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Author name code: brown-tim
ADS astronomy entries on 2022-09-14
=author:"Brown, T.M." OR =author:"Brown, Timothy M." OR =author:"Brown, Timothy" OR =author:"Brown, Tim"
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Title: VizieR Online Data Catalog: HST stellar photometry of Eridanus
II (Simon+, 2021)
Authors: Simon, J. D.; Brown, T. M.; Drlica-Wagner, A.; Li, T. S.;
Avila, R. J.; Bechtol, K.; Clementini, G.; Crnojevic, D.; Garofalo,
A.; Geha, M.; Sand, D. J.; Strader, J.; Willman, B.
2022yCat..19080018S Altcode:
We observed EriII with the Wide Field Channel of the Advanced Camera for
Surveys (ACS) on Hubble Space Telescope (HST) through program GO-14234
(PI:Simon). The observations were scheduled over seven visits between
2016 January 16 and 2016 February 8. We devoted four visits (8 orbits)
to imaging in the F814W filter, totaling 20680s. The remaining three
visits (two visits of two orbits each and one single-orbit visit)
were used to image EriII in the F606W filter, totaling 12830s. <P />(1
data file).
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Title: VizieR Online Data Catalog: AMIGA: The Circumgalactic Medium
of Andromeda (Lehner+, 2020)
Authors: Lehner, N.; Berek, S. C.; Howk, J. C.; Wakker, B. P.;
Tumlinson, J.; Jenkins, E. B.; Prochaska, J. X.; Augustin, R.; Ji,
S.; Faucher-Giguere, C. -A.; Hafen, Z.; Peeples, M. S.; Barger, K. A.;
Berg, M. A.; Bordoloi, R.; Brown, T. M.; Fox, A. J.; Gilbert, K. M.;
Guhathakurta, P.; Kalirai, J. S.; Lockman, F. J.; O'Meara, J. M.;
Pisano, D. J.; Ribaudo, J.; Werk, J. K.
2021yCat..19000009L Altcode:
With Project Absorption Maps In the Gas of Andromeda (AMIGA), we have
surveyed the circumgalactic medium (CGM) of a single galaxy (M31) with
an unprecedented number of background targets (43). The 43 QSOs were
all observed with Hubble Space Telescope/Cosmic Origins Spectrograph
(HST/COS) G130M/G160M or G130M (providing in particular OI, CII, CIV,
SiII, SiIII, and SiIV), and 11 were also observed with Far Ultraviolet
Spectroscopic Explorer (FUSE) (providing OVI). The resolution of the
COS G130M/G160M and the S/Ns have been key for the success of this
program. <P />(6 data files).
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Title: GF-GMD/gmtb-scm: GF-GMD/SCM & forcing data
Authors: Grantfirl; Heinzeller, Dom; DomHeinzeller; Pegion, Phil;
Carson, Laurie; Brown, Timothy; Tanyasmirnova
2021zndo...5292370G Altcode:
GMTB Single Column Model
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Title: Brightness Fluctuation Spectra of Sun-like Stars. I. The
Mid-frequency Continuum
Authors: Brown, Timothy M.; García, Rafael A.; Mathur, Savita;
Metcalfe, Travis S.; Santos, Ângela R. G.
2021ApJ...916...66B Altcode: 2021arXiv210512231B
We analyze space-based time-series photometry of Sun-like stars, mostly
in the Pleiades, but also field stars and the Sun itself. We focus
on timescales between roughly 1 hr and 1 day. In the corresponding
frequency band these stars display brightness fluctuations with a
decreasing power-law continuous spectrum. K2 and Kepler observations
show that the rms flicker due to this mid-frequency continuum (MFC)
can reach almost 1%, approaching the modulation amplitude from active
regions. The MFC amplitude varies by a factor up to 40 among Pleiades
members with similar T<SUB>eff</SUB>, depending mainly on the stellar
Rossby number Ro. For Ro ≤ 0.04, the mean amplitude is roughly
constant at about 0.4%; at larger Ro the amplitude decreases rapidly,
shrinking by about two orders of magnitude for Ro ≃ 1. Among stars,
the MFC amplitude correlates poorly with that of modulation from
rotating active regions. Among field stars observed for 3 yr by Kepler,
the quarterly average modulation amplitudes from active regions are
much more time variable than the quarterly MFC amplitudes. We argue
that the process causing the MFC is largely magnetic in nature and
that its power-law spectrum comes from magnetic processes distinct
from the star's global dynamo, with shorter timescales. By analogy with
solar phenomena, we hypothesize that the MFC arises from a (sometimes
energetic) variant of the solar magnetic network, perhaps combined
with rotation-related changes in the morphology of supergranules.
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Title: TOI-1830 and TOI-1312: Two EBs hosting very low-mass stellar
companions in eccentric orbits
Authors: Rabus, Markus; Carmichael, Theron W.; Shporer, Avi; Johnson,
Marshall; Latham, David W.; Brown, Tim; Gan, Tianjun; Collins, Karen
A.; Barkaoui, Khalid; Bieryla, Allyson; Kielkopf, John F.; Gonzalez,
Erica J.; Addison, Brett C.; Henriksen, Andreea I.; Buchhave, Lars;
Rasmussen, René Tronsgaard; Astudillo-Defru, Nicola; Fulton, Benjamin;
Howell, Steve B.; Ciardi, David; Hellier, Coel; Ghachoui, Mourad;
Timmermans, Mathilde
2021tsc2.confE.179R Altcode:
<strong>We describe in the underlying investigation the
discovery of two eclipsing binary systems. In both cases, the
companions are most likely fully convective low-mass stars. The TESS
team initially alerted the systems as TOI-1830 (TIC20182165, HD133725)
and TOI-1312 (TIC405904232), and we subsequently observed them with
spectroscopy. The TESS light curves and spectroscopic observations were
analyzed in a combined data-driven framework to estimate the systems'
parameters. Radial velocity (RV) measurements with LCO/NRES, NOT/FIES,
SONG, and TRES indicated for the TOI-1830 system a companion mass of
0.11 M⊙ in a 9.781-day eccentric orbit and a 0.10 M⊙ companion in an
11.080-day eccentric orbit for the TOI-1312 system. At the same time,
the spectroscopic observations were used to estimate the spectral
type of the main stars for TOI-1830 and TOI-1312. We measured the
radii ratio from the TESS light curves and estimated the companions'
radii, assuming the main stars' radii as measured from spectroscopy and
isochrones. Given the youth of TOI-1830 and the evolved age of TOI-1312,
both systems will provide valuable insights into the stellar evolution
of close binary systems.</strong>
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Title: LCO Key Project: Standing on the shoulders of the network -
Follow-up of TESS planet candidates with LCO
Authors: Shporer, Avi; Collins, Karen; Johnson, Marshall; Armstrong,
James; Brown, Tim; Conti, Dennis; Fulton, Ben; Gan, Tianjun; Keith,
Horne; Jensen, Eric; Jontof-Hutter, Daniel; Kielkopf, John; Latham,
Dave; Mao, Shude; Massey, Bob; Mazeh, Tsevi; Murgas, Felipe; Narita,
Norio; Palle, Enric; Rabus, Markus; Schwarz, Richard; Sefako,
Ramatholo; Shahaf, Sahar; Siverd, Rob; Srdoc, Gregor; Stockdale, Chris
2021tsc2.confE.136S Altcode:
Accomplishing the exoplanet science enabled by TESS requires follow-up
of many transiting planet candidates throughout the entire sky, to
identify false positives (FPs) and confirm real planets. An efficient
follow-up requires a global facility and a large amount of telescope
time. This Las Cumbres Observatory (LCO) Key Project is designed to do
just that, with about 2,500 hours of telescope time per semester for 6
semesters, 2020B - 2023A. LCO telescopes are fully automated, including
10 x 0.4m, 11 x 1.0m, and 2 x 2.0m telescopes in 7 sites. We are using
all LCO telescopes, equipped with imagers, and we also have time on
the high resolution NRES spectrographs, installed in 4 sites. Imagers
are used to observe the TESS candidates during transit and check if
the transit signal seen in TESS data originates from the target or
from a nearby star blended with the target in the TESS wide pixels and
wide PSF. The NRES spectrographs are used for measuring the stellar
parameters of bright TESS candidate host stars down to 10th magnitude,
identifying obvious FPs (SB1, SB2), and measuring the orbits of massive
planets. This Key Project is part of most TESS planet discoveries. We
present our methodologies and some of our discoveries.
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Title: VizieR Online Data Catalog: Internal kinematics of 9 globular
clusters with HST (Cohen+, 2021)
Authors: Cohen, R. E.; Bellini, A.; Libralato, M.; Correnti, M.;
Brown, T. M.; Kalirai, J. S.
2021yCat..51610041C Altcode:
We have obtained second-epoch photometry of all nine of these clusters,
between 2003 July and 2019 August, with the Advanced Camera for
Surveys/Wide Field Camera (ACS/WFC) onboard Hubble Space Telescope (HST)
in the F606W and F814W filters (GO-15065, PI:Cohen). <P />(1 data file).
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Title: VulcanClimateModeling/fv3gfs-fortran: GMD release
Authors: Heinzeller, Dom; Underwood, Seth; DomHeinzeller; Grantfirl;
Wang, Jun; Liang, Zhi; Menzel-Gfdl; Robinson, Tom; Brown, Timothy;
Bensonr; Hartnett, Ed; JulieSchramm; Uramirez8707; Gbw-Gfdl; Carson,
Laurie; McGibbon, Jeremy; Fuhrer, Oliver; Jess; Clark, Spencer;
Tanyasmirnova; Hallberg, Robert; Ligiabernardet; Potts, Mark; Zadeh,
Niki; Olson, Joseph; Jovic, Dusan; Rheacangeo; Fabienpaulot; Goldy;
Haiqinli
2021zndo...4470023H Altcode:
Code used in preparation of submission of manuscript on fv3gfs-wrapper
to GMD.
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Title: VizieR Online Data Catalog: Optical photometry and RVs of
TOI-481b and TOI-892b (Brahm+, 2020)
Authors: Brahm, R.; Nielsen, L. D.; Wittenmyer, R. A.; Wang, S.;
Rodriguez, J. E.; Espinoza, N.; Jones, M. I.; Jordan, A.; Henning,
T.; Hobson, M.; Kossakowski, D.; Rojas, F.; Sarkis, P.; Schlecker, M.;
Trifonov, T.; Shahaf, S.; Ricker, G.; Vanderspek, R.; Latham, D. W.;
Seager, S.; Winn, J. N.; Jenkins, J. M.; Addison, B. C.; Bakos, G. A.;
Bhatti, W.; Bayliss, D.; Berlind, P.; Bieryla, A.; Bouchy, F.; Bowler,
B. P.; Briceno, C.; Brown, T. M.; Bryant, E. M.; Caldwell, D. A.;
Charbonneau, D.; Collins, K. A.; Davis, A. B.; Esquerdo, G. A.; Fulton,
B. J.; Guerrero, N. M.; Henze, C. E.; Hogan, A.; Horner, J.; Huang,
C. X.; Irwin, J.; Kane, S. R.; Kielkopf, J.; Mann, A. W.; Mazeh, T.;
McCormac, J.; McCully, C.; Mengel, M. W.; Mireles, I.; Okumura, J.;
Plavchan, P.; Quinn, S. N.; Rabus, M.; Saesen, S.; Schlieder, J. E.;
Segransan, D.; Shiao, B.; Shporer, A.; Siverd, R. J.; Stassun, K. G.;
Suc, V.; Tan, T. -G.; Torres, P.; Tinney, C. G.; Udry, S.; Vanzi,
L.; Vezie, M.; Vines, J. I.; Vuckovic, M.; Wright, D. J.; Yahalomi,
D. A.; Zapata, A.; Zhang, H.; Ziegler, C.
2021yCat..51600235B Altcode:
TOI-481 and TOI-892 were monitored by Transiting Exoplanet Survey
Satellite (TESS) during its first year of operation. TOI-481 was
observed in short-cadence (2minutes) mode in Sectors 6, 7, 9, 10,
and 13, and in long-cadence (30minutes) mode in Sector 3. On the
other hand, TOI-892 was only observed in Sector 6, in long-cadence
mode. <P />TOI-481 and TOI-892 were monitored with seven different
spectrographs with the goal of measuring radial velocity variations
to confirm the planetary nature of the transiting candidates
and constrain their orbital parameters and masses. The Fiber-fed
Extended Range Optical Spectrograph (FEROS) has a resolving power of
R=48000 and is installed on the Max Planck Gesellschaft (MPG) 2.2 m
telescope at La Silla Observatory in Chile. The CHIRON instrument is
a high-resolution (R=80000) and fiber-fed spectrograph mounted on the
1.5m Smarts telescope at the Cerro Tololo Inter-American Observatory
(CTIO), Chile. The Tillinghast Reflector Echelle Spectrograph (TRES)
is a R=44000 fiber-fed instrument mounted on the 1.5m Tillinghast
Reflector at the Fred L. Whipple Observatory (FLWO) on Mt. Hopkins,
Arizona. CORALIE is a high-resolution (R=60000) fiber-fed spectrograph
mounted on the 1.2m Swiss Euler telescope at La Silla Observatory,
Chile. Minerva-Australis is an array of four PlaneWave CDK700
telescopes which can be simultaneously fiber-fed to a single KiwiSpec
R4-100 high-resolution (R=80000) spectrograph. TOI-481 was monitored
by Minerva-Australis using one and/or two telescopes in the array
Minerva3 and Minerva4. Las Cumbres Observatory's Network of Robotic
Echelle Spectrographs (NRES) is a global array of echelle spectrographs
mounted on 1 m telescopes, with a resolving power of R~53000. <P />(2
data files).
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Title: TOI-481 b and TOI-892 b: Two Long-period Hot Jupiters from
the Transiting Exoplanet Survey Satellite
Authors: Brahm, Rafael; Nielsen, Louise D.; Wittenmyer, Robert A.;
Wang, Songhu; Rodriguez, Joseph E.; Espinoza, Néstor; Jones, Matías
I.; Jordán, Andrés; Henning, Thomas; Hobson, Melissa; Kossakowski,
Diana; Rojas, Felipe; Sarkis, Paula; Schlecker, Martin; Trifonov,
Trifon; Shahaf, Sahar; Ricker, George; Vanderspek, Roland; Latham,
David W.; Seager, Sara; Winn, Joshua N.; Jenkins, Jon M.; Addison,
Brett C.; Bakos, Gáspár Á.; Bhatti, Waqas; Bayliss, Daniel;
Berlind, Perry; Bieryla, Allyson; Bouchy, Francois; Bowler, Brendan
P.; Briceño, César; Brown, Timothy M.; Bryant, Edward M.; Caldwell,
Douglas A.; Charbonneau, David; Collins, Karen A.; Davis, Allen B.;
Esquerdo, Gilbert A.; Fulton, Benjamin J.; Guerrero, Natalia M.; Henze,
Christopher E.; Hogan, Aleisha; Horner, Jonathan; Huang, Chelsea X.;
Irwin, Jonathan; Kane, Stephen R.; Kielkopf, John; Mann, Andrew W.;
Mazeh, Tsevi; McCormac, James; McCully, Curtis; Mengel, Matthew W.;
Mireles, Ismael; Okumura, Jack; Plavchan, Peter; Quinn, Samuel N.;
Rabus, Markus; Saesen, Sophie; Schlieder, Joshua E.; Segransan, Damien;
Shiao, Bernie; Shporer, Avi; Siverd, Robert J.; Stassun, Keivan G.;
Suc, Vincent; Tan, Thiam-Guan; Torres, Pascal; Tinney, Chris G.; Udry,
Stephane; Vanzi, Leonardo; Vezie, Michael; Vines, Jose I.; Vuckovic,
Maja; Wright, Duncan J.; Yahalomi, Daniel A.; Zapata, Abner; Zhang,
Hui; Ziegler, Carl
2020AJ....160..235B Altcode: 2020arXiv200908881B
We present the discovery of two new 10 day period giant planets from
the Transiting Exoplanet Survey Satellite mission, whose masses
were precisely determined using a wide diversity of ground-based
facilities. TOI-481 b and TOI-892 b have similar radii (0.99 ± 0.01
${R}_{{\rm{J}}}$ and 1.07 ± 0.02 ${R}_{{\rm{J}}}$ , respectively),
and orbital periods (10.3311 days and 10.6266 days, respectively),
but significantly different masses (1.53 ± 0.03 ${M}_{{\rm{J}}}$
versus 0.95 ± 0.07 ${M}_{{\rm{J}}}$ , respectively). Both planets
orbit metal-rich stars ( $[\mathrm{Fe}/{\rm{H}}]$ = $+0.26\pm 0.05$
dex and $[\mathrm{Fe}/{\rm{H}}]$ = $+0.24\pm 0.05$ for TOI-481 and
TOI-892, respectively) but at different evolutionary stages. TOI-481
is a ${M}_{\star }$ = 1.14 ± 0.02 ${M}_{\odot }$ , ${R}_{\star }$
= 1.66 ± 0.02 ${R}_{\odot }$ G-type star ( ${T}_{\mathrm{eff}}$
= $5735\pm 72$ K), that with an age of 6.7 Gyr, is in the turn-off
point of the main sequence. TOI-892 on the other hand, is a F-type
dwarf star ( ${T}_{\mathrm{eff}}$ = $6261\pm 80$ K), which has a
mass of ${M}_{\star }$ = 1.28 ± 0.03 ${M}_{\odot }$ and a radius of
${R}_{\star }$ = 1.39 ± 0.02 ${R}_{\odot }$ . TOI-481 b and TOI-892
b join the scarcely populated region of transiting gas giants with
orbital periods longer than 10 days, which is important to constrain
theories of the formation and structure of hot Jupiters.
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Title: Very regular high-frequency pulsation modes in young
intermediate-mass stars
Authors: Bedding, Timothy R.; Murphy, Simon J.; Hey, Daniel R.; Huber,
Daniel; Li, Tanda; Smalley, Barry; Stello, Dennis; White, Timothy R.;
Ball, Warrick H.; Chaplin, William J.; Colman, Isabel L.; Fuller,
Jim; Gaidos, Eric; Harbeck, Daniel R.; Hermes, J. J.; Holdsworth,
Daniel L.; Li, Gang; Li, Yaguang; Mann, Andrew W.; Reese, Daniel R.;
Sekaran, Sanjay; Yu, Jie; Antoci, Victoria; Bergmann, Christoph;
Brown, Timothy M.; Howard, Andrew W.; Ireland, Michael J.; Isaacson,
Howard; Jenkins, Jon M.; Kjeldsen, Hans; McCully, Curtis; Rabus,
Markus; Rains, Adam D.; Ricker, George R.; Tinney, Christopher G.;
Vanderspek, Roland K.
2020Natur.581..147B Altcode: 2020arXiv200506157B
Asteroseismology probes the internal structures of stars by using
their natural pulsation frequencies<SUP>1</SUP>. It relies on
identifying sequences of pulsation modes that can be compared with
theoretical models, which has been done successfully for many classes
of pulsators, including low-mass solar-type stars<SUP>2</SUP>,
red giants<SUP>3</SUP>, high-mass stars<SUP>4</SUP> and white
dwarfs<SUP>5</SUP>. However, a large group of pulsating stars of
intermediate mass—the so-called δ Scuti stars—have rich pulsation
spectra for which systematic mode identification has not hitherto been
possible<SUP>6,7</SUP>. This arises because only a seemingly random
subset of possible modes are excited and because rapid rotation tends
to spoil regular patterns<SUP>8-10</SUP>. Here we report the detection
of remarkably regular sequences of high-frequency pulsation modes in
60 intermediate-mass main-sequence stars, which enables definitive mode
identification. The space motions of some of these stars indicate that
they are members of known associations of young stars, as confirmed
by modelling of their pulsation spectra.
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Title: A new absorption component in the H-alpha line profile of
eta Carinae
Authors: Damineli, Augusto; Navarete, Felipe; Heathcote, Bernard;
Di Scala, Giorgio; Harrison, Ken; Di Scala, Giorigo; Johnston,
Mark; McGee, Padric; Cacella, Paulo; Bohlsen, Terry; Rabus, Markus;
Brown, Tim
2020ATel13639....1D Altcode:
Based on a high signal-to-noise and high plus intermediate resolution
(R=100,000 and R > 6,000) ground-based monitoring of eta Carinae
periastron (ATEL #13508, ATEL #13600), we report the following results:
The narrow absorption at -138 km/s (FWHM=25 km/s), believed to be
formed in the Little Homunculus, reached zero intensity already during
the past orbital cycle.
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Title: Ground-based spectroscopic monitoring of the 2020 periastron
in eta Carinae
Authors: Navarete, Felipe; Damineli, Augusto; Richardson, Noel;
Ibrahim, Nour; Heathcote, Bernard; Di Scala, Giorgio; Harrison,
Ken; Di Scala, Lidia; Johnston, Mark; McGee, Padric; Cacella, Paulo;
Bohlsen, Terry; Rabus, Markus; Brown, Tim
2020ATel13600....1N Altcode:
Based on a high signal-to-noise and high plus intermediate
resolution (R=100,000 and R > 6,000) ground-based monitoring of
eta Carinae periastron (ATEL #13508), we report the following results:
Representative lines of the extended primary's photosphere, (H- &
delta; and SiII & lambda;6347A) indicate no significant changes
as compared to the 2014.5 (Teodoro et al. 2016, ApJ 819, 131).
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Title: The Hubble Space Telescope UV Legacy Survey of Galactic
Globular Clusters. XX. Ages of Single and Multiple Stellar Populations
in Seven Bulge Globular Clusters
Authors: Oliveira, R. A. P.; Souza, S. O.; Kerber, L. O.; Barbuy,
B.; Ortolani, S.; Piotto, G.; Nardiello, D.; Pérez-Villegas, A.;
Maia, F. F. S.; Bica, E.; Cassisi, S.; D'Antona, F.; Lagioia, E. P.;
Libralato, M.; Milone, A. P.; Anderson, J.; Aparicio, A.; Bedin,
L. R.; Brown, T. M.; King, I. R.; Marino, A. F.; Pietrinferni, A.;
Renzini, A.; Sarajedini, A.; van der Marel, R.; Vesperini, E.
2020ApJ...891...37O Altcode: 2020arXiv200108611O
In the present work we analyzed seven globular clusters (GCs) selected
from their location in the Galactic bulge and with metallicity values
in the range -1.30 ≲ [Fe/H] ≲ -0.50. The aim of this work is first
to derive cluster ages assuming single stellar populations and second
to identify the stars from first (1G) and second generations (2G) from
the main sequence, subgiant, and red giant branches, and to derive their
age differences. Based on a combination of UV and optical filters used
in this project, we apply the Gaussian mixture models to distinguish
the multiple stellar populations. Applying statistical isochrone
fitting, we derive self-consistent ages, distances, metallicities,
and reddening values for the sample clusters. An average age of 12.3
± 0.4 Gyr was obtained both using DSED and BaSTI (accounting atomic
diffusion effects) isochrones, without a clear distinction between the
moderately metal-poor and the more metal-rich bulge clusters, except
for NGC 6717 and the inner halo NGC 6362 with ∼13.5 Gyr. We derived
a weighted mean age difference between the multiple populations hosted
by each GC of 41 ± 170 Myr adopting canonical He abundances; whereas
for higher He in 2G stars, this difference reduces to 17 ± 170 Myr,
but with individual uncertainties of 500 Myr.
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Title: Erratum: DQWD
Authors: Milone, A. P.; Vesperini, E.; Marino, A. F.; Hong, J.; van
der Marel, R.; Anderson, J.; Renzini, A.; Cordoni, G.; Bedin, L. R.;
Bellini, A.; Brown, T. M.; Antona, F. D.; Lagioia, E. P.; Libralato,
M.; Nardiello, D.; Piotto, G.; Tailo, M.; Cool, A.; Salaris, M.;
Sarajedini, A.
2020MNRAS.492.4589M Altcode: 2020MNRAS.tmp..150M
No abstract at ADS
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Title: The Hubble Space Telescope UV Legacy Survey of Galactic
globular clusters - XXI. Binaries among multiple stellar populations
Authors: Milone, A. P.; Vesperini, E.; Marino, A. F.; Hong, J.; van
der Marel, R.; Anderson, J.; Renzini, A.; Cordoni, G.; Bedin, L. R.;
Bellini, A.; Brown, T. M.; D'Antona, F.; Lagioia, E. P.; Libralato,
M.; Nardiello, D.; Piotto, G.; Tailo, M.; Cool, A.; Salaris, M.;
Sarajedini, A.
2020MNRAS.492.5457M Altcode: 2019MNRAS.tmp.3249M; 2020arXiv200206479M; 2019MNRAS.tmp..199M
A number of scenarios for the formation of multiple populations in
globular clusters (GCs) predict that second generation (2G) stars
form in a compact and dense subsystem embedded in a more extended
first-generation (1G) system. If these scenarios are accurate,
a consequence of the denser 2G formation environment is that 2G
binaries should be more significantly affected by stellar interactions
and disrupted at a larger rate than 1G binaries. The fractions and
properties of binary stars can thus provide a dynamical fingerprint
of the formation epoch of multiple-population GCs and their subsequent
dynamical evolution. We investigate the connection between binaries and
multiple populations in five GCs, NGC 288, NGC 6121 (M 4), NGC 6352,
NGC 6362, and NGC 6838 (M 71). To do this, we introduce a new method
based on the comparison of Hubble Space Telescope observations of
binaries in the F275W, F336W, F438W, F606W, and F814W filters with a
large number of simulated binaries. In the inner regions probed by our
data, we do not find large differences between the local 1G and the 2G
binary incidences in four of the studied clusters, the only exception
being M 4 where the 1G binary incidence is about three times larger
than the 2G incidence. The results found are in general agreement with
the results of simulations predicting significant differences in the
global 1G and 2G incidences and in the local values in the clusters'
outer regions but similar incidences in the inner regions. The
significant difference found in M 4 is consistent with simulations
with a larger fraction of wider binaries. Our analysis also provides
the first evidence of mixed (1G-2G) binaries, a population predicted
by numerical simulations to form in a cluster's inner regions as a
result of stellar encounters during which one component of a binary
is replaced by a star of a different population.
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Title: The 2020 periastron passage of eta Carine seen in He I and
He II lines
Authors: Navarete, Felipe; Damineli, Augusto; Jablonski, Francisco;
Brown, Tim; Rabus, Markus
2020ATel13508....1N Altcode:
In the framework of a monitoring campaign of the low excitation event
(Damineli et a. 1998, A & A Supp. 133, 299) in eta Carinae, we
report results on the periastron passage expected to occur on 2020
February 17 (Teodoro et al. 2016, ApJ 819:131).
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Title: TESS Spots a Compact System of Super-Earths around the
Naked-eye Star HR 858
Authors: Vanderburg, Andrew; Huang, Chelsea X.; Rodriguez, Joseph E.;
Becker, Juliette C.; Ricker, George R.; Vanderspek, Roland K.; Latham,
David W.; Seager, Sara; Winn, Joshua N.; Jenkins, Jon M.; Addison,
Brett; Bieryla, Allyson; Briceño, Cesar; Bowler, Brendan P.; Brown,
Timothy M.; Burke, Christopher J.; Burt, Jennifer A.; Caldwell,
Douglas A.; Clark, Jake T.; Crossfield, Ian; Dittmann, Jason A.;
Dynes, Scott; Fulton, Benjamin J.; Guerrero, Natalia; Harbeck, Daniel;
Horner, Jonathan; Kane, Stephen R.; Kielkopf, John; Kraus, Adam L.;
Kreidberg, Laura; Law, Nicolas; Mann, Andrew W.; Mengel, Matthew W.;
Morton, Timothy D.; Okumura, Jack; Pearce, Logan A.; Plavchan, Peter;
Quinn, Samuel N.; Rabus, Markus; Rose, Mark E.; Rowden, Pam; Shporer,
Avi; Siverd, Robert J.; Smith, Jeffrey C.; Stassun, Keivan; Tinney,
C. G.; Wittenmyer, Rob; Wright, Duncan J.; Zhang, Hui; Zhou, George;
Ziegler, Carl A.
2019ApJ...881L..19V Altcode: 2019arXiv190505193V
Transiting Exoplanet Survey Satellite (TESS) observations have revealed
a compact multiplanet system around the sixth-magnitude star HR 858
(TIC 178155732, TOI 396), located 32 pc away. Three planets, each about
twice the size of Earth, transit this slightly evolved, late F-type
star, which is also a member of a visual binary. Two of the planets
may be in mean motion resonance. We analyze the TESS observations,
using novel methods to model and remove instrumental systematic errors,
and combine these data with follow-up observations taken from a suite
of ground-based telescopes to characterize the planetary system. The
HR 858 planets are enticing targets for precise radial velocity
observations, secondary eclipse spectroscopy, and measurements of the
Rossiter-McLaughlin effect.
---------------------------------------------------------
Title: Do Sun-like stars experience a magnetic mid-life
crisis? Investigation from a new Ca HK activity survey using LCO NRES
Authors: Goga, Adam; Metcalfe, Travis S.; Egeland, Ricky; Brown,
Timothy M.
2019shin.confE.111G Altcode:
The dynamo effect, which modulates the magnetic field of stars,
is a topic of active research. While there are many dynamo models,
most only work for a small subgroup of stars and may be specifically
designed for the Sun. We have monitored the S-Index, a magnetic proxy,
for a sample of bright stars with known rotation rates (Prot <
22 days), to discover short magnetic activity cycles (Pcyc < 5
years) that are precursors of the 11-year solar cycle. This study adds
additional constraints to current and future dynamo models by producing
data for stars whose cycles are unknown. Las Cumbres Observatory's
Network of Robotic Echelle Spectrographs (NRES) has a large archive
of data for many stars. NRES is a global telescope system with six
sites whose main purpose is to study exoplanets. We have developed an
automated pipeline in Python to pull the intensity of the Ca II H and
K emission features from the NRES spectra which are used to find the
S-Index. With our pipeline, we have seen evidence of magnetic cycles
in stars whose activity is known through previous studies. Our study
demonstrates that the NRES system is sensitive enough to discover
magnetic activity in stars. We can now probe these stars deeper for
unknown underlying activity which may help understand their dynamo
process. The pipeline is highly extendable and allows users to add
features to find additional information from NRES data.
---------------------------------------------------------
Title: Star cluster catalogues for the LEGUS dwarf galaxies
Authors: Cook, D. O.; Lee, J. C.; Adamo, A.; Kim, H.; Chandar, R.;
Whitmore, B. C.; Mok, A.; Ryon, J. E.; Dale, D. A.; Calzetti, D.;
Andrews, J. E.; Aloisi, A.; Ashworth, G.; Bright, S. N.; Brown, T. M.;
Christian, C.; Cignoni, M.; Clayton, G. C.; da Silva, R.; de Mink,
S. E.; Dobbs, C. L.; Elmegreen, B. G.; Elmegreen, D. M.; Evans, A. S.;
Fumagalli, M.; Gallagher, J. S.; Gouliermis, D. A.; Grasha, K.; Grebel,
E. K.; Herrero, A.; Hunter, D. A.; Jensen, E. I.; Johnson, K. E.;
Kahre, L.; Kennicutt, R. C.; Krumholz, M. R.; Lee, N. J.; Lennon, D.;
Linden, S.; Martin, C.; Messa, M.; Nair, P.; Nota, A.; Östlin, G.;
Parziale, R. C.; Pellerin, A.; Regan, M. W.; Sabbi, E.; Sacchi, E.;
Schaerer, D.; Schiminovich, D.; Shabani, F.; Slane, F. A.; Small, J.;
Smith, C. L.; Smith, L. J.; Taibi, S.; Thilker, D. A.; de la Torre,
I. C.; Tosi, M.; Turner, J. A.; Ubeda, L.; Van Dyk, S. D.; Walterbos,
R. AM; Wofford, A.
2019MNRAS.484.4897C Altcode: 2019arXiv190200082C; 2019MNRAS.tmp..337C
We present the star cluster catalogues for 17 dwarf and irregular
galaxies in the HST Treasury Program `Legacy ExtraGalactic UV Survey'
(LEGUS). Cluster identification and photometry in this sub-sample are
similar to that of the entire LEGUS sample, but special methods were
developed to provide robust catalogues with accurate fluxes due to low
cluster statistics. The colours and ages are largely consistent for
two widely used aperture corrections, but a significant fraction of the
clusters are more compact than the average training cluster. However,
the ensemble luminosity, mass, and age distributions are consistent
suggesting that the systematics between the two methods are less than
the random errors. When compared with the clusters from previous dwarf
galaxy samples, we find that the LEGUS catalogues are more complete
and provide more accurate total fluxes. Combining all clusters
into a composite dwarf galaxy, we find that the luminosity and mass
functions can be described by a power law with the canonical index
of -2 independent of age and global SFR binning. The age distribution
declines as a power law, with an index of ≈- 0.80 ± 0.15, independent
of cluster mass and global SFR binning. This decline of clusters is
dominated by cluster disruption since the combined star formation
histories and integrated-light SFRs are both approximately constant
over the last few hundred Myr. Finally, we find little evidence for an
upper-mass cut-off (<2σ) in the composite cluster mass function, and
can rule out a truncation mass below ≈10<SUP>4.5</SUP>M<SUB>⊙</SUB>
but cannot rule out the existence of a truncation at higher masses.
---------------------------------------------------------
Title: TESS Delivers Its First Earth-sized Planet and a Warm
Sub-Neptune
Authors: Dragomir, Diana; Teske, Johanna; Günther, Maximilian N.;
Ségransan, Damien; Burt, Jennifer A.; Huang, Chelsea X.; Vanderburg,
Andrew; Matthews, Elisabeth; Dumusque, Xavier; Stassun, Keivan G.;
Pepper, Joshua; Ricker, George R.; Vanderspek, Roland; Latham, David
W.; Seager, Sara; Winn, Joshua N.; Jenkins, Jon M.; Beatty, Thomas;
Bouchy, François; Brown, Timothy M.; Butler, R. Paul; Ciardi, David
R.; Crane, Jeffrey D.; Eastman, Jason D.; Fossati, Luca; Francis, Jim;
Fulton, Benjamin J.; Gaudi, B. Scott; Goeke, Robert F.; James, David;
Klaus, Todd C.; Kuhn, Rudolf B.; Lovis, Christophe; Lund, Michael
B.; McDermott, Scott; Paegert, Martin; Pepe, Francesco; Rodriguez,
Joseph E.; Sha, Lizhou; Shectman, Stephen A.; Shporer, Avi; Siverd,
Robert J.; Garcia Soto, Aylin; Stevens, Daniel J.; Twicken, Joseph D.;
Udry, Stéphane; Villanueva, Steven, Jr.; Wang, Sharon X.; Wohler,
Bill; Yao, Xinyu; Zhan, Zhuchang
2019ApJ...875L...7D Altcode: 2019arXiv190100051D
The future of exoplanet science is bright, as Transiting Exoplanet
Survey Satellite (TESS) once again demonstrates with the discovery
of its longest-period confirmed planet to date. We hereby present
HD 21749b (TOI 186.01), a sub-Neptune in a 36 day orbit around a
bright (V = 8.1) nearby (16 pc) K4.5 dwarf. TESS measures HD 21749b
to be {2.61}<SUB>-0.16</SUB><SUP>+0.17</SUP> R <SUB>⊕</SUB>,
and combined archival and follow-up precision radial velocity data
put the mass of the planet at {22.7}<SUB>-1.9</SUB><SUP>+2.2</SUP>
M <SUB>⊕</SUB>. HD 21749b contributes to the TESS Level 1 Science
Requirement of providing 50 transiting planets smaller than 4
R <SUB>⊕</SUB> with measured masses. Furthermore, we report
the discovery of HD 21749c (TOI 186.02), the first Earth-sized
({R}<SUB>p</SUB>={0.892}<SUB>-0.058</SUB><SUP>+0.064</SUP>{R}<SUB>\oplus
</SUB>) planet from TESS. The HD 21749 system is a prime target
for comparative studies of planetary composition and architecture in
multi-planet systems. <P />This Letter includes data gathered with the
6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile.
---------------------------------------------------------
Title: HD 202772A b: A Transiting Hot Jupiter around a Bright,
Mildly Evolved Star in a Visual Binary Discovered by TESS
Authors: Wang, Songhu; Jones, Matias; Shporer, Avi; Fulton,
Benjamin J.; Paredes, Leonardo A.; Trifonov, Trifon; Kossakowski,
Diana; Eastman, Jason; Redfield, Seth; Günther, Maximilian N.;
Kreidberg, Laura; Huang, Chelsea X.; Millholland, Sarah; Seligman,
Darryl; Fischer, Debra; Brahm, Rafael; Wang, Xian-Yu; Cruz, Bryndis;
Henry, Todd; James, Hodari-Sadiki; Addison, Brett; Liang, En-Si;
Davis, Allen B.; Tronsgaard, René; Worku, Keduse; Brewer, John M.;
Kürster, Martin; Zhang, Hui; Beichman, Charles A.; Bieryla, Allyson;
Brown, Timothy M.; Christiansen, Jessie L.; Ciardi, David R.; Collins,
Karen A.; Esquerdo, Gilbert A.; Howard, Andrew W.; Isaacson, Howard;
Latham, David W.; Mazeh, Tsevi; Petigura, Erik A.; Quinn, Samuel N.;
Shahaf, Sahar; Siverd, Robert J.; Rodler, Florian; Reffert, Sabine;
Zakhozhay, Olga; Ricker, George R.; Vanderspek, Roland; Seager, Sara;
Winn, Joshua N.; Jenkins, Jon M.; Boyd, Patricia T.; Fűrész, Gábor;
Henze, Christopher; Levine, Alen M.; Morris, Robert; Paegert, Martin;
Stassun, Keivan G.; Ting, Eric B.; Vezie, Michael; Laughlin, Gregory
2019AJ....157...51W Altcode: 2018arXiv181002341W
We report the first confirmation of a hot Jupiter discovered by the
Transiting Exoplanet Survey Satellite (TESS) mission: HD 202772A
b. The transit signal was detected in the data from TESS Sector 1,
and was confirmed to be of planetary origin through radial velocity
(RV) measurements. HD 202772A b is orbiting a mildly evolved star with
a period of 3.3 days. With an apparent magnitude of V = 8.3, the star is
among the brightest and most massive known to host a hot Jupiter. Based
on the 27 days of TESS photometry and RV data from the CHIRON, HARPS,
and Tillinghast Reflector Echelle Spectrograph, the planet has a mass
of {1.017}<SUB>-0.068</SUB><SUP>+0.070</SUP> {M}<SUB>{{J</SUB>}} and
radius of {1.545}<SUB>-0.060</SUB><SUP>+0.052</SUP> {R}<SUB>{{J</SUB>}},
making it an inflated gas giant. HD 202772A b is a rare example of a
transiting hot Jupiter around a quickly evolving star. It is also one
of the most strongly irradiated hot Jupiters currently known.
---------------------------------------------------------
Title: The Las Cumbres Observatory's Network of Robotic Echelle
Spectrographs in 2019: Current status and next steps
Authors: Harbeck, Daniel R.; Brown, Tim; Siverd, Robert; McCully,
Curtis; Foale, Steve; Nation, Jon; Henderson, Todd; Taylor, Brook;
de Vera, Jon; Smith, Cary; Kirby, Annie
2019AAS...23314603H Altcode:
Over the last two years, the Las Cumbres Observatory (LCOGT) has
deployed the Network of Robotic Echelle Spectrographs (NRES), which
consists of optical high-precision spectrographs that are fed by 1-meter
telescopes at four sites: In Chile (CTIO), USA (McDonald Observatory),
South Africa (SAAO), and Israel (Wise Observatory). These spectrographs
are identically designed and built, and they cover a wavelength range
from 390nm to 860nm at a resolution of ~45000. After ~1.5 years of
installation and commissioning efforts, fully robotic science operations
are now regularly underway with the NRES system. Although significant
telescope time is currently assigned in support of NASA's TESS mission,
NRES is a valuable resource for the entire astronomical community
via open access through the NSF / NOAO. In this report we describe
the current performance of the spectrographs for both radial velocity
measurement and stellar classification and also discuss opportunities
and plans for further improvement.
---------------------------------------------------------
Title: Developing the infrastructure of bright-star exoplanet hunting:
the Kilodegree Extremely Little Telescope (KELT) and the Network of
Robotic Echelle Spectrographs (NRES)
Authors: Siverd, Robert; Stassun, Keivan G.; Lund, Michael B.; Stevens,
Daniel J.; Brown, Tim; Harbeck, Daniel R.
2019AAS...23342202S Altcode:
The Kilodegree Extremely Little Telescope (KELT) is an ongoing,
wide-field (26x26 deg) photometric survey for transiting exoplanets
using small-aperture telescopes in Arizona, USA and Sutherland, SA
to monitor ~70% of the sky at ~30-minute cadence. KELT was built to
find high-value transiting exoplanets around bright host stars. Using
off-the-shelf hardware, the KELT telescopes achieve better-than-1%
precision for 7.5 Reaching the needed photometric precision is
complicated by source blending (23"/pix) and PSF variability. Careful
use of existing and modified difference imaging tools brought success
but with significant compromises. Our new Catalog-Driven Extraction
(CDE) is a set of key changes to both our reduction pipelines and data
handling that markedly improve photometric accuracy and simplify the
candidate identification process. Further, CDE-generated light curves
are suited to a wider range of science tasks and will become a valuable
community resource. Confirming a transiting exoplanet involves other
hurdles beyond photometry. Chief among these is obtaining a radial
velocity (RV) orbit. The scarcity of spectroscopic resources is a
genuine bottleneck for exoplanet confirmation. To fill this void,
Las Cumbres Observatory (LCO) has designed, built, and deployed the
Network of Robotic Echelle Spectrographs (NRES) to its worldwide
network of robotic 1-meter telescopes. NRES consists of four,
optical, fiber-fed, R~45000 spectrographs designed for RV and stellar
classification. Now operational, NRES is poised to become an important
resource for exoplanet discovery and stellar astrophysics. The KELT and
NRES presented very different development challenges despite related
science goals. In this report I discuss the significant and different
infrastructural challenges involved in these two projects and share
important lessons learned. Finally, I discuss some of the exciting
prospects for future work in bright-star time-domain science.
---------------------------------------------------------
Title: The Hubble Space Telescope UV legacy survey of galactic
globular clusters - XVI. The helium abundance of multiple populations
Authors: Milone, A. P.; Marino, A. F.; Renzini, A.; D'Antona, F.;
Anderson, J.; Barbuy, B.; Bedin, L. R.; Bellini, A.; Brown, T. M.;
Cassisi, S.; Cordoni, G.; Lagioia, E. P.; Nardiello, D.; Ortolani,
S.; Piotto, G.; Sarajedini, A.; Tailo, M.; van der Marel, R. P.;
Vesperini, E.
2018MNRAS.481.5098M Altcode: 2018MNRAS.tmp.2453M; 2018arXiv180905006M
Recent work, based on data from the Hubble Space Telescope (HST )
UV Legacy Survey of Galactic Globular Clusters (GCs), has revealed
that all the analysed clusters host two groups of first- (1G) and
second-generation (2G) stars. In most GCs, both 1G and 2G stars
host substellar populations with different chemical composition. We
compare multiwavelength HST photometry with synthetic spectra to
determine for the first time the average helium difference between
the 2G and 1G stars in a large sample of 57 GCs and the maximum helium
variation within each of them. We find that in all clusters 2G stars
are consistent with being enhanced in helium with respect to 1G. The
maximum helium variation ranges from less than 0.01 to more than 0.10
in helium mass fraction and correlates with both the cluster mass and
the colour extension of the horizontal branch (HB). These findings
demonstrate that the internal helium variation is one of the main
(second) parameters governing the HB morphology.
---------------------------------------------------------
Title: VizieR Online Data Catalog: LEGUS galaxies1 observations
(Sabbi+, 2018)
Authors: Sabbi, E.; Calzetti, D.; Ubeda, L.; Adamo, A.; Cignoni,
M.; Thilker, D.; Aloisi, A.; Elmegreen, B. G.; Elmegreen, D. M.;
Gouliermis, D. A.; Grebel, E. K.; Messa, M.; Smith, L. J.; Tosi, M.;
Dolphin, A.; Andrews, J. E.; Ashworth, G.; Bright, S. N.; Brown, T. M.;
Chandar, R.; Christian, C.; Clayton, G. C.; Cook, D. O.; Dale, D. A.;
de Mink, S. E.; Dobbs, C.; Evans, A. S.; Fumagalli, M.; Gallagher,
J. S.; Grasha, K.; Herrero, A.; Hunter, D. A.; Johnson, K. E.; Kahre,
L.; Kennicutt, R. C.; Kim, H.; Krumholz, M. R.; Lee, J. C.; Lennon, D.;
Martin, C.; Nair, P.; Nota, A.; Ostlin, G.; Pellerin, A.; Prieto, J.;
Regan, M. W.; Ryon, J. E.; Sacchi, E.; Schaerer, D.; Schiminovich,
D.; Shabani, F.; van Dyk, S. D.; Walterbos, R.; Whitmore, B. C.;
Wofford, A.
