - 0.13 R ⊙. 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 ⊙. 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 {2, 3} <~ 1.0 M ⊙, 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 ⊙, 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. Bibcode: 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. Bibcode: 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 eff) versus lithium abundance (A Li) plane is observed such that no stars with T eff ~= 6075 K and A Li ~= 1.8 are found. We speculate that most of the stars on the low A Li 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 Li ~= 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 eff 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 Li planet-hosts are found in the desert T eff 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. Bibcode: 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 (epsilonV ~ 0.2 km s-1) 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 (σV ~ 30 km s-1), high-velocity peak (V GSR ≈ +200 km s-1) 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 Bibcode: 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. Bibcode: 2012ApJ...751..141K Altcode: 2012arXiv1204.0028K We present new radial velocity and X-ray observations of extremely low mass (ELM, ~0.2 M ⊙) 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.

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 Bibcode: 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 eff <~ 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 ⊙ and radius of 0.99 ± 0.18 R ⊙. 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-1. We determine the minimum companion mass (if sin i = 1) to be 97.7 ± 5.8 M Jup. 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 eff <~ 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 Bibcode: 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 Bibcode: 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. Bibcode: 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 Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 2012ApJ...744..142B Altcode: 2011arXiv1111.6588B Extremely low mass (ELM) white dwarfs (WDs) with masses < 0.25 M ⊙ 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.

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 Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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 Bibcode: 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. Bibcode: 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. Bibcode: 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 eff = 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 ⊙, R = 25.4 ± 0.2 R ⊙, and τ = 7.1+1.5 - 1.2 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. Bibcode: 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-1. 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⊙ primary +≥0.3 M⊙ invisible secondary, at a separation of ≥0.32 R⊙. 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 Bibcode: 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?

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.

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.

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. Bibcode: 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 Bibcode: 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 105 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-1, ~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" (2011, ApJS, 193, 29) 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 Bibcode: 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. Bibcode: 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 Bibcode: 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. Bibcode: 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-1 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 sun tidally distorted helium WD, only the second tidally distorted WD known. The unseen secondary is a 0.55 M sun 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 10-22, 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.

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. Bibcode: 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 Bibcode: 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-1. 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-1 implies a dSph with M tot >~ 109 M sun. 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. Bibcode: 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.

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.

(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. Bibcode: 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⊙) WDs using the 6.5-m Multiple Mirror Telescope. We detect peak-to-peak radial velocity variations of 740 km s-1 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⊙ primary + 0.43 M⊙ invisible secondary) at a separation of 0.32 R⊙. 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. Bibcode: 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 Bibcode: 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 deg2 in the southern Galactic cap, bringing the total footprint of the SDSS imaging to 14,555 deg2, 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 Bibcode: 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 eff = [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. Bibcode: 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. Bibcode: 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⊙ white dwarfs (WDs). We show, for the first time, that Milky Way disc ELM WDs have a merger rate of approximately 4 × 10-5 yr-1 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⊙ 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. Bibcode: 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. Bibcode: 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. Bibcode: 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 sun) 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.

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. Bibcode: 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

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. Bibcode: 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 eff < 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. Bibcode: 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-1 in the strongest Fe I features to 800 m s-1 in the weakest ones. Core wavelength shifts range from about -100 to -900 m s-1, 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. Bibcode: 2010ApJ...723.1072B Altcode: 2010arXiv1011.3050B We analyze radial velocity observations of the 12 extremely low-mass (ELM), with <=0.25 M sun, 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.

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 Bibcode: 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-1 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 eff = 8690 ± 140 K and log g = 6.54 ± 0.05, which correspond to a mass of 0.18 M sun. For an inclination angle of 89fdg9 derived from the eclipse modeling, the mass function requires a 0.76 M sun 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.

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. Bibcode: 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 Bibcode: 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. Bibcode: 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. Bibcode: 2010ApJ...716..122K Altcode: 2009arXiv0911.1781K We present radial velocity observations of four extremely low-mass (0.2 M sun) white dwarfs (WDs). All four stars show peak-to-peak radial velocity variations of 540-710 km s-1 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 sun; 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.