2018yCat..22350023S Altcode:
The Legacy ExtraGalactic UV Survey (LEGUS) is a multiwavelength Cycle 21
Treasury program on the Hubble Space Telescope (HST). LEGUS was awarded
154 orbits in Cycle 21 to observe 50 star-forming galaxies with the
UVIS channel of the Wide Field Camera 3 (WFC3) in the filters F275W,
F336W, and when not already available in the Mikulski Archive for
the Space Telescope (MAST) archive, also in the filters F438W, F555W,
and F814W. For simplicity, from now on, in the text we will refer to
these filters as NUV, U, B, V, and I, respectively. <P />To increase
the legacy value of the project, ACS archival data in the filters B,
V, and/or I have been aligned to the LEGUS data. <P />See the log
of the observations in Table 1 (spanning November 2002 to September
2014). <P />(4 data files).
---------------------------------------------------------
Title: UV and Optical Variability of the Young Star T Cha Produced
by Inner Disk Obscuration
Authors: Brown, Alexander; France, Kevin; Walter, Frederick; Schneider,
Christian P.; Brown, Timothy; Andrews, Sean; Wilner, David
2018csss.confE..28B Altcode:
The young (7 Myr) 1.5 M⊙ T Tauri star T Cha shows dramatic
variability. The optical extinction varies by at least 3 magnitudes on
few hour time-scales. The obscuration is produced by material at the
inner edge of the circumstellar disk and therefore characterizing
the absorbing material can reveal important clues regarding the
transport of gas and dust within such disks. The inner disk of T Cha is
particularly interesting, because T Cha has a transitional disk with a
large gap at 0.2- 15 AU in the dust disk and allows study of the gas
and dust structure in the terrestrial planet formation zone during
this important rapid phase of protoplanetary disk evolution. For this
reason we have conducted a comprehensive, multi-spectral- region,
observing campaign to study the UV/X-ray/optical variability of T
Cha. During 2018 February/March we monitored the optical photometric
and spectral variability using LCOGT and the SMARTS telescopes. These
optical data provide a broad context within which to interpret
our shorter UV and X-ray observations. We observed T Cha during 3
coordinated observations (each 5 HST orbits + 25 ksec XMM; on 2018
Feb 22, Feb 26, Mar 2) using HST COS/STIS to measure the UV-optical
spectra and XMM-Newton to measure the X-ray energy distribution. The
observed spectral changes are well correlated and demonstrate the
influence of the same absorbing material in the different spectral
regions. In this poster we examine which spectral features in the
different spectral regions (FUV/NUV/optical/X-ray) change and by how
much, and thereby determine the location of different emitting regions
within the complex stellar/inner disk system relative to the absorbers
along the line-of-sight to the stellar photosphere. Understanding these
contributions is vital for estimating the properties of the absorbing
gas and dust. (This work is supported by grant HST-GO-15128 and time
awarded by HST, XMM-Newton, LCOGT, and SMARTS.)
---------------------------------------------------------
Title: NRES: the network of robotic echelle spectrographs
Authors: Siverd, Robert J.; Brown, Timothy M.; Barnes, Stuart; Bowman,
Mark K.; De Vera, Jon; Foale, Stephen; Harbeck, Daniel-Rolf; Henderson,
Todd; Hygelund, John; Kirby, Annie; McCully, Curtis; Nation, Jon S.;
Smith, Cary; Taylor, Brook; Tufts, Joseph R.
2018SPIE10702E..6CS Altcode:
Las Cumbres Observatory Global Telescope Network (LCOGT) has built
the Network of Robotic Echelle Spectrographs (NRES), consisting of
four identical, high-resolution optical spectrographs, each fiber-fed
simultaneously by up to two 1-meter telescopes and a calibration
source. Two units have been installed and are currently executing
scientific observations. A third unit has been installed and is
presently in commissioning. A fourth unit has been shipped to site and
will be installed in mid 2018. Operating on four separate continents
in both the Northern and Southern hemispheres, these instruments
comprise a globally-distributed, autonomous spectrograph facility
for stellar classification and high-precision radial velocity of
bright stars. Simulations suggest we will achieve long-term radial
velocity precision of 3 m/s in less than an hour for stars with V <
12. Radial velocity precision of 75 m/s has already been demonstrated
with our automatic data-processing pipeline across multiple sites. Work
is ongoing to improve several NRES system components including
telescope control (robotic source acquisition in particular) and the
data-processing pipeline. In this document we briefly overview the NRES
design, its purpose and goals, results achieved to date in the field,
and the ongoing development effort to improve instrument performance.
---------------------------------------------------------
Title: UV, X-ray, and Optical Variability of the Young Star T Cha
Produced by Inner Disk Obscuration: Results from a Coordinated HST,
XMM-Newton, LCOGT, and SMARTS Observing Campaign
Authors: Brown, Alexander; France, Kevin; Walter, Frederick M.;
Schneider, P. Christian; Brown, Timothy M.; Andrews, Sean M.; Wilner,
David J.
2018AAS...23221909B Altcode:
The young (7 Myr) 1.5 solar mass T Tauri star T Chamaeleontis shows
dramatic variability. The optical extinction varies by at least 3
magnitudes on few hour time-scales with no obvious periodicity. The
obscuration is produced by material at the inner edge of the
circumstellar disk and therefore characterizing the absorbing material
can reveal important clues regarding the transport of gas and dust
within such disks. The inner disk of T Cha is particularly interesting,
because T Cha has a transitional disk with a large gap at 0.2-15 AU
in the dust disk and allows study of the gas and dust structure in the
terrestrial planet formation zone during this important rapid phase of
protoplanetary disk evolution. For this reason we have conducted a major
multi-spectral-region observing campaign to study the UV/X-ray/optical
variability of T Cha. During 2018 February/March we monitored the
optical photometric and spectral variability using LCOGT (Chile/South
Africa/Australia) and the SMARTS telescopes in Chile. These optical data
provide a broad context within which to interpret our shorter UV and
X-ray observations. We observed T Cha during 3 coordinated observations
(each 5 HST orbits + 25 ksec XMM; on 2018 Feb 22, Feb 26, Mar 2)
using the HST COS/STIS spectrographs to measure the FUV/NUV spectra and
XMM-Newton to measure the corresponding X-ray energy distribution. The
observed spectral changes are well correlated and demonstrate the
influence of the same absorbing material in all the spectral regions
observed. By examining which spectral features change and by how much
we can determine the location of different emitting regions relative to
the absorbers along the line-of-sight to the star. In this poster we
provide an overview of the variability seen in the different spectral
regions and quantify the dust and gas content of T Cha's inner disk
edge.(This work is supported by grant HST-GO-15128 and time awarded
by HST, XMM-Newton, LCOGT, and SMARTS. We acknowledge the assistance
provided by Dr. Todd Henry in conducting this observing campaign.)
---------------------------------------------------------
Title: The Hubble Space Telescope UV Legacy Survey of Galactic
globular clusters - XIII. ACS/WFC parallel-field catalogues
Authors: Simioni, M.; Bedin, L. R.; Aparicio, A.; Piotto, G.; Milone,
A. P.; Nardiello, D.; Anderson, J.; Bellini, A.; Brown, T. M.;
Cassisi, S.; Cunial, A.; Granata, V.; Ortolani, S.; van der Marel,
R. P.; Vesperini, E.
2018MNRAS.476..271S Altcode: 2018MNRAS.tmp..176S; 2018arXiv180107445S
As part of the Hubble Space Telescope UV Legacy Survey of Galactic
globular clusters, 110 parallel fields were observed with the Wide
Field Channel of the Advanced Camera for Surveys, in the outskirts of
48 globular clusters, plus the open cluster NGC 6791. Totalling about
0.3 deg<SUP>2</SUP> of observed sky, this is the largest homogeneous
Hubble Space Telescope photometric survey of Galalctic globular
clusters outskirts to date. In particular, two distinct pointings have
been obtained for each target on average, all centred at about 6.5
arcmin from the cluster centre, thus covering a mean area of about 23
arcmin<SUP>2</SUP> for each globular cluster. For each field, at least
one exposure in both F475W and F814W filters was collected. In this
work, we publicly release the astrometric and photometric catalogues
and the astrometrized atlases for each of these fields.
---------------------------------------------------------
Title: The K2 M67 Study: A Curiously Young Star in an Eclipsing
Binary in an Old Open Cluster
Authors: Sandquist, Eric L.; Mathieu, Robert D.; Quinn, Samuel N.;
Pollack, Maxwell L.; Latham, David W.; Brown, Timothy M.; Esselstein,
Rebecca; Aigrain, Suzanne; Parviainen, Hannu; Vanderburg, Andrew;
Stello, Dennis; Somers, Garrett; Pinsonneault, Marc H.; Tayar, Jamie;
Orosz, Jerome A.; Bedin, Luigi R.; Libralato, Mattia; Malavolta,
Luca; Nardiello, Domenico
2018AJ....155..152S Altcode: 2018arXiv180205854S
We present an analysis of a slightly eccentric (e = 0.05), partially
eclipsing, long-period (P = 69.73 days) main-sequence binary system
(WOCS 12009, Sanders 1247) in the benchmark old open cluster M67. Using
Kepler K2 and ground-based photometry, along with a large set of
new and reanalyzed spectra, we derived highly precise masses (1.111
± 0.015 and 0.748 ± 0.005 M <SUB>⊙</SUB>) and radii (1.071 ±
0.008 ± 0.003 and 0.713 ± 0.019 ± 0.026 R <SUB>⊙</SUB>, with
statistical and systematic error estimates) for the stars. The radius
of the secondary star is in agreement with theory. The primary, however,
is approximately 15% smaller than reasonable isochrones for the cluster
predict. Our best explanation is that the primary star was produced from
the merger of two stars, as this can also account for the nondetection
of photospheric lithium and its higher temperature relative to other
cluster main-sequence stars at the same V magnitude. To understand the
dynamical characteristics (low measured rotational line broadening of
the primary star and low eccentricity of the current binary orbit),
we believe that the most probable (but not the only) explanation
is the tidal evolution of a close binary within a primordial triple
system (possibly after a period of Kozai-Lidov oscillations), leading
to merger approximately 1 Gyr ago. This star appears to be a future
blue straggler that is being revealed as the cluster ages and the most
massive main-sequence stars die out. <P />Based on observations made at
Kitt Peak National Observatory, National Optical Astronomy Observatory,
which is operated by the Association of Universities for Research
in Astronomy (AURA) under a cooperative agreement with the National
Science Foundation; with the Tillinghast Reflector Echelle Spectrograph
(TRES) on the 1.5 m Tillinghast telescope, located at the Smithsonian
Astrophysical Observatory’s Fred L. Whipple Observatory on Mt. Hopkins
in Arizona; the HARPS-N spectrograph on the Italian Telescopio Nazionale
Galileo (TNG), operated on the island of La Palma by the INAF Fundacion
Galileo Galilei (Spanish Observatory of Roque de los Muchachos of the
IAC); and the Las Cumbres Observatory Global Telescope network.
---------------------------------------------------------
Title: Extinction Maps and Dust-to-gas Ratios in Nearby Galaxies
with LEGUS
Authors: Kahre, L.; Walterbos, R. A.; Kim, H.; Thilker, D.; Calzetti,
D.; Lee, J. C.; Sabbi, E.; Ubeda, L.; Aloisi, A.; Cignoni, M.; Cook,
D. O.; Dale, D. A.; Elmegreen, B. G.; Elmegreen, D. M.; Fumagalli,
M.; Gallagher, J. S., III; Gouliermis, D. A.; Grasha, K.; Grebel,
E. K.; Hunter, D. A.; Sacchi, E.; Smith, L. J.; Tosi, M.; Adamo, A.;
Andrews, J. E.; Ashworth, G.; Bright, S. N.; Brown, T. M.; Chandar,
R.; Christian, C.; de Mink, S. E.; Dobbs, C.; Evans, A. S.; Herrero,
A.; Johnson, K. E.; Kennicutt, R. C.; Krumholz, M. R.; Messa, M.;
Nair, P.; Nota, A.; Pellerin, A.; Ryon, J. E.; Schaerer, D.; Shabani,
F.; Van Dyk, S. D.; Whitmore, B. C.; Wofford, A.
2018ApJ...855..133K Altcode: 2018arXiv180206915K
We present a study of the dust-to-gas ratios in five nearby
galaxies: NGC 628 (M74), NGC 6503, NGC 7793, UGC 5139 (Holmberg I),
and UGC 4305 (Holmberg II). Using Hubble Space Telescope broadband
WFC3/UVIS UV and optical images from the Treasury program Legacy
ExtraGalactic UV Survey (LEGUS) combined with archival HST/Advanced
Camera for Surveys data, we correct thousands of individual stars
for extinction across these five galaxies using an isochrone-matching
(reddening-free Q) method. We generate extinction maps for each galaxy
from the individual stellar extinctions using both adaptive and fixed
resolution techniques and correlate these maps with neutral H I and CO
gas maps from the literature, including the H I Nearby Galaxy Survey
and the HERA CO-Line Extragalactic Survey. We calculate dust-to-gas
ratios and investigate variations in the dust-to-gas ratio with galaxy
metallicity. We find a power-law relationship between dust-to-gas
ratio and metallicity, consistent with other studies of dust-to-gas
ratio compared to metallicity. We find a change in the relation when
H<SUB>2</SUB> is not included. This implies that underestimation of
{N}<SUB>{{{H</SUB>}}<SUB>2</SUB>} in low-metallicity dwarfs from a
too-low CO-to-H<SUB>2</SUB> conversion factor X <SUB>CO</SUB> could have
produced too low a slope in the derived relationship between dust-to-gas
ratio and metallicity. We also compare our extinctions to those derived
from fitting the spectral energy distribution (SED) using the Bayesian
Extinction and Stellar Tool for NGC 7793 and find systematically lower
extinctions from SED fitting as compared to isochrone matching.
---------------------------------------------------------
Title: The Resolved Stellar Populations in the LEGUS Galaxies1
Authors: Sabbi, E.; Calzetti, D.; Ubeda, L.; Adamo, A.; Cignoni,
M.; Thilker, D.; Aloisi, A.; Elmegreen, B. G.; Elmegreen, D. M.;
Gouliermis, D. A.; Grebel, E. K.; Messa, M.; Smith, L. J.; Tosi, M.;
Dolphin, A.; Andrews, J. E.; Ashworth, G.; Bright, S. N.; Brown, T. M.;
Chandar, R.; Christian, C.; Clayton, G. C.; Cook, D. O.; Dale, D. A.;
de Mink, S. E.; Dobbs, C.; Evans, A. S.; Fumagalli, M.; Gallagher,
J. S., III; Grasha, K.; Herrero, A.; Hunter, D. A.; Johnson, K. E.;
Kahre, L.; Kennicutt, R. C.; Kim, H.; Krumholz, M. R.; Lee, J. C.;
Lennon, D.; Martin, C.; Nair, P.; Nota, A.; Östlin, G.; Pellerin,
A.; Prieto, J.; Regan, M. W.; Ryon, J. E.; Sacchi, E.; Schaerer,
D.; Schiminovich, D.; Shabani, F.; Van Dyk, S. D.; Walterbos, R.;
Whitmore, B. C.; Wofford, A.
2018ApJS..235...23S Altcode: 2018arXiv180105467S
The Legacy ExtraGalactic UV Survey (LEGUS) is a multiwavelength Cycle 21
Treasury program on the Hubble Space Telescope. It studied 50 nearby
star-forming galaxies in 5 bands from the near-UV to the I-band,
combining new Wide Field Camera 3 observations with archival Advanced
Camera for Surveys data. LEGUS was designed to investigate how star
formation occurs and develops on both small and large scales, and how
it relates to the galactic environments. In this paper we present the
photometric catalogs for all the apparently single stars identified
in the 50 LEGUS galaxies. Photometric catalogs and mosaicked images
for all filters are available for download. We present optical and
near-UV color-magnitude diagrams for all the galaxies. For each galaxy
we derived the distance from the tip of the red giant branch. We then
used the NUV color-magnitude diagrams to identify stars more massive
than 14 M <SUB>⊙</SUB>, and compared their number with the number of
massive stars expected from the GALEX FUV luminosity. Our analysis shows
that the fraction of massive stars forming in star clusters and stellar
associations is about constant with the star formation rate. This lack
of a relation suggests that the timescale for evaporation of unbound
structures is comparable or longer than 10 Myr. At low star formation
rates this translates to an excess of mass in clustered environments
as compared to model predictions of cluster evolution, suggesting that
a significant fraction of stars form in unbound systems. <P />Based
on observations with the NASA/ESA Hubble Space Telescope, obtained at
the Space Telescope Science Institute, which is operated by AURA Inc.,
under NASA contract NAS 5-26555.
---------------------------------------------------------
Title: A High-precision Trigonometric Parallax to an Ancient
Metal-poor Globular Cluster
Authors: Brown, T. M.; Casertano, S.; Strader, J.; Riess, A.;
VandenBerg, D. A.; Soderblom, D. R.; Kalirai, J.; Salinas, R.
2018ApJ...856L...6B Altcode: 2018arXiv180302927B
Using the Wide Field Camera 3 (WFC3) on the Hubble Space Telescope
(HST), we have obtained a direct trigonometric parallax for the
nearest metal-poor globular cluster, NGC 6397. Although trigonometric
parallaxes have been previously measured for many nearby open clusters,
this is the first parallax for an ancient metal-poor population—one
that is used as a fundamental template in many stellar population
studies. This high-precision measurement was enabled by the HST/WFC3
spatial-scanning mode, providing hundreds of astrometric measurements
for dozens of stars in the cluster and also for Galactic field stars
along the same sightline. We find a parallax of 0.418 ± 0.013 ±
0.018 mas (statistical, systematic), corresponding to a true distance
modulus of 11.89 ± 0.07 ± 0.09 mag (2.39 ± 0.07 ± 0.10 kpc). The
V luminosity at the stellar main-sequence turnoff implies an absolute
cluster age of 13.4 ± 0.7 ± 1.2 Gyr. <P />Based on observations
made with the NASA/ESA Hubble Space Telescope, obtained at the Space
Telescope Science Institute, which is operated by the Association of
Universities for Research in Astronomy, Inc., under NASA contract NAS
5-26555. These observations are associated with programs GO-13817,
GO-14336, and GO-14773.
---------------------------------------------------------
Title: The crucial role of ground-based, Doppler measurements for
the future of exoplanet science
Authors: Steffen, Jason H.; Plavchan, Peter; Brown, Timothy; Ford,
Eric B.; Howard, Andrew W.; Jang-Condell, Hannah; Latham, David W.;
Lissauer, Jack J.; Nelson, Benjamin E.; Newman, Patrick; Ragozzine,
Darin
2018arXiv180306057S Altcode:
We outline the important role that ground-based, Doppler monitoring
of exoplanetary systems will play in advancing our theories of planet
formation and dynamical evolution. A census of planetary systems
requires a well designed survey to be executed over the course of a
decade or longer. A coordinated survey to monitor several thousand
targets each at ~1000 epochs (~3-5 million new observations) will
require roughly 40 dedicated spectrographs. We advocate for improvements
in data management, data sharing, analysis techniques, and software
testing, as well as possible changes to the funding structures for
exoplanet science.
---------------------------------------------------------
Title: NRES: The Network of Robotic Echelle Spectrographs
Authors: Siverd, Robert; Brown, Tim; Henderson, Todd; Hygelund, John;
Barnes, Stuart; de Vera, Jon; Eastman, Jason; Kirby, Annie; Smith,
Cary; Taylor, Brook; Tufts, Joseph; van Eyken, Julian
2018AAS...23115224S Altcode:
Las Cumbres Observatory (LCO) is building the Network of Robotic Echelle
Spectrographs (NRES), which will consist of four (up to six in the
future) identical, optical (390 - 860 nm) high-precision spectrographs,
each fiber-fed simultaneously by up to two 1-meter telescopes and a
Thorium-Argon calibration source. We plan to install one at up to 6
observatory sites in the Northern and Southern hemispheres, creating
a single, globally-distributed, autonomous spectrograph facility
using up to ten 1-m telescopes. Simulations suggest we will achieve
long-term radial velocity precision of 3 m/s in less than an hour
for stars brighter than V = 11 or 12 once the system reaches full
capability. Acting in concert, these four spectrographs will provide
a new, unique facility for stellar characterization and precise radial
velocities.Following a few months of on-sky evaluation at our BPL test
facility, the first spectrograph unit was shipped to CTIO in late 2016
and installed in March 2017. After several more months of additional
testing and commissioning, regular science operations began with this
node in September 2017. The second NRES spectrograph was installed at
McDonald Observatory in September 2017 and released to the network after
its own brief commissioning period, extending spectroscopic capability
to the Northern hemisphere. The third NRES spectrograph was installed at
SAAO in November 2017 and released to our science community just before
year's end. The fourth NRES unit shipped in October and is currently
en route to Wise Observatory in Israel with an expected release to
the science community in early 2018.We will briefly overview the LCO
telescope network, the NRES spectrograph design, the advantages it
provides, and development challenges we encountered along the way. We
will further discuss real-world performance from our first three units,
initial science results, and the ongoing software development effort
needed to automate such a facility for a wide array of science cases.
---------------------------------------------------------
Title: A Universal Transition in Atmospheric Diffusion for Hot
Subdwarfs Near 18,000 K
Authors: Brown, T. M.; Taylor, J. M.; Cassisi, S.; Sweigart, A. V.;
Bellini, A.; Bedin, L. R.; Salaris, M.; Renzini, A.; Dalessandro, E.
2017ApJ...851..118B Altcode: 2017arXiv171108036B
In the color-magnitude diagrams of globular clusters, when the
locus of stars on the horizontal branch extends to hot temperatures,
discontinuities are observed at colors corresponding to ∼12,000 and
∼18,000 K. The former is the “Grundahl jump” that is associated
with the onset of radiative levitation in the atmospheres of hot
subdwarfs. The latter is the “Momany jump” that has remained
unexplained. Using the Space Telescope Imaging Spectrograph on
the Hubble Space Telescope, we have obtained ultraviolet and blue
spectroscopy of six hot subdwarfs straddling the Momany jump in the
massive globular cluster ω Cen. By comparison to model atmospheres
and synthetic spectra, we find that the feature is due primarily to a
decrease in atmospheric Fe for stars hotter than the feature, amplified
by the temperature dependence of the Fe absorption at these effective
temperatures. <P />Based on observations made with the NASA/ESA Hubble
Space Telescope, obtained at the Space Telescope Science Institute,
which is operated by the Association of Universities for Research in
Astronomy, Inc., under NASA contract NAS 5-26555. These observations
are associated with program GO-14759.
---------------------------------------------------------
Title: Christopherwharrop/Rocoto: Rocoto 1.2.4
Authors: Harrop, Christopher; samtrahan; christinaholt; Brown, Timothy
2017zndo....890939H Altcode:
This release contains a number of bug fixes and some new features. See
RELEASE_NOTES.md for details.
---------------------------------------------------------
Title: The Hubble Space Telescope "Program of Last Resort"
Authors: Bellini, A.; Grogin, N. A.; Hathi, N.; Brown, T. M.
2017acs..rept...12B Altcode:
Every year, the Space Telescope Science Institute allocates over
3000 orbits of Hubble time to approved Guest Observer, Snapshot, and
Director's Discretionary programs. The many targets among all these
programs are not distributed uniformly around the celestial sphere,
and most targets have observational constraints that limit their
schedulability to something less than the entire year. Despite the best
efforts of the Hubble schedulers to allocate every last orbit, a small
but persistent fraction ( 2 - 3%) of the orbits go unused. Salvaging
this unused observing time presents an opportunity for the Institute to
benefit the astronomy community. The Institute's Hubble Mission Office
has initiated a pilot, ultra-low priority SNAP program (14840, PI:
Bellini) in Cycle 24, with the goal of taking useful data in Hubble
orbits that absolutely no other program is able to use. The initial
target list comprises 500 moderately large, bright NGC/IC galaxies that
were not previously imaged by HST in V -like filters. As of September
2017, over 100 galaxies have been observed as part of this program
(≥ 2 galaxies per week). This document focuses on the data quality
of the first 10 months of observations. All data taken through the
SNAP-14840 program are intended for legacy science only, and STScI
strongly encourage the astronomical community to use these data for
science purposes.
---------------------------------------------------------
Title: NRES: The Network of Robotic Echelle Spectrographs
Authors: Siverd, Robert; Brown, Timothy M.; Henderson, Todd; Hygelund,
John; Barnes, Stuart; Bowman, Mark; De Vera, Jon; Eastman, Jason D.;
Kirby, Annie; Norbury, Martin; Smith, Cary; Taylor, Brook; Tufts,
Joseph; Van Eyken, Julian C.
2017AAS...23010207S Altcode:
Las Cumbres Observatory (LCO) is building the Network of Robotic Echelle
Spectrographs (NRES), which will consist of four to six identical,
optical (390 - 860 nm) high-precision spectrographs, each fiber-fed
simultaneously by up to two 1-meter telescopes and a Thorium-Argon
calibration source. We plan to install one at up to 6 observatory
sites in the Northern and Southern hemispheres, creating a single,
globally-distributed, autonomous spectrograph facility using up to ten
1-m telescopes. Simulations suggest we will achieve long-term radial
velocity precision of 3 m/s in less than an hour for stars brighter
than V = 11 or 12. Following a few months of on-sky evaluation at our
BPL test facility, the first spectrograph unit was shipped to CTIO in
late 2016 and installed in March 2017. Barring serious complications, we
expect regular scheduled science observing to begin in mid-2017. Three
additional units are in building or testing phases and slated for
deployment in late 2017. Acting in concert, these four spectrographs
will provide a new, unique facility for stellar characterization and
precise radial velocities. We will briefly overview the LCO telescope
network, the NRES spectrograph design, the advantages it provides,
and development challenges we encountered along the way. We will
further discuss real-world performance from our first unit, initial
science results, and the ongoing software development effort needed
to automate such a facility for a wide array of science cases.
---------------------------------------------------------
Title: Legacy ExtraGalactic UV Survey with The Hubble Space Telescope:
Stellar Cluster Catalogs and First Insights Into Cluster Formation
and Evolution in NGC 628
Authors: Adamo, A.; Ryon, J. E.; Messa, M.; Kim, H.; Grasha, K.; Cook,
D. O.; Calzetti, D.; Lee, J. C.; Whitmore, B. C.; Elmegreen, B. G.;
Ubeda, L.; Smith, L. J.; Bright, S. N.; Runnholm, A.; Andrews, J. E.;
Fumagalli, M.; Gouliermis, D. A.; Kahre, L.; Nair, P.; Thilker, D.;
Walterbos, R.; Wofford, A.; Aloisi, A.; Ashworth, G.; Brown, T. M.;
Chandar, R.; Christian, C.; Cignoni, M.; Clayton, G. C.; Dale, D. A.;
de Mink, S. E.; Dobbs, C.; Elmegreen, D. M.; Evans, A. S.; Gallagher,
J. S., III; Grebel, E. K.; Herrero, A.; Hunter, D. A.; Johnson, K. E.;
Kennicutt, R. C.; Krumholz, M. R.; Lennon, D.; Levay, K.; Martin,
C.; Nota, A.; Östlin, G.; Pellerin, A.; Prieto, J.; Regan, M. W.;
Sabbi, E.; Sacchi, E.; Schaerer, D.; Schiminovich, D.; Shabani, F.;
Tosi, M.; Van Dyk, S. D.; Zackrisson, E.
2017ApJ...841..131A Altcode: 2017arXiv170501588A
We report the large effort that is producing comprehensive high-level
young star cluster (YSC) catalogs for a significant fraction of galaxies
observed with the Legacy ExtraGalactic UV Survey (LEGUS) Hubble treasury
program. We present the methodology developed to extract cluster
positions, verify their genuine nature, produce multiband photometry
(from NUV to NIR), and derive their physical properties via spectral
energy distribution fitting analyses. We use the nearby spiral galaxy
NGC 628 as a test case for demonstrating the impact that LEGUS will
have on our understanding of the formation and evolution of YSCs and
compact stellar associations within their host galaxy. Our analysis
of the cluster luminosity function from the UV to the NIR finds a
steepening at the bright end and at all wavelengths suggesting a dearth
of luminous clusters. The cluster mass function of NGC 628 is consistent
with a power-law distribution of slopes ∼ -2 and a truncation of a
few times 10<SUP>5</SUP> {M}<SUB>⊙ </SUB>. After their formation,
YSCs and compact associations follow different evolutionary paths. YSCs
survive for a longer time frame, confirming their being potentially
bound systems. Associations disappear on timescales comparable to
hierarchically organized star-forming regions, suggesting that they are
expanding systems. We find mass-independent cluster disruption in the
inner region of NGC 628, while in the outer part of the galaxy there
is little or no disruption. We observe faster disruption rates for
low mass (≤10<SUP>4</SUP> {M}<SUB>⊙ </SUB>) clusters, suggesting
that a mass-dependent component is necessary to fully describe the YSC
disruption process in NGC 628. <P />Based on observations obtained with
the NASA/ESA Hubble Space Telescope, at the Space Telescope Science
Institute, which is operated by the Association of Universities for
Research in Astronomy, Inc., under NASA contract NAS 5-26555.
---------------------------------------------------------
Title: Just how hot are the ω Centauri extreme horizontal branch
pulsators?
Authors: Latour, M.; Randall, S. K.; Chayer, P.; Fontaine, G.;
Calamida, A.; Ely, J.; Brown, T. M.; Landsman, W.
2017A&A...600A.130L Altcode: 2017arXiv170207609L
Context. Past studies based on optical spectroscopy suggest that the
five <ASTROBJ>ω Cen</ASTROBJ> pulsators form a rather homogeneous group
of hydrogen-rich subdwarf O stars with effective temperatures of around
50 000 K. This places the stars below the red edge of the theoretical
instability strip in the log g-T<SUB>eff</SUB> diagram, where no
pulsation modes are predicted to be excited. <BR /> Aims: Our goal is
to determine whether this temperature discrepancy is real, or whether
the stars' effective temperatures were simply underestimated. <BR />
Methods: We present a spectral analysis of two rapidly pulsating extreme
horizontal branch (EHB) stars found in <ASTROBJ>ω Cen</ASTROBJ>. We
obtained Hubble Space Telescope/COS UV spectra of two ω Cen pulsators,
V1 and V5, and used the ionisation equilibrium of UV metallic lines
to better constrain their effective temperatures. As a by-product we
also obtained FUV lightcurves of the two pulsators. <BR /> Results:
Using the relative strength of the N iv and N v lines as a temperature
indicator yields T<SUB>eff</SUB> values close to 60 000 K, significantly
hotter than the temperatures previously derived. From the FUV light
curves we were able to confirm the main pulsation periods known from
optical data. <BR /> Conclusions: With the UV spectra indicating
higher effective temperatures than previously assumed, the sdO stars
would now be found within the predicted instability strip. Such higher
temperatures also provide consistent spectroscopic masses for both the
cool and hot EHB stars of our previously studied sample. <P />Based
on observations (proposal GO-13707) with the NASA/ESA Hubble Space
Telescope, obtained at the Space Telescope Science Institute, which is
operated by the Association of Universities for Research in Astronomy,
Inc., under NASA contract NAS5-26666.
---------------------------------------------------------
Title: The Hubble Space Telescope UV Legacy Survey of Galactic
globular clusters - XI. The horizontal branch in NGC 6388 and NGC 6441
Authors: Tailo, M.; D'Antona, F.; Milone, A. P.; Bellini, A.; Ventura,
P.; Di Criscienzo, M.; Cassisi, S.; Piotto, G.; Salaris, M.; Brown,
T. M.; Vesperini, E.; Bedin, L. R.; Marino, A. F.; Nardiello, D.;
Anderson, J.
2017MNRAS.465.1046T Altcode: 2016arXiv161008264T
The Hubble Space Telescope UV Legacy survey of Galactic globular
clusters (GC) is characterizing many different aspects of their multiple
stellar populations. The `Grundahl-jump' (G-jump) is a discontinuity in
ultraviolet brightness of blue horizontal branch (HB) stars, signalling
the onset of radiative metal levitation. The HB Legacy data confirmed
that the G-jump is located at the same T<SUB>eff</SUB> (≃11 500 K) in
nearly all clusters. The only exceptions are the metal-rich clusters NGC
6388 and NGC 6441, where the G-jump occurs at T<SUB>eff</SUB> ≃ 13-14
000 K. We compute synthetic HB models based on new evolutionary tracks
including the effect of helium diffusion, and approximately accounting
for the effect of metal levitation in a stable atmosphere. Our models
show that the G-jump location depends on the interplay between the
time-scale of diffusion and the time-scale of the evolution in the
T<SUB>eff</SUB> range 11 500 K≲T<SUB>eff</SUB>≲14 000 K. The
G-jump becomes hotter than 11 500 K only for stars that have, in this
T<SUB>eff</SUB> range, a helium mass fraction Y ≳ 0.35. Similarly
high Y values are also consistent with the modelling of the HB in NGC
6388 and NGC 6441. In these clusters, we predict that a significant
fraction of HB stars show helium in their spectra above 11 500 K,
and full helium settling should only be found beyond the hotter G-jump.
---------------------------------------------------------
Title: The Hubble Space Telescope UV Legacy Survey of Galactic
globular clusters - IX. The Atlas of multiple stellar populations
Authors: Milone, A. P.; Piotto, G.; Renzini, A.; Marino, A. F.; Bedin,
L. R.; Vesperini, E.; D'Antona, F.; Nardiello, D.; Anderson, J.; King,
I. R.; Yong, D.; Bellini, A.; Aparicio, A.; Barbuy, B.; Brown, T. M.;
Cassisi, S.; Ortolani, S.; Salaris, M.; Sarajedini, A.; van der Marel,
R. P.
2017MNRAS.464.3636M Altcode: 2016MNRAS.tmp.1516M; 2016arXiv161000451M
We use high-precision photometry of red-giant-branch (RGB) stars in
57 Galactic globular clusters (GCs), mostly from the `Hubble Space
Telescope (HST) UV Legacy Survey of Galactic GCs', to identify and
characterize their multiple stellar populations. For each cluster the
pseudo-two-colour diagram (or `chromosome map') is presented, built
with a suitable combination of stellar magnitudes in the F275W, F336W,
F438W, and F814W filters that maximizes the separation between multiple
populations. In the chromosome map of most GCs (type-I clusters),
stars separate in two distinct groups that we identify with the first
(1G) and the second generation (2G). This identification is further
supported by noticing that 1G stars have primordial (oxygen-rich,
sodium-poor) chemical composition, whereas 2G stars are enhanced in
sodium and depleted in oxygen. This 1G-2G separation is not possible
for a few GCs where the two sequences have apparently merged into an
extended, continuous sequence. In some GCs (type-II clusters) the 1G
and/or the 2G sequences appear to be split, hence displaying more
complex chromosome maps. These clusters exhibit multiple subgiant
branches (SGBs) also in purely optical colour-magnitude diagrams,
with the fainter SGB joining into a red RGB which is populated by
stars with enhanced heavy-element abundance. We measure the RGB width
by using appropriate colours and pseudo-colours. When the metallicity
dependence is removed, the RGB width correlates with the cluster
mass. The fraction of 1G stars ranges from ∼8 per cent to ∼67
per cent and anticorrelates with the cluster mass, indicating that
incidence and complexity of the multiple population phenomenon both
increase with cluster mass.
---------------------------------------------------------
Title: The Hubble Space Telescope UV Legacy Survey of Galactic
Globular Clusters. VIII. Preliminary Public Catalog Release
Authors: Soto, M.; Bellini, A.; Anderson, J.; Piotto, G.; Bedin,
L. R.; van der Marel, R. P.; Milone, A. P.; Brown, T. M.; Cool, A. M.;
King, I. R.; Sarajedini, A.; Granata, V.; Cassisi, S.; Aparicio, A.;
Hidalgo, S.; Ortolani, S.; Nardiello, D.
2017AJ....153...19S Altcode: 2016arXiv161200714S
The Hubble Space Telescope (HST) UV Legacy Survey of Galactic
Globular Clusters (GO-13297) has been specifically designed
to complement the existing F606W and F814W observations of the
Advanced Camera for Surveys (ACS) Globular Cluster Survey (GO-10775)
by observing the most accessible 47 of the previous survey’s 65
clusters in three WFC3/UVIS filters F275W, F336W, and F438W. The
new survey also adds super-solar metallicity open cluster NGC 6791
to increase the metallicity diversity. The combined survey provides
a homogeneous 5-band data set that can be used to pursue a broad
range of scientific investigations. In particular, the chosen UV
filters allow the identification of multiple stellar populations by
targeting the regions of the spectrum that are sensitive to abundance
variations in C, N, and O. In order to provide the community with
uniform preliminary catalogs, we have devised an automated procedure
that performs high-quality photometry on the new UV observations (along
with similar observations of seven other programs in the archive). This
procedure finds and measures the potential sources on each individual
exposure using library point-spread functions and cross-correlates
these observations with the original ACS-Survey catalog. The catalog
of 57 clusters we publish here will be useful to identify stars in
the different stellar populations, in particular for spectroscopic
follow-up. Eventually, we will construct a more sophisticated catalog
and artificial-star tests based on an optimal reduction of the UV
survey data, but the catalogs presented here give the community the
chance to make early use of this HST Treasury survey.
---------------------------------------------------------
Title: NRES: the network of robotic Echelle spectrographs
Authors: Siverd, Robert J.; Brown, Timothy M.; Hygelund, John;
Henderson, Todd; Tufts, Joseph R.; Eastman, Jason D.; van Eyken,
Julian; Barnes, Stuart
2016SPIE.9908E..6XS Altcode:
Las Cumbres Observatory Global Network (LCOGT) is building the Network
of Robotic Echelle Spectrographs (NRES), which will consist of six
identical, optical (390 - 860 nm) high-precision spectrographs,
each fiber-fed simultaneously by up to two 1-meter telescopes and a
thorium argon calibration source. We plan to install one at up to 6
observatory sites in the Northern and Southern hemispheres, creating a
single, globally-distributed, autonomous spectrograph facility using
up to twelve 1-meter telescopes. Simulations suggest we will achieve
long-term radial velocity precision of 3 m/s in less than an hour for
stars brighter than V = 12. We have been funded with NSF MRI and ATI
grants, and expect our first spectrograph to be deployed in fall 2016,
with the full network operation of 5 or 6 units beginning in 2017. We
will briefly overview the NRES design, goals, robotic operation,
and status. In addition, we will discuss early results from our
prototype spectrograph, the laboratory and on-sky performance of our
first production unit, and the ongoing software development effort to
bring this resource online.
---------------------------------------------------------
Title: Discovery of a Long-Period Eclipsing Binary in M67
Authors: Sandquist, Eric L.; Latham, David W.; Mathieu, Robert D.;
Vanderburg, Andrew; Brown, Timothy M.; M67 K2 Team
2016AAS...22811701S Altcode:
We announce the detection of an eclipsing binary (WOCS 12009 / Sanders
1247) near the turnoff of the heavily-studied old open cluster M67
using K2 Campaign 5 data. The object was previously known to be
a double-lined spectroscopic binary, and the orbit period (69.75 d)
agrees with the photometric period. We present a preliminary analysis of
the K2 photometry, multi-band ground-based photometry of the eclipses,
and extensive radial velocity observations of the two stars. Precise
measurements of the pair will begin to provide mass and radius scales
for cluster stars, and will constrain the age of this iconic open
cluster.We gratefully acknowledge support from NASA through grant
NNX15AW24A to R.D.M.
---------------------------------------------------------
Title: NRES: The Network of Robotic Echelle Spectrographs
Authors: Siverd, Robert; Brown, Timothy M.; Henderson, Todd; Hygelund,
John; Tufts, Joseph; Eastman, Jason; Barnes, Stuart; Van Eyken,
Julian C.
2016AAS...22840101S Altcode:
Las Cumbres Observatory Global Network (LCOGT) is building the Network
of Robotic Echelle Spectrographs (NRES), which will consist of six
identical, optical (390 - 860 nm) high-precision spectrographs, each
fiber-fed simultaneously by up to two 1-meter telescopes and a thorium
argon calibration source. We plan to install one at up to 6 observatory
sites in the Northern and Southern hemispheres, creating a single,
globally-distributed, autonomous spectrograph facility using up to
twelve 1-m telescopes. Simulations suggest we will achieve long-term
radial velocity precision of 3 m/s in less than an hour for stars
brighter than V = 12. We have been funded with NSF MRI and ATI grants,
and expect to deploy the first spectrograph in fall 2016, with the full
network operation of 5 or 6 units beginning in 2017. We will briefly
overview the NRES design, goals, robotic operation, and status. In
addition, we will discuss early results from our prototype spectrograph,
the laboratory and on-sky performance of our first production unit,
initial science results, and the ongoing software development effort
to bring this resource online.
---------------------------------------------------------
Title: The Hubble Space Telescope UV Legacy Survey of Galactic
Globular Clusters. VII. Implications from the Nearly Universal Nature
of Horizontal Branch Discontinuities
Authors: Brown, T. M.; Cassisi, S.; D'Antona, F.; Salaris, M.; Milone,
A. P.; Dalessandro, E.; Piotto, G.; Renzini, A.; Sweigart, A. V.;
Bellini, A.; Ortolani, S.; Sarajedini, A.; Aparicio, A.; Bedin, L. R.;
Anderson, J.; Pietrinferni, A.; Nardiello, D.
2016ApJ...822...44B Altcode: 2016arXiv160307651B
The UV-initiative Hubble Space Telescope Treasury survey of Galactic
globular clusters provides a new window into the phenomena that shape
the morphological features of the horizontal branch (HB). Using this
large and homogeneous catalog of UV and blue photometry, we demonstrate
that the HB exhibits discontinuities that are remarkably consistent
in color (effective temperature). This consistency is apparent even
among some of the most massive clusters hosting multiple distinct
sub-populations (such as NGC 2808, ω Cen, and NGC 6715), demonstrating
that these phenomena are primarily driven by atmospheric physics
that is independent of the underlying population properties. However,
inconsistencies arise in the metal-rich clusters NGC 6388 and NGC 6441,
where the discontinuity within the blue HB (BHB) distribution shifts
∼1000-2000 K hotter. We demonstrate that this shift is likely due to
a large helium enhancement in the BHB stars of these clusters, which in
turn affects the surface convection and evolution of such stars. Our
survey also increases the number of Galactic globular clusters known
to host blue-hook stars (also known as late hot flashers) from 6
to 23 clusters. These clusters are biased toward the bright end of
the globular cluster luminosity function, confirming that blue-hook
stars tend to form in the most massive clusters with significant
self-enrichment. <P />Based on observations made with the NASA/ESA
Hubble Space Telescope, obtained at the Space Telescope Science
Institute, which is operated by the Association of Universities for
Research in Astronomy, Inc., under NASA contract NAS 5-26555. These
observations are associated with program GO-13297.
---------------------------------------------------------
Title: VizieR Online Data Catalog: Photometry and redshifts of
galaxies in the UDF (Rafelski+, 2015)
Authors: Rafelski, M.; Teplitz, H. I.; Gardner, J. P.; Coe, D.; Bond,
N. A.; Koekemoer, A. M.; Grogin, N.; Kurczynski, P.; McGrath, E. J.;
Bourque, M.; Atek, H.; Brown, T. M.; Colbert, J. W.; Codoreanu,
A.; Ferguson, H. C.; Finkelstein, S. L.; Gawiser, E.; Giavalisco,
M.; Gronwall, C.; Hanish, D. J.; Lee, K. -S.; Mehta, V.; de Mello,
D. F.; Ravindranath, S.; Ryan, R. E.; Scarlata, C.; Siana, B.; Soto,
E.; Voyer, E. N.
2016yCat..51500031R Altcode:
We present photometry and derived redshifts from up to eleven bandpasses
for 9927 galaxies in the Hubble Ultra Deep field (UDF), covering
an observed wavelength range from the near-ultraviolet (NUV) to the
near-infrared (NIR) with Hubble Space Telescope (HST) observations. <P
/>The NUV coverage of the UDF (UVUDF) is comprised of three WFC3-UVIS
filters: F225W, F275W, and F336W. The UVUDF observations were obtained
in 2012. The optical data are covered by the four original Advanced
Camera for Surveys (ACS) optical filters: F435W, F606W, F775W, and
F850LP. The deep NIR coverage includes four WFC3-IR filters: F105W,
F125W, F140W, and F160W obtained in the UDF09 and UDF12 programs
(Oesch et al. 2010ApJ...709L..21O, 2010ApJ...709L..16O; Bouwens et
al. 2011ApJ...737...90B; Ellis et al. 2013ApJ...763L...7E; Koekemoer
et al. 2013ApJS..209....3K). The entire field is also covered by three
of the four WFC3-IR filters (F105W, F125W, and F160W) in the CANDELS
GOODS-S observations (Grogin et al. 2011ApJS..197...35G; Koekemoer et
al. 2011ApJS..197...36K). <P />(2 data files).
---------------------------------------------------------
Title: NRES: The Network of Robotic Echelle Spectrographs
Authors: Siverd, Robert; Brown, Timothy M.; Hygelund, John; Henderson,
Todd; Tufts, Joseph; Eastman, Jason; Van Eyken, Julian C.; Barnes,
Stuart
2016AAS...22711307S Altcode:
Las Cumbres Observatory Global Network (LCOGT) is building the Network
of Robotic Echelle Spectrographs (NRES), which will consist of six
identical, optical (390 - 860 nm) high-precision spectrographs, each
fiber-fed simultaneously by up to two 1-meter telescopes and a thorium
argon calibration source. We plan to install one at up to 6 observatory
sites in the Northern and Southern hemispheres, creating a single,
globally-distributed, autonomous spectrograph facility using up to
twelve 1-m telescopes. Simulations suggest we will achieve long-term
radial velocity precision of 3 m/s in less than an hour for stars
brighter than V = 12. We have been funded with NSF MRI and ATI grants,
and expect our first spectrograph to be deployed in early 2016, with
the full network operation of 5 or 6 units beginning in 2017. We
will briefly overview the NRES design, goals, robotic operation,
and status. In addition, we will discuss early results from our
prototype spectrograph, the laboratory and on-sky performance of our
first production unit, and the ongoing software development effort to
bring this resource online.
---------------------------------------------------------
Title: Follow-up of K2 planet candiates with the LCOGT network
Authors: Dragomir, Diana; Bayliss, Daniel; Colón, Knicole; Cochran,
William; Zhou, George; Brown, Timothy; Shporer, Avi; Espinoza, Nestor;
Fulton, Benjamin
2015ESS.....310303D Altcode:
K2 has proven to be an outstanding successor to the Kepler mission. It
has already revealed dozens of new planet candidates, and unlike those
found by the primary mission, many of these systems’ host stars are
sufficiently bright to allow extensive follow-up observations. This is
especially important since each of the K2 observing campaigns are only
~80 days long, leaving the community with the discovery of exciting
new systems but often not enough time coverage to enable a thorough
characterization of these systems.We are leading a large effort
to observe K2 transiting planet candidates with the LCOGT telescope
network. LCOGT’s longitudinal coverage, multiple identical telescopes
per site and automated queue observing make it an ideal facility for
fast, high-precision and multi-color follow-up. Our program focuses on
specific aspects of K2 follow-up for which the network is especially
powerful: period determination for candidates with fewer than three
K2 transits; transit timing variation monitoring to measure planetary
masses, orbital parameters and to search for additional planets in
multiple systems; and multi-color photometry to vet planet candidates
and carry-out preliminary atmospheric spectroscopy.We will present
new results for a selection of systems observed so far through this
program. These include K2-19, a multi-planet system extremely close
to 3:2 resonance and experiencing transit timing variations with
amplitudes as large as one hour; EPIC201702477, a long-period planet
with only two K2 transits; WASP-47, a system hosting a hot Jupiter and
two K2-discovered small planets; and EPIC201637175b, a disintegrating
rocky planet.Our program demonstrates that LCOGT is uniquely positioned
to be the primary ground-based photometric follow-up resource for K2
exoplanet discoveries, but also for the numerous bright systems that
will result from the TESS mission. LCOGT photometry complements ongoing
radial velocity and atmospheric spectroscopy efforts to reveal a more
complete picture of the bright, nearby exoplanet systems discovered
by these missions.
---------------------------------------------------------
Title: The Hubble Space Telescope UV Legacy Survey of Galactic
Globular Clusters - V. Constraints on formation scenarios
Authors: Renzini, A.; D'Antona, F.; Cassisi, S.; King, I. R.; Milone,
A. P.; Ventura, P.; Anderson, J.; Bedin, L. R.; Bellini, A.; Brown,
T. M.; Piotto, G.; van der Marel, R. P.; Barbuy, B.; Dalessandro, E.;
Hidalgo, S.; Marino, A. F.; Ortolani, S.; Salaris, M.; Sarajedini, A.
2015MNRAS.454.4197R Altcode: 2015arXiv151001468R
We build on the evidence provided by our Legacy Survey of Galactic
globular clusters (GC) to submit to a crucial test four scenarios
currently entertained for the formation of multiple stellar generations
in GCs. The observational constraints on multiple generations to be
fulfilled are manifold, including GC specificity, ubiquity, variety,
predominance, discreteness, supernova avoidance, p-capture processing,
helium enrichment and mass budget. We argue that scenarios appealing to
supermassive stars, fast rotating massive stars and massive interactive
binaries violate in an irreparable fashion two or more among such
constraints. Also the scenario appealing to asymptotic giant branch
(AGB) stars as producers of the material for next generation stars
encounters severe difficulties, specifically concerning the mass budget
problem and the detailed chemical composition of second-generation
stars. We qualitatively explore ways possibly allowing one to save
the AGB scenario, specifically appealing to a possible revision of
the cross-section of a critical reaction rate destroying sodium,
or alternatively by a more extensive exploration of the vast
parameter space controlling the evolutionary behaviour of AGB stellar
models. Still, we cannot ensure success for these efforts and totally
new scenarios may have to be invented to understand how GCs formed in
the early Universe.
---------------------------------------------------------
Title: The GIRAFFE Inner Bulge Survey (GIBS). II. Metallicity
distributions and alpha element abundances at fixed Galactic latitude
Authors: Gonzalez, O. A.; Zoccali, M.; Vasquez, S.; Hill, V.; Rejkuba,
M.; Valenti, E.; Rojas-Arriagada, A.; Renzini, A.; Babusiaux, C.;
Minniti, D.; Brown, T. M.
2015A&A...584A..46G Altcode: 2015arXiv150802576G
<BR /> Aims: We investigate metallicity and α-element abundance
gradients along a Galactic longitude strip, at latitude b ~ -4°, with
the aim of providing observational constraints for the structure and
origin of the Milky Way bulge. <BR /> Methods: High-resolution (R ~
22 500) spectra for 400 K giants, in four fields within -4.8° ≲ b
≲ -3.4° and -10° ≲ l ≲ +10°, were obtained within the GIRAFFE
Inner Bulge Survey (GIBS) project. To this sample we added another
~400 stars in Baade's Window at (l,b) = (1°,-4°), observed with the
identical instrumental configuration: FLAMES GIRAFFE in Medusa mode
with HR13 setup. All target stars lie within the red clump of the bulge
colour-magnitude diagram, thus minimising contamination from the disc or
halo stars. The spectroscopic stellar surface parameters were derived
with an automatic method based on the GALA code, while the [Ca/Fe]
and [Mg/Fe] abundances as a function of [Fe/H] were derived through a
comparison with the synthetic spectra using MOOG. We constructed the
metallicity distributions for the entire sample, and for each field
individually, in order to investigate the presence of gradients or
field-to-field variations in the shape of the distributions. <BR />
Results: The metallicity distributions in the five fields are consistent
with being drawn from a single parent population, indicating the
absence of a gradient along the major axis of the Galactic bar. The
global metallicity distribution is nicely fitted by two Gaussians. The
metal-poor component is rather broad, with a mean at ⟨ [Fe/H] ⟩ =
-0.31 dex and σ = 0.31 dex. The metal-rich component is narrower, with
mean ⟨ [Fe/H] ⟩ = + 0.26 and σ = 0.2 dex. The [Mg/Fe] ratio follows
a tight trend with [Fe/H], with enhancement with respect to solar in
the metal-poor regime similar to the value observed for giant stars in
the local thick disc. [Ca/Fe] abundances follow a similar trend, but
with a considerably larger scatter than [Mg/Fe]. A decrease in [Mg/Fe]
is observed at [Fe/H] = -0.44 dex. This knee is in agreement with our
previous bulge study of K-giants along the minor axis, but is 0.1 dex
lower in metallicity than the value reported for the microlensed dwarf
and subgiant stars in the bulge. We found no variation in α-element
abundance distributions between different fields. <P />Based on
observations taken with ESO telescopes at the La Silla Paranal
Observatory under programme IDs 187.B-909(A) and 71.B-0196.Full
Table 3 is only available at the CDS via anonymous ftp to <A
href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/584/A46">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/584/A46</A>
---------------------------------------------------------
Title: The Brightest Young Star Clusters in NGC 5253.
Authors: Calzetti, D.; Johnson, K. E.; Adamo, A.; Gallagher, J. S.,
III; Andrews, J. E.; Smith, L. J.; Clayton, G. C.; Lee, J. C.;
Sabbi, E.; Ubeda, L.; Kim, H.; Ryon, J. E.; Thilker, D.; Bright,
S. N.; Zackrisson, E.; Kennicutt, R. C.; de Mink, S. E.; Whitmore,
B. C.; Aloisi, A.; Chandar, R.; Cignoni, M.; Cook, D.; Dale, D. A.;
Elmegreen, B. G.; Elmegreen, D. M.; Evans, A. S.; Fumagalli, M.;
Gouliermis, D. A.; Grasha, K.; Grebel, E. K.; Krumholz, M. R.;
Walterbos, R.; Wofford, A.; Brown, T. M.; Christian, C.; Dobbs, C.;
Herrero, A.; Kahre, L.; Messa, M.; Nair, P.; Nota, A.; Östlin, G.;
Pellerin, A.; Sacchi, E.; Schaerer, D.; Tosi, M.
2015ApJ...811...75C Altcode: 2015arXiv150804476C
The nearby dwarf starburst galaxy NGC 5253 hosts a number of young,
massive star clusters, the two youngest of which are centrally
concentrated and surrounded by thermal radio emission (the “radio
nebula”). To investigate the role of these clusters in the starburst
energetics, we combine new and archival Hubble Space Telescope images
of NGC 5253 with wavelength coverage from 1500 Å to 1.9 μm in 13
filters. These include Hα, Pβ, and Pα, and the imaging from the
Hubble Treasury Program LEGUS (Legacy Extragalactic UV Survey). The
extraordinarily well-sampled spectral energy distributions enable
modeling with unprecedented accuracy the ages, masses, and extinctions
of the nine optically brightest clusters (M<SUB>V</SUB> < -8.8)
and the two young radio nebula clusters. The clusters have ages
∼1-15 Myr and masses ∼1 × 10<SUP>4</SUP>-2.5 × 10<SUP>5</SUP>
M<SUB>⊙</SUB>. The clusters’ spatial location and ages indicate that
star formation has become more concentrated toward the radio nebula
over the last ∼15 Myr. The most massive cluster is in the radio
nebula; with a mass ∼2.5 × 10<SUP>5</SUP> M<SUB>⊙</SUB> and an
age ∼1 Myr, it is 2-4 times less massive and younger than previously
estimated. It is within a dust cloud with A<SUB>V</SUB> ∼ 50 mag, and
shows a clear near-IR excess, likely from hot dust. The second radio
nebula cluster is also ∼1 Myr old, confirming the extreme youth of
the starburst region. These two clusters account for about half of the
ionizing photon rate in the radio nebula, and will eventually supply
about 2/3 of the mechanical energy in present-day shocks. Additional
sources are required to supply the remaining ionizing radiation, and may
include very massive stars. <P />Based on observations obtained with
the NASA/ESA Hubble Space Telescope, at the Space Telescope Science
Institute, which is operated by the Association of Universities for
Research in Astronomy, Inc., under NASA contract NAS 5-26555.
---------------------------------------------------------
Title: New Insights on the Galactic Bulge Initial Mass Function
Authors: Calamida, A.; Sahu, K. C.; Casertano, S.; Anderson, J.;
Cassisi, S.; Gennaro, M.; Cignoni, M.; Brown, T. M.; Kains, N.;
Ferguson, H.; Livio, M.; Bond, H. E.; Buonanno, R.; Clarkson, W.;
Ferraro, I.; Pietrinferni, A.; Salaris, M.; Valenti, J.
2015ApJ...810....8C Altcode: 2015arXiv150507128C
We have derived the Galactic bulge initial mass function (IMF) of the
Sagittarius Window Eclipsing Extrasolar Planet Search field in the
mass range 0.15 \lt M/{M}<SUB>⊙ </SUB> 1.0, using deep photometry
collected with the Advanced Camera for Surveys on the Hubble Space
Telescope. Observations at several epochs, spread over 9 years, allowed
us to separate the disk and bulge stars down to very faint magnitudes,
F814W ≈ 26 mag, with a proper-motion accuracy better than 0.5 mas
yr<SUP>-1</SUP> (20 km s<SUP>-1</SUP>). This allowed us to determine the
IMF of the pure bulge component uncontaminated by disk stars for this
low-reddening field in the Sagittarius window. In deriving the mass
function, we took into account the presence of unresolved binaries,
errors in photometry, distance modulus and reddening, as well as
the metallicity dispersion and the uncertainties caused by adopting
different theoretical color-temperature relations. We found that the
Galactic bulge IMF can be fitted with two power laws with a break at
M∼ 0.56 {M}<SUB>⊙ </SUB>, the slope being steeper (α =-2.41+/-
0.50) for the higher masses, and shallower (α =-1.25+/- 0.20) for
the lower masses. In the high-mass range, our derived mass function
agrees well with the mass function derived for other regions of the
bulge. In the low-mass range however, our mass function is slightly
shallower, which suggests that separating the disk and bulge components
is particularly important in the low-mass range. The slope of the
bulge mass function is also similar to the slope of the mass function
derived for the disk in the high-mass regime, but the bulge mass
function is slightly steeper in the low-mass regime. We used our new
mass function to derive stellar mass-to-light values for the Galactic
bulge and we obtained 2.1 \lt M/{L}<SUB>F814W</SUB> \lt 2.4 and 3.1
\lt M/{L}<SUB>F606W</SUB> \lt 3.6 according to different assumptions
on the slope of the IMF for masses larger than 1{M}<SUB>⊙ </SUB>. <P
/>Based on observations made with the NASA/ESA Hubble Space Telescope,
obtained by the Space Telescope Science Institute. STScI is operated
by the Association of Universities for Research in Astronomy, Inc.,
under NASA contract NAS 5-26555.
---------------------------------------------------------
Title: Is there a relation between stellar wind braking and the
spatial structure of surface magnetic fields?
Authors: Brown, Timothy M.
2015IAUGA..2257429B Altcode:
For open cluster ages between about 100 Myr and 500 Myr, plots of
rotational period vs. color (or equivalently, stellar mass) are almost
bimodal, with distinct groups fast and slow rotators at all masses
between roughly 0.5 and 1.3 M_sun. One cannot explain these diagrams
without invoking some process with a lifetime of a few hundred Myr,
that for some but not all stars isolates most of the stellar angular
momentum from the torque caused by a magnetized stellar wind. The
prevailing theory [e.g. Epstein & Pinsonneault 2014 (ApJ 780,
159) and references therein] locates this process at the base of the
stellar convection zone, allowing the wind to spin down the convection
zone without much affecting the core. In Brown 2014 (ApJ 789,101) I
suggested rather that the break occurs above the stellar photosphere,
with different spatial structures of the stellar dynamos accounting
for drastically different degrees of magnetic coupling to the stellar
wind. In this talk I will describe preliminary results from two
observing programs that aim to test the latter hypothesis.One program
uses photometry from the LCOGT (ground-based, world-wide) telescope
network to measure rotational periods of stars in fairly young
open clusters, to improve comparisons between modeled and observed
period-color diagrams by increasing sample sizes. The LCOGT network
proves nearly ideal for this kind of work, having already provided good
data sets for the clusters NGC 6281 and NGC 3532. These clusters are
both about 300 Myr old, filling a gap in the current age distribution
of observed clusters. The second program uses K2 photometry combined
with multicolor photometry (from LCOGT) and spectroscopy (from the ARC
3.5m telescope) to search for rotation-dependent differences in possible
proxies for the typical spatial scale of surface magnetic fields. These
include the spot/photosphere temperature contrast, and short-timescale
variations in various diagnostics of projected starspot area.
---------------------------------------------------------
Title: A New Method for Deriving the Stellar Birth Function of
Resolved Stellar Populations.
Authors: Gennaro, M.; Tchernyshyov, K.; Brown, T. M.; Gordon, K. D.
2015ApJ...808...45G Altcode: 2015arXiv150404865G
We present a new method for deriving the stellar birth function (SBF) of
resolved stellar populations. The SBF (stars born per unit mass, time,
and metallicity) is the combination of the initial mass function (IMF),
the star formation history (SFH), and the metallicity distribution
function (MDF). The framework of our analysis is that of Poisson Point
Processes (PPPs), a class of statistical models suitable when dealing
with points (stars) in a multidimensional space (the measurement
space of multiple photometric bands). The theory of PPPs easily
accommodates the modeling of measurement errors as well as that of
incompleteness. Our method avoids binning stars in the color-magnitude
diagram and uses the whole likelihood function for each data point;
combining the individual likelihoods allows the computation of the
posterior probability for the population's SBF. Within the proposed
framework it is possible to include nuisance parameters, such as
distance and extinction, by specifying their prior distributions and
marginalizing over them. The aim of this paper is to assess the validity
of this new approach under a range of assumptions, using only simulated
data. Forthcoming work will show applications to real data. Although
it has a broad scope of possible applications, we have developed
this method to study multi-band Hubble Space Telescope observations
of the Milky Way Bulge. Therefore we will focus on simulations with
characteristics similar to those of the Galactic Bulge. <P />Based on
observations made with the NASA/ESA Hubble Space Telescope, obtained at
STScI, which is operated by AURA, Inc., under NASA contract NAS 5-26555.
---------------------------------------------------------
Title: UV Insights into the Complex Populations of M87 Globular
Clusters
Authors: Bellini, A.; Renzini, A.; Anderson, J.; Bedin, L. R.; Piotto,
G.; Soto, M.; Brown, T. M.; Milone, A. P.; Sohn, S. T.; Sweigart, A. V.
2015ApJ...805..178B Altcode: 2015arXiv150401742B
We have imaged with Hubble Space Telescope WFC3/UVIS the central
2\buildrel{ \prime}\over{.} 7× 2\buildrel{ \prime}\over{.} 7 region
of the giant elliptical galaxy M87, using the ultraviolet filter
F275W. In combination with archival ACS/WFC data taken through the
F606W and F814W filters, covering the same field, we have constructed
integrated-light UV-optical colors and magnitudes for 1460 objects,
most of which are believed to be globular clusters (GCs) belonging to
M87. The purpose was to ascertain whether the multiple-populations
syndrome, ubiquitous among Galactic GCs, also exists among the M87
family of clusters. To achieve this goal, we sought those GCs with
exceptionally blue UV-to-optical colors because helium-enriched
sub-populations produce a horizontal-branch morphology that is well
populated at high effective temperature. For comparison, integrated,
synthetic UV-optical and purely optical colors and magnitudes have
been constructed for 45 Galactic GCs, starting from individual-star
photometry obtained with the same instruments and the same filters. We
identify a small group of M87 clusters exhibiting a radial UV-optical
color gradient, representing our best candidate GCs hosting multiple
populations with extreme helium content. We also find that the central
spatial distribution of the bluer GCs is flattened in a direction
parallel to the jet, while the distribution of redder GCs is more
spherical. We release to the astronomical community our photometric
catalog in F275W, F606W, and F814W bands and the high-quality image
stacks in the same bands. <P />Based on proprietary and archival
observations with the NASA/ESA Hubble Space Telescope, obtained at the
Space Telescope Science Institute, which is operated by AURA, Inc.,
under NASA contract NAS 5-26555.
---------------------------------------------------------
Title: Low False Positive Rate of Kepler Candidates Estimated From
A Combination Of Spitzer And Follow-Up Observations
Authors: Désert, Jean-Michel; Charbonneau, David; Torres, Guillermo;
Fressin, François; Ballard, Sarah; Bryson, Stephen T.; Knutson,
Heather A.; Batalha, Natalie M.; Borucki, William J.; Brown, Timothy
M.; Deming, Drake; Ford, Eric B.; Fortney, Jonathan J.; Gilliland,
Ronald L.; Latham, David W.; Seager, Sara
2015ApJ...804...59D Altcode: 2015arXiv150303173D
NASA’s Kepler mission has provided several thousand transiting
planet candidates during the 4 yr of its nominal mission, yet only
a small subset of these candidates have been confirmed as true
planets. Therefore, the most fundamental question about these
candidates is the fraction of bona fide planets. Estimating the
rate of false positives of the overall Kepler sample is necessary to
derive the planet occurrence rate. We present the results from two
large observational campaigns that were conducted with the Spitzer
Space Telescope during the the Kepler mission. These observations
are dedicated to estimating the false positive rate (FPR) among
the Kepler candidates. We select a sub-sample of 51 candidates,
spanning wide ranges in stellar, orbital, and planetary parameter
space, and we observe their transits with Spitzer at 4.5 μm. We use
these observations to measures the candidate’s transit depths and
infrared magnitudes. An authentic planet produces an achromatic transit
depth (neglecting the modest effect of limb darkening). Conversely
a bandpass-dependent depth alerts us to the potential presence of
a blending star that could be the source of the observed eclipse:
a false positive scenario. For most of the candidates (85%), the
transit depths measured with Kepler are consistent with the transit
depths measured with Spitzer as expected for planetary objects, while
we find that the most discrepant measurements are due to the presence of
unresolved stars that dilute the photometry. The Spitzer constraints on
their own yield FPRs between 5% and depending on the Kepler Objects of
Interest. By considering the population of the Kepler field stars, and
by combining follow-up observations (imaging) when available, we find
that the overall FPR of our sample is low. The measured upper limit
on the FPR of our sample is 8.8% at a confidence level of 3σ. This
observational result, which uses the achromatic property of planetary
transit signals that is not investigated by the Kepler observations,
provides an independent indication that Kepler’s FPR is low.
---------------------------------------------------------
Title: The Hubble Space Telescope UV Legacy Survey of Galactic
Globular Clusters. I. Overview of the Project and Detection of
Multiple Stellar Populations
Authors: Piotto, G.; Milone, A. P.; Bedin, L. R.; Anderson, J.;
King, I. R.; Marino, A. F.; Nardiello, D.; Aparicio, A.; Barbuy,
B.; Bellini, A.; Brown, T. M.; Cassisi, S.; Cool, A. M.; Cunial, A.;
Dalessandro, E.; D'Antona, F.; Ferraro, F. R.; Hidalgo, S.; Lanzoni,
B.; Monelli, M.; Ortolani, S.; Renzini, A.; Salaris, M.; Sarajedini,
A.; van der Marel, R. P.; Vesperini, E.; Zoccali, M.
2015AJ....149...91P Altcode: 2014arXiv1410.4564P
In this paper we describe a new UV-initiative Hubble Space Telescope
project (GO-13297) that will complement the existing F606W and F814W
database of the Advanced Camera for Surveys Globular Cluster (GC)
Treasury by imaging most of its clusters through UV/blue WFC3/UVIS
filters F275W, F336W, and F438W. This “magic trio” of filters
has shown an uncanny ability to disentangle and characterize multiple
population (MP) patterns in GCs in a way that is exquisitely sensitive
to C, N, and O abundance variations. Combination of these passbands
with those in the optical also gives the best leverage for measuring
helium enrichment. The dozen clusters that had previously been observed
in these bands exhibit a bewildering variety of MP patterns, and the
new survey will map the full variance of the phenomenon. The ubiquity
of multiple stellar generations in GCs has made the formation of these
cornerstone objects more intriguing than ever; GC formation and the
origin of their MPs have now become one and the same problem. In this
paper we will describe the database and our data reduction strategy, as
well as the uses we intend to make of the final photometry, astrometry,
and PMs. We will also present preliminary color-magnitude diagrams
from the data so far collected. These diagrams also draw on data
from GO-12605 and GO-12311, which served as a pilot project for the
present GO-13297. <P />Based on observations with the NASA/ESA Hubble
Space Telescope, obtained at the Space Telescope Science Institute,
which is operated by AURA, Inc., under NASA contract NAS 5-26555.
---------------------------------------------------------
Title: Legacy Extragalactic UV Survey (LEGUS) With the Hubble Space
Telescope. I. Survey Description
Authors: Calzetti, D.; Lee, J. C.; Sabbi, E.; Adamo, A.; Smith, L. J.;
Andrews, J. E.; Ubeda, L.; Bright, S. N.; Thilker, D.; Aloisi, A.;
Brown, T. M.; Chandar, R.; Christian, C.; Cignoni, M.; Clayton, G. C.;
da Silva, R.; de Mink, S. E.; Dobbs, C.; Elmegreen, B. G.; Elmegreen,
D. M.; Evans, A. S.; Fumagalli, M.; Gallagher, J. S., III; Gouliermis,
D. A.; Grebel, E. K.; Herrero, A.; Hunter, D. A.; Johnson, K. E.;
Kennicutt, R. C.; Kim, H.; Krumholz, M. R.; Lennon, D.; Levay, K.;
Martin, C.; Nair, P.; Nota, A.; Östlin, G.; Pellerin, A.; Prieto,
J.; Regan, M. W.; Ryon, J. E.; Schaerer, D.; Schiminovich, D.; Tosi,
M.; Van Dyk, S. D.; Walterbos, R.; Whitmore, B. C.; Wofford, A.
2015AJ....149...51C Altcode: 2014arXiv1410.7456C
The Legacy ExtraGalactic UV Survey (LEGUS) is a Cycle 21 Treasury
program on the Hubble Space Telescope aimed at the investigation of star
formation and its relation with galactic environment in nearby galaxies,
from the scales of individual stars to those of ∼kiloparsec-size
clustered structures. Five-band imaging from the near-ultraviolet to
the I band with the Wide-Field Camera 3 (WFC3), plus parallel optical
imaging with the Advanced Camera for Surveys (ACS), is being collected
for selected pointings of 50 galaxies within the local 12 Mpc. The
filters used for the observations with the WFC3 are F275W(λ2704 Å),
F336W(λ3355 Å), F438W(λ4325 Å), F555W(λ5308 Å), and F814W(λ8024
Å) the parallel observations with the ACS use the filters F435W(λ4328
Å), F606W(λ5921 Å), and F814W(λ8057 Å). The multiband images are
yielding accurate recent (≲50 Myr) star formation histories from
resolved massive stars and the extinction-corrected ages and masses of
star clusters and associations. The extensive inventories of massive
stars and clustered systems will be used to investigate the spatial
and temporal evolution of star formation within galaxies. This will, in
turn, inform theories of galaxy evolution and improve the understanding
of the physical underpinning of the gas-star formation relation and
the nature of star formation at high redshift. This paper describes
the survey, its goals and observational strategy, and the initial
scientific results. Because LEGUS will provide a reference survey
and a foundation for future observations with the James Webb Space
Telescope and with ALMA, a large number of data products are planned
for delivery to the community. <P />Based on observations obtained with
the NASA/ESA Hubble Space Telescope at the Space Telescope Science
Institute, which is operated by the Association of Universities for
Research in Astronomy under NASA Contract NAS 5-26555.
---------------------------------------------------------
Title: The Hubble Space Telescope UV Legacy Survey of galactic
globular clusters - II. The seven stellar populations of NGC 7089
(M2)<SUP>⋆</SUP>
Authors: Milone, A. P.; Marino, A. F.; Piotto, G.; Bedin, L. R.;
Anderson, J.; Renzini, A.; King, I. R.; Bellini, A.; Brown, T. M.;
Cassisi, S.; D'Antona, F.; Jerjen, H.; Nardiello, D.; Salaris,
M.; Marel, R. P. van der; Vesperini, E.; Yong, D.; Aparicio, A.;
Sarajedini, A.; Zoccali, M.
2015MNRAS.447..927M Altcode: 2014arXiv1411.5043M; 2015MNRAS.447..931M
We present high-precision multiband photometry for the globular cluster
(GC) M2. We combine the analysis of the photometric data obtained from
the Hubble Space Telescope UV Legacy Survey of Galactic GCs GO-13297,
with chemical abundances by Yong et al., and compare the photometry with
models in order to analyse the multiple stellar sequences we identified
in the colour-magnitude diagram. We find three main stellar components,
composed of metal-poor, metal-intermediate, and metal-rich stars
(hereafter referred to as population A, B, and C, respectively). The
components A and B include stars with different s-process element
abundances. They host six sub-populations with different light-element
abundances, and exhibit an internal variation in helium up to ΔY
∼ 0.07 dex. In contrast with M22, another cluster characterized
by the presence of populations with different metallicities, M2
contains a third stellar component, C, which shows neither evidence for
sub-populations nor an internal spread in light-elements. Population C
does not exhibit the typical photometric signatures that are associated
with abundance variations of light elements produced by hydrogen burning
at hot temperatures. We compare M2 with other GCs with intrinsic
heavy-element variations and conclude that M2 resembles M22, but it
includes an additional stellar component that makes it more similar to
the central region of the Sagittarius galaxy, which hosts a GC (M54)
and the nucleus of the Sagittarius galaxy itself.
---------------------------------------------------------
Title: NRES: The Network of Robotic Echelle Spectrographs
Authors: Siverd, Robert; Eastman, Jason D.; Brown, Timothy M.;
Hygelund, John; Henderson, Todd; Tufts, Joseph; Van Eyken, Julian C.;
Barnes, Stuart
2015AAS...22540904S Altcode:
Las Cumbres Observatory Global Network (LCOGT) is building the Network
of Robotic Echelle Spectrographs (NRES), which will consist of six
identical, optical (390 - 860 nm) high-precision spectrographs, each
fiber-fed simultaneously by two 1 meter telescopes and a thorium
argon calibration source, one at each of our observatory sites in
the Northern and Southern hemispheres. Thus, NRES will be a single,
globally-distributed, autonomous observing facility using twelve 1-m
telescopes. Simulations suggest we will achieve long-term radial
velocity precision of better than 3 m/s in less than an hour for
stars brighter than V = 12. We have been funded with NSF MRI and ATI
grants, and expect our first spectrograph to be deployed in mid 2015,
with the full network operation of all 6 units beginning in 2016. We
will discuss the NRES design, goals, robotic operation, and status,
as well as the early results from our prototype spectrograph.
---------------------------------------------------------
Title: Transiting Exoplanet Survey Satellite (TESS)
Authors: Ricker, George R.; Winn, Joshua N.; Vanderspek, Roland;
Latham, David W.; Bakos, Gáspár Á.; Bean, Jacob L.; Berta-Thompson,
Zachory K.; Brown, Timothy M.; Buchhave, Lars; Butler, Nathaniel
R.; Butler, R. Paul; Chaplin, William J.; Charbonneau, David;
Christensen-Dalsgaard, Jørgen; Clampin, Mark; Deming, Drake; Doty,
John; De Lee, Nathan; Dressing, Courtney; Dunham, Edward W.; Endl,
Michael; Fressin, Francois; Ge, Jian; Henning, Thomas; Holman, Matthew
J.; Howard, Andrew W.; Ida, Shigeru; Jenkins, Jon M.; Jernigan,
Garrett; Johnson, John Asher; Kaltenegger, Lisa; Kawai, Nobuyuki;
Kjeldsen, Hans; Laughlin, Gregory; Levine, Alan M.; Lin, Douglas;
Lissauer, Jack J.; MacQueen, Phillip; Marcy, Geoffrey; McCullough,
Peter R.; Morton, Timothy D.; Narita, Norio; Paegert, Martin; Palle,
Enric; Pepe, Francesco; Pepper, Joshua; Quirrenbach, Andreas; Rinehart,
Stephen A.; Sasselov, Dimitar; Sato, Bun'ei; Seager, Sara; Sozzetti,
Alessandro; Stassun, Keivan G.; Sullivan, Peter; Szentgyorgyi, Andrew;
Torres, Guillermo; Udry, Stephane; Villasenor, Joel
2015JATIS...1a4003R Altcode:
The Transiting Exoplanet Survey Satellite (TESS) will search for
planets transiting bright and nearby stars. TESS has been selected
by NASA for launch in 2017 as an Astrophysics Explorer mission. The
spacecraft will be placed into a highly elliptical 13.7-day orbit
around the Earth. During its 2-year mission, TESS will employ four
wide-field optical charge-coupled device cameras to monitor at least
200,000 main-sequence dwarf stars with I<SUB>C</SUB>≈4-13 for
temporary drops in brightness caused by planetary transits. Each
star will be observed for an interval ranging from 1 month to 1
year, depending mainly on the star's ecliptic latitude. The longest
observing intervals will be for stars near the ecliptic poles, which
are the optimal locations for follow-up observations with the James
Webb Space Telescope. Brightness measurements of preselected target
stars will be recorded every 2 min, and full frame images will be
recorded every 30 min. TESS stars will be 10 to 100 times brighter
than those surveyed by the pioneering Kepler mission. This will make
TESS planets easier to characterize with follow-up observations. TESS
is expected to find more than a thousand planets smaller than Neptune,
including dozens that are comparable in size to the Earth. Public data
releases will occur every 4 months, inviting immediate community-wide
efforts to study the new planets. The TESS legacy will be a catalog
of the nearest and brightest stars hosting transiting planets, which
will endure as highly favorable targets for detailed investigations.
---------------------------------------------------------
Title: Transiting Exoplanet Survey Satellite (TESS)
Authors: Ricker, George R.; Winn, Joshua N.; Vanderspek, Roland;
Latham, David W.; Bakos, Gáspár. Á.; Bean, Jacob L.; Berta-Thompson,
Zachory K.; Brown, Timothy M.; Buchhave, Lars; Butler, Nathaniel
R.; Butler, R. Paul; Chaplin, William J.; Charbonneau, David;
Christensen-Dalsgaard, Jørgen; Clampin, Mark; Deming, Drake; Doty,
John; De Lee, Nathan; Dressing, Courtney; Dunham, E. W.; Endl, Michael;
Fressin, Francois; Ge, Jian; Henning, Thomas; Holman, Matthew J.;
Howard, Andrew W.; Ida, Shigeru; Jenkins, Jon; Jernigan, Garrett;
Johnson, John A.; Kaltenegger, Lisa; Kawai, Nobuyuki; Kjeldsen, Hans;
Laughlin, Gregory; Levine, Alan M.; Lin, Douglas; Lissauer, Jack J.;
MacQueen, Phillip; Marcy, Geoffrey; McCullough, P. R.; Morton, Timothy
D.; Narita, Norio; Paegert, Martin; Palle, Enric; Pepe, Francesco;
Pepper, Joshua; Quirrenbach, Andreas; Rinehart, S. A.; Sasselov,
Dimitar; Sato, Bun'ei; Seager, Sara; Sozzetti, Alessandro; Stassun,
Keivan G.; Sullivan, Peter; Szentgyorgyi, Andrew; Torres, Guillermo;
Udry, Stephane; Villasenor, Joel
2014SPIE.9143E..20R Altcode: 2014arXiv1406.0151R
The Transiting Exoplanet Survey Satellite (TESS ) will search for
planets transiting bright and nearby stars. TESS has been selected
by NASA for launch in 2017 as an Astrophysics Explorer mission. The
spacecraft will be placed into a highly elliptical 13.7-day orbit
around the Earth. During its two-year mission, TESS will employ
four wide-field optical CCD cameras to monitor at least 200,000
main-sequence dwarf stars with I<SUB>C</SUB> (approximately less than)
13 for temporary drops in brightness caused by planetary transits. Each
star will be observed for an interval ranging from one month to one
year, depending mainly on the star's ecliptic latitude. The longest
observing intervals will be for stars near the ecliptic poles, which
are the optimal locations for follow-up observations with the James
Webb Space Telescope. Brightness measurements of preselected target
stars will be recorded every 2 min, and full frame images will be
recorded every 30 min. TESS stars will be 10-100 times brighter than
those surveyed by the pioneering Kepler mission. This will make TESS
planets easier to characterize with follow-up observations. TESS is
expected to find more than a thousand planets smaller than Neptune,
including dozens that are comparable in size to the Earth. Public data
releases will occur every four months, inviting immediate community-wide
efforts to study the new planets. The TESS legacy will be a catalog
of the nearest and brightest stars hosting transiting planets, which
will endure as highly favorable targets for detailed investigations.
---------------------------------------------------------
Title: The Metastable Dynamo Model of Stellar Rotational Evolution
Authors: Brown, Timothy M.
2014ApJ...789..101B Altcode: 2014arXiv1403.4525B
This paper introduces a new empirical model for the rotational
evolution of Sun-like stars—those with surface convection zones
and non-convective interior regions. Previous models do not match the
morphology of observed (rotation period)-color diagrams, notably the
existence of a relatively long-lived "C-sequence" of fast rotators first
identified by Barnes. This failure motivates the Metastable Dynamo Model
(MDM) described here. The MDM posits that stars are born with their
magnetic dynamos operating in a mode that couples very weakly to the
stellar wind, so their (initially very short) rotation periods at first
change little with time. At some point, this mode spontaneously and
randomly changes to a strongly coupled mode, the transition occurring
with a mass-dependent lifetime that is of the order of 100 Myr. I show
that with this assumption, one can obtain good fits to observations of
young clusters, particularly for ages of 150-200 Myr. Previous models
and the MDM both give qualitative agreement with the morphology of
the slower-rotating "I-sequence" stars, but none of them have been
shown to accurately reproduce the stellar-mass-dependent evolution
of the I-sequence stars, especially for clusters older than a few
hundred million years. I discuss observational experiments that can
test aspects of the MDM, and speculate that the physics underlying the
MDM may be related to other situations described in the literature,
in which stellar dynamos may have a multi-modal character.
---------------------------------------------------------
Title: NRES: the network of robotic Echelle spectrographs
Authors: Eastman, Jason D.; Brown, Timothy M.; Hygelund, John; van
Eyken, Julian; Tufts, Joseph R.; Barnes, Stuart
2014SPIE.9147E..16E Altcode:
Las Cumbres Observatory Global Network (LCOGT) is building the Network
of Robotic Echelle Spectrographs (NRES), which will consist of six
identical, optical (390 - 860 nm) high-precision spectrographs, each
fiber-fed simultaneously by two 1 meter telescopes and a thorium
argon calibration source, one at each of our observatory sites in
the Northern and Southern hemispheres. Thus, NRES will be a single,
globally-distributed, autonomous observing facility using twelve 1-m
telescopes. Simulations suggest we will achieve long-term precision
of better than 3 m/s in less than an hour for stars brighter than V =
12. We have been fully funded with an NSF MRI grant, and expect our
first spectrograph to be deployed in Spring of 2015, with the full
network operation of all 6 units beginning in Spring of 2016. We
discuss the NRES design, goals, and robotic operation, as well as the
early results from our prototype spectrograph.
---------------------------------------------------------
Title: VizieR Online Data Catalog: Small Kepler planets radial
velocities (Marcy+, 2014)
Authors: Marcy, G. W.; Isaacson, H.; Howard, A. W.; Rowe, J. F.;
Jenkins, J. M.; Bryson, S. T.; Latham, D. W.; Howell, S. B.;
Gautier, T. N., III; Batalha, N. M.; Rogers, L.; Ciardi, D.; Fischer,
D. A.; Gilliland, R. L.; Kjeldsen, H.; Christensen-Dalsgaard, J.;
Huber, D.; Chaplin, W. J.; Basu, S.; Buchhave, L. A.; Quinn, S. N.;
Borucki, W. J.; Koch, D. G.; Hunter, R.; Caldwell, D. A.; van Cleve,
J.; Kolbl, R.; Weiss, L. M.; Petigura, E.; Seager, S.; Morton, T.;
Johnson, J. A.; Ballard, S.; Burke, C.; Cochran, W. D.; Endl, M.;
MacQueen, P.; Everett, M. E.; Lissauer, J. J.; Ford, E. B.; Torres,
G.; Fressin, F.; Brown, T. M.; Steffen, J. H.; Charbonneau, D.; Basri,
G. S.; Sasselov, D. D.; Winn, J.; Sanchis-Ojeda, R.; Christiansen,
J.; Adams, E.; Henze, C.; Dupree, A.; Fabrycky, D. C.; Fortney, J. J.;
Tarter, J.; Holman, M. J.; Tenenbaum, P.; Shporer, A.; Lucas, P. W.;
Welsh, W. F.; Orosz, J. A.; Bedding, T. R.; Campante, T. L.; Davies,
G. R.; Elsworth, Y.; Handberg, R.; Hekker, S.; Karoff, C.; Kawaler,
S. D.; Lund, M. N.; Lundkvist, M.; Metcalfe, T. S.; Miglio, A.; Silva
Aguirre, V.; Stello, D.; White, T. R.; Boss, A.; Devore, E.; Gould,
A.; Prsa, A.; Agol, E.; Barclay, T.; Coughlin, J.; Brugamyer, E.;
Mullally, F.; Quintana, E. V.; Still, M.; Thompson, S. E.; Morrison,
D.; Twicken, J. D.; Desert, J. -M.; Carter, J.; Crepp, J. R.; Hebrard,
G.; Santerne, A.; Moutou, C.; Sobeck, C.; Hudgins, D.; Haas, M. R.;
Robertson, P.; Lillo-Box, J.; Barrado, D.
2014yCat..22100020M Altcode:
Here we report measured masses, radii, and densities (or upper limits
on those values) for 42 transiting planet candidates contained within
22 bright Kepler Objects of Interest (KOIs) from Batalha et al. (2013,
Cat. J/ApJS/204/24). We carried out multiple Doppler-shift measurements
of the host stars using the Keck 1 telescope. From the spectroscopy
and Doppler measurements, we compute self-consistent measurements of
stellar and planet radii, employing either stellar structure models
or asteroseismology measurements from the Kepler photometry. We also
search for (and report) 7 additional non-transiting planets revealed
by the precise radial velocities (RVs), for a total of 49 planets. <P
/>We carried out "reconnaissance" high-resolution spectroscopy on ~1000
KOIs with spectral resolution, R~50000, and S/N=20-100 per pixel. The
dual goals were searching for false positives and refining the stellar
parameters. We obtained one or two such reconnaissance spectra using
one of four facilities: the McDonald Observatory 2.7m, the Tillinghast
1.5m on Mt. Hopkins, the Lick Observatory 3m, and the 2.6m Nordic
Optical Telescope. <P />Speckle imaging of each of the selected 22
KOIs was obtained using the two-color DSSI speckle camera at the WIYN
3.5m telescope on Kitt Peak. <P />All 22 KOIs were observed with the
Keck NIRC2-AO system. <P />(3 data files).
---------------------------------------------------------
Title: PTFO 8-8695b: An Extremely Young T-Tauri-Transiting Planet
Authors: van Eyken, J. C.; Ciardi, D. R.; Barnes, J. W.; Brown,
T. M.; Dragomir, D.; Eastman, J.; Beichman, C. A.; Belle, G. v.;
Braun, K. v.; Carey, S.; Crockett, C.; Fortney, J. J.; Howell, S. B.;
Jackson, B. K.; Johns-Krull, C.; Kane, S. R.; Lister, T.; Mazin, B.;
McLane, J.; Plavchan, P.; Prato, L.; Shporer, A.; Stauffer, J. R.;
PTF Collaboration
2014ebi..confP3.57V Altcode:
Estimated at only ~3Myr old, PTFO 8-8695b is a candidate for the
youngest transiting planet yet found, and presents a potentially
valuable snapshot of a close-in pre-main-sequence planet still in its
infancy. Ongoing investigation is painting an unusual but increasingly
compelling picture: orbiting a rapidly-rotating T-Tauri star at just
under a half-day period, it appears the planet's orbit may be inclined
and precessing on timescales as short as ~hundreds of days - a timescale
easily accessible to observation. The star shows substantial flaring
activity, and the planet's measured radius suggests that it may be
actively be losing mass. The unusual properties of this object make
it particularly interesting for continued investigation. We present
some of our current observations and our interpretation of the data.
---------------------------------------------------------
Title: Masses, Radii, and Orbits of Small Kepler Planets: The
Transition from Gaseous to Rocky Planets
Authors: Marcy, Geoffrey W.; Isaacson, Howard; Howard, Andrew W.;
Rowe, Jason F.; Jenkins, Jon M.; Bryson, Stephen T.; Latham, David
W.; Howell, Steve B.; Gautier, Thomas N., III; Batalha, Natalie M.;
Rogers, Leslie; Ciardi, David; Fischer, Debra A.; Gilliland, Ronald
L.; Kjeldsen, Hans; Christensen-Dalsgaard, Jørgen; Huber, Daniel;
Chaplin, William J.; Basu, Sarbani; Buchhave, Lars A.; Quinn, Samuel
N.; Borucki, William J.; Koch, David G.; Hunter, Roger; Caldwell,
Douglas A.; Van Cleve, Jeffrey; Kolbl, Rea; Weiss, Lauren M.;
Petigura, Erik; Seager, Sara; Morton, Timothy; Johnson, John Asher;
Ballard, Sarah; Burke, Chris; Cochran, William D.; Endl, Michael;
MacQueen, Phillip; Everett, Mark E.; Lissauer, Jack J.; Ford, Eric
B.; Torres, Guillermo; Fressin, Francois; Brown, Timothy M.; Steffen,
Jason H.; Charbonneau, David; Basri, Gibor S.; Sasselov, Dimitar D.;
Winn, Joshua; Sanchis-Ojeda, Roberto; Christiansen, Jessie; Adams,
Elisabeth; Henze, Christopher; Dupree, Andrea; Fabrycky, Daniel C.;
Fortney, Jonathan J.; Tarter, Jill; Holman, Matthew J.; Tenenbaum,
Peter; Shporer, Avi; Lucas, Philip W.; Welsh, William F.; Orosz,
Jerome A.; Bedding, T. R.; Campante, T. L.; Davies, G. R.; Elsworth,
Y.; Handberg, R.; Hekker, S.; Karoff, C.; Kawaler, S. D.; Lund,
M. N.; Lundkvist, M.; Metcalfe, T. S.; Miglio, A.; Silva Aguirre, V.;
Stello, D.; White, T. R.; Boss, Alan; Devore, Edna; Gould, Alan; Prsa,
Andrej; Agol, Eric; Barclay, Thomas; Coughlin, Jeff; Brugamyer, Erik;
Mullally, Fergal; Quintana, Elisa V.; Still, Martin; Thompson, Susan
E.; Morrison, David; Twicken, Joseph D.; Désert, Jean-Michel; Carter,
Josh; Crepp, Justin R.; Hébrard, Guillaume; Santerne, Alexandre;
Moutou, Claire; Sobeck, Charlie; Hudgins, Douglas; Haas, Michael R.;
Robertson, Paul; Lillo-Box, Jorge; Barrado, David
2014ApJS..210...20M Altcode: 2014arXiv1401.4195M
We report on the masses, sizes, and orbits of the planets orbiting
22 Kepler stars. There are 49 planet candidates around these stars,
including 42 detected through transits and 7 revealed by precise
Doppler measurements of the host stars. Based on an analysis of the
Kepler brightness measurements, along with high-resolution imaging and
spectroscopy, Doppler spectroscopy, and (for 11 stars) asteroseismology,
we establish low false-positive probabilities (FPPs) for all of the
transiting planets (41 of 42 have an FPP under 1%), and we constrain
their sizes and masses. Most of the transiting planets are smaller
than three times the size of Earth. For 16 planets, the Doppler
signal was securely detected, providing a direct measurement of the
planet's mass. For the other 26 planets we provide either marginal mass
measurements or upper limits to their masses and densities; in many
cases we can rule out a rocky composition. We identify six planets
with densities above 5 g cm<SUP>-3</SUP>, suggesting a mostly rocky
interior for them. Indeed, the only planets that are compatible with a
purely rocky composition are smaller than ~2 R <SUB>⊕</SUB>. Larger
planets evidently contain a larger fraction of low-density material (H,
He, and H<SUB>2</SUB>O). <P />Based in part on observations obtained
at the W. M. Keck Observatory, which is operated by the University of
California and the California Institute of Technology.