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 Bibcode: 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 Bibcode: 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. Bibcode: 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. Bibcode: 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

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.

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: 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 Bibcode: 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.

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. Bibcode: 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. Bibcode: 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 Bibcode: 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+0.02 -0.02 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-3. In addition, we estimate that there are of order 103 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. Bibcode: 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.
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.
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-1, depending on line strength, with the stronger features showing larger span. The corresponding core wavelength shifts range from about -200 m s-1 for the weak Fe i lines to almost +100 m s-1 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-1. 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. Bibcode: 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 Bibcode: 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. Bibcode: 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 deg2 of imaging data, with most of the ~2000 deg2 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 deg2. The survey has completed spectroscopy over 9380 deg2 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 Bibcode: 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.

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 Bibcode: 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 deg2 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. Bibcode: 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-1 and a 0.98776 day period, which implies a companion mass of M >= 0.37 M sun. 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-1, 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. Bibcode: 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. Bibcode: 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.

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. Bibcode: 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. Bibcode: 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. Bibcode: 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-1. 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-1. 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-1. 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 Bibcode: 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.

The SEGUE Stellar Parameter Pipeline (SSPP) has obtained estimates of the atmospheric parameters (Teff, 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.

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. Bibcode: 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. Bibcode: 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.
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.
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-1 for the strongest lines (residual core flux ≃0.3), while wavelength shifts range from about -150 m s-1 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-1 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. Bibcode: 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. Bibcode: 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. Bibcode: 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 Bibcode: 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 Bibcode: 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-1, 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.

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. Bibcode: 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 Bibcode: 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 Bibcode: 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 eff)< 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. Bibcode: 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. Bibcode: 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. Bibcode: 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-1, 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 Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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-1 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. Bibcode: 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.

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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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 deg2, 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 deg2. 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. Bibcode: 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.

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.

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 DEG2 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. Bibcode: 2008AJ....135..564B Altcode: 2007arXiv0711.2886B We present a complete spectroscopic survey of 2414 2MASS-selected blue horizontal branch (BHB) candidates selected over 4300 deg2 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 dvrot/d|Z| = -28 ± 3.4 km s-1 in the region |Z| < 6 kpc, and a density scale height of hZ = 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-1. We infer the density of halo and thick disk BHB stars is 104 ± 37 kpc-3 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 Bibcode: 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 Bibcode: 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. Bibcode: 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.
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.
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.
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.
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.

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. Bibcode: 2008mru..conf...69R Altcode: No abstract at ADS Title: Solar chemical peculiarities? Authors: Allende Prieto, C. Bibcode: 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. Bibcode: 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.

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 Bibcode: 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 Bibcode: 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 2×1011 cm-2). We limit any circumstellar absorption lines to be weaker than ~10 mÅ (6×1010 cm-2). For the case of material distributed in spherically symmetric shells of radius ~1016 cm surrounding the progenitor system, we place an upper limit on the shell mass of ~(3×10-8)/X Msolar, 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.

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.

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. Bibcode: 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. Bibcode: 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 Bibcode: 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. Bibcode: 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 Bibcode: 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. Bibcode: 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.
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.
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.
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 V349 Vel and BC Gru, for the composite spectrum star V4385 Sgr, for the T Tauri star V1045 Sco, and for DM Boo which we re-classify as a BY Draconis variable. The complete data release can be accessed via the VSOP web site.

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. Bibcode: 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. Bibcode: 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 Msolar. The radial velocity of the white dwarf shows variations with a semi-amplitude of 148.8+/-6.9 km s-1 and a period of 7.5936+/-0.0024 hr, which implies a companion mass of M>=0.28 Msolar. The lack of evidence of a companion in the optical photometry forces any main-sequence companion to be smaller than 0.1 Msolar, 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.