---------------------------------------------------------
Title: Adapting Low-Tech Gear to Exoplanet Discovery
Authors: Brown, Timothy M.
2014AAS...223.9106B Altcode:
The discovery of 51 Peg b by Mayor and Queloz revealed (among other
things) that discovering extrasolar planets, though certainly difficult,
was not as hard as professional astronomers had previously thought. At
the same time, the astronomical equipment available to amateurs --
including optics, mountings, and CCD detectors -- had become quite
capable. This combination of factors led to successful exoplanet
programs that leaned heavily on amateur-grade hardware, seeking faster
development times and lower costs than were possible for traditional
no-compromises astronomical instrument programs. I will describe two of
these in which I played a role: the AFOE (Advanced Fiber Optic Echelle)
spectrograph, and the STellar Astrophysics and Research on Exoplanets
(STARE) transit-search wide-field imager.
---------------------------------------------------------
Title: Legacy ExtraGalactic UV Survey (LEGUS): The HST View of Star
Formation in Nearby Galaxies
Authors: Calzetti, Daniela; Lee, J. C.; Adamo, A.; Aloisi, A.; Andrews,
J. E.; Brown, T. M.; Chandar, R.; Christian, C. A.; Cignoni, M.;
Clayton, G. C.; Da Silva, R. L.; de Mink, S. E.; Dobbs, C.; Elmegreen,
B.; Elmegreen, D. M.; Evans, A. S.; Fumagalli, M.; Gallagher, J. S.;
Gouliermis, D.; Grebel, E.; Herrero-Davo`, A.; Hilbert, B.; Hunter,
D. A.; Johnson, K. E.; Kennicutt, R.; Kim, H.; Krumholz, M. R.; Lennon,
D. J.; Martin, C. D.; Nair, P.; Nota, A.; Pellerin, A.; Prieto, J.;
Regan, M. W.; Sabbi, E.; Schaerer, D.; Schiminovich, D.; Smith, L. J.;
Thilker, D. A.; Tosi, M.; Van Dyk, S. D.; Walterbos, R. A.; Whitmore,
B. C.; Wofford, A.
2014AAS...22325408C Altcode:
The Treasury program LEGUS (HST/GO-13364) is the first HST UV Atlas
of nearby galaxies, and is aimed at the thorough investigation of star
formation and its relation with galaxy environment, from the scales of
individual stars to those of ~kpc clustered structures. The 154-orbits
program is obtaining NUV,U,B,V,I images of 50 star-forming galaxies
in the distance range 4-12 Mpc, covering the full range of morphology,
star formation rate (SFR), mass, metallicity, internal structure, and
interaction state found in the local Universe. The imaging survey will
yield accurate recent (<50 Myr) star formation histories (SFHs)
from resolved massive stars, and the extinction-corrected ages and
masses of star clusters and associations. These extensive inventories
of massive stars, clustered systems, and SFHs will be used to: (1)
quantify how the clustering of star formation evolves both in space and
in time; (2) discriminate among models of star cluster evolution; (3)
investigate the effects of SFH on the UV SFR calibrations; (4) explore
the impact of environment on star formation and cluster evolution across
the full range of galactic and ISM properties. LEGUS observations
will inform theories of star formation and galaxy evolution, and
improve the understanding of the physical underpinning of the gas-star
formation relation and the nature of the clumpy star formation at high
redshift. LEGUS will generate the most homogeneous high-resolution,
wide-field UV dataset to date, building and expanding on the GALEX
legacy. Data products that will be delivered to the community include:
catalogs of massive stars and star clusters, catalogs of star cluster
properties (ages, masses, extinction), and a one-stop shop for all the
ancillary data available for this well-studied galaxy sample. LEGUS will
provide the reference survey and the foundation for future observations
with JWST and with ALMA. This abstract accompanies another one from the
same project, and presents the status of the project, its structure,
and the data products that will be delivered to the community; the
other abstract presents the science goals of LEGUS and how these will
be addressed by the HST observations.
---------------------------------------------------------
Title: The white dwarf cooling sequence of the Galactic bulge
Authors: Calamida, Annalisa; Sahu, K. C.; Anderson, J.; Casertano,
S.; Brown, T. M.; Cassisi, S.; Sokol, J.; Bond, H. E.; Ferguson,
H. C.; Livio, M.; Salaris, M.; Ferraro, I.; Valenti, J. A.
2014AAS...22331508C Altcode:
We present F606W,F814W (V,I)-band time-series data of ~1 million stars
in the low-reddening Sagittarius window in the Galactic bulge. Images
were collected with the Advanced Camera far Surveys (ACS) and the Wide
Field Camera 3 mounted on the Hubble Space Telescope. The total field
of view is ~ 17x18 arcminutes, which was observed approximately every
two weeks for two consecutive years, with the principal aim to detect
a hidden population of isolated black holes and neutron stars in the
Galactic disk through astrometric microlensing. Here we present some
results based on the combined deep images of the four ACS fields. The
final photometric catalog of ~ 1 million stars reaches down to V ~ 31
mag. Proper motions were also measured, with an accuracy of better than
~ 0.15 mas/yr at V ~ 26 mag in both coordinates. We were then able to
separate disk and bulge stars and obtain a clean bulge color-magnitude
diagram. Together with several candidate extreme horizontal branch
(EHB) stars we were able to identify for the first time a clearly
defined white dwarf (WD) cooling sequence in the bulge. The comparison
between theory and observations shows that a fraction of the WDs is
systematically redder than the canonical cooling tracks for CO-core DA
WDs. This evidence would suggest the presence of He-core WDs in the
bulge, formed in close binaries, as has been found in some Galactic
globular and open clusters. The presence of close binaries in the EHB
and WD bulge population is further supported by the finding of two
EHB ellipsoidal variables and a candidate dwarf nova in outburst in
one of the ACS fields.
---------------------------------------------------------
Title: Noise characteristics of LCOGT time series photometry
Authors: Dragomir, Diana; Brown, T. M.
2014AAS...22330202D Altcode:
The Las Cumbres Observatory Global Telescope (LCOGT) facility consists
of a network of robotic telescopes located at multiple sites in both the
northern and southern hemispheres. We have deployed and commissioned
nine 1.0m telescopes. Eight of these are distributed longitudinally
at three sites to provide continuous night-time coverage in the
south. LCOGT's unique capabilities can contribute to a wide range of
research in the field of time-domain astronomy. To ensure optimal data
quality for individual as well as combined multi-telescope time series,
it is essential that we understand and correct - whenever possible - the
instrument systematics affecting LCOGT network observations. We identify
physical sources of noise present in LCOGT 1.0m photometry, and we use
singular value decomposition (SVD) to filter correlated noise patterns
common to an ensemble of stars in a given time series data set. We
quantify and compare the levels of uncorrelated and correlated noise
before and after SVD filtering using power spectral analysis. Finally,
we discuss the properties of and methods to reduce any remaining
post-SVD red noise that is due to instrumental systematics.
---------------------------------------------------------
Title: The formation history of the Ultra-Faint Dwarf galaxies
Authors: Brown, T. M.; Tumlinson, J.; Geha, M.; Kirby, E.; VandenBerg,
D. A.; Kalirai, J. S.; Simon, J. D.; Avila, R. J.; Munoz, R. R.;
Guhathakurta, P.; Renzini, A.; Ferguson, H. C.; Vargas, L. C.;
Gennaro, M.
2014MmSAI..85..493B Altcode: 2013arXiv1310.0824B
We present early results from a Hubble Space Telescope survey of the
ultra-faint dwarf galaxies. These Milky Way satellites were discovered
in the Sloan Digital Sky Survey, and appear to be an extension of the
classical dwarf spheroidals to low luminosities, offering a new front
in the efforts to understand the missing satellite problem. Because they
are the least luminous, most dark matter dominated, and least chemically
evolved galaxies known, the ultra-faint dwarfs are the best candidate
fossils from the early universe. The primary goal of the survey is
to measure the star-formation histories of these galaxies and discern
any synchronization due to the reionization of the universe. We find
that the six galaxies of our survey have very similar star-formation
histories, and that each is dominated by stars older than 12 Gyr.
---------------------------------------------------------
Title: The LCOGT Science Collaboration
Authors: Brown, Timothy M.; Boroson, T. A.; Howell, D. A.; Street,
R.; Lister, T.
2014AAS...22325443B Altcode:
Las Cumbres Observatory Global Telescope (LCOGT) has deployed a
global network of 1-m and 2m optical telescopes, optimized for work
in time-domain astronomy. Since our scientific staff is rather small,
and since network operation necessarily involves close collaborations
with other astronomical institutions, we aim to extend the scientific
depth and scope of the Observatory by creating a formal Science
Collaboration. This poster explains the structure and membership
of the Collaboration, with emphasis on the notion of Key Projects
that we intend as vehicles to perform scientific programs for which
LCOGT's facilities are uniquely suited, and which will have the
greatest scientific impact. The general subjects of these projects
are already defined (Supernovae, Extrasolar Planets, Solar System,
AGN, and Stellar Astrophysics). A Collaboration-wide proposal process
to be carried out in early 2014 will determine which problems within
these categories will be addressed in the first round of Key Projects.
---------------------------------------------------------
Title: NRES: The Network of Robotic Echelle Spectrographs
Authors: Eastman, Jason; Brown, T. M.; Hygelund, J.; Van Eyken, J. C.
2014AAS...22313605E Altcode:
Las Cumbres Observatory Global Network (LCOGT) is building the Network
of Robotic Echelle Spectrographs (NRES), which will consist of six
identical, optical (390 - 860 nm) high-precision spectrographs, each
fiber-fed simultaneously by two 1 meter telescopes and a thorium
argon calibration source, one at each of our observatory sites in
the Northern and Southern hemispheres. Thus, NRES will be a single,
globally-distributed, autonomous observing facility using twelve 1-m
telescopes. Simulations suggest we will achieve long-term precision
of better than 3 m/s in less than an hour for stars brighter than V =
12. We have been fully funded with an NSF MRI grant, and expect our
first spectrograph to be deployed in Spring of 2015, with the full
network operation of all 6 units beginning in Spring of 2015. We will
discuss the NRES design, goals, and robotic operation, as well as the
early results from our prototype spectrograph.
---------------------------------------------------------
Title: The IMF and SFH of the Galactic Bulge from HST
Authors: Gennaro, M.; Brown, T. M.; Anderson, J.; Avila, R.; van den
Berg, D. A.; Sahu, K.; Bond, H. E.; Casertano, S.; Ferguson, H. C.;
Livio, M.; Minniti, D.; Panagia, N.; Renzini, A.; Tumlinson, J.;
Valenti, E.; Valenti, J. A.; Zoccali, M.
2014fegb.confE..23G Altcode:
No abstract at ADS
---------------------------------------------------------
Title: LEGUS: A Legacy ExtraGalactic UV Survey of Nearby Galaxies
with HST
Authors: Lee, Janice C.; Calzetti, D.; Adamo, A.; Aloisi, A.; Andrews,
J. E.; Brown, T. M.; Chandar, R.; Christian, C. A.; Cignoni, M.;
Clayton, G. C.; Da Silva, R. L.; de Mink, S. E.; Dobbs, C.; Elmegreen,
B.; Elmegreen, D. M.; Evans, A. S.; Fumagalli, M.; Gallagher, J. S.;
Gouliermis, D.; Grebel, E.; Herrero-Davo`, A.; Hilbert, B.; Hunter,
D. A.; Johnson, K. E.; Kennicutt, R.; Kim, H.; Krumholz, M. R.; Lennon,
D. J.; Martin, C. D.; Nair, P.; Nota, A.; Pellerin, A.; Prieto, J.;
Regan, M. W.; Sabbi, E.; Schaerer, D.; Schiminovich, D.; Smith, L. J.;
Thilker, D. A.; Tosi, M.; Van Dyk, S. D.; Walterbos, R. A.; Whitmore,
B. C.; Wofford, A.
2014AAS...22321701L Altcode:
We introduce LEGUS, a Hubble Space Telescope program which will
provide a critical missing piece in our efforts to solve the star
formation puzzle: a robust characterization of the links between star
formation on two fundamental scales, those of individual young stars,
stellar clusters and associations over parsec scales, and of galaxy
disks over kiloparsec scales. As a 154-orbit Treasury survey, LEGUS
has begun obtaining NUV,U,B,V,I imaging of 50 star-forming galaxies,
at distances of 4-12 Mpc. The dataset is guaranteed to have exceptional
legacy value, as the targets have been carefully selected to uniformly
sample a full range of global galaxy properties, as well as have
the largest suites of multi-wavelength ancillary data available. The
high-resolution HST NUV and U imaging are key for deriving accurate
recent (<50 Myr) star formation histories from resolved massive
stars, along with the ages and masses for complete samples of star
clusters and associations in each galaxy. We present an overview of
the sample, the observations, and provide a first look at the science
that the LEGUS team is pursuing. A companion poster presents the status
of the program, and a more detailed description of the extensive data
products being developed which will seed community science, and provide
a foundation for studies of star formation with ALMA and JWST.
---------------------------------------------------------
Title: The History of the Fourier Tachometer
Authors: Beckers, J. M.; Brown, T. M.
2013ASPC..478...93B Altcode:
Following a suggestion by one of us (T. Brown) we developed in 1978
at the Sacramento Peak Observatory the first version of what we
called a Fourier Tachometer which measured the phase of a single
frequency component of the Fourier transform of the solar spectrum
associated with a specific solar spectrum line (Beckers & Brown
1978). This phase is a direct measure of the wavelength of that
Line, its Doppler shift and by using polarization optics, its Zeeman
splitting. This first version based on a Michelson interferometer
(FT I) was later (Evans 1081) greatly improved by J.W. Evans by using
a Solid Polarizing Interferometer (version FT II). The latest version
stands out by its ability to: (i) get wavelength measurements over a
large 2D field-of-view without the cumbersome use of a high-resolution
spectrograph, (ii) have a wide angular field-of-view and étendue, (iii)
be mechanically stable and use much real-time digital processing. The
FT II was selected for use in Global Oscillation Network Group (GONG)
in about 1985 and has since then also been used in the space based
helioseismometers — Micheson Doppler Imager (MDI) onboard Solar
and Heliospheric Observatory (Scherrer et al. 1995) and Helioseismic
Magnetic Imager (HMI) onboard Solar Dynamics Observatory (Scherrer et
al. 2012). The FT II performance has increased over the years with the
current HMI version having 4096 × 4096 pixels, or 0.5 × 0.5 arcsec
for the HMI full disk facility, and a cadence of 45 seconds. However,
except for some early observations at the Sacramento Peak, the Fourier
Tachometer has not appeared to have been applied to non-helioseismology
ground-based observations. In ground-based telescopes science full
precise line profiles are generally desired making the FT II undesirable
since it only measures something close to their center-of-gravity. For
future very large diameter (1.5 - 8 m) ground-based solar telescopes
that will also be the case. But complimentary FT II observations,
for example from the spectrograph reflecting slit-jaws, would
provide valuable, high time and spatial resolution complimentary
observations. The HMI version would have pixel sizes of about 0.03
× 0.03 arcsec, closely matching the telescope resolution over a 2
× 2 arcmin field-of-view provided by its Multi-Conjugate Adaptive
Optics system.
---------------------------------------------------------
Title: Observations and Orbits of Comets
Authors: Bacci, P.; Tesi, L.; Fagioli, G.; Cernis, K.; Foglia, S.;
Galli, G.; Buzzi, L.; Snodgrass, C.; Sarneczky, K.; Bill, H.; Arnold,
L.; Wainscoat, R. J.; Micheli, M.; Forshay, P.; Scotti, J. V.; Hill,
R. E.; Kowalski, R. A.; Boattini, A.; Christensen, E. J.; Gibbs,
A. R.; Grauer, A. D.; Johnson, J. A.; Larson, S. M.; Shelly, F. C.;
Durig, D. T.; Wilkinson, I. J.; Brown, T. M.; Hergenrother, C. W.;
Schwartz, M.; Holvorcem, P. R.; Castellano, J.; Vidal, J. R.; Dupouy,
P.; de Vanssay, J. B.; Storey, D.; Salto, J. L.; Naves, R.; Kocher, P.;
Cozzi, E.; Klotz, A.; Kugel, F.; Nicolas, J.; Aymami, J. M.; Montoro,
L.; Bosch, J. M.; Olivera, R.; Audejean, M.; Bryssinck, E.; Soulier,
J. -F.; Diepvens, A.; Gerke, V.; Plaksa, S.; Prystavski, T.; Hegedus,
T.; Borkovits, T.; Biro, I. B.; Szing, A.; Csorgei, T.; Dangl, G.;
Tercu, O.; Dumitriu, A.; Mantero, A.; Zhao, H. B.; Li, B.; Xia, Y.;
Zhaori, G.; Hong, R. Q.; Hu, L. F.; Lu, H.; Takahashi, T.; Herald, D.;
Primak, N.; Schultz, A.; Goggia, T.; Willman, M.; Veres, P.; Owens,
R. P.; Angelone, C. G.; Christou, A. A.; Dymock, R.; Guido, E.; Howes,
N.; Nicolini, M.; Thaluang, T.; Sato, H.; Hug, G.; Sherrod, P. C.;
Bell, C.; Transient Factory, P.; Waszczak, A.; Masek, M.; Cerny, J.;
Ebr, J.; Prouza, M.; Kubanek, P.; Jelinek, M.; Honkova, K.; Jurysek,
J.; Lozano, J.; Martin, J. L.; Luis Martin Velasco, J.; Buczynski,
D.; Limon, F.; Gonzalez, J.; Carreno, A.; Piqueras, J.; Hernandez,
J. F.; Garcia, F.; Benishek, V.; Hudin, L.; Vintdevara, C.; Lake,
P. B.; Maury, A.; F Soulier, J.; G Bosch, J.; Tremosa, L.; Soldan A.,
F. C.; Williams, G. V.
2013MPEC....V...07B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Stellar ages through the corners of the boxy bulge
Authors: Valenti, E.; Zoccali, M.; Renzini, A.; Brown, T. M.; Gonzalez,
O. A.; Minniti, D.; Debattista, V. P.; Mayer, L.
2013A&A...559A..98V Altcode: 2013arXiv1309.4570V
<BR /> Aims: In some scenarios for the formation of the Milky Way bulge,
the stellar population at the edges of the boxy bulge may be younger
than those on the minor axis or close to the Galactic center. So far
the only bulge region where deep color-magnitude diagrams have been
obtained is indeed along the minor axis. To overcome this limitation,
we aim to age-date the bulge stellar populations far away from
the bulge minor axis. <BR /> Methods: Color-magnitude diagrams and
luminosity functions have been obtained from deep near-IR VLT/HAWK-I
images taken at the two Southern corners of the boxy bulge, i.e.,
near the opposite edges of the Galactic bar. The foreground disk
contamination has been statistically removed using a pure disk field
observed with the same instrument and located approximately at similar
Galactic latitudes of the two bulge fields and ~30° in longitude
away from the Galactic center. For each bulge field, mean reddening
and distance are determined using the position of red clump stars,
and the metallicity distribution is derived photometrically using
the color distribution of stars in the upper red giant branch. <BR
/> Results: The resulting metallicity distribution function of both
fields peaks around [Fe/H] ~ -0.1 dex, with the bulk of the stellar
population having a metallicity within the range: -1 dex ≲ [Fe/H] ≲
+0.4 dex, quite similar to that of other inner bulge fields. As for the
previously explored inner fields, the color-magnitude diagrams of the
two bar fields are consistent with their stellar population being older
than ~10 Gyr, with no obvious evidence of younger population. <BR />
Conclusions: The stellar population of the corners of the boxy bulge
appears to be coeval with those within the innermost ~4° from the
Galactic center. <P />Based on data taken at the ESO/VLT Telescope,
within the observing program 081.B-0489(A).The derived photometric
catalogs are only available at the CDS via anonymous ftp to <A
href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/559/A98">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/559/A98</A>
---------------------------------------------------------
Title: Las Cumbres Observatory Global Telescope Network
Authors: Brown, T. M.; Baliber, N.; Bianco, F. B.; Bowman, M.;
Burleson, B.; Conway, P.; Crellin, M.; Depagne, É.; De Vera, J.;
Dilday, B.; Dragomir, D.; Dubberley, M.; Eastman, J. D.; Elphick, M.;
Falarski, M.; Foale, S.; Ford, M.; Fulton, B. J.; Garza, J.; Gomez,
E. L.; Graham, M.; Greene, R.; Haldeman, B.; Hawkins, E.; Haworth,
B.; Haynes, R.; Hidas, M.; Hjelstrom, A. E.; Howell, D. A.; Hygelund,
J.; Lister, T. A.; Lobdill, R.; Martinez, J.; Mullins, D. S.; Norbury,
M.; Parrent, J.; Paulson, R.; Petry, D. L.; Pickles, A.; Posner, V.;
Rosing, W. E.; Ross, R.; Sand, D. J.; Saunders, E. S.; Shobbrook, J.;
Shporer, A.; Street, R. A.; Thomas, D.; Tsapras, Y.; Tufts, J. R.;
Valenti, S.; Vander Horst, K.; Walker, Z.; White, G.; Willis, M.
2013PASP..125.1031B Altcode: 2013arXiv1305.2437B
Las Cumbres Observatory Global Telescope (LCOGT) is a young organization
dedicated to time-domain observations at optical and (potentially)
near-IR wavelengths. To this end, LCOGT is constructing a world-wide
network of telescopes, including the two 2m Faulkes telescopes, as
many as 17 x 1m telescopes, and as many as 23 x 40cm telescopes. These
telescopes initially will be outfitted for imaging and (excepting the
40cm telescopes) spectroscopy at wavelengths between the atmospheric
UV cutoff and the roughly 1-micron limit of silicon detectors. Since
the first of LCOGT's 1m telescopes are now being deployed, we lay
out here LCOGT's scientific goals and the requirements that these
goals place on network architecture and performance, we summarize
the network's present and projected level of development, and we
describe our expected schedule for completing it. In the bulk of
the paper, we describe in detail the technical approaches that we
have adopted to attain the desired performance. In particular, we
discuss our choices for the number and location of network sites,
for the number and sizes of telescopes, for the specifications of the
first generation of instruments, for the software that will schedule
and control the network's telescopes and reduce and archive its data,
and for the structure of the scientific and educational programs for
which the network will provide observations.
---------------------------------------------------------
Title: VizieR Online Data Catalog: JK photometry in BUL<SUB>SC9 and
BUL</SUB>SC29 (Valenti+,
Authors: Valenti, E.; Zoccali, M.; Renzini, A.; Brown, T. M.; Gonzalez,
O.; Minniti, D.; Debattista, V. P.; Mayer, L.
2013yCat..35590098V Altcode: 2013yCat..35599098V
Photometric catalogues of two bulge fields located at the edge of the
edge of the Galactic bar. The J and K magnitudes have been calibrated
onto the 2MASS photometric system. The position of the detected sources
has been astrometrized by using 2MASS catalogs. <P />(2 data files).
---------------------------------------------------------
Title: 2013 RT73
Authors: Okumura, S.; Hashimoto, N.; Manca, F.; Testa, A.; Pettarin,
E.; Boattini, A.; Hill, R. E.; Christensen, E. J.; Gibbs, A. R.;
Grauer, A. D.; Johnson, J. A.; Kowalski, R. A.; Larson, S. M.; Shelly,
F. C.; Durig, D. T.; Boclair, C. A.; Schmidt, A. R.; Brown, T. M.;
McCarthy Obs, J. J.; Polansky, M.; Robson, M.; Galli, G.; Mantero,
A.; Holmes, R.; Vorobjov, T.; Buzzi, L.; Foglia, S.; Linder, T.; Hug,
G.; Spagnotto, J.; Losse, F.; Birtwhistle, P.; Baj, G.
2013MPEC....S...02O Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Transit Photometry with the LCOGT Network
Authors: Dragomir, Diana; Eastman, Jason; Brown, Tim; Street, Rachel;
Lister, Tim; Tsapras, Yannis; Ross, Rachel; Fulton, Benjamin
2013prpl.conf2K045D Altcode:
Within a single year, we deployed and commissioned a total of seven 1m
telescopes to three sites (McDonald Observatory, CTIO and SAAO). These
are complemented by two existing 2m telescopes, located in the northern
(Haleakala) and southern (Siding Spring Observatory) hemispheres. Before
the end of 2013, one additional 1m telescope will be deployed at
McDonald Observatory, and two at Siding Spring Observatory, which will
complete the southern ring and enable continuous LCOGT dark time in
the southern hemisphere. We present transit observations acquired at
each site with currently-deployed 1m telescopes. These data demonstrate
some of the network's unique capabilities, such as simultaneous transit
observations from multiple sites and construction of full transits by
combining partial transit light curves from two sites. Such exercises
pave the path toward searching for and characterizing transits of long
period exoplanets, simultaneous multi-color transit observations, as
well as studying spot distributions and rotation periods of exoplanet
host stars using the LCOGT network.
---------------------------------------------------------
Title: The Velocity Anisotropy of Distant Milky Way Halo Stars from
Hubble Space Telescope Proper Motions
Authors: Deason, A. J.; Van der Marel, R. P.; Guhathakurta, P.; Sohn,
S. T.; Brown, T. M.
2013ApJ...766...24D Altcode: 2013arXiv1302.5111D
Based on long baseline (5-7 years) multi-epoch HST/ACS photometry,
used previously to measure the proper motion of M31, we present the
proper motions (PMs) of 13 main-sequence Milky Way halo stars. The
sample lies at an average distance of r ~= 24 kpc from the Galactic
center, with a root-mean-square spread of 6 kpc. At this distance,
the median PM accuracy is 5 km s<SUP>-1</SUP>. We devise a maximum
likelihood routine to determine the tangential velocity ellipsoid of
the stellar halo. The velocity second moments in the directions of the
Galactic (l, b) system are < v^2_l > ^{1/2} = 123^{+29}_{-23}
km s<SUP>-1</SUP>, and < v^2_b > ^{1/2} = 83^{+24}_{-16} km
s<SUP>-1</SUP>. We combine these results with the known line-of-sight
second moment, < v^2_los > ^{1/2} = 105 +/- 5 km s<SUP>-1</SUP>,
at this langrrang to study the velocity anisotropy of the halo. We
find approximate isotropy between the radial and tangential velocity
distributions, with anisotropy parameter β = 0.0^{+0.2}_{-0.4}. Our
results suggest that the stellar halo velocity anisotropy out to r ~ 30
kpc is less radially biased than solar neighborhood measurements. This
is opposite to what is expected from violent relaxation, and may
indicate the presence of a shell-type structure at r ~ 24 kpc. With
additional multi-epoch HST data, the method presented here has the
ability to measure the transverse kinematics of the halo for more stars,
and to larger distances. This can yield new improved constraints on
the stellar halo formation mechanism, and the mass of the Milky Way.
---------------------------------------------------------
Title: VizieR Online Data Catalog: Kepler planetary
candidates. III. (Batalha+, 2013)
Authors: Batalha, N. M.; Rowe, J. F.; Bryson, S. T.; Barclay, T.;
Burke, C. J.; Caldwell, D. A.; Christiansen, J. L.; Mullally, F.;
Thompson, S. E.; Brown, T. M.; Dupree, A. K.; Fabrycky, D. C.; Ford,
E. B.; Fortney, J. J.; Gilliland, R. L.; Isaacson, H.; Latham,
D. W.; Marcy, G. W.; Quinn, S. N.; Ragozzine, D.; Shporer, A.;
Borucki, W. J.; Ciardi, D. R.; Gautier, T. N., III; Haas, M. R.;
Jenkins, J. M.; Koch, D. G.; Lissauer, J. J.; Rapin, W.; Basri,
G. S.; Boss, A. P.; Buchhave, L. A.; Carter, J. A.; Charbonneau, D.;
Christensen-Dalsgaard, J.; Clarke, B. D.; Cochran, W. D.; Demory,
B. -O.; Desert, J. -M.; DeVore, E.; Doyle, L. R.; Esquerdo, G. A.;
Everett, M.; Fressin, F.; Geary, J. C.; Girouard, F. R.; Gould, A.;
Hall, J. R.; Holman, M. J.; Howard, A. W.; Howell, S. B.; Ibrahim,
K. A.; Kinemuchi, K.; Kjeldsen, H.; Klaus, T. C.; Li, J.; Lucas,
P. W.; Meibom, S.; Morris, R. L.; Prsa, A.; Quintana, E.; Sanderfer,
D. T.; Sasselov, D.; Seader, S. E.; Smith, J. C.; Steffen, J. H.;
Still, M.; Stumpe, M. C.; Tarter, J. C.; Tenenbaum, P.; Torres, G.;
Twicken, J. D.; Uddin, K.; van Cleve, J.; Walkowicz, L.; Welsh, W. F.
2013yCat..22040024B Altcode:
The data employed for transit identification were acquired between 2009
May 13 00:15 UTC and 2010 Sep 22 19:03 UTC (Q1-Q6). Over 190000 stars
were observed at some time during this period. <P />(6 data files).
---------------------------------------------------------
Title: Planetary Candidates Observed by Kepler. III. Analysis of
the First 16 Months of Data
Authors: Batalha, Natalie M.; Rowe, Jason F.; Bryson, Stephen
T.; Barclay, Thomas; Burke, Christopher J.; Caldwell, Douglas A.;
Christiansen, Jessie L.; Mullally, Fergal; Thompson, Susan E.; Brown,
Timothy M.; Dupree, Andrea K.; Fabrycky, Daniel C.; Ford, Eric B.;
Fortney, Jonathan J.; Gilliland, Ronald L.; Isaacson, Howard; Latham,
David W.; Marcy, Geoffrey W.; Quinn, Samuel N.; Ragozzine, Darin;
Shporer, Avi; Borucki, William J.; Ciardi, David R.; Gautier, Thomas
N., III; Haas, Michael R.; Jenkins, Jon M.; Koch, David G.; Lissauer,
Jack J.; Rapin, William; Basri, Gibor S.; Boss, Alan P.; Buchhave,
Lars A.; Carter, Joshua A.; Charbonneau, David; Christensen-Dalsgaard,
Joergen; Clarke, Bruce D.; Cochran, William D.; Demory, Brice-Olivier;
Desert, Jean-Michel; Devore, Edna; Doyle, Laurance R.; Esquerdo,
Gilbert A.; Everett, Mark; Fressin, Francois; Geary, John C.; Girouard,
Forrest R.; Gould, Alan; Hall, Jennifer R.; Holman, Matthew J.; Howard,
Andrew W.; Howell, Steve B.; Ibrahim, Khadeejah A.; Kinemuchi, Karen;
Kjeldsen, Hans; Klaus, Todd C.; Li, Jie; Lucas, Philip W.; Meibom,
Søren; Morris, Robert L.; Prša, Andrej; Quintana, Elisa; Sanderfer,
Dwight T.; Sasselov, Dimitar; Seader, Shawn E.; Smith, Jeffrey C.;
Steffen, Jason H.; Still, Martin; Stumpe, Martin C.; Tarter, Jill C.;
Tenenbaum, Peter; Torres, Guillermo; Twicken, Joseph D.; Uddin, Kamal;
Van Cleve, Jeffrey; Walkowicz, Lucianne; Welsh, William F.
2013ApJS..204...24B Altcode: 2012arXiv1202.5852B
New transiting planet candidates are identified in 16 months (2009
May-2010 September) of data from the Kepler spacecraft. Nearly 5000
periodic transit-like signals are vetted against astrophysical and
instrumental false positives yielding 1108 viable new planet candidates,
bringing the total count up to over 2300. Improved vetting metrics
are employed, contributing to higher catalog reliability. Most notable
is the noise-weighted robust averaging of multi-quarter photo-center
offsets derived from difference image analysis that identifies likely
background eclipsing binaries. Twenty-two months of photometry are used
for the purpose of characterizing each of the candidates. Ephemerides
(transit epoch, T <SUB>0</SUB>, and orbital period, P) are tabulated
as well as the products of light curve modeling: reduced radius
(R <SUB>P</SUB>/R <SUB>sstarf</SUB>), reduced semimajor axis (d/R
<SUB>sstarf</SUB>), and impact parameter (b). The largest fractional
increases are seen for the smallest planet candidates (201% for
candidates smaller than 2 R <SUB>⊕</SUB> compared to 53% for
candidates larger than 2 R <SUB>⊕</SUB>) and those at longer orbital
periods (124% for candidates outside of 50 day orbits versus 86% for
candidates inside of 50 day orbits). The gains are larger than expected
from increasing the observing window from 13 months (Quarters 1-5)
to 16 months (Quarters 1-6) even in regions of parameter space where
one would have expected the previous catalogs to be complete. Analyses
of planet frequencies based on previous catalogs will be affected by
such incompleteness. The fraction of all planet candidate host stars
with multiple candidates has grown from 17% to 20%, and the paucity of
short-period giant planets in multiple systems is still evident. The
progression toward smaller planets at longer orbital periods with each
new catalog release suggests that Earth-size planets in the habitable
zone are forthcoming if, indeed, such planets are abundant.
---------------------------------------------------------
Title: LCOGT's New Telescopes and Instruments
Authors: Brown, Timothy M.; Becker, M.; Burleson, B.; De Vera, J.;
Dragomir, D.; Dubberley, M.; Eastman, J.; Graham, M.; Haldeman, B.;
Hawkins, E.; Haynes, R.; Hjelstrom, A.; Howell, D. A.; Hygelund,
J.; Lister, T.; Lobdill, R.; Norbury, M.; Petry, D.; Pickles, A.;
Posner, V.; Rosing, W.; Sand, D.; Street, R.; Tsapras, Y.; Tufts,
J.; Valenti, S.
2013AAS...22134523B Altcode:
Las Cumbres Observatory Global Telescope (LCOGT) is developing
a world-wide network of robotic optical telescopes dedicated to
time-domain astronomy. The last year has seen 3 major expansions in
our observing capabilities. (1) We have deployed and commissioned
4 new 1m telescopes at McDonald Observatory and at CTIO, and we are
in the process of deploying 5 more at the South African Astronomical
Observatory and at Siding Spring Observatory in Australia. (2) We have
commissioned low-resolution spectrographs on the Faulkes 2m telescopes;
these will become available to users in the 2013A semester, beginning 1
April 2013. (3) We have commissioned the NRES Prototype cross-dispersed
echelle spectrograph on our 0.8m telescope in California, giving
LCOGT its first capability to perform radial-velocity and spectral
classification observations. We describe here early science results
from each of these 3 new systems.
---------------------------------------------------------
Title: The Panchromatic Hubble Ultra Deep Field: Ultraviolet Coverage
Authors: Teplitz, Harry I.; Rafelski, M.; Grogin, N. A.; Koekemoer,
A. M.; Siana, B. D.; Atek, H.; Bond, N. A.; Brown, T. M.; Coe, D. A.;
Colbert, J. W.; De Mello, D. F.; Ferguson, H. C.; Finkelstein, S. L.;
Gardner, J. P.; Gawiser, E. J.; Giavalisco, M.; Gronwall, C.; Hanish,
D.; Kurczynski, P.; Lee, K.; Ravindranath, S.; Ryan, R. E.; Scarlata,
C.; Voyer, E.; Wolfe, A. M.
2013AAS...22122801T Altcode:
We present intial results from the UVUDF project: a Cycle 19 HST
Treasury program that obtained ultraviolet imaging of the Hubble Ultra
Deep Field. The data consist of 30 orbits with WFC3/UVIS in each of
F225W, F275W, and F336W, divided between three epochs. The science
goals of the UVUDF project are to: (i) Investigate the episode of peak
star formation activity in galaxies at 1 < z < 2.5; (ii) Study the
star formation properties of moderate redshift starburst galaxies; (iii)
Probe the evolution of massive galaxies by resolving sub-galactic units
(clumps); (iv) Examine the escape fraction of ionizing radiation from
galaxies at 2-3; and (v) Measure the star formation rate efficiency of
neutral atomic-dominated hydrogen gas at 1-3. In addition to the first
UVUDF science results, we discuss technical lessons learned that may
be of interst in planning future deep UV surveys with HST.
---------------------------------------------------------
Title: The PTF Orion Project: A Possible Planet Transiting a
T-Tauri Star
Authors: van Eyken, Julian C.; Ciardi, David R.; von Braun, Kaspar;
Kane, Stephen R.; Plavchan, Peter; Bender, Chad F.; Brown, Timothy
M.; Crepp, Justin R.; Fulton, Benjamin J.; Howard, Andrew W.; Howell,
Steve B.; Mahadevan, Suvrath; Marcy, Geoffrey W.; Shporer, Avi; Szkody,
Paula; Akeson, Rachel L.; Beichman, Charles A.; Boden, Andrew F.;
Gelino, Dawn M.; Hoard, D. W.; Ramírez, Solange V.; Rebull, Luisa
M.; Stauffer, John R.; Bloom, Joshua S.; Cenko, S. Bradley; Kasliwal,
Mansi M.; Kulkarni, Shrinivas R.; Law, Nicholas M.; Nugent, Peter E.;
Ofek, Eran O.; Poznanski, Dovi; Quimby, Robert M.; Walters, Richard;
Grillmair, Carl J.; Laher, Russ; Levitan, David B.; Sesar, Branimir;
Surace, Jason A.
2012ApJ...755...42V Altcode: 2012arXiv1206.1510V
We report observations of a possible young transiting planet orbiting
a previously known weak-lined T-Tauri star in the 7-10 Myr old
Orion-OB1a/25-Ori region. The candidate was found as part of the
Palomar Transient Factory (PTF) Orion project. It has a photometric
transit period of 0.448413 ± 0.000040 days, and appears in both
2009 and 2010 PTF data. Follow-up low-precision radial velocity (RV)
observations and adaptive optics imaging suggest that the star is not
an eclipsing binary, and that it is unlikely that a background source
is blended with the target and mimicking the observed transit. RV
observations with the Hobby-Eberly and Keck telescopes yield an RV
that has the same period as the photometric event, but is offset in
phase from the transit center by ≈ - 0.22 periods. The amplitude
(half range) of the RV variations is 2.4 km s<SUP>-1</SUP> and is
comparable with the expected RV amplitude that stellar spots could
induce. The RV curve is likely dominated by stellar spot modulation
and provides an upper limit to the projected companion mass of M
<SUB>p</SUB>sin i <SUB>orb</SUB> <~ 4.8 ± 1.2 M <SUB>Jup</SUB>;
when combined with the orbital inclination, i <SUB>orb</SUB>, of the
candidate planet from modeling of the transit light curve, we find an
upper limit on the mass of the planetary candidate of M <SUB>p</SUB>
<~ 5.5 ± 1.4 M <SUB>Jup</SUB>. This limit implies that the planet
is orbiting close to, if not inside, its Roche limiting orbital radius,
so that it may be undergoing active mass loss and evaporation.
---------------------------------------------------------
Title: Planet Occurrence within 0.25 AU of Solar-type Stars from
Kepler
Authors: Howard, Andrew W.; Marcy, Geoffrey W.; Bryson, Stephen T.;
Jenkins, Jon M.; Rowe, Jason F.; Batalha, Natalie M.; Borucki, William
J.; Koch, David G.; Dunham, Edward W.; Gautier, Thomas N., III; Van
Cleve, Jeffrey; Cochran, William D.; Latham, David W.; Lissauer,
Jack J.; Torres, Guillermo; Brown, Timothy M.; Gilliland, Ronald
L.; Buchhave, Lars A.; Caldwell, Douglas A.; Christensen-Dalsgaard,
Jørgen; Ciardi, David; Fressin, Francois; Haas, Michael R.; Howell,
Steve B.; Kjeldsen, Hans; Seager, Sara; Rogers, Leslie; Sasselov,
Dimitar D.; Steffen, Jason H.; Basri, Gibor S.; Charbonneau, David;
Christiansen, Jessie; Clarke, Bruce; Dupree, Andrea; Fabrycky,
Daniel C.; Fischer, Debra A.; Ford, Eric B.; Fortney, Jonathan J.;
Tarter, Jill; Girouard, Forrest R.; Holman, Matthew J.; Johnson,
John Asher; Klaus, Todd C.; Machalek, Pavel; Moorhead, Althea V.;
Morehead, Robert C.; Ragozzine, Darin; Tenenbaum, Peter; Twicken,
Joseph D.; Quinn, Samuel N.; Isaacson, Howard; Shporer, Avi; Lucas,
Philip W.; Walkowicz, Lucianne M.; Welsh, William F.; Boss, Alan;
Devore, Edna; Gould, Alan; Smith, Jeffrey C.; Morris, Robert L.;
Prsa, Andrej; Morton, Timothy D.; Still, Martin; Thompson, Susan E.;
Mullally, Fergal; Endl, Michael; MacQueen, Phillip J.
2012ApJS..201...15H Altcode: 2011arXiv1103.2541H
We report the distribution of planets as a function of planet radius,
orbital period, and stellar effective temperature for orbital periods
less than 50 days around solar-type (GK) stars. These results are based
on the 1235 planets (formally "planet candidates") from the Kepler
mission that include a nearly complete set of detected planets as
small as 2 R <SUB>⊕</SUB>. For each of the 156,000 target stars,
we assess the detectability of planets as a function of planet
radius, R <SUB>p</SUB>, and orbital period, P, using a measure of the
detection efficiency for each star. We also correct for the geometric
probability of transit, R <SUB>sstarf</SUB>/a. We consider first
Kepler target stars within the "solar subset" having T <SUB>eff</SUB>
= 4100-6100 K, log g = 4.0-4.9, and Kepler magnitude Kp < 15 mag,
i.e., bright, main-sequence GK stars. We include only those stars
having photometric noise low enough to permit detection of planets
down to 2 R <SUB>⊕</SUB>. We count planets in small domains of R
<SUB>p</SUB> and P and divide by the included target stars to calculate
planet occurrence in each domain. The resulting occurrence of planets
varies by more than three orders of magnitude in the radius-orbital
period plane and increases substantially down to the smallest radius
(2 R <SUB>⊕</SUB>) and out to the longest orbital period (50 days,
~0.25 AU) in our study. For P < 50 days, the distribution of planet
radii is given by a power law, df/dlog R = k<SUB>R</SUB>R <SUP>α</SUP>
with k<SUB>R</SUB> = 2.9<SUP>+0.5</SUP> <SUB>- 0.4</SUB>, α = -1.92 ±
0.11, and R ≡ R <SUB>p</SUB>/R <SUB>⊕</SUB>. This rapid increase
in planet occurrence with decreasing planet size agrees with the
prediction of core-accretion formation but disagrees with population
synthesis models that predict a desert at super-Earth and Neptune
sizes for close-in orbits. Planets with orbital periods shorter than
2 days are extremely rare; for R <SUB>p</SUB> > 2 R <SUB>⊕</SUB>
we measure an occurrence of less than 0.001 planets per star. For all
planets with orbital periods less than 50 days, we measure occurrence
of 0.130 ± 0.008, 0.023 ± 0.003, and 0.013 ± 0.002 planets per
star for planets with radii 2-4, 4-8, and 8-32 R <SUB>⊕</SUB>,
in agreement with Doppler surveys. We fit occurrence as a function
of P to a power-law model with an exponential cutoff below a critical
period P <SUB>0</SUB>. For smaller planets, P <SUB>0</SUB> has larger
values, suggesting that the "parking distance" for migrating planets
moves outward with decreasing planet size. We also measured planet
occurrence over a broader stellar T <SUB>eff</SUB> range of 3600-7100
K, spanning M0 to F2 dwarfs. Over this range, the occurrence of 2-4 R
<SUB>⊕</SUB> planets in the Kepler field increases with decreasing
T <SUB>eff</SUB>, with these small planets being seven times more
abundant around cool stars (3600-4100 K) than the hottest stars in
our sample (6600-7100 K). <P />Based in part on observations obtained
at the W. M. Keck Observatory, which is operated by the University of
California and the California Institute of Technology.
---------------------------------------------------------
Title: Ultraviolet Observations of the Hubble Ultra Deep Field
Authors: Rafelski, Marc; Teplitz, H.; Grogin, N.; Koekemoer, A.;
Siana, B.; Atek, H.; Bond, N. A.; Brown, T. M.; Coe, D.; Colbert, J.;
Ferguson, H. C.; Finkelstein, S. L.; Gardner, J. P.; Gawiser, E.;
Giavalisco, M.; Gronwall, C.; Hanish, D.; Kurczynski, P.; Lee, K.;
Ravindranath, S.; Scarlata, C.; Voyer, E.; Wolfe, A.; de Mello, D. F.
2012AAS...22042104R Altcode:
We present details of a 90-orbit HST treasury program to obtain
Ultraviolet (UV) imaging of the Hubble Ultra Deep Field (UDF) using
the WFC3-UVIS detector with the F225W, F275W, and F336W filters. These
UV images will reach point source detection limits of AB=29 at 10
sigma. This survey is designed to: (i) Investigate the episode of peak
star formation activity in galaxies at 1 < z < 2.5. (ii) Study the
star formation properties of moderate redshift starburst galaxies. (iii)
Probe the evolution of massive galaxies by resolving sub-galactic units
(clumps). (iv) Examine the escape fraction of ionizing radiation from
galaxies at z 2-3. (v) Measure the star formation rate efficiency
of neutral atomic-dominated hydrogen gas at z 1-3. We will present
preliminary results from the UVUDF team based on the first observations
(beginning March 2012).
---------------------------------------------------------
Title: Using HST to Detect Isolated Black Holes and Neutron Stars
through Astrometric Microlensing
Authors: Sahu, Kailash C.; Albrow, M.; Anderson, J.; Bond, H. E.;
Bond, I.; Brown, T. M.; Casertano, S.; Dominik, M.; Ferguson, H. C.;
Fryer, C.; Livio, M.; Mao, S.; Perrott, Y.; Udalski, A.; Yock, P.
2012AAS...22030703S Altcode:
To date, Black Hole (BH) and Neutron Star (NS) masses have been
directly measured only in binaries; no isolated stellar-mass BH has
been detected unambiguously within our Galaxy. We have underway a
large, 3-year HST program (192 orbits) designed to detect microlensing
events caused by non-luminous isolated BHs and NSs in the direction
of the Galactic bulge. Our program consists of monitoring of 12
fields in the Sagittarius window of the Galactic bulge, containing
a total of 1.5 million stars down to V=28. Our observations have a
typical cadence of one observation every two weeks, and are primarily
targeted towards detecting microlensing events caused by non-luminous
isolated BHs and NSs in the Galactic disk and bulge. <P />The unique
capability of HST imaging for microlensing observations is the addition
of high-precision astrometry, allowing detection of the astrometric
shift of the source during the event. Combined with the lens parallax,
which can be determined from the light curve as measured by HST (and
supplemented by GEMINI) observations, the astrometric shift provides a
direct measurement of the lens mass. Our program is optimized to detect
long-duration events, which are more likely to be caused by massive
lenses. We expect to detect a few dozen long-duration microlensing
events, of which 45% will show astrometric deflections, leading to
direct determinations of the lens masses.
---------------------------------------------------------
Title: On using the beaming effect to measure spin-orbit alignment
in stellar binaries with Sun-like components
Authors: Shporer, Avi; Brown, Tim; Mazeh, Tsevi; Zucker, Shay
2012NewA...17..309S Altcode: 2011arXiv1107.4458S
The beaming effect (aka Doppler boosting) induces a variation in the
observed flux of a luminous object, following its observed radial
velocity variation. We describe a photometric signal induced by the
beaming effect during eclipse of binary systems, where the stellar
components are late type Sun-like stars. The shape of this signal is
sensitive to the angle between the eclipsed star's spin axis and the
orbital angular momentum axis, thereby allowing its measurement. We show
that during eclipse there are in fact two effects, superimposed on the
known eclipse light curve. One effect is produced by the rotation of
the eclipsed star, and is the photometric analog of the spectroscopic
Rossiter-McLaughlin effect, thereby it contains information about
the sky-projected spin-orbit angle. The other effect is produced by
the varying weighted difference, during eclipse, between the beaming
signals of the two stars. We give approximated analytic expressions for
the amplitudes of the two effects, and present a numerical simulation
where we show the light curves for the two effects for various orbital
orientations, for a low mass ratio stellar eclipsing binary system. We
show that although the overall signal is small, it can be detected
in the primary eclipse when using Kepler Long Cadence data of bright
systems accumulated over the mission lifetime.
---------------------------------------------------------
Title: New Observational Evidence of Flash Mixing on the White Dwarf
Cooling Curve
Authors: Brown, T. M.; Lanz, T.; Sweigart, A. V.; Cracraft, M.;
Hubeny, I.; Landsman, W. B.
2012ASPC..452...23B Altcode: 2012arXiv1201.4204B
Blue hook stars are a class of subluminous extreme horizontal branch
stars that were discovered in UV images of the massive globular clusters
ω Cen and NGC 2808. These stars occupy a region of the HR diagram
that is unexplained by canonical stellar evolution theory. Using
new theoretical evolutionary and atmospheric models, we have shown
that the blue hook stars are very likely the progeny of stars that
undergo extensive internal mixing during a late helium-core flash
on the white dwarf cooling curve. This “flash mixing” produces
hotter-than-normal EHB stars with atmospheres significantly enhanced
in helium and carbon. The larger bolometric correction, combined with
the decrease in hydrogen opacity, makes these stars appear subluminous
in the optical and UV. Flash mixing is more likely to occur in stars
born with a high helium abundance, due to their lower mass at the
main sequence turnoff. For this reason, the phenomenon is more common
in those massive globular clusters that show evidence for secondary
populations enhanced in helium. However, a high helium abundance does
not, by itself, explain the presence of blue hook stars in massive
globular clusters. Here, we present new observational evidence for flash
mixing, using recent HST observations. These include UV color-magnitude
diagrams of six massive globular clusters and far-UV spectroscopy of
hot subdwarfs in one of these clusters (NGC 2808).
---------------------------------------------------------
Title: An eclipsing post-common-envelope binary in the field of the
Kepler mission
Authors: Almenara, J. M.; Alonso, R.; Rabus, M.; Lázaro, C.; Arévalo,
M. J.; Belmonte, J. A.; Deeg, H. J.; Brown, T. M.; Vázquez Ramió, H.
2012MNRAS.420.3017A Altcode:
We present a new eclipsing post-common-envelope binary,
identified inside the Kepler field prior to the launch of the
spacecraft. Multifilter photometry and radial velocity data are analysed
with an eclipsing-binary modelling code to determine the physical
parameters of the binary. Spectra of the system within the primary
eclipse and uneclipsed allow us to identify the spectral characteristics
of the primary and secondary components. The primary component of
the binary is a DA white dwarf, with M≃ 0.61 M<SUB>⊙</SUB>, log
g≃ 7.95 and T<SUB>eff</SUB>≃ 20 500 K. <P />The detection of two
flares and the emission signatures displayed in the spectra show that
the secondary component of the system is chromospherically active and
is classified as an active M4 main-sequence star. Its mass, radius
and temperature are estimated as M≃ 0.39 M<SUB>⊙</SUB>, R≃
0.37 R<SUB>⊙</SUB> and T<SUB>eff</SUB>≃ 3200 K. The ephemeris
of the system is HJD = 245 3590.436 126(10) + 0.350 468 722(6)
×E. <P />This binary is a new post-common-envelope binary (PCEB),
with physical parameters within the range found in other systems of
this small group of evolved binaries.
---------------------------------------------------------
Title: VizieR Online Data Catalog: Masses and radii of eclipsing
binaries (Brown, 2010)
Authors: Brown, T. M.
2012yCat..17090535B Altcode:
I implemented the {rho}<SUB>*</SUB> method, using the Yonsei-Yale evo
tracks (Yi et al. 2001ApJS..136..417Y; Kim et al. 2002ApJS..143..499K;
Yi et al. 2003ApJS..144..259Y; Demarque et al. 2004ApJS..155..667D)
as the needed stellar evolution models, and I then applied it to the
Torres et al., (2009, Cat. J/other/A+ARV/18.67) tabulation of EBs and
to 15 stars with asteroseismic measurements. <P />(1 data file).
---------------------------------------------------------
Title: Spectroscopy at LCOGT
Authors: Brown, Timothy M.; Becker, M.; Burleson, B.; De Vera, J.;
Dubberley, M.; Eastman, J.; Haldeman, B.; Hawkins, E.; Haynes, R.;
Hygelund, J.; Lister, T.; Lobdill, R.; Norbury, M.; Pickles, A.;
Rosing, W.; Sand, D.; Tufts, J.
2012AAS...21942203B Altcode:
Las Cumbres Observatory Global Telescope (LCOGT) is developing a
world-wide network of optical telescopes dedicated to time-domain
astronomy. In a few years, the network will consist of more than twenty
0.4m telescopes, about fifteen 1m telescopes, and two 2m telescopes. We
are now developing spectrographs to use with this network; here we
describe the performance goals and status of these instruments. Furthest
along is FLOYDS, a low-resolution spectrograph that will cover 330nm -
1040 nm in one shot, using two diffraction orders. FLOYDS is intended
mostly for SN classification and time-evolution studies. We will install
copies of this spectrograph on each of LCOGT's 2m Faulkes telescopes,
beginning with FTN early in 2012. Still in the prototype stage is
MRES, a medium-resolution (R=45,000) fiber-fed cross-dispersed echelle
covering 380nm-850nm. It will accept fibers from up to 3 co-located
1m telescopes, so that we can observe multiple targets at once, or
gain S/N by devoting multiple telescopes to a single target. The
spectrograph is designed for easy control of its light path and
environment, to facilitate accurate and repeatable measurements. MRES
will be used mostly for validation and study of extrasolar planets,
and for time-domain studies of pulsating and magnetically active stars.
---------------------------------------------------------
Title: The Atmospheres of the Hot-Jupiters Kepler-5b and Kepler-6b
Observed during Occultations with Warm-Spitzer and Kepler
Authors: Désert, Jean-Michel; Charbonneau, David; Fortney, Jonathan
J.; Madhusudhan, Nikku; Knutson, Heather A.; Fressin, François;
Deming, Drake; Borucki, William J.; Brown, Timothy M.; Caldwell,
Douglas; Ford, Eric B.; Gilliland, Ronald L.; Latham, David W.; Marcy,
Geoffrey W.; Seager, Sara
2011ApJS..197...11D Altcode: 2011arXiv1102.0555D
This paper reports the detection and the measurements of occultations of
the two transiting hot giant exoplanets Kepler-5b and Kepler-6b by their
parent stars. The observations are obtained in the near-infrared with
Warm-Spitzer Space Telescope and at optical wavelengths by combining
more than a year of Kepler photometry. The investigation consists of
constraining the eccentricities of these systems and of obtaining
broadband emergent photometric data for individual planets. For
both targets, the occultations are detected at the 3σ level at
each wavelength with mid-occultation times consistent with circular
orbits. The brightness temperatures of these planets are deduced from
the infrared observations and reach T <SUB>Spitzer</SUB> = 1930 ± 100 K
and T <SUB>Spitzer</SUB> = 1660 ± 120 K for Kepler-5b and Kepler-6b,
respectively. We measure optical geometric albedos A<SUB>g</SUB>
in the Kepler bandpass and find A<SUB>g</SUB> = 0.12 ± 0.04 for
Kepler-5b and A<SUB>g</SUB> = 0.11 ± 0.04 for Kepler-6b, leading to
upper an limit for the Bond albedo of A <SUB>B</SUB> <= 0.17 in both
cases. The observations for both planets are best described by models
for which most of the incident energy is redistributed on the dayside,
with only less than 10% of the absorbed stellar flux redistributed to
the nightside of these planets.
---------------------------------------------------------
Title: Kepler-10 c: a 2.2 Earth Radius Transiting Planet in a
Multiple System
Authors: Fressin, François; Torres, Guillermo; Désert, Jean-Michel;
Charbonneau, David; Batalha, Natalie M.; Fortney, Jonathan J.; Rowe,
Jason F.; Allen, Christopher; Borucki, William J.; Brown, Timothy M.;
Bryson, Stephen T.; Ciardi, David R.; Cochran, William D.; Deming,
Drake; Dunham, Edward W.; Fabrycky, Daniel C.; Gautier, Thomas N.,
III; Gilliland, Ronald L.; Henze, Christopher E.; Holman, Matthew
J.; Howell, Steve B.; Jenkins, Jon M.; Kinemuchi, Karen; Knutson,
Heather; Koch, David G.; Latham, David W.; Lissauer, Jack J.; Marcy,
Geoffrey W.; Ragozzine, Darin; Sasselov, Dimitar D.; Still, Martin;
Tenenbaum, Peter; Uddin, Kamal
2011ApJS..197....5F Altcode: 2011arXiv1105.4647F
The Kepler mission has recently announced the discovery of Kepler-10
b, the smallest exoplanet discovered to date and the first rocky
planet found by the spacecraft. A second, 45 day period transit-like
signal present in the photometry from the first eight months of data
could not be confirmed as being caused by a planet at the time of that
announcement. Here we apply the light curve modeling technique known as
BLENDER to explore the possibility that the signal might be due to an
astrophysical false positive (blend). To aid in this analysis we report
the observation of two transits with the Spitzer Space Telescope at 4.5
μm. When combined, they yield a transit depth of 344 ± 85 ppm that
is consistent with the depth in the Kepler passband (376 ± 9 ppm,
ignoring limb darkening), which rules out blends with an eclipsing
binary of a significantly different color than the target. Using these
observations along with other constraints from high-resolution imaging
and spectroscopy, we are able to exclude the vast majority of possible
false positives. We assess the likelihood of the remaining blends, and
arrive conservatively at a false alarm rate of 1.6 × 10<SUP>-5</SUP>
that is small enough to validate the candidate as a planet (designated
Kepler-10 c) with a very high level of confidence. The radius of
this object is measured to be R<SUB>p</SUB> = 2.227<SUP>+0.052</SUP>
<SUB>-0.057</SUB> R <SUB>⊕</SUB> (in which the error includes
the uncertainty in the stellar properties), but currently available
radial-velocity measurements only place an upper limit on its mass
of about 20 M <SUB>⊕</SUB>. Kepler-10 c represents another example
(with Kepler-9 d and Kepler-11 g) of statistical "validation" of a
transiting exoplanet, as opposed to the usual "confirmation" that
can take place when the Doppler signal is detected or transit timing
variations are measured. It is anticipated that many of Kepler's
smaller candidates will receive a similar treatment since dynamical
confirmation may be difficult or impractical with the sensitivity of
current instrumentation.
---------------------------------------------------------
Title: Kepler-14b: A Massive Hot Jupiter Transiting an F Star in a
Close Visual Binary
Authors: Buchhave, Lars A.; Latham, David W.; Carter, Joshua A.;
Désert, Jean-Michel; Torres, Guillermo; Adams, Elisabeth R.; Bryson,
Stephen T.; Charbonneau, David B.; Ciardi, David R.; Kulesa, Craig;
Dupree, Andrea K.; Fischer, Debra A.; Fressin, François; Gautier,
Thomas N., III; Gilliland, Ronald L.; Howell, Steve B.; Isaacson,
Howard; Jenkins, Jon M.; Marcy, Geoffrey W.; McCarthy, Donald W.;
Rowe, Jason F.; Batalha, Natalie M.; Borucki, William J.; Brown,
Timothy M.; Caldwell, Douglas A.; Christiansen, Jessie L.; Cochran,
William D.; Deming, Drake; Dunham, Edward W.; Everett, Mark; Ford,
Eric B.; Fortney, Jonathan J.; Geary, John C.; Girouard, Forrest R.;
Haas, Michael R.; Holman, Matthew J.; Horch, Elliott; Klaus, Todd C.;
Knutson, Heather A.; Koch, David G.; Kolodziejczak, Jeffrey; Lissauer,
Jack J.; Machalek, Pavel; Mullally, Fergal; Still, Martin D.; Quinn,
Samuel N.; Seager, Sara; Thompson, Susan E.; Van Cleve, Jeffrey
2011ApJS..197....3B Altcode: 2011arXiv1106.5510B
We present the discovery of a hot Jupiter transiting an F star in
a close visual (0farcs3 sky projected angular separation) binary
system. The dilution of the host star's light by the nearly equal
magnitude stellar companion (~0.5 mag fainter) significantly affects
the derived planetary parameters, and if left uncorrected, leads
to an underestimate of the radius and mass of the planet by 10%
and 60%, respectively. Other published exoplanets, which have not
been observed with high-resolution imaging, could similarly have
unresolved stellar companions and thus have incorrectly derived
planetary parameters. Kepler-14b (KOI-98) has a period of P = 6.790
days and, correcting for the dilution, has a mass of M<SUB>p</SUB> =
8.40<SUP>+0.35</SUP> <SUB> - 0.34</SUB> M <SUB>J</SUB> and a radius
of R<SUB>p</SUB> = 1.136<SUP>+0.073</SUP> <SUB> - 0.054</SUB> R
<SUB>J</SUB>, yielding a mean density of ρ<SUB> p </SUB> = 7.1 ±
1.1 g cm<SUP>-3</SUP>.
---------------------------------------------------------
Title: The Hot-Jupiter Kepler-17b: Discovery, Obliquity from
Stroboscopic Starspots, and Atmospheric Characterization
Authors: Désert, Jean-Michel; Charbonneau, David; Demory,
Brice-Olivier; Ballard, Sarah; Carter, Joshua A.; Fortney, Jonathan
J.; Cochran, William D.; Endl, Michael; Quinn, Samuel N.; Isaacson,
Howard T.; Fressin, François; Buchhave, Lars A.; Latham, David W.;
Knutson, Heather A.; Bryson, Stephen T.; Torres, Guillermo; Rowe,
Jason F.; Batalha, Natalie M.; Borucki, William J.; Brown, Timothy
M.; Caldwell, Douglas A.; Christiansen, Jessie L.; Deming, Drake;
Fabrycky, Daniel C.; Ford, Eric B.; Gilliland, Ronald L.; Gillon,
Michaël; Haas, Michaël R.; Jenkins, Jon M.; Kinemuchi, Karen; Koch,
David; Lissauer, Jack J.; Lucas, Philip; Mullally, Fergal; MacQueen,
Phillip J.; Marcy, Geoffrey W.; Sasselov, Dimitar D.; Seager, Sara;
Still, Martin; Tenenbaum, Peter; Uddin, Kamal; Winn, Joshua N.
2011ApJS..197...14D Altcode: 2011arXiv1107.5750D
This paper reports the discovery and characterization of the
transiting hot giant exoplanet Kepler-17b. The planet has an orbital
period of 1.486 days, and radial velocity measurements from the
Hobby-Eberly Telescope show a Doppler signal of 419.5<SUP>+13.3</SUP>
<SUB>-15.6</SUB> m s<SUP>-1</SUP>. From a transit-based estimate
of the host star's mean density, combined with an estimate of the
stellar effective temperature T <SUB>eff</SUB> = 5630 ± 100 from
high-resolution spectra, we infer a stellar host mass of 1.06 ± 0.07 M
<SUB>⊙</SUB> and a stellar radius of 1.02 ± 0.03 R <SUB>⊙</SUB>. We
estimate the planet mass and radius to be M <SUB>P</SUB> = 2.45 ± 0.11
M <SUB>J</SUB> and R <SUB>P</SUB> = 1.31 ± 0.02 R <SUB>J</SUB>. The
host star is active, with dark spots that are frequently occulted by
the planet. The continuous monitoring of the star reveals a stellar
rotation period of 11.89 days, eight times the planet's orbital period;
this period ratio produces stroboscopic effects on the occulted
starspots. The temporal pattern of these spot-crossing events shows
that the planet's orbit is prograde and the star's obliquity is smaller
than 15°. We detected planetary occultations of Kepler-17b with both
the Kepler and Spitzer Space Telescopes. We use these observations to
constrain the eccentricity, e, and find that it is consistent with
a circular orbit (e < 0.011). The brightness temperatures of the
planet's infrared bandpasses are T_{3.6\, {\mu m}} = 1880 ± 100 K and
T_{4.5\, {\mu m}} = 1770 ± 150 K. We measure the optical geometric
albedo A<SUB>g</SUB> in the Kepler bandpass and find A<SUB>g</SUB>
= 0.10 ± 0.02. The observations are best described by atmospheric
models for which most of the incident energy is re-radiated away from
the day side.
---------------------------------------------------------
Title: Discovery and Atmospheric Characterization of Giant Planet
Kepler-12b: An Inflated Radius Outlier
Authors: Fortney, Jonathan J.; Demory, Brice-Olivier; Désert,
Jean-Michel; Rowe, Jason; Marcy, Geoffrey W.; Isaacson, Howard;
Buchhave, Lars A.; Ciardi, David; Gautier, Thomas N.; Batalha, Natalie
M.; Caldwell, Douglas A.; Bryson, Stephen T.; Nutzman, Philip; Jenkins,
Jon M.; Howard, Andrew; Charbonneau, David; Knutson, Heather A.;
Howell, Steve B.; Everett, Mark; Fressin, François; Deming, Drake;
Borucki, William J.; Brown, Timothy M.; Ford, Eric B.; Gilliland,
Ronald L.; Latham, David W.; Miller, Neil; Seager, Sara; Fischer, Debra
A.; Koch, David; Lissauer, Jack J.; Haas, Michael R.; Still, Martin;
Lucas, Philip; Gillon, Michael; Christiansen, Jessie L.; Geary, John C.
2011ApJS..197....9F Altcode: 2011arXiv1109.1611F
We report the discovery of planet Kepler-12b (KOI-20), which at 1.695 ±
0.030 R <SUB>J</SUB> is among the handful of planets with super-inflated
radii above 1.65 R <SUB>J</SUB>. Orbiting its slightly evolved G0 host
with a 4.438 day period, this 0.431 ± 0.041 M <SUB>J</SUB> planet
is the least irradiated within this largest-planet-radius group,
which has important implications for planetary physics. The planet's
inflated radius and low mass lead to a very low density of 0.111 ±
0.010 g cm<SUP>-3</SUP>. We detect the occultation of the planet at a
significance of 3.7σ in the Kepler bandpass. This yields a geometric
albedo of 0.14 ± 0.04; the planetary flux is due to a combination of
scattered light and emitted thermal flux. We use multiple observations
with Warm Spitzer to detect the occultation at 7σ and 4σ in the 3.6
and 4.5 μm bandpasses, respectively. The occultation photometry timing
is consistent with a circular orbit at e < 0.01 (1σ) and e <
0.09 (3σ). The occultation detections across the three bands favor an
atmospheric model with no dayside temperature inversion. The Kepler
occultation detection provides significant leverage, but conclusions
regarding temperature structure are preliminary, given our ignorance of
opacity sources at optical wavelengths in hot Jupiter atmospheres. If
Kepler-12b and HD 209458b, which intercept similar incident stellar
fluxes, have the same heavy-element masses, the interior energy
source needed to explain the large radius of Kepler-12b is three times
larger than that of HD 209458b. This may suggest that more than one
radius-inflation mechanism is at work for Kepler-12b or that it is
less heavy-element rich than other transiting planets.
---------------------------------------------------------
Title: Kepler-18b, c, and d: A System of Three Planets Confirmed
by Transit Timing Variations, Light Curve Validation, Warm-Spitzer
Photometry, and Radial Velocity Measurements
Authors: Cochran, William D.; Fabrycky, Daniel C.; Torres, Guillermo;
Fressin, François; Désert, Jean-Michel; Ragozzine, Darin; Sasselov,
Dimitar; Fortney, Jonathan J.; Rowe, Jason F.; Brugamyer, Erik J.;
Bryson, Stephen T.; Carter, Joshua A.; Ciardi, David R.; Howell,
Steve B.; Steffen, Jason H.; Borucki, William. J.; Koch, David G.;
Winn, Joshua N.; Welsh, William F.; Uddin, Kamal; Tenenbaum, Peter;
Still, M.; Seager, Sara; Quinn, Samuel N.; Mullally, F.; Miller, Neil;
Marcy, Geoffrey W.; MacQueen, Phillip J.; Lucas, Phillip; Lissauer,
Jack J.; Latham, David W.; Knutson, Heather; Kinemuchi, K.; Johnson,
John A.; Jenkins, Jon M.; Isaacson, Howard; Howard, Andrew; Horch,
Elliott; Holman, Matthew J.; Henze, Christopher E.; Haas, Michael R.;
Gilliland, Ronald L.; Gautier, Thomas N., III; Ford, Eric B.; Fischer,
Debra A.; Everett, Mark; Endl, Michael; Demory, Brice-Oliver; Deming,
Drake; Charbonneau, David; Caldwell, Douglas; Buchhave, Lars; Brown,
Timothy M.; Batalha, Natalie
2011ApJS..197....7C Altcode: 2011arXiv1110.0820C
We report the detection of three transiting planets around a Sun-like
star, which we designate Kepler-18. The transit signals were detected in
photometric data from the Kepler satellite, and were confirmed to arise
from planets using a combination of large transit-timing variations
(TTVs), radial velocity variations, Warm-Spitzer observations, and
statistical analysis of false-positive probabilities. The Kepler-18 star
has a mass of 0.97 M <SUB>sun</SUB>, a radius of 1.1 R <SUB>sun</SUB>,
an effective temperature of 5345 K, and an iron abundance of [Fe/H] =
+0.19. The planets have orbital periods of approximately 3.5, 7.6, and
14.9 days. The innermost planet "b" is a "super-Earth" with a mass of
6.9 ± 3.4 M <SUB>⊕</SUB>, a radius of 2.00 ± 0.10 R <SUB>⊕</SUB>,
and a mean density of 4.9 ± 2.4 g cm<SUP>3</SUP>. The two outer planets
"c" and "d" are both low-density Neptune-mass planets. Kepler-18c has
a mass of 17.3 ± 1.9 M <SUB>⊕</SUB>, a radius of 5.49 ± 0.26 R
<SUB>⊕</SUB>, and a mean density of 0.59 ± 0.07 g cm<SUP>3</SUP>,
while Kepler-18d has a mass of 16.4 ± 1.4 M <SUB>⊕</SUB>, a radius
of 6.98 ± 0.33 R <SUB>⊕</SUB> and a mean density of 0.27 ± 0.03 g
cm<SUP>3</SUP>. Kepler-18c and Kepler-18d have orbital periods near
a 2:1 mean-motion resonance, leading to large and readily detected
TTVs. <P />Based in part on observations obtained at the W. M. Keck
Observatory, which is operated by the University of California and
the California Institute of Technology.
---------------------------------------------------------
Title: TrES-5: A Massive Jupiter-sized Planet Transiting a Cool
G Dwarf
Authors: Mandushev, Georgi; Quinn, Samuel N.; Buchhave, Lars A.;
Dunham, Edward W.; Rabus, Markus; Oetiker, Brian; Latham, David W.;
Charbonneau, David; Brown, Timothy M.; Belmonte, Juan A.; O'Donovan,
Francis T.
2011ApJ...741..114M Altcode: 2011arXiv1108.3572M
We report the discovery of TrES-5, a massive hot Jupiter that transits
the star GSC 03949-00967 every 1.48 days. From spectroscopy of the
star we estimate a stellar effective temperature of T <SUB>eff</SUB>
= 5171 ± 36 K, and from high-precision B, R, and I photometry of
the transit we constrain the ratio of the semimajor axis a and the
stellar radius R <SUB>sstarf</SUB> to be a/R <SUB>sstarf</SUB> =
6.07 ± 0.14. We compare these values to model stellar isochrones
to obtain a stellar mass of M <SUB>sstarf</SUB> = 0.893 ± 0.024 M
<SUB>⊙</SUB>. Based on this estimate and the photometric time series,
we constrain the stellar radius to be R <SUB>sstarf</SUB> = 0.866 ±
0.013 R <SUB>⊙</SUB> and the planet radius to be R <SUB>p</SUB>
= 1.209 ± 0.021 R <SUB>J</SUB>. We model our radial-velocity data
assuming a circular orbit and find a planetary mass of 1.778 ± 0.063 M
<SUB>J</SUB>. Our radial-velocity observations rule out line-bisector
variations that would indicate a specious detection resulting from
a blend of an eclipsing binary system. TrES-5 orbits one of the
faintest stars with transiting planets found to date from the ground
and demonstrates that precise photometry and followup spectroscopy
are possible, albeit challenging, even for such faint stars.
---------------------------------------------------------
Title: KOI-54: The Kepler Discovery of Tidally Excited Pulsations
and Brightenings in a Highly Eccentric Binary
Authors: Welsh, William F.; Orosz, Jerome A.; Aerts, Conny; Brown,
Timothy M.; Brugamyer, Erik; Cochran, William D.; Gilliland, Ronald L.;
Guzik, Joyce Ann; Kurtz, D. W.; Latham, David W.; Marcy, Geoffrey W.;
Quinn, Samuel N.; Zima, Wolfgang; Allen, Christopher; Batalha, Natalie
M.; Bryson, Steve; Buchhave, Lars A.; Caldwell, Douglas A.; Gautier,
Thomas N., III; Howell, Steve B.; Kinemuchi, K.; Ibrahim, Khadeejah
A.; Isaacson, Howard; Jenkins, Jon M.; Prsa, Andrej; Still, Martin;
Street, Rachel; Wohler, Bill; Koch, David G.; Borucki, William J.
2011ApJS..197....4W Altcode: 2011arXiv1102.1730W
Kepler observations of the star HD 187091 (KIC 8112039, hereafter
KOI-54) revealed a remarkable light curve exhibiting sharp
periodic brightening events every 41.8 days with a superimposed
set of oscillations forming a beating pattern in phase with the
brightenings. Spectroscopic observations revealed that this is a binary
star with a highly eccentric orbit, e = 0.83. We are able to match the
Kepler light curve and radial velocities with a nearly face-on (i =
5fdg5) binary star model in which the brightening events are caused by
tidal distortion and irradiation of nearly identical A stars during
their close periastron passage. The two dominant oscillations in the
light curve, responsible for the beating pattern, have frequencies
that are the 91st and 90th harmonic of the orbital frequency. The power
spectrum of the light curve, after removing the binary star brightening
component, reveals a large number of pulsations, 30 of which have
a signal-to-noise ratio gsim7. Nearly all of these pulsations have
frequencies that are either integer multiples of the orbital frequency
or are tidally split multiples of the orbital frequency. This pattern
of frequencies unambiguously establishes the pulsations as resonances
between the dynamic tides at periastron and the free oscillation
modes of one or both of the stars. KOI-54 is only the fourth star to
show such a phenomenon and is by far the richest in terms of excited
modes. <P />Based in part on observations obtained at the W. M. Keck
Observatory, which is operated by the University of California and
the California Institute of Technology.
---------------------------------------------------------
Title: VizieR Online Data Catalog: Kepler planetary
candidates. I. (Borucki+, 2011)
Authors: Borucki, W. J.; Koch, D. G.; Basri, G.; Batalha, N.; Boss,
A.; Brown, T. M.; Caldwell, D.; Christensen-Dalsgaard, J.; Cochran,
W. D.; DeVore, E.; Dunham, E. W.; Dupree, A. K.; Gautier, T. N.,
III; Geary, J. C.; Gilliland, R.; Gould, A.; Howell, S. B.; Jenkins,
J. M.; Kjeldsen, H.; Latham, D. W.; Lissauer, J. J.; Marcy, G. W.;
Monet, D. G.; Sasselov, D.; Tarter, J.; Charbonneau, D.; Doyle, L.;
Ford, E. B.; Fortney, J.; Holman, M. J.; Seager, S.; Steffen, J. H.;
Welsh, W. F.; Allen, C.; Bryson, S. T.; Buchhave, L.; Chandrasekaran,
H.; Christiansen, J. L.; Ciardi, D.; Clarke, B. D.; Dotson, J. L.;
Endl, M.; Fischer, D.; Fressin, F.; Haas, M.; Horch, E.; Howard,
A.; Isaacson, H.; Kolodziejczak, J.; Li, J.; MacQueen, P.; Meibom,
S.; Prsa, A.; Quintana, E. V.; Rowe, J.; Sherry, W.; Tenenbaum, P.;
Torres, G.; Twicken, J. D.; van Cleve, J.; Walkowicz, L.; Wu, H.
2011yCat..17280117B Altcode:
In the spring of 2009, the Kepler Mission commenced high-precision
photometry on nearly 156000 stars to determine the frequency and
characteristics of small exoplanets, conduct a guest observer program,
and obtain asteroseismic data on a wide variety of stars. On 2010
June 15, the Kepler Mission released most of the data from the first
quarter of observations. At the time of this data release, 705 stars
from this first data set have exoplanet candidates with sizes from as
small as that of Earth to larger than that of Jupiter. Here we give
the identity and characteristics of 305 released stars with planetary
candidates. Data for the remaining 400 stars with planetary candidates
will be released in 2011 February. More than half the candidates on
the released list have radii less than half that of Jupiter. Five
candidates are present in and near the habitable zone; two near
super-Earth size, and three bracketing the size of Jupiter. The
released stars also include five possible multi-planet systems. One
of these has two Neptune-size (2.3 and 2.5 Earth radius) candidates
with near-resonant periods. <P />(1 data file).
---------------------------------------------------------
Title: The LCOGT Network
Authors: Shporer, Avi; Brown, Tim; Lister, Tim; Street, Rachel;
Tsapras, Yiannis; Bianco, Federica; Fulton, Benjamin; Howell, Andy
2011IAUS..276..553S Altcode: 2010arXiv1011.6394S
Motivated by the increasing need for observational resources for the
study of time varying astronomy, the Las Cumbres Observatory Global
Telescope (LCOGT) is a private foundation, whose goal is to build
a global network of robotic telescopes for scientific research and
education. Once completed, the network will become a unique tool,
capable of continuous monitoring from both the Northern and Southern
Hemispheres. The network currently includes 2 × 2.0 m telescopes,
already making an impact in the field of exoplanet research. In the next
few years they will be joined by at least 12 × 1.0 m and 20 × 0.4 m
telescopes. The increasing amount of LCOGT observational resources in
the coming years will be of great service to the astronomical community
in general, and the exoplanet community in particular.
---------------------------------------------------------
Title: VizieR Online Data Catalog: Kepler planetary
candidates. II. (Borucki+, 2011)
Authors: Borucki, W. J.; Koch, D. G.; Basri, G.; Batalha, N.; Brown,
T. M.; Bryson, S. T.; Caldwell, D.; Christensen-Dalsgaard, J.;
Cochran, W. D.; DeVore, E.; Dunham, E. W.; Gautier, T. N.; Geary,
J. C.; Gilliland, R.; Gould, A.; Howell, S. B.; Jenkins, J. M.;
Latham, D. W.; Lissauer, J. J.; Marcy, G. W.; Rowe, J.; Sasselov,
D.; Boss, A.; Charbonneau, D.; Ciardi, D.; Doyle, L.; Dupree, A. K.;
Ford, E. B.; Fortney, J.; Holman, M. J.; Seager, S.; Steffen, J. H.;
Tarter, J.; Welsh, W. F.; Allen, C.; Buchhave, L. A.; Christiansen,
J. L.; Clarke, B. D.; Das, S.; Desert, J. -M.; Endl, M.; Fabrycky,
D.; Fressin, F.; Haas, M.; Horch, E.; Howard, A.; Isaacson, H.;
Kjeldsen, H.; Kolodziejczak, J.; Kulesa, C.; Li, J.; Lucas, P. W.;
Machalek, P.; McCarthy, D.; MacQueen, P.; Meibom, S.; Miquel, T.;
Prsa, A.; Quinn, S. N.; Quintana, E. V.; Ragozzine, D.; Sherry, W.;
Shporer, A.; Tenenbaum, P.; Torres, G.; Twicken, J. D.; van Cleve,
J.; Walkowicz, L.; Witteborn, F. C.; Still, M.
2011yCat..17360019B Altcode:
The results discussed in this paper are based on three data segments:
the first segment (labeled Q0) started on JD 2454953.53 and ended on
2454963.25 and was taken during commissioning operations, the second
data segment (labeled Q1) taken at the beginning of science operations
that started on JD 2454964.50 and finished on JD 2454997.99, and a
third segment (labeled Q2) starting on JD 2455002.51 and finishing on
JD 2455091.48. The durations of the segments are 9.7, 33.5, and 89.0
days, respectively. The observations span a total period of 137.95
days including the gaps. A total of 156097 long cadence (LC) targets
in Q1, and 166247 LC and 1492 short cadence (SC) targets in Q2 were
observed. The results reported here are for the LC observations of
153196 stars observed during Q2. The selected stars are primarily
main-sequence dwarfs chosen from the Kepler Input Catalog (KIC,
Cat. V/133). <P />(4 data files).
---------------------------------------------------------
Title: Kepler Input Catalog: Photometric Calibration and Stellar
Classification
Authors: Brown, Timothy M.; Latham, David W.; Everett, Mark E.;
Esquerdo, Gilbert A.
2011AJ....142..112B Altcode: 2011arXiv1102.0342B
We describe the photometric calibration and stellar classification
methods used by the Stellar Classification Project to produce the Kepler
Input Catalog (KIC). The KIC is a catalog containing photometric and
physical data for sources in the Kepler mission field of view; it is
used by the mission to select optimal targets. Four of the visible-light
(g, r, i, z) magnitudes used in the KIC are tied to Sloan Digital Sky
Survey magnitudes; the fifth (D51) is an AB magnitude calibrated to be
consistent with Castelli & Kurucz (CK) model atmosphere fluxes. We
derived atmospheric extinction corrections from hourly observations of
secondary standard fields within the Kepler field of view. For these
filters and extinction estimates, repeatability of absolute photometry
for stars brighter than magnitude 15 is typically 2%. We estimated
stellar parameters {T <SUB>eff</SUB>, log (g), log (Z), E <SUB> B -
V </SUB>} using Bayesian posterior probability maximization to match
observed colors to CK stellar atmosphere models. We applied Bayesian
priors describing the distribution of solar-neighborhood stars in the
color-magnitude diagram, in log (Z), and in height above the galactic
plane. Several comparisons with samples of stars classified by other
means indicate that for 4500 K <=T <SUB>eff</SUB> <= 6500 K, our
classifications are reliable within about ±200 K and 0.4 dex in log (g)
for dwarfs, with somewhat larger log (g) uncertainties for giants. It
is difficult to assess the reliability of our log (Z) estimates, but
there is reason to suspect that it is poor, particularly at extreme T
<SUB>eff</SUB>. Comparisons between the CK models and observed colors
are generally satisfactory with some exceptions, notably for stars
cooler than 4500 K. Of great importance for the Kepler mission, for
T <SUB>eff</SUB> <= 5400 K, comparison with asteroseismic results
shows that the distinction between main-sequence stars and giants is
reliable with about 98% confidence. Larger errors in log (g) occur
for warmer stars, for which our filter set provides inadequate gravity
diagnostics. The KIC is available through the MAST data archive.
---------------------------------------------------------
Title: Verification of the Kepler Input Catalog from Asteroseismology
of Solar-type Stars
Authors: Verner, G. A.; Chaplin, W. J.; Basu, S.; Brown, T. M.;
Hekker, S.; Huber, D.; Karoff, C.; Mathur, S.; Metcalfe, T. S.;
Mosser, B.; Quirion, P. -O.; Appourchaux, T.; Bedding, T. R.; Bruntt,
H.; Campante, T. L.; Elsworth, Y.; García, R. A.; Handberg, R.;
Régulo, C.; Roxburgh, I. W.; Stello, D.; Christensen-Dalsgaard, J.;
Gilliland, R. L.; Kawaler, S. D.; Kjeldsen, H.; Allen, C.; Clarke,
B. D.; Girouard, F. R.
2011ApJ...738L..28V Altcode: 2011arXiv1109.0869V
We calculate precise stellar radii and surface gravities from the
asteroseismic analysis of over 500 solar-type pulsating stars observed
by the Kepler space telescope. These physical stellar properties
are compared with those given in the Kepler Input Catalog (KIC),
determined from ground-based multi-color photometry. For the stars
in our sample, we find general agreement but we detect an average
overestimation bias of 0.23 dex in the KIC determination of log (g)
for stars with log (g)<SUB>KIC</SUB> > 4.0 dex, and a resultant
underestimation bias of up to 50% in the KIC radii estimates for stars
with R <SUB>KIC</SUB> < 2 R <SUB>sun</SUB>. Part of the difference
may arise from selection bias in the asteroseismic sample; nevertheless,
this result implies there may be fewer stars characterized in the KIC
with R ~ 1 R <SUB>sun</SUB> than is suggested by the physical properties
in the KIC. Furthermore, if the radius estimates are taken from the
KIC for these affected stars and then used to calculate the size of
transiting planets, a similar underestimation bias may be applied to
the planetary radii.
---------------------------------------------------------
Title: The GHOSTS Survey. I. Hubble Space Telescope Advanced Camera
for Surveys Data
Authors: Radburn-Smith, D. J.; de Jong, R. S.; Seth, A. C.; Bailin,
J.; Bell, E. F.; Brown, T. M.; Bullock, J. S.; Courteau, S.; Dalcanton,
J. J.; Ferguson, H. C.; Goudfrooij, P.; Holfeltz, S.; Holwerda, B. W.;
Purcell, C.; Sick, J.; Streich, D.; Vlajic, M.; Zucker, D. B.
2011ApJS..195...18R Altcode:
We present an overview of the GHOSTS survey, the largest study to
date of the resolved stellar populations in the outskirts of disk
galaxies. The sample consists of 14 disk galaxies within 17 Mpc,
whose outer disks and halos are imaged with the Hubble Space Telescope
Advanced Camera for Surveys (ACS). In the first paper of this series,
we describe the sample, explore the benefits of using resolved stellar
populations, and discuss our ACS F606W and F814W photometry. We use
artificial star tests to assess completeness and use overlapping regions
to estimate photometric uncertainties. The median depth of the survey
at 50% completeness is 2.7 mag below the tip of the red giant branch
(TRGB). We comprehensively explore and parameterize contamination from
unresolved background galaxies and foreground stars using archival
fields of high-redshift ACS observations. Left uncorrected, these
would account for 10<SUP>0.65 × F814W - 19.0</SUP> detections per
mag per arcsec<SUP>2</SUP>. We therefore identify several selection
criteria that typically remove 95% of the contaminants. Even with these
culls, background galaxies are a significant limitation to the surface
brightness detection limit which, for this survey, is typically V ~ 30
mag arcsec<SUP>-2</SUP>. The resulting photometric catalogs are publicly
available and contain some 3.1 million stars across 76 ACS fields,
predominantly of low extinction. The uniform magnitudes of TRGB stars
in these fields enable galaxy distance estimates with 2%-7% accuracy.
---------------------------------------------------------
Title: The pulsations of PG 1351+489
Authors: Redaelli, M.; Kepler, S. O.; Costa, J. E. S.; Winget, D. E.;
Handler, G.; Castanheira, B. G.; Kanaan, A.; Fraga, L.; Henrique,
P.; Giovannini, O.; Provencal, J. L.; Shipman, H. L.; Dalessio, J.;
Thompson, S. E.; Mullally, F.; Brewer, M. M.; Childers, D.; Oksala,
M. E.; Rosen, R.; Wood, M. A.; Reed, M. D.; Walter, B.; Strickland,
W.; Chandler, D.; Watson, T. K.; Nather, R. E.; Montgomery, M. H.;
Bischoff-Kim, A.; Hansen, C. J.; Nitta, A.; Kleinman, S. J.; Claver,
C. F.; Brown, T. M.; Sullivan, D. J.; Kim, S. -L.; Chen, W. -P.;
Yang, M.; Shih, C. -Y.; Zhang, X.; Jiang, X.; Fu, J. N.; Seetha,
S.; Ashoka, B. N.; Marar, T. M. K.; Baliyan, K. S.; Vats, H. O.;
Chernyshev, A. V.; Ibbetson, P.; Leibowitz, E.; Hemar, S.; Sergeev,
A. V.; Andreev, M. V.; Janulis, R.; Meištas, E. G.; Moskalik, P.;
Pajdosz, G.; Baran, A.; Winiarski, M.; Zola, S.; Ogloza, W.; Siwak, M.;
Bognár, Zs.; Solheim, J. -E.; Sefako, R.; Buckley, D.; O'Donoghue,
D.; Nagel, T.; Silvotti, R.; Bruni, I.; Fremy, J. R.; Vauclair, G.;
Chevreton, M.; Dolez, N.; Pfeiffer, B.; Barstow, M. A.; Creevey,
O. L.; Kawaler, S. D.; Clemens, J. C.
2011MNRAS.415.1220R Altcode: 2011MNRAS.tmp..999R
PG 1351+489 is one of the 20 DBVs - pulsating helium-atmosphere white
dwarf stars - known and has the simplest power spectrum for this class
of star, making it a good candidate to study cooling rates. We report
accurate period determinations for the main peak at 489.334 48 s and
two other normal modes using data from the Whole Earth Telescope
(WET) observations of 1995 and 2009. In 2009, we detected a new
pulsation mode and the main pulsation mode exhibited substantial
change in its amplitude compared to all previous observations. We were
able to estimate the star's rotation period, of 8.9 h, and discuss a
possible determination of the rate of period change of (2.0 ± 0.9) ×
10<SUP>-13</SUP> s s <SUP>-1</SUP>, the first such estimate for a DBV.