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 Bibcode: 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. Bibcode: 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).
Methods: Time-resolved optical spectroscopy and photometry were carried out to determine the properties of this new cataclysmic variable progenitor (pre-CV).
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}⊙ 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}⊙ and i≃ 45°-55°, respectively.
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 105 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. Bibcode: 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.

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.

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. Bibcode: 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. Bibcode: 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.

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.

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. Bibcode: 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 Teff=11,288+/-72 K and logg=5.48+/-0.03 with an estimated mass of 0.17 Msolar, 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 Msolar. 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. Bibcode: 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 Teff>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.

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. Bibcode: 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.

(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. Bibcode: 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 Bibcode: 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).

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.

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 Bibcode: 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. 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. Bibcode: 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

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.

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.

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. Bibcode: 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. 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. Bibcode: 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 Teff=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, fbol=(4.89±0.10) × 10-9 erg cm-2 s-1, 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 (Teff) 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 Teff (~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 AFe,⊙=7.51) while that from the Fe I lines is A_Fe=5.92 ± 0.11, and therefore with our preferred Teff (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 Teff 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. Bibcode: 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.

(2 data files). Title: Stellar Abundances: Recent and Foreseeable Trends Authors: Allende Prieto, C. Bibcode: 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. 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. Bibcode: 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. Bibcode: 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. 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. Bibcode: 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. 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. Bibcode: 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. Title: Elemental abundance survey of the Galactic thick disc Authors: Reddy, Bacham E.; Lambert, David L.; Allende Prieto, Carlos Bibcode: 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.

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.

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. 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. Bibcode: 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-1. 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-1). 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. 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. Bibcode: 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-1. 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 >106 Msolar 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 Bibcode: 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. 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 Bibcode: 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-1. 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-1 kpc-1 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 Bibcode: 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. Bibcode: 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. Bibcode: 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.

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.

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. Bibcode: 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.

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. Bibcode: 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.

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.

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. Bibcode: 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.

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. Bibcode: 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. Bibcode: 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. Bibcode: 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 Bibcode: 2005AJ....130.1097B Altcode: 2005astro.ph..5328B We discuss a 175 deg2 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-1, and the mean Galactic rotation of the BHB stars 3 kpc<|z|<15 kpc is -4+/-30 km s-1. We discuss the theoretical basis of the Preston, Shectman, and Beers MV-color relation for BHB stars and conclude that the intrinsic shape of the BHB MV-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<MV<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. Bibcode: 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-1. 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. Bibcode: 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. Bibcode: 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 Bibcode: 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-, 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. Bibcode: 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. Bibcode: 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).

We secured spectra for 8 spectral setups in 6 different positions across the solar disk, as summarized in Table 1.

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).

(2 data files). Title: Line formation in solar granulation. VI. [C I], C I, CH and C2 lines and the photospheric C abundance Authors: Asplund, M.; Grevesse, N.; Sauval, A. J.; Allende Prieto, C.; Blomme, R. Bibcode: 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 C2 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, C2 Swan) is log ɛC = 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. Bibcode: 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.

(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 Bibcode: 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. Bibcode: 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. Bibcode: 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.

We use radial velocities, proper motions, and estimates of [Fe/H], Teff, 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.

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. Bibcode: 2004AAS...205.2108B Altcode: 2004BAAS...36R1377B We report atmospheric parameter estimates (Teff, 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.

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. Bibcode: 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. Bibcode: 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 Teff=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*=0.89+/-0.05 Msolar and R*=0.83+/-0.05 Rsolar. Our improved estimates of the stellar parameters are utilized in a new analysis of the transit photometry of TrES-1 to derive a mass Mp=(0.76+/-0.05)MJ, a radius Rp=1.04+0.08-0.05RJ, and an inclination i=89.5+0.5-1.3 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. Bibcode: 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. Bibcode: 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.

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.

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 (Teff, log g, [Fe/H]) for SDSS stars that will be obtained during the course of SEGUE.