---------------------------------------------------------
Title: Characteristics of Planetary Candidates Observed by
Kepler. II. Analysis of the First Four Months of Data
Authors: Borucki, William J.; Koch, David G.; Basri, Gibor; Batalha,
Natalie; Brown, Timothy M.; Bryson, Stephen T.; Caldwell, Douglas;
Christensen-Dalsgaard, Jørgen; Cochran, William D.; DeVore, Edna;
Dunham, Edward W.; Gautier, Thomas N., III; Geary, John C.; Gilliland,
Ronald; Gould, Alan; Howell, Steve B.; Jenkins, Jon M.; Latham, David
W.; Lissauer, Jack J.; Marcy, Geoffrey W.; Rowe, Jason; Sasselov,
Dimitar; Boss, Alan; Charbonneau, David; Ciardi, David; Doyle,
Laurance; Dupree, Andrea K.; Ford, Eric B.; Fortney, Jonathan; Holman,
Matthew J.; Seager, Sara; Steffen, Jason H.; Tarter, Jill; Welsh,
William F.; Allen, Christopher; Buchhave, Lars A.; Christiansen,
Jessie L.; Clarke, Bruce D.; Das, Santanu; Désert, Jean-Michel;
Endl, Michael; Fabrycky, Daniel; Fressin, Francois; Haas, Michael;
Horch, Elliott; Howard, Andrew; Isaacson, Howard; Kjeldsen, Hans;
Kolodziejczak, Jeffery; Kulesa, Craig; Li, Jie; Lucas, Philip W.;
Machalek, Pavel; McCarthy, Donald; MacQueen, Phillip; Meibom, Søren;
Miquel, Thibaut; Prsa, Andrej; Quinn, Samuel N.; Quintana, Elisa V.;
Ragozzine, Darin; Sherry, William; Shporer, Avi; Tenenbaum, Peter;
Torres, Guillermo; Twicken, Joseph D.; Van Cleve, Jeffrey; Walkowicz,
Lucianne; Witteborn, Fred C.; Still, Martin
2011ApJ...736...19B Altcode: 2011arXiv1102.0541B
On 2011 February 1 the Kepler mission released data for 156,453
stars observed from the beginning of the science observations on
2009 May 2 through September 16. There are 1235 planetary candidates
with transit-like signatures detected in this period. These are
associated with 997 host stars. Distributions of the characteristics
of the planetary candidates are separated into five class sizes:
68 candidates of approximately Earth-size (R <SUB>p</SUB> <
1.25 R <SUB>⊕</SUB>), 288 super-Earth-size (1.25 R <SUB>⊕</SUB>
<= R <SUB>p</SUB> < 2 R <SUB>⊕</SUB>), 662 Neptune-size
(2 R <SUB>⊕</SUB> <= R <SUB>p</SUB> < 6 R <SUB>⊕</SUB>),
165 Jupiter-size (6 R <SUB>⊕</SUB> <= R <SUB>p</SUB> <
15 R <SUB>⊕</SUB>), and 19 up to twice the size of Jupiter (15 R
<SUB>⊕</SUB> <= R <SUB>p</SUB> < 22 R <SUB>⊕</SUB>). In the
temperature range appropriate for the habitable zone, 54 candidates
are found with sizes ranging from Earth-size to larger than that
of Jupiter. Six are less than twice the size of the Earth. Over 74%
of the planetary candidates are smaller than Neptune. The observed
number versus size distribution of planetary candidates increases to a
peak at two to three times the Earth-size and then declines inversely
proportional to the area of the candidate. Our current best estimates
of the intrinsic frequencies of planetary candidates, after correcting
for geometric and sensitivity biases, are 5% for Earth-size candidates,
8% for super-Earth-size candidates, 18% for Neptune-size candidates,
2% for Jupiter-size candidates, and 0.1% for very large candidates; a
total of 0.34 candidates per star. Multi-candidate, transiting systems
are frequent; 17% of the host stars have multi-candidate systems,
and 34% of all the candidates are part of multi-candidate systems.
---------------------------------------------------------
Title: A First Comparison of Kepler Planet Candidates in Single and
Multiple Systems
Authors: Latham, David W.; Rowe, Jason F.; Quinn, Samuel N.; Batalha,
Natalie M.; Borucki, William J.; Brown, Timothy M.; Bryson, Stephen
T.; Buchhave, Lars A.; Caldwell, Douglas A.; Carter, Joshua A.;
Christiansen, Jessie L.; Ciardi, David R.; Cochran, William D.;
Dunham, Edward W.; Fabrycky, Daniel C.; Ford, Eric B.; Gautier,
Thomas N., III; Gilliland, Ronald L.; Holman, Matthew J.; Howell,
Steve B.; Ibrahim, Khadeejah A.; Isaacson, Howard; Jenkins, Jon M.;
Koch, David G.; Lissauer, Jack J.; Marcy, Geoffrey W.; Quintana,
Elisa V.; Ragozzine, Darin; Sasselov, Dimitar; Shporer, Avi; Steffen,
Jason H.; Welsh, William F.; Wohler, Bill
2011ApJ...732L..24L Altcode: 2011arXiv1103.3896L
In this Letter, we present an overview of the rich population of systems
with multiple candidate transiting planets found in the first four
months of Kepler data. The census of multiples includes 115 targets
that show two candidate planets, 45 with three, eight with four,
and one each with five and six, for a total of 170 systems with 408
candidates. When compared to the 827 systems with only one candidate,
the multiples account for 17% of the total number of systems, and
one-third of all the planet candidates. We compare the characteristics
of candidates found in multiples with those found in singles. False
positives due to eclipsing binaries are much less common for the
multiples, as expected. Singles and multiples are both dominated by
planets smaller than Neptune; 69<SUP>+2</SUP> <SUB> - 3</SUB>% for
singles and 86<SUP>+2</SUP> <SUB> - 5</SUB>% for multiples. This result,
that systems with multiple transiting planets are less likely to include
a transiting giant planet, suggests that close-in giant planets tend
to disrupt the orbital inclinations of small planets in flat systems,
or maybe even prevent the formation of such systems in the first place.
---------------------------------------------------------
Title: Constraining the Properties of Delta Scuti Stars Using
Spectroscopic Eclipsing Binary Systems
Authors: Creevey, O. L.; Metcalfe, T. S.; Brown, T. M.; Jiménez-Reyes,
S.; Belmonte, J. A.
2011ApJ...733...38C Altcode: 2011arXiv1105.1045C
Many stars exhibit stellar pulsations, favoring them for asteroseismic
analyses. Interpreting the oscillations requires some knowledge
of the oscillation mode geometry (spherical degree, radial, and
azimuthal orders). The δ Scuti stars (1.5-2.5 M <SUB>sun</SUB>)
often show just one or few pulsation frequencies. Although this may
promise a successful seismological analysis, we may not know enough
about either the mode or the star to use the oscillation frequency to
improve the determination of the stellar model or to probe the star's
structure. For the observed frequencies to be used successfully as
seismic probes of these objects, we need to concentrate on stars for
which we can reduce the number of free parameters in the problem,
such as binary systems or open clusters. We investigate how much
our understanding of a δ Scuti star is improved when it is in a
detached eclipsing binary system instead of being a single field
star. We use singular value decomposition to explore the precision
we expect in stellar parameters (mass, age, and chemical composition)
for both cases. We examine how the parameter uncertainties propagate
to the luminosity-effective temperature diagram and determine when the
effort of obtaining a new measurement is justified. We show that for
the single star, a correct identification of the oscillation mode is
necessary to produce strong constraints on the stellar model properties,
while for the binary system the observations without the pulsation mode
provide the same or better constraints on the stellar parameters. In
the latter case, the strong constraints provided by the binary system
not only allow us to detect an incorrectly identified oscillation mode,
but we can also constrain the oscillation mode geometry by comparing
the distribution of possible solutions with and without including the
oscillation frequency as a constraint.
---------------------------------------------------------
Title: HST/ACS Observations of RR Lyrae Stars in Six Ultra-deep
Fields of M31
Authors: Jeffery, E. J.; Smith, E.; Brown, T. M.; Sweigart, A. V.;
Kalirai, J. S.; Ferguson, H. C.; Guhathakurta, P.; Renzini, A.; Rich,
R. M.
2011AJ....141..171J Altcode: 2011arXiv1103.1400J
We present HST/ACS observations of RR Lyrae variable stars in six
ultra-deep fields of the Andromeda galaxy (M31), including parts
of the halo, disk, and giant stellar stream. Past work on the RR
Lyrae stars in M31 has focused on various aspects of the stellar
populations that make up the galaxy's halo, including their distances
and metallicities. This study builds upon this previous work by
increasing the spatial coverage (something that has been lacking
in previous studies) and by searching for these variable stars in
constituents of the galaxy not yet explored. Besides the 55 RR Lyrae
stars we found in our initial field located 11 kpc from the galactic
nucleus, we find additional RR Lyrae stars in four of the remaining
five ultra-deep fields as follows: 21 in the disk, 24 in the giant
stellar stream, three in the halo field 21 kpc from the galactic
nucleus, and five in one of the halo fields at 35 kpc. No RR Lyrae
stars were found in the second halo field at 35 kpc. The RR Lyrae
populations of these fields appear to be mostly of Oosterhoff I type,
although the 11 kpc field appears to be intermediate or mixed. We will
discuss the properties of these stars including period and reddening
distributions. We calculate metallicities and distances for the stars in
each of these fields using different methods and compare the results,
to an extent that has not yet been done. We compare these methods not
just on RR Lyrae stars in our M31 fields, but also on a data set of
Milky Way field RR Lyrae stars. <P />Based on observations made with
the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope
Science Institute, which is operated by the Association of Universities
for Research in Astronomy, Incorporated, under NASA contract NAS5-26555.
---------------------------------------------------------
Title: The Impact of the Convective Blueshift Effect on Spectroscopic
Planetary Transits
Authors: Shporer, Avi; Brown, Tim
2011ApJ...733...30S Altcode: 2011arXiv1103.0775S
We present here a small anomalous radial velocity (RV) signal expected
to be present in RV curves measured during planetary transits. This
signal is induced by the convective blueshift (CB) effect—a net
blueshift emanating from the stellar surface, resulting from a larger
contribution of rising hot and bright gas relative to the colder and
darker sinking gas. Since the CB radial component varies across the
stellar surface, the light blocked by the planet during a transit
will have a varying RV component, resulting in a small shift of
the measured RVs. The CB-induced anomalous RV curve is different
than, and independent of, the well-known Rossiter-McLaughlin (RM)
effect, where the latter is used for determining the sky-projected
angle between the host star rotation axis and the planet's orbital
angular momentum axis. The observed RV curve is the sum of the CB
and RM signals, and they are both superposed on the orbital Keplerian
curve. If not accounted for, the presence of the CB RV signal in the
spectroscopic transit RV curve may bias the estimate of the spin-orbit
angle. In addition, future very high precision RVs will allow the use
of transiting planets to study the CB of their host stars.
---------------------------------------------------------
Title: The First Detection of Blue Straggler Stars in the Milky
Way Bulge
Authors: Clarkson, Will; Sahu, K. C.; Anderson, J.; Rich, M.; Smith,
E.; Brown, T. M.; Bond, H. E.; Livio, M.; Minniti, D.; Renzini, A.;
Zoccali, M.
2011AAS...21821705C Altcode: 2011BAAS..43G21705C
We report the first detections of Blue Straggler Stars (BSS) in
the bulge of the Milky Way galaxy. Proper motions from extensive
space-based observations along a single sight-line allow us to separate
a sufficiently clean and well-characterized bulge sample that we are
able to detect a small population of bulge objects in the region of
the color-magnitude diagram commonly occupied young objects and blue
strgglers. However, variability measurements of these objects clearly
establish that a fraction of them are blue stragglers. Out of the 42
objects found in this region of the CMD, we estimate that at least 18
are genuine BSS. We normalize the BSS population by our estimate of the
number of horizontal branch stars in the bulge in order to compare the
bulge to other stellar systems. The BSS fraction is clearly discrepant
from that found in stellar clusters. The blue straggler population
of dwarf spheroidals remains a subject of debate; some authors claim
an anticorrelation between the normalised blue straggler fraction
and integrated light. If this trend is real, then the bulge extends
it by three orders of magnitude in mass. Conversely, we find that the
genuinely young (< 5Gy) population in the bulge, must be at most 3.3%
under the most conservative scenario for the BSS population.
---------------------------------------------------------
Title: Validating the First Habitable-Zone Planet Candidates
Identified by the NASA Kepler Mission
Authors: Charbonneau, David; Desert, Jean-Michel; Fressin, Francois;
Ballard, Sarah; Borucki, William; Latham, David; Gilliland, Ronald;
Seager, Sara; Knutson, Heather; Fortney, Jonathan; Brown, Timothy;
Ford, Eric; Deming, Drake; Torres, Guillermo
2011sptz.prop80117C Altcode:
At the beginning of Cycle 8, the NASA Kepler Mission will have completed
two years of science observations, the minimum baseline sufficient
to identify candidate transiting exoplanets orbiting within the
habitable-zones of Sun-like stars. The principal task that lies ahead
is to reject from this sample the false positives (blends of eclipsing
binaries that precisely mimic the signal of a transiting exoplanet), and
to confirm the planetary nature of the remaining candidates. For planets
more massive than Neptune, the direct confirmation of their planetary
status can be accomplished by radial-velocity measurements. However,
such planets possess primordial envelopes of hydrogen and helium
that make them unsuitable to life as we know it. The most exciting
candidates -- and the ones that Kepler is specifically tasked with
finding -- are super-Earth and Earth-sized planets orbiting within their
stellar habitable zones. Kepler has just begun to identify such planet
candidates, and it will identify many more as its baseline increases
throughout the coming year. While the Kepler team has developed powerful
tools to weed out the impostors, Spitzer possesses the unique ability
to provide the final validation of these candidates as planets, namely
by measuring the depth of the transit at infrared wavelengths. By
combining the infrared and optical measurements of the transit depth
with models of hypothetical stellar blends, we can definitively test
the stellar-blend hypothesis. We propose to observe the transits of 20
candidate habitable-zone super-Earths to be identified by the Kepler
Mission. The results from this Exploration Science Program will be
twofold: First, we will definitively validate the first potentially
habitable planets ever identified. Second, we will determine the rate
of occurrence of impostors. This rate of false positives can then be
applied to the much larger sample of candidates identified by Kepler,
to deduce the true rate of planetary companions.
---------------------------------------------------------
Title: Predicting the Detectability of Oscillations in Solar-type
Stars Observed by Kepler
Authors: Chaplin, W. J.; Kjeldsen, H.; Bedding, T. R.;
Christensen-Dalsgaard, J.; Gilliland, R. L.; Kawaler, S. D.;
Appourchaux, T.; Elsworth, Y.; García, R. A.; Houdek, G.; Karoff, C.;
Metcalfe, T. S.; Molenda-Żakowicz, J.; Monteiro, M. J. P. F. G.;
Thompson, M. J.; Verner, G. A.; Batalha, N.; Borucki, W. J.;
Brown, T. M.; Bryson, S. T.; Christiansen, J. L.; Clarke, B. D.;
Jenkins, J. M.; Klaus, T. C.; Koch, D.; An, D.; Ballot, J.; Basu,
S.; Benomar, O.; Bonanno, A.; Broomhall, A. -M.; Campante, T. L.;
Corsaro, E.; Creevey, O. L.; Esch, L.; Gai, N.; Gaulme, P.; Hale,
S. J.; Handberg, R.; Hekker, S.; Huber, D.; Mathur, S.; Mosser, B.;
New, R.; Pinsonneault, M. H.; Pricopi, D.; Quirion, P. -O.; Régulo,
C.; Roxburgh, I. W.; Salabert, D.; Stello, D.; Suran, M. D.
2011ApJ...732...54C Altcode: 2011arXiv1103.0702C
Asteroseismology of solar-type stars has an important part to play
in the exoplanet program of the NASA Kepler Mission. Precise and
accurate inferences on the stellar properties that are made possible
by the seismic data allow very tight constraints to be placed on the
exoplanetary systems. Here, we outline how to make an estimate of the
detectability of solar-like oscillations in any given Kepler target,
using rough estimates of the temperature and radius, and the Kepler
apparent magnitude.
---------------------------------------------------------
Title: LCOGT Imaging Capabilities
Authors: Brown, Timothy M.; Burleson, B.; De Vera, J.; Dubberley,
M.; Haldeman, B.; Hawkins, E.; Haynes, R.; Hjelstrom, A.; Hygelund,
J.; Lister, T.; Lobdill, R.; Pickles, A.; Rosing, W.; Tufts, J.
2011AAS...21813202B Altcode: 2011BAAS..43G13202B
Las Cumbres Observatory Global Telescope (LCOGT) is developing a
world-wide network of optical telescopes dedicated to time-domain
astronomy. In a few years, the network will consist of more than twenty
0.4m telescopes, about fifteen 1m telescopes, and two 2m telescopes, all
of which will initially be equipped for both high-speed and traditional
CCD imaging. Instruments for high-speed applications are described
in Bianco et al. (this session). Here we describe LCOGT's instruments
for relatively wide-field imaging at moderate time cadence. The most
notable of these is the "Sinistro" camera system being built for the 1m
network. It consists of corrector optics, filter changer, photometric
shutter, 16 Mpix CCD camera, and custom CCD controller. Each Sinistro
component is optimized for precision photometric measurements, and the
system provides a large critically sampled field to the full CCD, rapid
access to as many as 21 different filters, minimized shutter overhead,
flexible high-speed readout, support for multiple independent regions
of interest, the ability to autoguide independently of camera focus,
precision CCD temperature control and telemetry, and a dry nitrogen
filter environment.
---------------------------------------------------------
Title: Ensemble Asteroseismology of Solar-Type Stars with the NASA
Kepler Mission
Authors: Chaplin, W. J.; Kjeldsen, H.; Christensen-Dalsgaard, J.;
Basu, S.; Miglio, A.; Appourchaux, T.; Bedding, T. R.; Elsworth, Y.;
García, R. A.; Gilliland, R. L.; Girardi, L.; Houdek, G.; Karoff,
C.; Kawaler, S. D.; Metcalfe, T. S.; Molenda-Żakowicz, J.; Monteiro,
M. J. P. F. G.; Thompson, M. J.; Verner, G. A.; Ballot, J.; Bonanno,
A.; Brandão, I. M.; Broomhall, A. -M.; Bruntt, H.; Campante, T. L.;
Corsaro, E.; Creevey, O. L.; Doğan, G.; Esch, L.; Gai, N.; Gaulme,
P.; Hale, S. J.; Handberg, R.; Hekker, S.; Huber, D.; Jiménez, A.;
Mathur, S.; Mazumdar, A.; Mosser, B.; New, R.; Pinsonneault, M. H.;
Pricopi, D.; Quirion, P. -O.; Régulo, C.; Salabert, D.; Serenelli,
A. M.; Silva Aguirre, V.; Sousa, S. G.; Stello, D.; Stevens, I. R.;
Suran, M. D.; Uytterhoeven, K.; White, T. R.; Borucki, W. J.; Brown,
T. M.; Jenkins, J. M.; Kinemuchi, K.; Van Cleve, J.; Klaus, T. C.
2011Sci...332..213C Altcode: 2011arXiv1109.4723C
In addition to its search for extrasolar planets, the NASA Kepler
mission provides exquisite data on stellar oscillations. We report the
detections of oscillations in 500 solar-type stars in the Kepler field
of view, an ensemble that is large enough to allow statistical studies
of intrinsic stellar properties (such as mass, radius, and age) and
to test theories of stellar evolution. We find that the distribution
of observed masses of these stars shows intriguing differences to
predictions from models of synthetic stellar populations in the Galaxy.
---------------------------------------------------------
Title: Kepler Detected Gravity-Mode Period Spacings in a Red
Giant Star
Authors: Beck, P. G.; Bedding, T. R.; Mosser, B.; Stello, D.; Garcia,
R. A.; Kallinger, T.; Hekker, S.; Elsworth, Y.; Frandsen, S.; Carrier,
F.; De Ridder, J.; Aerts, C.; White, T. R.; Huber, D.; Dupret, M. -A.;
Montalbán, J.; Miglio, A.; Noels, A.; Chaplin, W. J.; Kjeldsen, H.;
Christensen-Dalsgaard, J.; Gilliland, R. L.; Brown, T. M.; Kawaler,
S. D.; Mathur, S.; Jenkins, J. M.
2011Sci...332..205B Altcode:
Stellar interiors are inaccessible through direct observations. For
this reason, helioseismologists made use of the Sun’s acoustic
oscillation modes to tune models of its structure. The quest to detect
modes that probe the solar core has been ongoing for decades. We
report the detection of mixed modes penetrating all the way to the
core of an evolved star from 320 days of observations with the Kepler
satellite. The period spacings of these mixed modes are directly
dependent on the density gradient between the core region and the
convective envelope.
---------------------------------------------------------
Title: Gravity modes as a way to distinguish between hydrogen-
and helium-burning red giant stars
Authors: Bedding, Timothy R.; Mosser, Benoit; Huber, Daniel;
Montalbán, Josefina; Beck, Paul; Christensen-Dalsgaard, Jørgen;
Elsworth, Yvonne P.; García, Rafael A.; Miglio, Andrea; Stello,
Dennis; White, Timothy R.; De Ridder, Joris; Hekker, Saskia; Aerts,
Conny; Barban, Caroline; Belkacem, Kevin; Broomhall, Anne-Marie;
Brown, Timothy M.; Buzasi, Derek L.; Carrier, Fabien; Chaplin,
William J.; di Mauro, Maria Pia; Dupret, Marc-Antoine; Frandsen,
Søren; Gilliland, Ronald L.; Goupil, Marie-Jo; Jenkins, Jon M.;
Kallinger, Thomas; Kawaler, Steven; Kjeldsen, Hans; Mathur, Savita;
Noels, Arlette; Silva Aguirre, Victor; Ventura, Paolo
2011Natur.471..608B Altcode: 2011arXiv1103.5805B
Red giants are evolved stars that have exhausted the supply of hydrogen
in their cores and instead burn hydrogen in a surrounding shell. Once a
red giant is sufficiently evolved, the helium in the core also undergoes
fusion. Outstanding issues in our understanding of red giants include
uncertainties in the amount of mass lost at the surface before helium
ignition and the amount of internal mixing from rotation and other
processes. Progress is hampered by our inability to distinguish between
red giants burning helium in the core and those still only burning
hydrogen in a shell. Asteroseismology offers a way forward, being
a powerful tool for probing the internal structures of stars using
their natural oscillation frequencies. Here we report observations of
gravity-mode period spacings in red giants that permit a distinction
between evolutionary stages to be made. We use high-precision
photometry obtained by the Kepler spacecraft over more than a year
to measure oscillations in several hundred red giants. We find many
stars whose dipole modes show sequences with approximately regular
period spacings. These stars fall into two clear groups, allowing us
to distinguish unambiguously between hydrogen-shell-burning stars
(period spacing mostly ~50seconds) and those that are also burning
helium (period spacing ~100 to 300 seconds).
---------------------------------------------------------
Title: Kepler's First Rocky Planet: Kepler-10b
Authors: Batalha, Natalie M.; Borucki, William J.; Bryson, Stephen
T.; Buchhave, Lars A.; Caldwell, Douglas A.; Christensen-Dalsgaard,
Jørgen; Ciardi, David; Dunham, Edward W.; Fressin, Francois;
Gautier, Thomas N., III; Gilliland, Ronald L.; Haas, Michael R.;
Howell, Steve B.; Jenkins, Jon M.; Kjeldsen, Hans; Koch, David G.;
Latham, David W.; Lissauer, Jack J.; Marcy, Geoffrey W.; Rowe, Jason
F.; Sasselov, Dimitar D.; Seager, Sara; Steffen, Jason H.; Torres,
Guillermo; Basri, Gibor S.; Brown, Timothy M.; Charbonneau, David;
Christiansen, Jessie; Clarke, Bruce; Cochran, William D.; Dupree,
Andrea; Fabrycky, Daniel C.; Fischer, Debra; Ford, Eric B.; Fortney,
Jonathan; Girouard, Forrest R.; Holman, Matthew J.; Johnson, John;
Isaacson, Howard; Klaus, Todd C.; Machalek, Pavel; Moorehead, Althea
V.; Morehead, Robert C.; Ragozzine, Darin; Tenenbaum, Peter; Twicken,
Joseph; Quinn, Samuel; VanCleve, Jeffrey; Walkowicz, Lucianne M.;
Welsh, William F.; Devore, Edna; Gould, Alan
2011ApJ...729...27B Altcode: 2011arXiv1102.0605B
NASA's Kepler Mission uses transit photometry to determine
the frequency of Earth-size planets in or near the habitable
zone of Sun-like stars. The mission reached a milestone toward
meeting that goal: the discovery of its first rocky planet,
Kepler-10b. Two distinct sets of transit events were detected: (1)
a 152 ± 4 ppm dimming lasting 1.811 ± 0.024 hr with ephemeris
T [BJD] =2454964.57375<SUP>+0.00060</SUP> <SUB>-0.00082</SUB> +
N*0.837495<SUP>+0.000004</SUP> <SUB>-0.000005</SUB> days and (2)
a 376 ± 9 ppm dimming lasting 6.86 ± 0.07 hr with ephemeris
T [BJD] =2454971.6761<SUP>+0.0020</SUP> <SUB>-0.0023</SUB> +
N*45.29485<SUP>+0.00065</SUP> <SUB>-0.00076</SUB> days. Statistical
tests on the photometric and pixel flux time series established the
viability of the planet candidates triggering ground-based follow-up
observations. Forty precision Doppler measurements were used to confirm
that the short-period transit event is due to a planetary companion. The
parent star is bright enough for asteroseismic analysis. Photometry was
collected at 1 minute cadence for >4 months from which we detected
19 distinct pulsation frequencies. Modeling the frequencies resulted in
precise knowledge of the fundamental stellar properties. Kepler-10 is
a relatively old (11.9 ± 4.5 Gyr) but otherwise Sun-like main-sequence
star with T <SUB>eff</SUB> = 5627 ± 44 K, M <SUB>sstarf</SUB> = 0.895
± 0.060 M <SUB>sun</SUB>, and R <SUB>sstarf</SUB> = 1.056 ± 0.021 R
<SUB>sun</SUB>. Physical models simultaneously fit to the transit light
curves and the precision Doppler measurements yielded tight constraints
on the properties of Kepler-10b that speak to its rocky composition: M
<SUB>P</SUB> = 4.56<SUP>+1.17</SUP> <SUB>-1.29</SUB> M <SUB>⊕</SUB>,
R <SUB>P</SUB> = 1.416<SUP>+0.033</SUP> <SUB>-0.036</SUB> R
<SUB>⊕</SUB>, and ρ<SUB>P</SUB> = 8.8<SUP>+2.1</SUP> <SUB>-2.9</SUB>
g cm<SUP>-3</SUP>. Kepler-10b is the smallest transiting exoplanet
discovered to date. <P />Based in part on observations obtained at
the W. M. Keck Observatory, which is operated by the University of
California and the California Institute of Technology.
---------------------------------------------------------
Title: LCOGT Sites and Facilities
Authors: Martinez, John; Brown, Timothy M.; Conway, Patrick; Elphick,
Mark; Falarski, Michael; Hawkins, Eric; Rosing, Wayne; Shobbrook, John
2011tfa..confE..32M Altcode:
LCOGT is currently building and deploying a world-wide network of
at least twelve 1-meter and twenty-four 0.4-meter telescopes to as
many as 4 sites in the Southern hemisphere (Chile, South Africa,
Eastern Australia) and 4 in the Northern hemisphere (Hawaii, West
Texas, Canary Islands). Our deployment and operations model emphasizes
modularity and interchangeability of major components, maintenance and
troubleshooting personnel who are local to the site, and autonomy of
operation. We plan to ship, install, and spare large units (in many
cases entire telescopes), with minimal assembly on site.
---------------------------------------------------------
Title: White-light Flares on Cool Stars in the Kepler Quarter 1 Data
Authors: Walkowicz, Lucianne M.; Basri, Gibor; Batalha, Natalie;
Gilliland, Ronald L.; Jenkins, Jon; Borucki, William J.; Koch, David;
Caldwell, Doug; Dupree, Andrea K.; Latham, David W.; Meibom, Soeren;
Howell, Steve; Brown, Timothy M.; Bryson, Steve
2011AJ....141...50W Altcode: 2010arXiv1008.0853W
We present the results of a search for white-light flares on ~23,000
cool dwarfs in the Kepler Quarter 1 long cadence data. We have
identified 373 flaring stars, some of which flare multiple times during
the observation period. We calculate relative flare energies, flare
rates, and durations and compare these with the quiescent photometric
variability of our sample. We find that M dwarfs tend to flare more
frequently but for shorter durations than K dwarfs and that they emit
more energy relative to their quiescent luminosity in a given flare than
K dwarfs. Stars that are more photometrically variable in quiescence
tend to emit relatively more energy during flares, but variability is
only weakly correlated with flare frequency. We estimate distances for
our sample of flare stars and find that the flaring fraction agrees
well with other observations of flare statistics for stars within
300 pc above the Galactic plane. These observations provide a more
rounded view of stellar flares by sampling stars that have not been
pre-selected by their activity, and are informative for understanding
the influence of these flares on planetary habitability.
---------------------------------------------------------
Title: Characteristics of Kepler Planetary Candidates Based on the
First Data Set
Authors: Borucki, William J.; Koch, David G.; Basri, Gibor;
Batalha, Natalie; Boss, Alan; Brown, Timothy M.; Caldwell, Douglas;
Christensen-Dalsgaard, Jørgen; Cochran, William D.; DeVore, Edna;
Dunham, Edward W.; Dupree, Andrea K.; Gautier, Thomas N., III;
Geary, John C.; Gilliland, Ronald; Gould, Alan; Howell, Steve B.;
Jenkins, Jon M.; Kjeldsen, Hans; Latham, David W.; Lissauer, Jack
J.; Marcy, Geoffrey W.; Monet, David G.; Sasselov, Dimitar; Tarter,
Jill; Charbonneau, David; Doyle, Laurance; Ford, Eric B.; Fortney,
Jonathan; Holman, Matthew J.; Seager, Sara; Steffen, Jason H.; Welsh,
William F.; Allen, Christopher; Bryson, Stephen T.; Buchhave, Lars;
Chandrasekaran, Hema; Christiansen, Jessie L.; Ciardi, David; Clarke,
Bruce D.; Dotson, Jessie L.; Endl, Michael; Fischer, Debra; Fressin,
Francois; Haas, Michael; Horch, Elliott; Howard, Andrew; Isaacson,
Howard; Kolodziejczak, Jeffery; Li, Jie; MacQueen, Phillip; Meibom,
Søren; Prsa, Andrej; Quintana, Elisa V.; Rowe, Jason; Sherry, William;
Tenenbaum, Peter; Torres, Guillermo; Twicken, Joseph D.; Van Cleve,
Jeffrey; Walkowicz, Lucianne; Wu, Hayley
2011ApJ...728..117B Altcode: 2010arXiv1006.2799B
In the spring of 2009, the Kepler Mission commenced high-precision
photometry on nearly 156,000 stars to determine the frequency and
characteristics of small exoplanets, conduct a guest observer program,
and obtain asteroseismic data on a wide variety of stars. On 2010
June 15, the Kepler Mission released most of the data from the first
quarter of observations. At the time of this data release, 705 stars
from this first data set have exoplanet candidates with sizes from as
small as that of Earth to larger than that of Jupiter. Here we give
the identity and characteristics of 305 released stars with planetary
candidates. Data for the remaining 400 stars with planetary candidates
will be released in 2011 February. More than half the candidates on
the released list have radii less than half that of Jupiter. Five
candidates are present in and near the habitable zone; two near
super-Earth size, and three bracketing the size of Jupiter. The
released stars also include five possible multi-planet systems. One
of these has two Neptune-size (2.3 and 2.5 Earth radius) candidates
with near-resonant periods.
---------------------------------------------------------
Title: Modeling Kepler Transit Light Curves as False Positives:
Rejection of Blend Scenarios for Kepler-9, and Validation of Kepler-9
d, A Super-earth-size Planet in a Multiple System
Authors: Torres, Guillermo; Fressin, François; Batalha, Natalie M.;
Borucki, William J.; Brown, Timothy M.; Bryson, Stephen T.; Buchhave,
Lars A.; Charbonneau, David; Ciardi, David R.; Dunham, Edward W.;
Fabrycky, Daniel C.; Ford, Eric B.; Gautier, Thomas N., III; Gilliland,
Ronald L.; Holman, Matthew J.; Howell, Steve B.; Isaacson, Howard;
Jenkins, Jon M.; Koch, David G.; Latham, David W.; Lissauer, Jack J.;
Marcy, Geoffrey W.; Monet, David G.; Prsa, Andrej; Quinn, Samuel N.;
Ragozzine, Darin; Rowe, Jason F.; Sasselov, Dimitar D.; Steffen,
Jason H.; Welsh, William F.
2011ApJ...727...24T Altcode: 2010arXiv1008.4393T
Light curves from the Kepler Mission contain valuable information on the
nature of the phenomena producing the transit-like signals. To assist
in exploring the possibility that they are due to an astrophysical
false positive, we describe a procedure (BLENDER) to model the
photometry in terms of a "blend" rather than a planet orbiting a
star. A blend may consist of a background or foreground eclipsing
binary (or star-planet pair) whose eclipses are attenuated by the
light of the candidate and possibly other stars within the photometric
aperture. We apply BLENDER to the case of Kepler-9 (KIC 3323887), a
target harboring two previously confirmed Saturn-size planets (Kepler-9
b and Kepler-9 c) showing transit timing variations, and an additional
shallower signal with a 1.59 day period suggesting the presence of a
super-Earth-size planet. Using BLENDER together with constraints from
other follow-up observations we are able to rule out all blends for
the two deeper signals and provide independent validation of their
planetary nature. For the shallower signal, we rule out a large
fraction of the false positives that might mimic the transits. The
false alarm rate for remaining blends depends in part (and inversely)
on the unknown frequency of small-size planets. Based on several
realistic estimates of this frequency, we conclude with very high
confidence that this small signal is due to a super-Earth-size planet
(Kepler-9 d) in a multiple system, rather than a false positive. The
radius is determined to be 1.64<SUP>+0.19</SUP> <SUB>-0.14</SUB>
R <SUB>⊕</SUB>, and current spectroscopic observations are as yet
insufficient to establish its mass.
---------------------------------------------------------
Title: Photometric Variability in Kepler Target Stars. II. An Overview
of Amplitude, Periodicity, and Rotation in First Quarter Data
Authors: Basri, Gibor; Walkowicz, Lucianne M.; Batalha, Natalie;
Gilliland, Ronald L.; Jenkins, Jon; Borucki, William J.; Koch, David;
Caldwell, Doug; Dupree, Andrea K.; Latham, David W.; Marcy, Geoffrey
W.; Meibom, Soeren; Brown, Tim
2011AJ....141...20B Altcode: 2010arXiv1008.1092B
We provide an overview of stellar variability in the first quarter
data from the Kepler mission. The intent of this paper is to examine
the entire sample of over 150,000 target stars for periodic behavior
in their light curves and relate this to stellar characteristics. This
data set constitutes an unprecedented study of stellar variability
given its great precision and complete time coverage (with a half
hour cadence). Because the full Kepler pipeline is not currently
suitable for a study of stellar variability of this sort, we describe
our procedures for treating the "raw" pipeline data. About half of
the total sample exhibits convincing periodic variability up to two
weeks, with amplitudes ranging from differential intensity changes of
less than 10<SUP>-4</SUP> up to more than 10%. K and M dwarfs have a
greater fraction of period behavior than G dwarfs. The giants in the
sample have distinctive quasi-periodic behavior, but are not periodic
in the way we define it. Not all periodicities are due to rotation,
and the most significant period is not necessarily the rotation
period. We discuss properties of the light curves, and in particular
look at a sample of very clearly periodic G dwarfs. It is clear that
a large number of them do vary because of rotation and starspots,
but it will take further analysis to fully exploit this.
---------------------------------------------------------
Title: Asteroseismology of the Transiting Exoplanet Host HD 17156
with Hubble Space Telescope Fine Guidance Sensor
Authors: Gilliland, Ronald L.; McCullough, Peter R.; Nelan,
Edmund P.; Brown, Timothy M.; Charbonneau, David; Nutzman, Philip;
Christensen-Dalsgaard, Jørgen; Kjeldsen, Hans
2011ApJ...726....2G Altcode: 2010arXiv1011.0435G
Observations conducted with the Fine Guidance Sensor on the Hubble
Space Telescope (HST) providing high cadence and precision time-series
photometry were obtained over 10 consecutive days in 2008 December on
the host star of the transiting exoplanet HD 17156b. During this time,
1.0 × 10<SUP>12</SUP> photons (corrected for detector dead time) were
collected in which a noise level of 163 parts per million per 30 s sum
resulted, thus providing excellent sensitivity to the detection of the
analog of the solar 5-minute p-mode oscillations. For HD 17156, robust
detection of p modes supports the determination of the stellar mean
density of langρ<SUB>*</SUB>rang = 0.5301 ± 0.0044 g cm<SUP>-3</SUP>
from a detailed fit to the observed frequencies of modes of degree l =
0, 1, and 2. This is the first star for which the direct determination
of langρ<SUB>*</SUB>rang has been possible using both asteroseismology
and detailed analysis of a transiting planet light curve. Using
the density constraint from asteroseismology, and stellar evolution
modeling results in M <SUB>*</SUB> = 1.285 ± 0.026 M <SUB>sun</SUB>,
R <SUB>*</SUB> = 1.507 ± 0.012 R <SUB>sun</SUB>, and a stellar age of
3.2 ± 0.3 Gyr. <P />Based on observations with the NASA/ESA Hubble
Space Telescope, obtained at the Space Telescope Science Institute,
which is operated by AURA, Inc., under NASA contract NAS 5-26555.
---------------------------------------------------------
Title: Precise Estimates of the Physical Parameters for the Exoplanet
System HD 17156 Enabled by Hubble Space Telescope Fine Guidance
Sensor Transit and Asteroseismic Observations
Authors: Nutzman, Philip; Gilliland, Ronald L.; McCullough, Peter R.;
Charbonneau, David; Christensen-Dalsgaard, Jørgen; Kjeldsen, Hans;
Nelan, Edmund P.; Brown, Timothy M.; Holman, Matthew J.
2011ApJ...726....3N Altcode: 2010arXiv1011.0440N
We present observations of three distinct transits of HD 17156b
obtained with the Fine Guidance Sensors on board the Hubble Space
Telescope. We analyzed both the transit photometry and previously
published radial velocities to find the planet-star radius ratio
R<SUB>p</SUB> /R <SUB>sstarf</SUB> = 0.07454 ± 0.00035, inclination i =
86.49<SUP>+0.24</SUP> <SUB>-0.20</SUB> deg, and scaled semimajor axis
a/R <SUB>sstarf</SUB> = 23.19<SUP>+0.32</SUP> <SUB>-0.27</SUB>. This
last value translates directly to a mean stellar density determination
ρ<SUB>sstarf</SUB> = 0.522<SUP>+0.021</SUP> <SUB>-0.018</SUB>
g cm<SUP>-3</SUP>. Analysis of asteroseismology observations by
the companion paper of Gilliland et al. provides a consistent but
significantly refined measurement of ρ<SUB>sstarf</SUB> = 0.5308 ±
0.0040. We compare stellar isochrones to this density estimate and find
M <SUB>sstarf</SUB> = 1.275 ± 0.018 M <SUB>sun</SUB> and a stellar
age of 3.37<SUP>+0.20</SUP> <SUB>-0.47</SUB> Gyr. Using this estimate
of M <SUB>sstarf</SUB> and incorporating the density constraint from
asteroseismology, we model both the photometry and published radial
velocities to estimate the planet radius R<SUB>p</SUB> = 1.0870 ±
0.0066 R<SUB>J</SUB> and the stellar radius R <SUB>sstarf</SUB> =
1.5007 ± 0.0076 R <SUB>sun</SUB>. The planet radius is larger than
that found in previous studies and consistent with theoretical models
of a solar-composition gas giant of the same mass and equilibrium
temperature. For the three transits, we determine the times of
mid-transit to a precision of 6.2 s, 7.6 s, and 6.9 s, and the
transit times for HD 17156 do not show any significant departures
from a constant period. The joint analysis of transit photometry and
asteroseismology presages similar studies that will be enabled by the
NASA Kepler Mission. <P />Based on observations with the NASA/ESA Hubble
Space Telescope obtained at the Space Telescope Science Institute,
which is operated by the Association of Universities for Research in
Astronomy, Incorporated, under NASA contract NAS5-26555.
---------------------------------------------------------
Title: KOI-54: The Remarkable Pulsating, Periastron-Pumped Binary Star
Authors: Welsh, William F.; Orosz, J. A.; Gilliland, R. L.; Aerts,
C.; Brown, T. M.; Brugamyer, E.; Cochran, W. D.; Guzik, J. A.; Kurtz,
D. W.; Latham, D. W.; Marcy, G. W.; Quinn, S. A.; Zima, W.; Koch,
D. G.; Borucki, W. J.; Kepler Science Team
2011AAS...21710307W Altcode: 2011BAAS...4310307W
A previously-known unremarkable A star has been discovered by Kepler
to be a fascinating object: KOI-54 exhibits sharp brightening events
every 42 days and a beat-pattern of pulsations locked in phase with the
brightenings. We have determined that this is a highly eccentric face-on
binary star system and the brightenings are due to tidal distortion
plus mutual irradiation of the stars at periastron passage. The periodic
driving produces a rich set of tidally-induced g-mode pulsations locked
to the orbital period. We present spectral analysis, radial velocities,
the exquisite Kepler photometry of KOI-54, and a model that successfully
reproduces these observations. <P />Kepler was selected as the 10th
mission of the Discovery Program. Funding for this mission is provided
by NASA, Science Mission Directorate.
---------------------------------------------------------
Title: Kepler observations: Light shed on the hybrid γ Doradus -
δ Scuti pulsation phenomenon
Authors: Grigahcène, A.; Uytterhoeven, K.; Antoci, V.; Balona, L.;
Catanzaro, G.; Daszyńska-Daszkiewicz, J.; Guzik, J. A.; Handler, G.;
Houdek, G.; Kurtz, D. W.; Marconi, M.; Monteiro, M. J. P. F. G.;
Moya, A.; Ripepi, V.; Suárez, J. -C.; Borucki, W. J.; Brown,
T. M.; Christensen-Dalsgaard, J.; Gilliland, R. L.; Jenkins, J. M.;
Kjeldsen, H.; Koch, D.; Bernabei, S.; Bradley, P.; Breger, M.; Di
Criscienzo, M.; Dupret, M. -A.; García, R. A.; García Hernández, A.;
Jackiewicz, J.; Kaiser, A.; Lehmann, H.; Martín-Ruiz, S.; Mathias,
P.; Molenda-Żakowicz, J.; Nemec, J. M.; Nuspl, J.; Paparó, M.;
Roth, M.; Szabó, R.; Suran, M. D.; Ventura, R.
2010AN....331..989G Altcode:
Through the observational study of stellar pulsations, the internal
structure of stars can be probed and theoretical models can be
tested. The main sequence γ Doradus (Dor) and δ Scuti (Sct) stars
with masses 1.2-2.5 M<SUB>⊙</SUB> are particularly interesting for
asteroseismic study. The γ Dor stars pulsate in high-order gravity (g)
modes, with pulsational periods of order of one day. The δ Sct stars,
on the other hand, show low-order g and pressure (p) modes with periods
of order of 2 hours. Theory predicts the existence of `hybrid' stars,
i.e. stars pulsating in both types of modes, in an overlap region
between the instability strips of γ Dor and δ Sct stars in the
Hertzsprung-Russell diagram. Hybrid stars are particularly interesting
as the two types of modes probe different regions of the stellar
interior and hence provide complementary model constraints. Before
the advent of Kepler, only a few hybrid stars had been confirmed. The
{{Kepler}} satellite is providing a true revolution in the study
of and search for hybrid stars. Analysis of the first 50 days of
{{Kepler}} data of hundreds of γ Dor and δ Sct candidates reveals
extremely rich frequency spectra, with most stars showing frequencies
in both the δ Sct and γ Dor frequency range. As these results show
that there are practically no pure δ Sct or γ Dor pulsators, a new
observational classification scheme is proposed by \cite{Grig10}. We
present their results and characterize 234 stars in terms of δ Sct,
γ Dor, δ Sct/γ Dor or γ Dor/δ Sct hybrids.
---------------------------------------------------------
Title: The Kepler Asteroseismic Investigation: Scientific goals and
first results
Authors: Kjeldsen, H.; Christensen-Dalsgaard, J.; Handberg, R.; Brown,
T. M.; Gilliland, R. L.; Borucki, W. J.; Koch, D.
2010AN....331..966K Altcode: 2010arXiv1007.1816K
Kepler is a NASA mission designed to detect exoplanets and characterize
the properties of exoplanetary systems. Kepler also includes an
asteroseismic programme which is being conducted through the Kepler
Asteroseismic Science Consortium (KASC), whose 400 members are organized
into 13 working groups by type of variable star. So far data have been
available from the first 7 month of the mission containing a total of
2937 targets observed at a 1-min cadence for periods between 10 days and
7 months. The goals of the asteroseismic part of the Kepler project is
to perform detailed studies of stellar interiors. The first results of
the asteroseismic analysis are orders of magnitude better than seen
before, and this bodes well for how the future analysis of Kepler
data for many types of stars will impact our general understanding of
stellar structure and evolution.
---------------------------------------------------------
Title: Discovery and Rossiter-Mclaughlin Effect of Exoplanet Kepler-8b
Authors: Jenkins, Jon M.; Borucki, William J.; Koch, David G.;
Marcy, Geoffrey W.; Cochran, William D.; Welsh, William F.; Basri,
Gibor; Batalha, Natalie M.; Buchhave, Lars A.; Brown, Timothy M.;
Caldwell, Douglas A.; Dunham, Edward W.; Endl, Michael; Fischer,
Debra A.; Gautier, Thomas N., III; Geary, John C.; Gilliland,
Ronald L.; Howell, Steve B.; Isaacson, Howard; Johnson, John Asher;
Latham, David W.; Lissauer, Jack J.; Monet, David G.; Rowe, Jason F.;
Sasselov, Dimitar D.; Howard, Andrew W.; MacQueen, Phillip; Orosz,
Jerome A.; Chandrasekaran, Hema; Twicken, Joseph D.; Bryson, Stephen
T.; Quintana, Elisa V.; Clarke, Bruce D.; Li, Jie; Allen, Christopher;
Tenenbaum, Peter; Wu, Hayley; Meibom, Søren; Klaus, Todd C.; Middour,
Christopher K.; Cote, Miles T.; McCauliff, Sean; Girouard, Forrest R.;
Gunter, Jay P.; Wohler, Bill; Hall, Jennifer R.; Ibrahim, Khadeejah;
Kamal Uddin, AKM; Wu, Michael S.; Bhavsar, Paresh A.; Van Cleve,
Jeffrey; Pletcher, David L.; Dotson, Jessie L.; Haas, Michael R.
2010ApJ...724.1108J Altcode: 2010arXiv1001.0416J
We report on the discovery and the Rossiter-McLaughlin (R-M) effect
of Kepler-8b, a transiting planet identified by the NASA Kepler
Mission. Kepler photometry and Keck-HIRES radial velocities yield the
radius and mass of the planet around this F8IV subgiant host star. The
planet has a radius R <SUB>P</SUB> = 1.419 R <SUB>J</SUB> and a mass
M <SUB>P</SUB> = 0.60 M <SUB>J</SUB>, yielding a density of 0.26 g
cm<SUP>-3</SUP>, one of the lowest planetary densities known. The
orbital period is P = 3.523 days and the orbital semimajor axis is
0.0483<SUP>+0.0006</SUP> <SUB>-0.0012</SUB> AU. The star has a large
rotational vsin i of 10.5 ± 0.7 km s<SUP>-1</SUP> and is relatively
faint (V ≈ 13.89 mag); both properties are deleterious to precise
Doppler measurements. The velocities are indeed noisy, with scatter of
30 m s<SUP>-1</SUP>, but exhibit a period and phase that are consistent
with those implied by transit photometry. We securely detect the R-M
effect, confirming the planet's existence and establishing its orbit
as prograde. We measure an inclination between the projected planetary
orbital axis and the projected stellar rotation axis of λ = -26fdg4 ±
10fdg1, indicating a significant inclination of the planetary orbit. R-M
measurements of a large sample of transiting planets from Kepler will
provide a statistically robust measure of the true distribution of
spin-orbit orientations for hot Jupiters around F and early G stars. <P
/>Based in part on observations obtained at the W. M. Keck Observatory,
which is operated as a scientific partnership between 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: Constraints of a pulsation frequency on stellar parameters
in the eclipsing spectroscopic binary system V577 Oph
Authors: Creevey, O. L.; Telting, J.; Belmonte, J. A.; Brown, T. M.;
Handler, G.; Metcalfe, T. S.; Pinheiro, F.; Sousa, S.; Terrell, D.;
Zhou, A.
2010AN....331..952C Altcode: 2010arXiv1011.3028C
We present a preliminary spectroscopic analysis of the binary system
V577Oph, observed during the summer of 2007 on the 2.6 m NOT telescope
on La Palma. We have obtained time series spectroscopic observations,
which show clear binary motion as well as radial velocity variations due
to pulsation in the primary star. By modelling the radial velocities
we determine a full orbital solution of the system, which yields
{M_A sin<SUP>3</SUP> i = 1.562 ± 0.012} M<SUB>⊙</SUB> and {M_B
sin<SUP>3</SUP> i = 1.461 ± 0.020} M<SUB>⊙</SUB>. An estimate
of inclination from photometry yields a primary mass of ∼ 1.6
M<SUB>⊙</SUB>. Using this derived mass, and the known pulsation
frequency we can impose a lower limit of 1 Gyr on the age of the system,
and constrain the parameters of the oscillation mode. We show that with
further analysis of the spectra (extracting the atmospheric parameters),
tighter constraints could be imposed on the age, metallicity and the
mode parameters. This work emphasizes the power that a single pulsation
frequency can have for constraining stellar parameters in an eclipsing
binary system.
---------------------------------------------------------
Title: A Precise Asteroseismic Age and Radius for the Evolved Sun-like
Star KIC 11026764
Authors: Metcalfe, T. S.; Monteiro, M. J. P. F. G.; Thompson, M. J.;
Molenda-Żakowicz, J.; Appourchaux, T.; Chaplin, W. J.; Doǧan, G.;
Eggenberger, P.; Bedding, T. R.; Bruntt, H.; Creevey, O. L.; Quirion,
P. -O.; Stello, D.; Bonanno, A.; Silva Aguirre, V.; Basu, S.; Esch,
L.; Gai, N.; Di Mauro, M. P.; Kosovichev, A. G.; Kitiashvili, I. N.;
Suárez, J. C.; Moya, A.; Piau, L.; García, R. A.; Marques, J. P.;
Frasca, A.; Biazzo, K.; Sousa, S. G.; Dreizler, S.; Bazot, M.; Karoff,
C.; Frandsen, S.; Wilson, P. A.; Brown, T. M.; Christensen-Dalsgaard,
J.; Gilliland, R. L.; Kjeldsen, H.; Campante, T. L.; Fletcher, S. T.;
Handberg, R.; Régulo, C.; Salabert, D.; Schou, J.; Verner, G. A.;
Ballot, J.; Broomhall, A. -M.; Elsworth, Y.; Hekker, S.; Huber, D.;
Mathur, S.; New, R.; Roxburgh, I. W.; Sato, K. H.; White, T. R.;
Borucki, W. J.; Koch, D. G.; Jenkins, J. M.
2010ApJ...723.1583M Altcode: 2010arXiv1010.4329M
The primary science goal of the Kepler Mission is to provide
a census of exoplanets in the solar neighborhood, including the
identification and characterization of habitable Earth-like planets. The
asteroseismic capabilities of the mission are being used to determine
precise radii and ages for the target stars from their solar-like
oscillations. Chaplin et al. published observations of three bright
G-type stars, which were monitored during the first 33.5 days of science
operations. One of these stars, the subgiant KIC 11026764, exhibits a
characteristic pattern of oscillation frequencies suggesting that it
has evolved significantly. We have derived asteroseismic estimates of
the properties of KIC 11026764 from Kepler photometry combined with
ground-based spectroscopic data. We present the results of detailed
modeling for this star, employing a variety of independent codes and
analyses that attempt to match the asteroseismic and spectroscopic
constraints simultaneously. We determine both the radius and the age
of KIC 11026764 with a precision near 1%, and an accuracy near 2%
for the radius and 15% for the age. Continued observations of this
star promise to reveal additional oscillation frequencies that will
further improve the determination of its fundamental properties.
---------------------------------------------------------
Title: Characteristics of the Kepler target stars
Authors: Batalha, Natalie M.; Borucki, William J.; Koch, David G.;
Brown, Timothy M.; Caldwell, Douglas A.; Latham, David W.
2010HiA....15..712B Altcode:
The Kepler Mission successfully launched March 6, 2009, beginning
its 3.5-year mission to determine the frequency of Earth-size planets
in the habitable zones of late-type stars. The brightnesses of over
100,000 stars are currently being monitored for transit events with
an expected differential photometric precision of 20 ppm at V=12 for a
6.5-hour transit. The same targets will be observed continuously over
the mission duration in order to broaden the detection space to orbital
periods comparable to that of Earth. This paper provides an overview
of the selection and prioritization criteria used to choose the stars
that Kepler is observing from the > 4.5 million objects in the 100
square degree field of view. The characteristics of the Kepler targets
are described as well as the implications for detectability of planets
in the habitable zone smaller than 2R<SUB>⊕</SUB>.
---------------------------------------------------------
Title: Observational detection of eclipses of J5 Amalthea by the
Galilean satellites
Authors: Christou, A. A.; Lewis, F.; Roche, P.; Hidas, M. G.; Brown,
T. M.
2010A&A...522A...6C Altcode: 2011arXiv1104.0042C
<BR /> Aims: We carried out observations of the small jovian satellite
Amalthea (J5) as it was being eclipsed by the Galilean satellites near
the 2009 equinox of Jupiter in order to apply the technique of mutual
event photometry to the astrometric determination of this satellite's
position. <BR /> Methods: The observations were carried out during
the period 06/2009-09/2009 from the island of Maui, Hawaii and Siding
Spring, Australia with the 2m Faulkes Telescopes North and South
respectively. We observed in the near-infrared part of the spectrum
using a PanStarrs-Z filter with Jupiter near the edge of the field
in order to mitigate against the glare from the planet. Frames were
acquired at rates > 1/min during eclipse times predicted using
recent JPL ephemerides for the satellites. Following subtraction
of the sky background from these frames, differential aperture
photometry was carried out on Amalthea and a nearby field star. <BR />
Results: We have obtained three lightcurves which show a clear drop
in the flux from Amalthea, indicating that an eclipse took place as
predicted. These were model-fitted to yield best estimates of the time
of maximum flux drop and the impact parameter. These are consistent with
Amalthea's ephemeris but indicate that Amalthea is slightly ahead of,
and closer to Jupiter than, its predicted position by approximately
half the ephemeris uncertainty in these directions. We argue that a
ground-based campaign of higher-cadence photometry accurate at the 5%
level or better during the next season of eclipses in 2014-15 should
yield positions to within 0.05 arcsec and affect a corresponding
improvement in Amalthea's ephemeris.
---------------------------------------------------------
Title: Kepler-9: A System of Multiple Planets Transiting a Sun-Like
Star, Confirmed by Timing Variations
Authors: Holman, Matthew J.; Fabrycky, Daniel C.; Ragozzine, Darin;
Ford, Eric B.; Steffen, Jason H.; Welsh, William F.; Lissauer,
Jack J.; Latham, David W.; Marcy, Geoffrey W.; Walkowicz, Lucianne
M.; Batalha, Natalie M.; Jenkins, Jon M.; Rowe, Jason F.; Cochran,
William D.; Fressin, Francois; Torres, Guillermo; Buchhave, Lars A.;
Sasselov, Dimitar D.; Borucki, William J.; Koch, David G.; Basri,
Gibor; Brown, Timothy M.; Caldwell, Douglas A.; Charbonneau, David;
Dunham, Edward W.; Gautier, Thomas N.; Geary, John C.; Gilliland,
Ronald L.; Haas, Michael R.; Howell, Steve B.; Ciardi, David R.;
Endl, Michael; Fischer, Debra; Fürész, Gábor; Hartman, Joel D.;
Isaacson, Howard; Johnson, John A.; MacQueen, Phillip J.; Moorhead,
Althea V.; Morehead, Robert C.; Orosz, Jerome A.
2010Sci...330...51H Altcode:
The Kepler spacecraft is monitoring more than 150,000 stars for
evidence of planets transiting those stars. We report the detection of
two Saturn-size planets that transit the same Sun-like star, based on
7 months of Kepler observations. Their 19.2- and 38.9-day periods are
presently increasing and decreasing at respective average rates of 4 and
39 minutes per orbit; in addition, the transit times of the inner body
display an alternating variation of smaller amplitude. These signatures
are characteristic of gravitational interaction of two planets near a
2:1 orbital resonance. Six radial-velocity observations show that these
two planets are the most massive objects orbiting close to the star and
substantially improve the estimates of their masses. After removing the
signal of the two confirmed giant planets, we identified an additional
transiting super-Earth-size planet candidate with a period of 1.6 days.
---------------------------------------------------------
Title: Scheduling observations on the LCOGT network
Authors: Hawkins, Eric; Baliber, Nairn; Bowman, Mark; Brown, Timothy;
Burleson, Benjamin; Foale, Steven; Ford, Martyn; Lister, Timothy;
Norbury, Martin; Saunders, Eric; Walker, Zachary
2010SPIE.7737E..0PH Altcode: 2010SPIE.7737E..17H
LCOGT is deploying a world-wide telescope network to enable
near-continuous coverage of variable or transient sources. We desire the
telescopes in this network to be scheduled for efficiency with respect
to a coherent set of science goals. To achieve this, we are developing
a software structure to carry observing programs from initial proposal
through data acquisition and feedback to the schedule. Key elements in
this structure are a database of observation requests, requirements,
and status, a protocol to describe observations, and a set of planners
that work by successive refinement of the schedule.
---------------------------------------------------------
Title: LCOGT Telescope network capabilities
Authors: Pickles, A.; Rosing, W.; Brown, T. M.; de Vera, J.; Dubberley,
M.; Haldeman, B.; Hausler, S.; Haynes, R.; Hjelstrom, A.; Lobdill,
R.; Mullins, D.; Posner, V.; Tufts, J.; Walker, Z.
2010SPIE.7733E..2XP Altcode: 2010SPIE.7733E..90P
LCOGT are currently building and deploying a worldwide network of at
least fifteen 1-meter and twenty-four 0.4-meter telescopes to three
sites in each hemisphere, enabling extended, redundant and optimally
continuous coverage of time variable or transient sources. Each
site will support two or more 1m telescopes and four or more 0.4m
telescopes. All telescope classes provide a full range of optical
narrow-band and broad-band UBVRI and ugriZY imaging filters. All
telescopes are being equipped with a moving light-bar flatfielding
system called Lambert. The 1m network is intended primarily for science
observing while the 0.4m network additionally provides educational
opportunities to participating schools and institutes. The global
network is designed to accommodate multiple science, educational and
rapid response capabilities. For LCOGT, the network IS the telescope.
---------------------------------------------------------
Title: LCOGT sites and site operations
Authors: Martinez, John J.; Brown, Timothy M.; Conway, Patrick;
Elphick, Mark; Falarski, Michael; Hawkins, Eric; Rosing, Wayne;
Shobbrook, John
2010SPIE.7737E..0OM Altcode: 2010SPIE.7737E..16M
LCOGT is currently building and deploying a world-wide network of at
least twelve 1-meter and twenty-four 0.4-meter telescopes to as many
as 4 sites in the Southern hemisphere (Chile, South Africa, Eastern
Australia; 4 in the Northern hemisphere (Hawaii, West Texas, Canary
Islands). Our deployment and operations model emphasizes modularity and
interchangeability of major components, maintenance and troubleshooting
personnel who are local to the site, and autonomy of operation. We
plan to ship, install, and spare large units (in many cases entire
telescopes), with minimal assembly on site.
---------------------------------------------------------
Title: Non-Axisymmetric Structure in the Inner Disks of YSOs --
Signposts of Planet Formation?
Authors: Stauffer, John; Morales-Calderon, Maria; Rebull, Luisa;
Barrado, David; Bouvier, Jerome; Brown, Tim; Carey, Sean; Carpenter,
John; Grankin, Konstantin; Gutermuth, Rob; Hartmann, Lee; Hillenbrand,
Lynne; Holtzman, Jon; Hora, Joe; Ibrahimov, Mansur; James, David;
Megeath, S. Tom; Skrutzkie, Mike; Vrba, Fred; Wasserman, Lawrence;
Whitney, Barb
2010sptz.prop70025S Altcode:
We have identified a well-populated class of young stellar objects
(YSOs) in the Orion Nebula cluster whose light curves show narrow (few
day timescale) flux dips. Based on comparison to the only previously
well-documented member of this class (AA Tau), we believe these flux
dips are due to 'clouds' in the inner circumstellar disk of these
stars that pass through our line of sight. Our 2009 data suggest that
most YSO disks have similar structures and that those which exhibit
these flux dips are simply those whose disks are close to edge-on to
our line of sight. We propose here to obtain IRAC time series data
of much higher cadence and significantly better RMS noise for twelve
members of this class over a 10 day timespan. These data will allow
us to constrain better the size distribution of the occulting bodies,
their grain properties and their internal density structure. These
data will therefore provide quantitative inputs to realistic models
of circumstellar disk evolution and planet formation/migration.
---------------------------------------------------------
Title: Photometric Variability in Kepler Target Stars: The Sun Among
Stars—a First Look
Authors: Basri, Gibor; Walkowicz, Lucianne M.; Batalha, Natalie;
Gilliland, Ronald L.; Jenkins, Jon; Borucki, William J.; Koch, David;
Caldwell, Doug; Dupree, Andrea K.; Latham, David W.; Meibom, Søren;
Howell, Steve; Brown, Tim
2010ApJ...713L.155B Altcode: 2010arXiv1001.0414B
The Kepler mission provides an exciting opportunity to study the
light curves of stars with unprecedented precision and continuity
of coverage. This is the first look at a large sample of stars with
photometric data of a quality that has heretofore been only available
for our Sun. It provides the first opportunity to compare the irradiance
variations of our Sun to a large cohort of stars ranging from very
similar to rather different stellar properties, at a wide variety of
ages. Although Kepler data are in an early phase of maturity, and we
only analyze the first month of coverage, it is sufficient to garner the
first meaningful measurements of our Sun's variability in the context
of a large cohort of main-sequence stars in the solar neighborhood. We
find that nearly half of the full sample is more active than the active
Sun, although most of them are not more than twice as active. The active
fraction is closer to a third for the stars most similar to the Sun, and
rises to well more than half for stars cooler than mid-K spectral types.
---------------------------------------------------------
Title: Asteroseismic Investigation of Known Planet Hosts in the
Kepler Field
Authors: Christensen-Dalsgaard, J.; Kjeldsen, H.; Brown, T. M.;
Gilliland, R. L.; Arentoft, T.; Frandsen, S.; Quirion, P. -O.; Borucki,
W. J.; Koch, D.; Jenkins, J. M.
2010ApJ...713L.164C Altcode: 2010arXiv1001.0032C
In addition to its great potential for characterizing extra-solar
planetary systems, the Kepler Mission is providing unique data on
stellar oscillations. A key aspect of Kepler asteroseismology is the
application to solar-like oscillations of main-sequence stars. As
an example, we here consider an initial analysis of data for three
stars in the Kepler field for which planetary transits were known
from ground-based observations. For one of these, HAT-P-7, we obtain
a detailed frequency spectrum and hence strong constraints on the
stellar properties. The remaining two stars show definite evidence
for solar-like oscillations, yielding a preliminary estimate of their
mean densities.
---------------------------------------------------------
Title: Kepler Observations of Transiting Hot Compact Objects
Authors: Rowe, Jason F.; Borucki, William J.; Koch, David; Howell,
Steve B.; Basri, Gibor; Batalha, Natalie; Brown, Timothy M.; Caldwell,
Douglas; Cochran, William D.; Dunham, Edward; Dupree, Andrea K.;
Fortney, Jonathan J.; Gautier, Thomas N., III; Gilliland, Ronald L.;
Jenkins, Jon; Latham, David W.; Lissauer, Jack J.; Marcy, Geoff;
Monet, David G.; Sasselov, Dimitar; Welsh, William F.
2010ApJ...713L.150R Altcode: 2010arXiv1001.3420R
Kepler photometry has revealed two unusual transiting companions: one
orbiting an early A-star and the other orbiting a late B-star. In both
cases, the occultation of the companion is deeper than the transit. The
occultation and transit with follow-up optical spectroscopy reveal a
9400 K early A-star, KOI-74 (KIC 6889235), with a companion in a 5.2
day orbit with a radius of 0.08 R <SUB>sun</SUB> and a 10,000 K late
B-star KOI-81 (KIC 8823868) that has a companion in a 24 day orbit with
a radius of 0.2 R <SUB>sun</SUB>. We infer a temperature of 12,250 K
for KOI-74b and 13,500 K for KOI-81b. We present 43 days of high duty
cycle, 30 minute cadence photometry, with models demonstrating the
intriguing properties of these objects, and speculate on their nature.
---------------------------------------------------------
Title: Automated Classification of Variable Stars in the
Asteroseismology Program of the Kepler Space Mission
Authors: Blomme, J.; Debosscher, J.; De Ridder, J.; Aerts, C.;
Gilliland, R. L.; Christensen-Dalsgaard, J.; Kjeldsen, H.; Brown,
T. M.; Borucki, W. J.; Koch, D.; Jenkins, J. M.; Kurtz, D. W.; Stello,
D.; Stevens, I. R.; Suran, M. D.; Derekas, A.
2010ApJ...713L.204B Altcode: 2010arXiv1001.0507B
We present the first results of the application of supervised
classification methods to the Kepler Q1 long-cadence light curves of a
subsample of 2288 stars measured in the asteroseismology program of the
mission. The methods, originally developed in the framework of the CoRoT
and Gaia space missions, are capable of identifying the most common
types of stellar variability in a reliable way. Many new variables have
been discovered, among which a large fraction are eclipsing/ellipsoidal
binaries unknown prior to launch. A comparison is made between our
classification from the Kepler data and the pre-launch class based
on data from the ground, showing that the latter needs significant
improvement. The noise properties of the Kepler data are compared to
those of the exoplanet program of the CoRoT satellite. We find that
Kepler improves on CoRoT by a factor of 2-2.3 in point-to-point scatter.
---------------------------------------------------------
Title: Kepler-6b: A Transiting Hot Jupiter Orbiting a Metal-rich Star
Authors: Dunham, Edward W.; Borucki, William J.; Koch, David G.;
Batalha, Natalie M.; Buchhave, Lars A.; Brown, Timothy M.; Caldwell,
Douglas A.; Cochran, William D.; Endl, Michael; Fischer, Debra;
Fűrész, Gabor; Gautier, Thomas N., III; Geary, John C.; Gilliland,
Ronald L.; Gould, Alan; Howell, Steve B.; Jenkins, Jon M.; Kjeldsen,
Hans; Latham, David W.; Lissauer, Jack J.; Marcy, Geoffrey W.; Meibom,
Søren; Monet, David G.; Rowe, Jason F.; Sasselov, Dimitar D.
2010ApJ...713L.136D Altcode: 2010arXiv1001.0333D
We announce the discovery of Kepler-6b, a transiting hot Jupiter
orbiting a star with unusually high metallicity, {[Fe/H]}= +0.34+/-
0.04. The planet's mass is about 2/3 that of Jupiter, M <SUB>P</SUB>
= 0.67 M <SUB>J</SUB>, and the radius is 30% larger than that
of Jupiter, R <SUB>P</SUB> = 1.32 R <SUB>J</SUB>, resulting in a
density of ρ<SUB>P</SUB> = 0.35 g cm<SUP>-3</SUP>, a fairly typical
value for such a planet. The orbital period is P = 3.235 days. The
host star is both more massive than the Sun, M <SUB>sstarf</SUB> =
1.21 M <SUB>sun</SUB>, and larger than the Sun, R <SUB>sstarf</SUB>
= 1.39 R <SUB>sun</SUB>. <P />Based in part on observations obtained
at the W. M. Keck Observatory, which is operated by the University of
California and the California Institute of Technology.
---------------------------------------------------------
Title: Detection of Solar-like Oscillations from Kepler Photometry
of the Open Cluster NGC 6819
Authors: Stello, Dennis; Basu, Sarbani; Bruntt, Hans; Mosser, Benoît;
Stevens, Ian R.; Brown, Timothy M.; Christensen-Dalsgaard, Jørgen;
Gilliland, Ronald L.; Kjeldsen, Hans; Arentoft, Torben; Ballot,
Jérôme; Barban, Caroline; Bedding, Timothy R.; Chaplin, William
J.; Elsworth, Yvonne P.; García, Rafael A.; Goupil, Marie-Jo;
Hekker, Saskia; Huber, Daniel; Mathur, Savita; Meibom, Søren;
Sangaralingam, Vinothini; Baldner, Charles S.; Belkacem, Kevin;
Biazzo, Katia; Brogaard, Karsten; Suárez, Juan Carlos; D'Antona,
Francesca; Demarque, Pierre; Esch, Lisa; Gai, Ning; Grundahl, Frank;
Lebreton, Yveline; Jiang, Biwei; Jevtic, Nada; Karoff, Christoffer;
Miglio, Andrea; Molenda-Żakowicz, Joanna; Montalbán, Josefina; Noels,
Arlette; Roca Cortés, Teodoro; Roxburgh, Ian W.; Serenelli, Aldo M.;
Silva Aguirre, Victor; Sterken, Christiaan; Stine, Peter; Szabó,
Robert; Weiss, Achim; Borucki, William J.; Koch, David; Jenkins, Jon M.
2010ApJ...713L.182S Altcode: 2010arXiv1001.0026S
Asteroseismology of stars in clusters has been a long-sought goal
because the assumption of a common age, distance, and initial chemical
composition allows strong tests of the theory of stellar evolution. We
report results from the first 34 days of science data from the Kepler
Mission for the open cluster NGC 6819—one of the four clusters in
the field of view. We obtain the first clear detections of solar-like
oscillations in the cluster red giants and are able to measure
the large frequency separation, Δν, and the frequency of maximum
oscillation power, ν<SUB>max</SUB>. We find that the asteroseismic
parameters allow us to test cluster membership of the stars, and
even with the limited seismic data in hand, we can already identify
four possible non-members despite their having a better than 80%
membership probability from radial velocity measurements. We are also
able to determine the oscillation amplitudes for stars that span about
2 orders of magnitude in luminosity and find good agreement with the
prediction that oscillation amplitudes scale as the luminosity to the
power of 0.7. These early results demonstrate the unique potential of
asteroseismology of the stellar clusters observed by Kepler.
---------------------------------------------------------
Title: First Kepler Results on RR Lyrae Stars
Authors: Kolenberg, K.; Szabó, R.; Kurtz, D. W.; Gilliland, R. L.;
Christensen-Dalsgaard, J.; Kjeldsen, H.; Brown, T. M.; Benkő,
J. M.; Chadid, M.; Derekas, A.; Di Criscienzo, M.; Guggenberger, E.;
Kinemuchi, K.; Kunder, A.; Kolláth, Z.; Kopacki, G.; Moskalik, P.;
Nemec, J. M.; Nuspl, J.; Silvotti, R.; Suran, M. D.; Borucki, W. J.;
Koch, D.; Jenkins, J. M.
2010ApJ...713L.198K Altcode: 2010arXiv1001.0417K
We present the first results of our analyses of selected RR Lyrae stars
for which data have been obtained by the Kepler Mission. As expected,
we find a significant fraction of the RRab stars to show the Blazhko
effect, a still unexplained phenomenon that manifests itself as periodic
amplitude and phase modulations of the light curve, on timescales of
typically tens to hundreds of days. The long time span of the Kepler
Mission of 3.5 yr and the unprecedentedly high precision of its data
provide a unique opportunity for the study of RR Lyrae stars. Using
data of a modulated star observed in the first roll as a showcase, we
discuss the data, our analyses, findings, and their implications for our
understanding of RR Lyrae stars and the Blazhko effect. With at least
40% of the RR Lyrae stars in our sample showing modulation, we confirm
the high incidence rate that was only found in recent high-precision
studies. Moreover, we report the occurrence of additional frequencies,
beyond the main pulsation mode and its modulation components. Their
half-integer ratio to the main frequency is reminiscent of a period
doubling effect caused by resonances, observed for the first time in
RR Lyrae stars.
---------------------------------------------------------
Title: Hybrid γ Doradus-δ Scuti Pulsators: New Insights into the
Physics of the Oscillations from Kepler Observations
Authors: Grigahcène, A.; Antoci, V.; Balona, L.; Catanzaro, G.;
Daszyńska-Daszkiewicz, J.; Guzik, J. A.; Handler, G.; Houdek,
G.; Kurtz, D. W.; Marconi, M.; Monteiro, M. J. P. F. G.; Moya, A.;
Ripepi, V.; Suárez, J. -C.; Uytterhoeven, K.; Borucki, W. J.; Brown,
T. M.; Christensen-Dalsgaard, J.; Gilliland, R. L.; Jenkins, J. M.;
Kjeldsen, H.; Koch, D.; Bernabei, S.; Bradley, P.; Breger, M.; Di
Criscienzo, M.; Dupret, M. -A.; García, R. A.; García Hernández, A.;
Jackiewicz, J.; Kaiser, A.; Lehmann, H.; Martín-Ruiz, S.; Mathias,
P.; Molenda-Żakowicz, J.; Nemec, J. M.; Nuspl, J.; Paparó, M.;
Roth, M.; Szabó, R.; Suran, M. D.; Ventura, R.
2010ApJ...713L.192G Altcode: 2010arXiv1001.0747G
Observations of the pulsations of stars can be used to infer their
interior structure and test theoretical models. The main-sequence
γ Doradus (Dor) and δ Scuti (Sct) stars with masses 1.2-2.5 M
<SUB>sun</SUB> are particularly useful for these studies. The γ
Dor stars pulsate in high-order g-modes with periods of order 1
day, driven by convective blocking at the base of their envelope
convection zone. The δ Sct stars pulsate in low-order g- and p-modes
with periods of order 2 hr, driven by the κ mechanism operating in
the He II ionization zone. Theory predicts an overlap region in the
Hertzsprung-Russell diagram between instability regions, where "hybrid"
stars pulsating in both types of modes should exist. The two types of
modes with properties governed by different portions of the stellar
interior provide complementary model constraints. Among the known γ
Dor and δ Sct stars, only four have been confirmed as hybrids. Now,
analysis of combined Quarter 0 and Quarter 1 Kepler data for hundreds of
variable stars shows that the frequency spectra are so rich that there
are practically no pure δ Sct or γ Dor pulsators, i.e., essentially
all of the stars show frequencies in both the δ Sct and the γ Dor
frequency range. A new observational classification scheme is proposed
that takes into account the amplitude as well as the frequency and is
applied to categorize 234 stars as δ Sct, γ Dor, δ Sct/γ Dor or
γ Dor/δ Sct hybrids.
---------------------------------------------------------
Title: Kepler-7b: A Transiting Planet with Unusually Low Density
Authors: Latham, David W.; Borucki, William J.; Koch, David G.;
Brown, Timothy M.; Buchhave, Lars A.; Basri, Gibor; Batalha, Natalie
M.; Caldwell, Douglas A.; Cochran, William D.; Dunham, Edward W.;
Fűrész, Gabor; Gautier, Thomas N., III; Geary, John C.; Gilliland,
Ronald L.; Howell, Steve B.; Jenkins, Jon M.; Lissauer, Jack J.; Marcy,
Geoffrey W.; Monet, David G.; Rowe, Jason F.; Sasselov, Dimitar D.
2010ApJ...713L.140L Altcode: 2010arXiv1001.0190L
We report on the discovery and confirmation of Kepler-7b, a transiting
planet with unusually low density. The mass is less than half that of
Jupiter, M <SUB>P</SUB> = 0.43 M <SUB>J</SUB>, but the radius is 50%
larger, R <SUB>P</SUB> = 1.48 R <SUB>J</SUB>. The resulting density,
ρ<SUB>P</SUB> = 0.17 g cm<SUP>-3</SUP>, is the second lowest reported
so far for an extrasolar planet. The orbital period is fairly long,
P = 4.886 days, and the host star is not much hotter than the Sun, T
<SUB>eff</SUB> = 6000 K. However, it is more massive and considerably
larger than the Sun, M <SUB>sstarf</SUB> = 1.35 M <SUB>sun</SUB> and
R <SUB>sstarf</SUB> = 1.84 R <SUB>sun</SUB>, and must be near the end
of its life on the main sequence. <P />Based in part on observations
obtained at the W. M. Keck Observatory, which is operated by the
University of California and the California Institute of Technology.
---------------------------------------------------------
Title: The Asteroseismic Potential of Kepler: First Results for
Solar-Type Stars
Authors: Chaplin, W. J.; Appourchaux, T.; Elsworth, Y.; García,
R. A.; Houdek, G.; Karoff, C.; Metcalfe, T. S.; Molenda-Żakowicz,
J.; Monteiro, M. J. P. F. G.; Thompson, M. J.; Brown, T. M.;
Christensen-Dalsgaard, J.; Gilliland, R. L.; Kjeldsen, H.; Borucki,
W. J.; Koch, D.; Jenkins, J. M.; Ballot, J.; Basu, S.; Bazot, M.;
Bedding, T. R.; Benomar, O.; Bonanno, A.; Brandão, I. M.; Bruntt,
H.; Campante, T. L.; Creevey, O. L.; Di Mauro, M. P.; Doǧan,
G.; Dreizler, S.; Eggenberger, P.; Esch, L.; Fletcher, S. T.;
Frandsen, S.; Gai, N.; Gaulme, P.; Handberg, R.; Hekker, S.; Howe,
R.; Huber, D.; Korzennik, S. G.; Lebrun, J. C.; Leccia, S.; Martic,
M.; Mathur, S.; Mosser, B.; New, R.; Quirion, P. -O.; Régulo, C.;
Roxburgh, I. W.; Salabert, D.; Schou, J.; Sousa, S. G.; Stello, D.;
Verner, G. A.; Arentoft, T.; Barban, C.; Belkacem, K.; Benatti, S.;
Biazzo, K.; Boumier, P.; Bradley, P. A.; Broomhall, A. -M.; Buzasi,
D. L.; Claudi, R. U.; Cunha, M. S.; D'Antona, F.; Deheuvels, S.;
Derekas, A.; García Hernández, A.; Giampapa, M. S.; Goupil, M. J.;
Gruberbauer, M.; Guzik, J. A.; Hale, S. J.; Ireland, M. J.; Kiss,
L. L.; Kitiashvili, I. N.; Kolenberg, K.; Korhonen, H.; Kosovichev,
A. G.; Kupka, F.; Lebreton, Y.; Leroy, B.; Ludwig, H. -G.; Mathis, S.;
Michel, E.; Miglio, A.; Montalbán, J.; Moya, A.; Noels, A.; Noyes,
R. W.; Pallé, P. L.; Piau, L.; Preston, H. L.; Roca Cortés, T.;
Roth, M.; Sato, K. H.; Schmitt, J.; Serenelli, A. M.; Silva Aguirre,
V.; Stevens, I. R.; Suárez, J. C.; Suran, M. D.; Trampedach, R.;
Turck-Chièze, S.; Uytterhoeven, K.; Ventura, R.; Wilson, P. A.
2010ApJ...713L.169C Altcode: 2010arXiv1001.0506C
We present preliminary asteroseismic results from Kepler on three G-type
stars. The observations, made at one-minute cadence during the first
33.5 days of science operations, reveal high signal-to-noise solar-like
oscillation spectra in all three stars: about 20 modes of oscillation
may be clearly distinguished in each star. We discuss the appearance of
the oscillation spectra, use the frequencies and frequency separations
to provide first results on the radii, masses, and ages of the stars,
and comment in the light of these results on prospects for inference
on other solar-type stars that Kepler will observe.
---------------------------------------------------------
Title: Discovery of the Transiting Planet Kepler-5b
Authors: Koch, David G.; Borucki, William J.; Rowe, Jason F.; Batalha,
Natalie M.; Brown, Timothy M.; Caldwell, Douglas A.; Caldwell, John;
Cochran, William D.; DeVore, Edna; Dunham, Edward W.; Dupree, Andrea
K.; Gautier, Thomas N., III; Geary, John C.; Gilliland, Ron L.; Howell,
Steve B.; Jenkins, Jon M.; Latham, David W.; Lissauer, Jack J.; Marcy,
Geoff W.; Morrison, David; Tarter, Jill
2010ApJ...713L.131K Altcode: 2010arXiv1001.0913K
We present 44 days of high duty cycle, ultra precise photometry of
the 13th magnitude star Kepler-5 (KIC 8191672, T <SUB>eff</SUB>=
6300 K, log g= 4.1), which exhibits periodic transits with a depth
of 0.7%. Detailed modeling of the transit is consistent with a
planetary companion with an orbital period of 3.548460 ± 0.000032
days and a radius of 1.431<SUP>+0.041</SUP> <SUB>-0.052</SUB>
R <SUB>J</SUB>. Follow-up radial velocity measurements with the
Keck HIRES spectrograph on nine separate nights demonstrate that
the planet is more than twice as massive as Jupiter with a mass of
2.114<SUP>+0.056</SUP> <SUB>-0.059</SUB> M <SUB>J</SUB> and a mean
density of 0.894 ± 0.079 g cm<SUP>-3</SUP>.
---------------------------------------------------------
Title: Kepler-4b: A Hot Neptune-like Planet of a G0 Star Near
Main-sequence Turnoff
Authors: Borucki, William J.; Koch, David G.; Brown, Timothy M.;
Basri, Gibor; Batalha, Natalie M.; Caldwell, Douglas A.; Cochran,
William D.; Dunham, Edward W.; Gautier, Thomas N., III; Geary, John
C.; Gilliland, Ronald L.; Howell, Steve B.; Jenkins, Jon M.; Latham,
David W.; Lissauer, Jack J.; Marcy, Geoffrey W.; Monet, David; Rowe,
Jason F.; Sasselov, Dimitar
2010ApJ...713L.126B Altcode: 2010arXiv1001.0604B
Early time-series photometry from NASA's Kepler spacecraft
has revealed a planet transiting the star we term Kepler-4,
at R.A. = 19<SUP>h</SUP>02<SUP>m</SUP>27.<SUP>s</SUP>68, δ =
+50°08'08farcs7. The planet has an orbital period of 3.213 days
and shows transits with a relative depth of 0.87 × 10<SUP>-3</SUP>
and a duration of about 3.95 hr. Radial velocity (RV) measurements
from the Keck High Resolution Echelle Spectrometer show a reflex
Doppler signal of 9.3<SUP>+1.1</SUP> <SUB>-1.9</SUB> m s<SUP>-1</SUP>,
consistent with a low-eccentricity orbit with the phase expected from
the transits. Various tests show no evidence for any companion star
near enough to affect the light curve or the RVs for this system. From
a transit-based estimate of the host star's mean density, combined
with analysis of high-resolution spectra, we infer that the host
star is near turnoff from the main sequence, with estimated mass and
radius of 1.223<SUP>+0.053</SUP> <SUB>-0.091</SUB> M <SUB>sun</SUB> and
1.487<SUP>+0.071</SUP> <SUB>-0.084</SUB> R <SUB>sun</SUB>. We estimate
the planet mass and radius to be {M <SUB>P</SUB>, R <SUB>P</SUB>} =
{24.5 ± 3.8 M <SUB>⊕</SUB>, 3.99 ± 0.21 R <SUB>⊕</SUB>}. The
planet's density is near 1.9 g cm<SUP>-3</SUP> it is thus slightly
denser and more massive than Neptune, but about the same size. <P
/>Some of the data presented herein were obtained at the W. M. Keck
Observatory, which is operated as a scientific partnership among the
California Institute of Technology, the University of California,
and the National Aeronautics and Space Administration. The Observatory
was made possible by the generous financial support of the W. M. Keck
Foundation.
---------------------------------------------------------
Title: Discovery of a Red Giant with Solar-like Oscillations in an
Eclipsing Binary System from Kepler Space-based Photometry
Authors: Hekker, S.; Debosscher, J.; Huber, D.; Hidas, M. G.; De
Ridder, J.; Aerts, C.; Stello, D.; Bedding, T. R.; Gilliland, R. L.;
Christensen-Dalsgaard, J.; Brown, T. M.; Kjeldsen, H.; Borucki, W. J.;
Koch, D.; Jenkins, J. M.; Van Winckel, H.; Beck, P. G.; Blomme,
J.; Southworth, J.; Pigulski, A.; Chaplin, W. J.; Elsworth, Y. P.;
Stevens, I. R.; Dreizler, S.; Kurtz, D. W.; Maceroni, C.; Cardini,
D.; Derekas, A.; Suran, M. D.
2010ApJ...713L.187H Altcode: 2010arXiv1001.0399H
Oscillating stars in binary systems are among the most interesting
stellar laboratories, as these can provide information on the stellar
parameters and stellar internal structures. Here we present a red
giant with solar-like oscillations in an eclipsing binary observed
with the NASA Kepler satellite. We compute stellar parameters of the
red giant from spectra and the asteroseismic mass and radius from
the oscillations. Although only one eclipse has been observed so far,
we can already determine that the secondary is a main-sequence F star
in an eccentric orbit with a semi-major axis larger than 0.5 AU and
orbital period longer than 75 days.
---------------------------------------------------------
Title: Selection, Prioritization, and Characteristics of Kepler
Target Stars
Authors: Batalha, Natalie M.; Borucki, William J.; Koch, David G.;
Bryson, Stephen T.; Haas, Michael. R.; Brown, Timothy M.; Caldwell,
Douglas A.; Hall, Jennifer R.; Gilliland, Ronald L.; Latham, David W.;
Meibom, Soren; Monet, David G.
2010ApJ...713L.109B Altcode: 2010arXiv1001.0349B
The Kepler Mission began its 3.5 year photometric monitoring campaign in
2009 May on a select group of approximately 150,000 stars. The stars
were chosen from the ~ half million in the field of view that are
brighter than 16th magnitude. The selection criteria are quantitative
metrics designed to optimize the scientific yield of the mission
with regard to the detection of Earth-size planets in the habitable
zone. This yields more than 90,000 G-type stars on or close to the main
sequence, >20, 000 of which are brighter than 14th magnitude. At the
temperature extremes, the sample includes approximately 3000 M-type
dwarfs and a small sample of O- and B-type MS stars (<200). The
small numbers of giants are included in the sample: ~5000 stars with
surface gravities log(g) < 3.5. We present a brief summary of the
selection process and the stellar populations it yields in terms of
surface gravity, effective temperature, and apparent magnitude. In
addition to the primary, statistically derived target set, several
ancillary target lists were manually generated to enhance the science
of the mission, examples being: known eclipsing binaries, open cluster
members, and high proper motion stars.
---------------------------------------------------------
Title: Kepler Mission Design, Realized Photometric Performance,
and Early Science
Authors: Koch, David G.; Borucki, William J.; Basri, Gibor;
Batalha, Natalie M.; Brown, Timothy M.; Caldwell, Douglas;
Christensen-Dalsgaard, Jørgen; Cochran, William D.; DeVore, Edna;
Dunham, Edward W.; Gautier, Thomas N., III; Geary, John C.; Gilliland,
Ronald L.; Gould, Alan; Jenkins, Jon; Kondo, Yoji; Latham, David W.;
Lissauer, Jack J.; Marcy, Geoffrey; Monet, David; Sasselov, Dimitar;
Boss, Alan; Brownlee, Donald; Caldwell, John; Dupree, Andrea K.;
Howell, Steve B.; Kjeldsen, Hans; Meibom, Søren; Morrison, David;
Owen, Tobias; Reitsema, Harold; Tarter, Jill; Bryson, Stephen T.;
Dotson, Jessie L.; Gazis, Paul; Haas, Michael R.; Kolodziejczak,
Jeffrey; Rowe, Jason F.; Van Cleve, Jeffrey E.; Allen, Christopher;
Chandrasekaran, Hema; Clarke, Bruce D.; Li, Jie; Quintana, Elisa V.;
Tenenbaum, Peter; Twicken, Joseph D.; Wu, Hayley
2010ApJ...713L..79K Altcode: 2010arXiv1001.0268K
The Kepler Mission, launched on 2009 March 6, was designed with the
explicit capability to detect Earth-size planets in the habitable zone
of solar-like stars using the transit photometry method. Results from
just 43 days of data along with ground-based follow-up observations
have identified five new transiting planets with measurements of their
masses, radii, and orbital periods. Many aspects of stellar astrophysics
also benefit from the unique, precise, extended, and nearly continuous
data set for a large number and variety of stars. Early results for
classical variables and eclipsing stars show great promise. To fully
understand the methodology, processes, and eventually the results from
the mission, we present the underlying rationale that ultimately led
to the flight and ground system designs used to achieve the exquisite
photometric performance. As an example of the initial photometric
results, we present variability measurements that can be used to
distinguish dwarf stars from red giants.
---------------------------------------------------------
Title: VizieR Online Data Catalog: The Lick AGN monitoring project
(Walsh+, 2009)
Authors: Walsh, J. L.; Minezaki, T.; Bentz, M. C.; Barth, A. J.;
Baliber, N.; Li, W.; Stern, D.; Bennert, V. N.; Brown, T. M.; Canalizo,
G.; Filippenko, A. V.; Gates, E. L.; Greene, J. E.; Malkan, M. A.;
Sakata, Y.; Street, R. A.; Treu, T.; Woo, J. -H.; Yoshii, Y.
2010yCat..21850156W Altcode:
The Lick AGN Monitoring Project targeted 13 nearby Seyfert 1
galaxies with the intent of measuring the masses of their central
black holes using reverberation mapping. The sample includes 12
galaxies selected to have black holes with masses roughly in the range
106<SUP>-107</SUP>M<SUB>⊙</SUB>, as well as the well-studied active
galactic nucleus (AGN) NGC 5548. In conjunction with a spectroscopic
monitoring campaign, we obtained broadband B and V images on most
nights from 2008 February through 2008 May. The imaging observations
were carried out by four telescopes: the 0.76m Katzman Automatic
Imaging Telescope, the 2m Multicolor Active Galactic Nuclei Monitoring
telescope, the Palomar 60 inch (1.5m) telescope, and the 0.80m Tenagra
II telescope. Having well-sampled light curves over the course of a
few months is useful for obtaining the broad-line reverberation lag and
black hole mass, and also allows us to examine the characteristics of
the continuum variability. In this paper, we discuss the observational
methods and the photometric measurements, and present the AGN continuum
light curves. We measure various variability characteristics of each
of the light curves. We do not detect any evidence for a time lag
between the B- and V-band variations, and we do not find significant
color variations for the AGNs in our sample. <P />(2 data files).