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. Bibcode: 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. Bibcode: 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. Bibcode: 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 NH/Ne 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 χ2 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.

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 Bibcode: 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 26MJ, 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.

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. Bibcode: 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 1012 M⊙. 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: S4N: 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. Bibcode: 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.

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).

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. Bibcode: 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 ɛO = 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. Bibcode: 2004ApJ...603..697Y Altcode: 2003astro.ph.12054Y Using classical model atmospheres and an LTE analysis, Mg isotope ratios 24Mg:25Mg:26Mg are measured in 32 Hyades dwarfs covering effective temperatures 4000K<=Teff<=5000K. We find no significant trend in any isotope ratio versus Teff, 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<=Teff<=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]II-[Fe/H]I~=0.3dex, while at 4000 K [Fe/H]II-[Fe/H]I~=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.

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. Bibcode: 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/

(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. Bibcode: 2004oee..sympE...1A Altcode: 2003astro.ph..4352A; 2003astro.ph..4352P The Sloan Digital Sky Survey (SDSS) is collecting photometry and intermediate resolution spectra for ∼105 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 Bibcode: 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 eff, 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. Bibcode: 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).

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.

By combining our sample with published studies, we deduced properties of thin and thick disk stars. Thick disk stars are primarily identified by their VLSR in the range - 40 to -100 km s-1. 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 VLSR ∼0 km s-1, 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 Bibcode: 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.

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 Teff 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.

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.

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. Bibcode: 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.

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 (Teff, 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 (qm = 0.9) as found by Ibata et. al.

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. Bibcode: 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.

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: S4N: A Spectroscopic Survey of Stars in the Solar Neighborhood Authors: Lambert, D. L.; Allende Prieto, C.; Cunha, K. Bibcode: 2003csss...12..875L Altcode: We are using the McDonald 2.7m and ESO 1.52m telescopes

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 MV = 6.5 (∼ K2 V) within a 12770 pc3 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-1); 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. Bibcode: 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 Bibcode: 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.

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. Bibcode: 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. Bibcode: 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.

(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. Bibcode: 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 Bibcode: 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 Bibcode: 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 (Teff) 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 Teff 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.

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.

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 VLSR in the range -40 to -100 km s-1. 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 VLSR~ 0 km s-1, 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. Bibcode: 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. Bibcode: 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 Bibcode: 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. Bibcode: 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. Bibcode: 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 1o x 64o 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. Bibcode: 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 1o x 64o Century Survey strip, and for every star with (J-H)<0.15 and J<15 mag in an adjacent 1o x 64o 2MASS region. The Century Survey is placed along a roughly constant line of galactic longitude and spans 35o < b < 88o. 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-1 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 Bibcode: 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 Bibcode: 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 Bibcode: 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. Bibcode: 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. Bibcode: 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 ~103 and a resolving power of 2×105. 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. Bibcode: 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 Msun 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 Msun), 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. Bibcode: 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 Bibcode: 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 Bibcode: 2001ApJ...562..528S Altcode: 2001astro.ph..7409S We explore the application of artificial neural networks (ANNs) for the estimation of atmospheric parameters (Teff, 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 Teff with an accuracy of σ(Teff)=135-150 K over the range 4250<=Teff<=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 Bibcode: 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~5×104 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 Bibcode: 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. Bibcode: 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 Bibcode: 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. Bibcode: 2001hsa..conf..153A Altcode: No abstract at ADS Title: (Teff, 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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 Bibcode: 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)0 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. Bibcode: 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-1 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. Bibcode: 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 Teff 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 Teff 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<=Teff<=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 Bibcode: 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 Bibcode: 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, C2 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. Bibcode: 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 Bibcode: 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 b1 and b2 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 Bibcode: 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. Bibcode: 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. Bibcode: 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)-Teff to the observational Mv-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 Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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 Bibcode: 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. Bibcode: 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. Bibcode: 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.

(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 Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 1995IAUS..176P.107A Altcode: No abstract at ADS