---------------------------------------------------------
Title: VizieR Online Data Catalog: Deep optical photometry in M31
(Brown+, 2009)
Authors: Brown, T. M.; Smith, E.; Ferguson, H. C.; Guhathakurta, P.;
Kalirai, J. S.; Kimble, R. A.; Renzini, A.; Rich, R. M.; Sweigart,
A. V.; Vandenberg, D. A.
2010yCat..21840152B Altcode:
Images were obtained using the Wide Field Camera on the ACS, in the
F606W (broad V) and F814W (I) filters. The characteristics of the six
fields observed are summarized in Table 1. <P />(7 data files).
---------------------------------------------------------
Title: Kepler Asteroseismology Program: Introduction and First Results
Authors: Gilliland, Ronald L.; Brown, Timothy M.;
Christensen-Dalsgaard, Jørgen; Kjeldsen, Hans; Aerts, Conny;
Appourchaux, Thierry; Basu, Sarbani; Bedding, Timothy R.; Chaplin,
William J.; Cunha, Margarida S.; De Cat, Peter; De Ridder, Joris;
Guzik, Joyce A.; Handler, Gerald; Kawaler, Steven; Kiss, László;
Kolenberg, Katrien; Kurtz, Donald W.; Metcalfe, Travis S.; Monteiro,
Mario J. P. F. G.; Szabó, Robert; Arentoft, Torben; Balona, Luis;
Debosscher, Jonas; Elsworth, Yvonne P.; Quirion, Pierre-Olivier;
Stello, Dennis; Suárez, Juan Carlos; Borucki, William J.; Jenkins,
Jon M.; Koch, David; Kondo, Yoji; Latham, David W.; Rowe, Jason F.;
Steffen, Jason H.
2010PASP..122..131G Altcode: 2010arXiv1001.0139G
Asteroseismology involves probing the interiors of stars and quantifying
their global properties, such as radius and age, through observations of
normal modes of oscillation. The technical requirements for conducting
asteroseismology include ultrahigh precision measured in photometry
in parts per million, as well as nearly continuous time series over
weeks to years, and cadences rapid enough to sample oscillations with
periods as short as a few minutes. We report on results from the first
43 days of observations, in which the unique capabilities of Kepler
in providing a revolutionary advance in asteroseismology are already
well in evidence. The Kepler asteroseismology program holds intrinsic
importance in supporting the core planetary search program through
greatly enhanced knowledge of host star properties, and extends well
beyond this to rich applications in stellar astrophysics.
---------------------------------------------------------
Title: Kepler Planet-Detection Mission: Introduction and First Results
Authors: Borucki, William J.; Koch, David; Basri, Gibor; Batalha,
Natalie; Brown, Timothy; Caldwell, Douglas; Caldwell, John;
Christensen-Dalsgaard, Jørgen; Cochran, William D.; DeVore, Edna;
Dunham, Edward W.; Dupree, Andrea K.; Gautier, Thomas N.; Geary, John
C.; Gilliland, Ronald; Gould, Alan; Howell, Steve B.; Jenkins, Jon M.;
Kondo, Yoji; Latham, David W.; Marcy, Geoffrey W.; Meibom, Søren;
Kjeldsen, Hans; Lissauer, Jack J.; Monet, David G.; Morrison, David;
Sasselov, Dimitar; Tarter, Jill; Boss, Alan; Brownlee, Don; Owen,
Toby; Buzasi, Derek; Charbonneau, David; Doyle, Laurance; Fortney,
Jonathan; Ford, Eric B.; Holman, Matthew J.; Seager, Sara; Steffen,
Jason H.; Welsh, William F.; Rowe, Jason; Anderson, Howard; Buchhave,
Lars; Ciardi, David; Walkowicz, Lucianne; Sherry, William; Horch,
Elliott; Isaacson, Howard; Everett, Mark E.; Fischer, Debra; Torres,
Guillermo; Johnson, John Asher; Endl, Michael; MacQueen, Phillip;
Bryson, Stephen T.; Dotson, Jessie; Haas, Michael; Kolodziejczak,
Jeffrey; Van Cleve, Jeffrey; Chandrasekaran, Hema; Twicken, Joseph
D.; Quintana, Elisa V.; Clarke, Bruce D.; Allen, Christopher; Li,
Jie; Wu, Haley; Tenenbaum, Peter; Verner, Ekaterina; Bruhweiler,
Frederick; Barnes, Jason; Prsa, Andrej
2010Sci...327..977B Altcode:
The Kepler mission was designed to determine the frequency of
Earth-sized planets in and near the habitable zone of Sun-like
stars. The habitable zone is the region where planetary temperatures
are suitable for water to exist on a planet’s surface. During the
first 6 weeks of observations, Kepler monitored 156,000 stars, and
five new exoplanets with sizes between 0.37 and 1.6 Jupiter radii and
orbital periods from 3.2 to 4.9 days were discovered. The density of
the Neptune-sized Kepler-4b is similar to that of Neptune and GJ 436b,
even though the irradiation level is 800,000 times higher. Kepler-7b
is one of the lowest-density planets (~0.17 gram per cubic centimeter)
yet detected. Kepler-5b, -6b, and -8b confirm the existence of planets
with densities lower than those predicted for gas giant planets.
---------------------------------------------------------
Title: Transiting Exoplanet Survey Satellite (TESS)
Authors: Ricker, George R.; Latham, D. W.; Vanderspek, R. K.; Ennico,
K. A.; Bakos, G.; Brown, T. M.; Burgasser, A. J.; Charbonneau,
D.; Clampin, M.; Deming, L. D.; Doty, J. P.; Dunham, E. W.; Elliot,
J. L.; Holman, M. J.; Ida, S.; Jenkins, J. M.; Jernigan, J. G.; Kawai,
N.; Laughlin, G. P.; Lissauer, J. J.; Martel, F.; Sasselov, D. D.;
Schingler, R. H.; Seager, S.; Torres, G.; Udry, S.; Villasenor, J. N.;
Winn, J. N.; Worden, S. P.
2010AAS...21545006R Altcode: 2010BAAS...42..459R
TESS is a low-cost SMEX-class satellite mission. In a two-year all-sky
survey, TESS will observe more than 2,000,000 nearby stars, searching
for temporary drops in brightness caused by planetary transits. <P
/>TESS is expected to identify more than 1000 transiting exoplanet
candidates, including a sample of about 100 Super Earths---small
rock-and-ice planets in the range 1 to 10 Earth masses---orbiting F,
G, K, and M dwarfs. TESS's "wide-shallow” survey complements the
"narrow-deep” CoRoT and Kepler surveys. TESS-discovered transiting
systems will be nearby (< 50 pc), and typically 10-20 x brighter than
those discovered by CoRoT and Kepler. Thus, the resulting TESS Transit
Catalog will comprise all of the best transiting systems for follow-up
observations. TESS will identify Super Earths orbiting IR-bright stars,
within reach of JWST spectroscopic searches for planetary water and
carbon dioxide. <P />TESS is a collaborative effort led by researchers
at the Massachusetts Institute of Technology, the Harvard-Smithsonian
Center for Astrophysics, and the NASA Ames Research Center. Additional
TESS scientific partners include Las Cumbres Observatory Global
Telescope, Lowell Observatory, the NASA Goddard Space Flight Center,
the Infrared Processing and Analysis Center at the California Institute
of Technology, the Geneva Observatory (Switzerland), the Tokyo Institute
of Technology (Japan), and Institut Supérieur de l'Aéronautique et
de l'Espace (France). <P />TESS was funded by NASA for a Phase A study
from May 2008 - June 2009, but was not selected for flight. Additional
funding leading to a flight opportunity is being sought. Support has
also been provided by the Kavli Foundation, Google, and the Smithsonian
Institution. TESS could launch as early as 2013-2014.
---------------------------------------------------------
Title: Radii of Rapidly Rotating Stars, with Application to
Transiting-Planet Hosts
Authors: Brown, Timothy M.
2010ApJ...709..535B Altcode: 2009arXiv0912.1639B
The currently favored method for estimating radii and other parameters
of transiting-planet host stars is to match theoretical models to
observations of the stellar mean density ρ<SUB>*</SUB>, the effective
temperature T <SUB>eff</SUB>, and the composition parameter [Z]. This
explicitly model-dependent approach is based on readily available
observations, and results in small formal errors. Its performance
will be central to the reliability of results from ground-based
transit surveys such as TrES, HAT, and SuperWASP, as well as to
the space-borne missions MOST, CoRoT, and Kepler. Here, I use two
calibration samples of stars (eclipsing binaries (EBs) and stars for
which asteroseismic analyses are available) having well-determined
masses and radii to estimate the accuracy and systematic errors
inherent in the ρ<SUB>*</SUB> method. When matching to the Yonsei-Yale
stellar evolution models, I find the most important systematic error
results from selection bias favoring rapidly rotating (hence probably
magnetically active) stars among the EB sample. If unaccounted for,
this bias leads to a mass-dependent underestimate of stellar radii
by as much as 4% for stars of 0.4 M <SUB>sun</SUB>, decreasing to
zero for masses above about 1.4 M <SUB>sun</SUB>. Relative errors
in estimated stellar masses are three times larger than those in
radii. The asteroseismic sample suggests (albeit with significant
uncertainty) that systematic errors are small for slowly rotating,
inactive stars. Systematic errors arising from failings of the
Yonsei-Yale models of inactive stars probably exist, but are difficult
to assess because of the small number of well-characterized comparison
stars having low mass and slow rotation. Poor information about [Z]
is an important source of random error, and may be a minor source of
systematic error as well. With suitable corrections for rotation, it
is likely that systematic errors in the ρ<SUB>*</SUB> method can be
comparable to or smaller than the random errors, yielding radii that
are accurate to about 2% for most stars.
---------------------------------------------------------
Title: The Kepler Mission and Early Results
Authors: Koch, David; Borucki, William; Jenkins, Jon; Basri,
Gibor; Batalha, Natalie M.; Brown, Timothy M.; Caldwell, Douglas;
Christensen-Dalsgaard, Jørgen; Cochran, William D.; Devore, Edna;
Dunham, Edward W.; Gautier, Thomas N., III; Geary, John C.; Gilliland,
Ronald L.; Gould, Alan; Jenkins, Jon; Latham, David W.; Lissauer,
Jack J.; Marcy, Geoffrey; Monet, David; Sasselov, Dimitar; Boss, Alan;
Caldwell, John; Dupree, Andrea K.; Howell, Steve B.; Kjeldsen, Hans;
Meibom, Søren; Morrison, David; Tarter, Jill; Bryson, Stephen T.;
Dotson, Jessie L.; Haas, Michael R.; Kolodziejczak, Jeffrey; Rowe,
Jason F.; van Cleve, Jeffrey E.; Buzasi, Derek; Charbonneau, David;
Doyle, Lau-Rance; Ford, Eric; Fortney, Jonathan; Holman, Matthew;
Seager, Sara; Steffen, Jason; Welsh, William
2010cosp...38.2513K Altcode: 2010cosp.meet.2513K
Kepler is a Discovery-class mission designed to determine the frequency
of Earth-size planets in and near the habitable zone of solar-like
stars. The instrument consists of a 0.95 m aperture photometer designed
to obtain high-precision photometric measurement for more than 3.5
years of more than 100,000 stars to search for patterns of transits
of exoplanets. The focal plane of the Schmidt telescope contains 42
CCDs with a total of 95 megapixels that cover 115 square degrees of
sky. The single star field will be viewed for the entire duration
of the mission. The photometer was launched into an Earth-trailing
heliocentric orbit on March 6, 2009, finished its commissioning on May
12, and is now in the science operations mode. The bases for a number of
the design choices are described. Although the data have not yet been
fully corrected for the presence of systematic errors and artifacts,
the data show the presence of thousands of eclipsing binaries and
variable stars of amazing variety. The character of stellar variability
allows us to distinguish dwarf stars from giants. Astrometric stability
at the sub-millipixel level of the photocenters of stars allows us in
many cases to distinguish transit candidates from background eclipsing
binaries. Analysis of the early data shows transits, occultations and
even visible light emission from the hot exoplanet HAT-P-7b. The latest
results on exoplanet detections from Kepler will be presented. Funding
for this mission is provided by NASA's Science Mission Directorate.
---------------------------------------------------------
Title: The Kepler Short Cadence Data and Applications for
Asteroseismology and Transit Light Curves
Authors: Gilliland, Ronald L.; Brown, T. M.; Christensen-Dalsgaard,
J.; Kjeldsen, H.; Borucki, W. J.; Bryson, S.; Caldwell, D. A.; Jenkins,
J. M.; Koch, D.; Kepler Team
2010AAS...21530504G Altcode: 2010BAAS...42..302G
The Kepler data acquisition allows 512 targets to be followed in a
'short cadence' mode with roughly 1-minute integrations as needed for
asteroseismology of solar analogs having p-mode oscillations of a few
minutes, and to study fine details of high S/N transits. Characteristics
of these data will be described. An application of asteroseismology in
support of the core Kepler mission of characterizing detected planets
follows from stellar radius determinations needed to in turn provide
radii for the planets. The steps from processing of Kepler short cadence
data, derivation of asteroseismic frequencies from power spectra of
these time series, constraint on the mean stellar density and ultimately
stellar radius will be illustrated for a few planet host stars yielding
radii to accuracies approaching 1%. Analysis of individual oscillation
frequencies will provide information about the properties of stellar
interiors, resulting in some cases in determinations of ages to about
10%. Asteroseismic results will ultimately be expected for several
thousand stars ranging from the solar analog oscillations mentioned
above, to oscillations in red giants and a full spectrum of classical
variable stars (both at short, and the 30-minute long cadence) including
delta Scuti, RR Lyrae, RoAp stars etc. <P />Kepler was selected as
the 10th mission of the Discovery Program. Funding for this mission
is provided by NASA, Science Mission Directorate.
---------------------------------------------------------
Title: Estimates of the Population of Exoplanets Discoverable by
the Transiting Exoplanet Survey Satellite (TESS)
Authors: Seager, Sara; Winn, J. N.; Ricker, G. R.; Latham, D. W.;
Vanderspek, R. K.; Ennico, K. A.; Bakos, G.; Brown, T. M.; Burgasser,
A. J.; Charbonneau, D.; Clampin, M.; Deming, L. D.; Doty, J. P.;
Dunham, E. W.; Elliot, J. L.; Holman, M. J.; Ida, S.; Jenkins,
J. M.; Jernigan, J. G.; Kawai, N.; Laughlin, G. P.; Lissauer, J. J.;
Martel, F.; Sasselov, D. D.; Schingler, R. H.; Torres, G.; Udry, S.;
Villasenor, J. N.; Worden, S. P.
2010AAS...21545004S Altcode: 2010BAAS...42R.458S
In a two year survey, the Transiting Exoplanet Survey Satellite
(TESS) will search the entire sky for planets orbiting nearby,
bright stars. In this paper, we calculate the number of transiting
planets that TESS will detect, as a function of the properties of the
planet and the properties of the host star. The ingredients in this
calculation are divided into five groups: <P />The properties of the
planet: its radius r and orbital distance a. <P />The properties of
the star: its luminosity L, mass M, radius R, and number density n in
our Galactic neighborhood. <P />The TESS instrumental parameters: its
effective area, bandpass, and limiting photometric precision. <P />The
TESS survey parameters: the characteristics of the input catalog (2.5
million V < 13.5 dwarfs over the whole sky), observing duty cycle
(observing a given star 10.3% of the time), and duration of observations
for a given star (72 days). <P />The abundance of planets around stars,
which may depend on r, a, and L <P />The calculation is performed for
a three-dimensional grid of planet/star/orbit combinations, in which
the three parameters are the planet radius r, the stellar luminosity L,
and the orbital distance a. For the range of instrument and population
parameters and assumptions considered, we estimate that TESS will detect
1600-2700 planets in total, of which 100-300 should be small planets:
SuperEarths or Earths. <P />Support for this work has been provided
by NASA, the Kavli Foundation, Google, and the Smithsonian Institution.
---------------------------------------------------------
Title: Monte Carlo Simulations of Transit Light Curves for the
Transiting Exoplanet Survey Satellite (TESS)
Authors: Jernigan, J. G.; Villasenor, J. N.; Ricker, G. R.; Latham,
D. W.; Vanderspek, R. K.; Ennico, K. A.; Bakos, G.; Brown, T. M.;
Burgasser, A. J.; Charbonneau, D.; Clampin, M.; Deming, L. D.;
Doty, J. P.; Dunham, E. W.; Elliot, J. L.; Holman, M. J.; Ida, S.;
Jenkins, J. M.; Kawai, N.; Laughlin, G. P.; Lissauer, J. J.; Martel,
F.; Sasselov, D. D.; Schingler, R. H.; Seager, S.; Torres, G.; Udry,
S.; Winn, J. N.; Worden, S. P.
2010AAS...21545003J Altcode: 2010BAAS...42..458J
During the Phase A for TESS, simulations of planetary transits were
performed to confirm the instrument's ability to detect transits. The
simulations cover the full TESS discovery space in the planet
period-transit duration plane. Examples included a 36-day period planet,
two previously known systems (HAT-P-11 and CoRoT 7B), and one Earth
and one SuperEarth. In addition, a broad matrix of planetary periods
and transit depths were also simulated. We present simulated light
curves of transiting planets that are typical of those that TESS will
detect. Each light curve is computed via a Monte Carlo algorithm. The
timing of the optical emission includes the parameters of orbital
motion for the planet-star system. All simulations include estimates
of the noise from the following effects: spacecraft pointing jitter,
vignetting, optical PSF wings, background effects, CCD gain and bias
instability, sky background, and intrinsic stellar variability. The
stellar variability includes a scaled, full temporal power spectrum
of the Sun. Typical light curves of planet-star systems are simulated
for a 72 day duration with a 10 minute time resolution of each TESS
sample. These simulated light curves are analyzed to determine estimates
of the S/N for detection for each simulated system. Support for this
work has been provided by NASA, the Kavli Foundation, Google, and the
Smithsonian Institution.
---------------------------------------------------------
Title: High-Precision Imaging Photometers for the Transient Exoplanet
Survey Satellite
Authors: Kraft Vanderspek, Roland; Ricker, G. R.; Latham, D. W.;
Ennico, K.; Bakos, G.; Brown, T. M.; Burgasser, A. J.; Charbonneau,
D.; Clampin, M.; Deming, L.; Doty, J. P.; Dunham, E. W.; Elliot,
J. L.; Holman, M. J.; Ida, S.; Jenkins, J. M.; Jernigan, J. G.;
Kawai, N.; Laughlin, G. P.; Lissauer, J. J.; Martel, F.; Sasselov,
D. D.; Schingler, R. H.; Seager, S.; Szentgyorgyi, A.; Torres, G.;
Udry, S.; Villasenor, J. N.; Winn, J. N.; Worden, S. P.
2010AAS...21545007K Altcode: 2010BAAS...42..459K
The Transient Exoplanet Survey Satellite (TESS) is designed to
search for transiting exoplanet systems around all stars with V <
12. The TESS payload consists of a bank of six identical, wide-field,
high-precision imaging photometers. When deployed on the highly-stable
TESS satellite platform, these photometers can perform <200 ppm
photometry for V=8 stars (∼100 ppm for V=6 stars) in a 10-minute
observation. We describe the components of the TESS imaging photometers:
the custom, wide-field optics; the large-area CCD arrays; and the
low-power, high precision CCD electronics. Support for TESS has been
provided by NASA, the Kavli Foundation, Google, and the Smithsonian
Institution.
---------------------------------------------------------
Title: Characteristics of the Kepler Target Stars
Authors: Batalha, Natalie M.; Borucki, W. J.; Koch, D. G.; Brown,
T. M.; Bryson, S. T.; Caldwell, D. A.; Gilliland, R. L.; Latham,
D. W.; Meibom, S.; Monet, D. G.; Kepler Team
2010AAS...21530506B Altcode: 2010BAAS...42Q.303B
In May, 2009, the Kepler spacecraft began its 3.5-year photometric
monitoring campaign on a select group of approximately 150,000
stars. The stars were chosen from the ∼half million in the field of
view that are brighter than 16th magnitude. The selection criteria
are quantitative metrics designed to optimize the scientific yield
of the mission with regards to the detection of earth-size planets
in the habitable zone. This yields more than 90,000 G-type stars
on or close to the Main Sequence, ∼20,000 of which are brighter
than 14th magnitude. At the temperature extremes, the sample includes
approximately 3,000 M-type dwarfs and a small sample of O and B-type MS
stars (< 200). The brightest giants are captured in the sample with
∼16,000 stars with surface gravities less than 3.5 dex. We present a
brief summary of the selection process and the stellar populations it
yields in terms of surface gravity, effective temperature, and apparent
magnitude. In addition to the primary, statistically derived, target
set, several ancillary target lists were manually generated to enhance
the science of the mission, examples being: known eclipsing binaries,
open cluster members, and high proper-motion stars. To highlight
the stellar sample, we present light curves from the first months of
science operations of the twenty brightest G, K, and M dwarfs as well
as a direct comparison with the solar irradiance variations at maximum
and minimum activity levels. This cursory look at the data suggests that
stars as photometrically quiet as the Sun are not a rarity. <P />Kepler
was selected as the 10th mission of the Discovery Program. Funding
for this mission is provided by NASA, Science Mission Directorate.
---------------------------------------------------------
Title: Data Network for the TESS Mission
Authors: Martel, Francois; Villasenor, J. N.; Ricker, G. R.; Latham,
D. W.; Vanderspek, R. K.; Ennico, K. A.; Bakos, G.; Brown, T. M.;
Burgasser, A. J.; Charbonneau, D.; Clampin, M.; Deming, L. D.; Doty,
J. P.; Dunham, E. W.; Elliot, J. L.; Holman, M. J.; Ida, S.; Jenkins,
J. M.; Jernigan, J. G.; Kawai, N.; Laughlin, G. P.; Lissauer, J. J.;
Sasselov, D. D.; Schingler, R. H.; Seager, S.; Torres, G.; Udry, S.;
Winn, J. N.; Worden, S. P.
2010AAS...21545002M Altcode: 2010BAAS...42..458M
The Transiting Exoplanet Survey Satellite (TESS) is designed for an
all-sky photometric survey of bright stars, extending&nbspover the
entire celestial sphere.&nbspTESS will catalog planetary transits
of nearby stars that can be followed-up with ground observatories. The
satellite cameras will perform measurements of 2,500,000 stars with
brightness ranging from V=4.5 to V=13.5 within two years, and download
typically 4.7 G Bytes of data per day.&nbspWe describe the TESS
operation plan and the communication and ground system designed to
download and process the TESS data. The dedicated ground system uses
a network of S-band ground stations spaced around the equator which
allows three communications passes per orbit, at data rates of 3.5
Mbit/sec, for up to 45 data downloads per day. Satellite operations
and data download are controlled remotely through the internet by
the TESS Mission Operation Center at NASA Ames Research Center, which
transfers the TESS observation data for processing and distribution to
the Science Operation Center managed by &nbspMIT and Harvard-SAO
in Cambridge. Support for this work has been provided by NASA, the
Kavli Foundation, Google, and the Smithsonian Institution.
---------------------------------------------------------
Title: Transiting Exoplanet Survey Satellite (TESS) Community Observer
Program including the Science Enhancement Option Box (SEO Box) -
12 TB On-board Flash Memory for Serendipitous Science
Authors: Schingler, Robert; Villasenor, J. N.; Ricker, G. R.; Latham,
D. W.; Vanderspek, R. K.; Ennico, K. A.; Lewis, B. S.; Bakos, G.;
Brown, T. M.; Burgasser, A. J.; Charbonneau, D.; Clampin, M.; Deming,
L. D.; Doty, J. P.; Dunham, E. W.; Elliot, J. L.; Holman, M. J.; Ida,
S.; Jenkins, J. M.; Jernigan, J. G.; Kawai, N.; Laughlin, G. P.;
Lissauer, J. J.; Martel, F.; Sasselov, D. D.; Seager, S.; Torres,
G.; Udry, S.; Winn, J. N.; Worden, S. P.
2010AAS...21545001S Altcode: 2010BAAS...42Q.458S
The Transiting Exoplanet Survey Satellite (TESS) will perform an
all-sky survey in a low-inclination, low-Earth orbit. TESS's 144
GB of raw data collected each orbit will be stacked, cleaned, cut,
compressed and downloaded. The Community Observer Program is a Science
Enhancement Option (SEO) that takes advantage of the low-radiation
environment, technology advances in flash memory, and the vast amount
of astronomical data collected by TESS. The Community Observer Program
requires the addition of a 12 TB "SEO Box” inside the TESS Bus. The
hardware can be built using low-cost Commercial Off-The-Shelf (COTS)
components and fits within TESS's margins while accommodating GSFC
gold rules. <P />The SEO Box collects and stores a duplicate of the
TESS camera data at a "raw” stage ( 4.3 GB/orbit, after stacking and
cleaning) and makes them available for on-board processing. The sheer
amount of onboard storage provided by the SEO Box allows the stacking
and storing of several months of data, allowing the investigator
to probe deeper in time prior to a given event. Additionally, with
computation power and data in standard formats, investigators can
utilize data-mining techniques to investigate serendipitous phenomenon,
including pulsating stars, eclipsing binaries, supernovae or other
transient phenomena. <P />The Community Observer Program enables ad-hoc
teams of citizen scientists to propose, test, refine and rank algorithms
for on-board analysis to support serendipitous science. Combining
"best practices” of online collaboration, with careful moderation
and community management, enables this `crowd sourced’ participatory
exploration with a minimal risk and impact on the core TESS Team. This
system provides a powerful and independent tool opening a wide range of
opportunity for science enhancement and secondary science. <P />Support
for this work has been provided by NASA, the Kavli Foundation, Google,
and the Smithsonian Institution.
---------------------------------------------------------
Title: HST/ACS Observations of RR Lyrae Stars in Six Ultra-deep
Fields of M31
Authors: Jeffery, Elizabeth; Brown, T. M.; Smith, E.; Ferguson, H. C.;
Guhathakurta, P.; Kalirai, J. S.; Kimble, R. A.; Renzini, A.; Rich,
R. M.; Sweigart, A. V.; VandenBerg, D. A.
2010AAS...21541713J Altcode: 2010BAAS...42..273J
We present HST/ACS observations of RR Lyrae variable stars obtained
in ultra-deep observations of the Andromeda galaxy (M31). These
observations probe the disk, giant stellar stream, and several halo
fields with distinct star formation histories. Earlier RR Lyrae data
from this series of observing programs have probed various aspects
of the populations that make up Andromeda's inner halo, including
distances and metallicities. The current study builds and expands
on that earlier work, investigating a sample of substructures and
environments that is much more diverse. The quality of the light curves
is akin to that usually associated with RR Lyrae stars of the Milky Way,
both in terms of photometric accuracy and time series sampling. These
data will provide additional insights into the stellar populations
with techniques that are independent of the traditional fitting of
color-magnitude diagrams.
---------------------------------------------------------
Title: WFC3: The Photometric Performance Of The UVIS And IR Cameras
Authors: Borders, Tiffany M.; Kalirai, J.; Brown, T. M.; Deustua,
S.; Rajan, A.; Riess, A.; WFC3 Team
2010AAS...21546313B Altcode: 2010BAAS...42S.496B
The on-orbit throughput of WFC3 has been measured by observing bright
spectrophotometric standard stars during SMOV4. For the UVIS channel,
we observed the hot white dwarf GD 153 in 37 of 62 filters, and on
the IR channel we observed both GD 153 and the solar analogue P330 in
all 15 filters. Repeat measurements, at multiple dither positions,
confirm that the throughput of both cameras is stable to <1% in
wide and medium band filters. Relative to the calibrations determined
during ground tests in Thermal Vacuum Test #3, the instrument is
performing more efficiently in all filters. For the UVIS channel,
we measure efficiencies that are higher than ground tests by 15-20%
at central wavelengths and 5-10% at the blue and red ends of the UVIS
spectral range. For the IR channel, the instrument throughput is 10-15%
higher in all filters. New photometric zero points have been calculated,
and updates to the exposure time calculator have been implemented.
---------------------------------------------------------
Title: WFC3: SMOV and Cycle 17 Calibration Programs
Authors: Deustua, Susana E.; MacKenty, J.; Kimble, R.; Martel,
A. R.; Baggett, S.; Barker, E.; Borders, T.; Bushouse, H.; Brown,
T. M.; Dressel, L.; Dulude, M.; Hartig, G.; Hilbert, B.; Kalirai, J.;
Quijano, J. Kim; Kozhurina-Platais, V.; McLean, B.; McCullough, P.;
Pavlovsky, C.; Petro, L.; Pirzkal, N.; Rajan, A.; Riess, A.; Sabbi,
E.; Viana, A.; Wheeler, T.; Wong, M. H.; Kuemmel, M.; Kuntschner,
H.; Walsh, J.; WFC3 Team
2010AAS...21546319D Altcode: 2010BAAS...42R.497D
The Servicing Mission Observatory Verification (SMOV4) commissioning
activities were carried out over 3 months following the installation
of Wide Field Camera 3 (WFC3) into HST during Servicing Mission
4. Following SMOV4, once WFC3 was enabled for routine science
observations, the WFC3 Cycle 17 Calibration program began. Both
SMOV4 and Cycle 17 calibration programs characterize the UVIS and IR
channels, monitor their behavior with time, and provide the reference
files used in the data reduction pipeline. Comprising 43 SMOV4 and 35
Cycle 17 programs, the commissioning and calibration of WFC3 require
approximately 400 orbits during its first 15 months on-orbit. This
paper discusses the contents, rationale, and initial results of WFC3
SMOV4 and Cycle 17 Calibration Programs. We also highlight some issues
that may affect GO programs.
---------------------------------------------------------
Title: Las Cumbres Observatory Global Telescope 1-meter Telescope
Project: Design, Deployment Plans, Status
Authors: Brown, Timothy M.; Burleson, B.; Crellin, M.; De Vera, J.;
Dubberly, M.; Greene, R.; Falarski, M.; Haldeman, B.; Hausler, S.;
Haynes, R.; Hjelstrom, A.; Hygelund, J.; Johnson, D.; Lobdill, R.;
Martinez, J.; Mullins, D.; Pickles, A.; Posner, V.; Rosing, W.; Tufts,
J.; Vander Horst, K.; Vanderhyden, B.; Walker, Z.
2010AAS...21544106B Altcode: 2010BAAS...42..401B
Las Cumbres Observatory Global Telescope (LCOGT) is a privately-funded
observatory dedicated to time-domain astronomy. Our main observing tool
will be a homogeneous world-wide network of 12 x 1m optical telescopes,
each equipped for both imaging and spectroscopy. Here we describe
the LCOGT 1m telescope design, its development status, and our plans
for deploying a dozen or so such telescopes in a worldwide network
capable of continuous observing. We also describe the 80 cm Sedgwick
telescope, which is now in regular operation as a research instrument,
and which has served as a prototype for many of the 1m mechanical and
control systems.
---------------------------------------------------------
Title: The Star Formation Histories of the M31 and M33 Spheroids
Authors: Brown, T. M.
2009ASPC..419..110B Altcode: 2009arXiv0901.2577B
I review the observational constraints on the star formation histories
in the spheroids of M33 and M31, the other two spiral galaxies in the
Local Group. M33 does not possess a traditional bulge; instead, it has a
small nuclear region hosting stars with a wide range of ages. The star
formation history of the M33 halo is poorly constrained, but composite
spectra of its halo globular clusters imply a wide age spread of 5-7
years, while the presence of RR Lyrae stars in the halo implies at least
some of the population is ancient. Although it is possible to obtain the
detailed star formation history of the M33 halo via deep photometry,
this has not been done to date. M31 hosts a traditional bulge that is
apparently dominated by stars older than 10 Gyr. Deep photometry of
the M31 halo demonstrates that it hosts both a population of ancient
metal-poor stars and a significant population extending to younger
ages and high metallicity, apparently due to its active merger history.
---------------------------------------------------------
Title: The Palomar Transient Factory: System Overview, Performance,
and First Results
Authors: Law, Nicholas M.; Kulkarni, Shrinivas R.; Dekany, Richard G.;
Ofek, Eran O.; Quimby, Robert M.; Nugent, Peter E.; Surace, Jason;
Grillmair, Carl C.; Bloom, Joshua S.; Kasliwal, Mansi M.; Bildsten,
Lars; Brown, Tim; Cenko, S. Bradley; Ciardi, David; Croner, Ernest;
Djorgovski, S. George; van Eyken, Julian; Filippenko, Alexei V.;
Fox, Derek B.; Gal-Yam, Avishay; Hale, David; Hamam, Nouhad; Helou,
George; Henning, John; Howell, D. Andrew; Jacobsen, Janet; Laher,
Russ; Mattingly, Sean; McKenna, Dan; Pickles, Andrew; Poznanski,
Dovi; Rahmer, Gustavo; Rau, Arne; Rosing, Wayne; Shara, Michael;
Smith, Roger; Starr, Dan; Sullivan, Mark; Velur, Viswa; Walters,
Richard; Zolkower, Jeff
2009PASP..121.1395L Altcode: 2009arXiv0906.5350L
The Palomar Transient Factory (PTF) is a fully-automated, wide-field
survey aimed at a systematic exploration of the optical transient
sky. The transient survey is performed using a new 8.1 square degree
camera installed on the 48 inch Samuel Oschin telescope at Palomar
Observatory; colors and light curves for detected transients are
obtained with the automated Palomar 60 inch telescope. PTF uses 80%
of the 1.2 m and 50% of the 1.5 m telescope time. With an exposure
of 60 s the survey reaches a depth of m<SUB>g<SUP>‧</SUP></SUB>
≈ 21.3 and m<SUB>R</SUB> ≈ 20.6 (5σ, median seeing). Four major
experiments are planned for the five-year project: (1) a 5 day cadence
supernova search; (2) a rapid transient search with cadences between 90
s and 1 day (3) a search for eclipsing binaries and transiting planets
in Orion; and (4) a 3π sr deep H-alpha survey. PTF provides automatic,
real-time transient classification and follow-up, as well as a database
including every source detected in each frame. This paper summarizes
the PTF project, including several months of on-sky performance tests
of the new survey camera, the observing plans, and the data reduction
strategy. We conclude by detailing the first 51 PTF optical transient
detections, found in commissioning data.
---------------------------------------------------------
Title: The Lick AGN Monitoring Project: Photometric Light Curves
and Optical Variability Characteristics
Authors: Walsh, Jonelle L.; Minezaki, Takeo; Bentz, Misty C.; Barth,
Aaron J.; Baliber, Nairn; Li, Weidong; Stern, Daniel; Bennert, Vardha
Nicola; Brown, Timothy M.; Canalizo, Gabriela; Filippenko, Alexei V.;
Gates, Elinor L.; Greene, Jenny E.; Malkan, Matthew A.; Sakata, Yu;
Street, Rachel A.; Treu, Tommaso; Woo, Jong-Hak; Yoshii, Yuzuru
2009ApJS..185..156W Altcode: 2009arXiv0909.5455W
The Lick AGN Monitoring Project targeted 13 nearby Seyfert 1
galaxies with the intent of measuring the masses of their central
black holes using reverberation mapping. The sample includes 12
galaxies selected to have black holes with masses roughly in the
range 10<SUP>6</SUP>-10<SUP>7</SUP> M <SUB>sun</SUB>, as well as the
well-studied active galactic nucleus (AGN) NGC 5548. In conjunction
with a spectroscopic monitoring campaign, we obtained broadband B
and V images on most nights from 2008 February through 2008 May. The
imaging observations were carried out by four telescopes: the 0.76 m
Katzman Automatic Imaging Telescope, the 2 m Multicolor Active Galactic
Nuclei Monitoring telescope, the Palomar 60 inch (1.5 m) telescope,
and the 0.80 m Tenagra II telescope. Having well-sampled light curves
over the course of a few months is useful for obtaining the broad-line
reverberation lag and black hole mass, and also allows us to examine
the characteristics of the continuum variability. In this paper, we
discuss the observational methods and the photometric measurements, and
present the AGN continuum light curves. We measure various variability
characteristics of each of the light curves. We do not detect any
evidence for a time lag between the B- and V-band variations, and we
do not find significant color variations for the AGNs in our sample.
---------------------------------------------------------
Title: The Kepler mission
Authors: Christensen-Dalsgaard, J.; Arentoft, T.; Brown, T. M.;
Gilliland, R. L.; Kjeldsen, H.; Borucki, W. J.; Koch, D.
2009CoAst.158..328C Altcode:
The Kepler mission will provide a vast improvement in the
characterization of extrasolar planetary systems, and in addition give
a dramatic increase in the data available for asteroseismology. The
present paper gives a brief overview of the mission, emphasizing
the asteroseismic aspects, and with references to more detailed
presentations.
---------------------------------------------------------
Title: Las Cumbres Observatory Global Telescope
Authors: Brown, Timothy M.; Rosing, W.; Pickles, A.; Howell, D. A.
2009AAS...21440914B Altcode:
Las Cumbres Observatory Global Telescope (LCOGT) is a privately-funded
observatory dedicated to time-domain astronomy. Our main observing
tool will be a homogeneous world-wide network of 12 x 1m optical
telescopes, each equipped for both imaging and spectroscopy. We will
also continue to operate 2m telscopes in Hawaii and Australia, and we
plan to deploy a few tens of 0.4m imaging telescopes for education and
for bright-object research. LCOGT has membership in the Pan-STARRS1
consortium, in the Palomar Transient Factory (PTF), and in LSST. In
accord with these affiliations, our staff's scientific interests are
concentrated in (but not restricted to) the areas of extrasolar planets,
extragalactic transients (especially SNe), and pulsating stars. <P />In
this poster we describe the observatory in general terms, including
its research agenda, its telescope deployment plans and schedule, its
notable technical challenges, and its anticipated methods of working
with the wider astronomical community. For more detailed information
about LCOGT's aims and projects, please see the related posters in
this session.
---------------------------------------------------------
Title: Transiting Exoplanet Survey Satellite (TESS)
Authors: Ricker, George R.; Latham, D. W.; Vanderspek, R. K.; Ennico,
K. A.; Bakos, G.; Brown, T. M.; Burgasser, A. J.; Charbonneau,
D.; Clampin, M.; Deming, L. D.; Doty, J. P.; Dunham, E. W.; Elliot,
J. L.; Holman, M. J.; Ida, S.; Jenkins, J. M.; Jernigan, J. G.; Kawai,
N.; Laughlin, G. P.; Lissauer, J. J.; Martel, F.; Sasselov, D. D.;
Schingler, R. H.; Seager, S.; Torres, G.; Udry, S.; Villasenor, J. S.;
Winn, J. N.; Worden, S. P.
2009AAS...21430605R Altcode:
The Transiting Exoplanet Survey Satellite (TESS) is a low
cost, SMEX-class planet finder. In a two year all-sky survey,
TESS will observe more than two million bright, nearby stars,
searching for temporary drops in brightness that are caused by
planetary transits. Such transits not only provide the means of
identifying the planet, but also provide knowledge of the planet's
diameter, mass density, surface gravity, temperature, and other key
properties. TESS is expected to detect more than 1000 transiting
exoplanet candidates. These detections will include a sample of
100 Super Earths -- small rock-and-ice planets with masses in the
range 1 to 10 Earth masses -- orbiting nearby stars with spectral
types spanning a broad range, including F, G, K, and M dwarfs. No
ground-based survey can achieve this feat. TESS's "wide-shallow" survey
complements the "narrow-deep" Corot and Kepler mission surveys. The
resulting TESS Transit Catalog of the nearest and brightest stars
in the sky will constitute a unique scientific legacy for followup
observations. TESS will identify Super Earths orbiting IR-bright stars,
ideal for JWST searches for planetary water and carbon dioxide. <P
/>The TESS mission is a collaborative effort led by researchers at
the Massachusetts Institute of Technology, the Harvard-Smithsonian
Center for Astrophysics, and the NASA Ames Research Center. Additional
TESS partners include ATK Space Systems, the Las Cumbres Observatory
Global Telescope Network, Lowell Observatory, the NASA Goddard Space
Flight Center, the Infrared Processing and Analysis Center at the
California Institute of Technology, the University of California
(Berkeley and Santa Cruz), the SETI Institute, Espace Incorporated,
the Geneva Observatory (Switzerland), the Tokyo Institute of Technology
(Japan), and Institut Supérieur de l'Aéronautique et de l'Espace
(France). <P />TESS is currently completing a NASA-funded Phase A study,
and is proposed for launch in December 2012.
---------------------------------------------------------
Title: Observational detection of eight mutual eclipses and
occultations between the satellites of Uranus
Authors: Christou, A. A.; Lewis, F.; Roche, P.; Hashimoto, Y.;
O'Donoghue, D.; Worters, H.; Buckley, D. A. H.; Michalowski, T.;
Asher, D. J.; Bitsaki, A.; Psalidas, A.; Tsamis, V.; Gourgouliatos,
K. N.; Liakos, A.; Hidas, M. G.; Brown, T. M.
2009A&A...497..589C Altcode: 2009arXiv0902.4582C
Aims: We carried out observations, with five different instruments
ranging in aperture from 0.4 m to 10 m, of the satellites of
Uranus during that planet's 2007 Equinox. Our observations covered
specific intervals of time when mutual eclipses and occultations were
predicted. <BR />Methods: The observations were carried out in the
near-infrared part of the spectrum to mitigate the glare from the
planet. Frames were acquired at rates >1/min. Following modelling
and subtraction of the planetary source from these frames, differential
aperture photometry was carried out on the satellite pairs involved in
the predicted events. In all cases but one, nearby bright satellites
were used as reference sources. <BR />Results: We have obtained
fifteen individual lightcurves, eight of which show a clear drop in
the flux from the satellite pair, indicating that a mutual event took
place. Three of these involve the faint satellite Miranda. All eight
lightcurves were model-fitted to yield best estimates of the time of
maximum flux drop and the impact parameter. In three cases best-fit
albedo ratios were also derived. We used these estimates to generate
intersatellite astrometric positions with typical formal uncertainties
of <0.01 arcsec, several times better than conventional astrometry of
these satellites. The statistics of our estimated event midtimes show
a systematic lag, with the observations later than predictions. In
addition, lightcurves of two partial eclipses of Miranda show no
statistically significant evidence of a light drop, at variance with
the predictions. These indicate that new information about the Uranian
satellite system is contained in observations of mutual events acquired
here and by other groups.
---------------------------------------------------------
Title: Transit timing variability in TrES-1
Authors: Rabus, M.; Alonso, R.; Deeg, H. J.; Belmonte, J. A.; Almenara,
J. M.; Gilliland, R. L.; Brown, T. M.
2009IAUS..253..432R Altcode:
We observed several transits of the exoplanet TrES-1 distributed over
four years from 2004 to 2007. On the basis of these observations and
additional published data, we present a mid-transit time analysis. The
aim is to find indications of the presence of a third body by analysing
the difference between the calculated and observed transit times.
---------------------------------------------------------
Title: Transiting Planets in the Galactic Bulge from SWEEPS Survey
and Implications
Authors: Sahu, Kailash C.; Casertano, Stefano; Valenti, Jeff; Bond,
Howard E.; Brown, Thomas M.; Smith, T. Ed; Clarkson, Will; Minniti,
Dante; Zoccali, Manuela; Livio, Mario; Renzini, Alvio; Rich, R. M.;
Panagia, Nino; Lubow, Stephen; Brown, Timothy; Piskunov, Nikolai
2009IAUS..253...45S Altcode:
The SWEEPS (Sagittarius Window Eclipsing Extrasolar Planet Search)
program was aimed at detecting planets around stars in the Galactic
bulge, not only to determine their physical properties, but also
to determine whether the properties of planets found in the solar
neighborhood, such as their frequency and the metallicity dependence,
also hold for the planets in the Galactic bulge. We used the Hubble
Space Telescope to monitor 180,000 F, G, K, and M dwarfs in the
Galactic bulge continuously for 7 days in order to look for transiting
planets. We discovered 16 candidate transiting extrasolar planets
with periods of 0.6 to 4.2 days, including a possible new class of
ultra-short period planets (USPPs) with P < 1 day. The facts that
(i) the coverage in the monitoring program is continuous, (ii) most
of the stars are at a known distance (in the Galctic bulge), (iii)
monitoring was carried out in 2 passbands, and (iv) the images have
high spatial resolution, were crucial in minimizing and estimating the
false positive rates. We estimate that at least 45% of the candidates
are genuine planets. Radial velocity observations of the two brightest
host stars further support the planetary nature of the transiting
companions. These results suggest that the planet frequency in the
Galactic bulge is similar to that in the solar neighborhood. They
also suggest that higher metallicity favors planet formation even
in the Galactic bulge. The USPPs occur only around low-mass stars
which may suggest that close-in planets around higher-mass stars are
irradiately evaporated, or that planets are able to migrate to and
survive in close-in orbits only around such old and low-mass stars.
---------------------------------------------------------
Title: The Transiting Exoplanet Survey Satellite (TESS)
Authors: Ricker, George R.; Latham, D. W.; Vanderspek, R. K.; Ennico,
K. A.; Bakos, G.; Brown, T. M.; Burgasser, A. J.; Charbonneau, D.;
Deming, L. D.; Doty, J. P.; Dunham, E. W.; Elliot, J. L.; Holman,
M. J.; Ida, S.; Jenkins, J. M.; Jernigan, J. G.; Kawai, N.; Laughlin,
G. P.; Lissauer, J. J.; Martel, F.; Sasselov, D. D.; Schingler,
R. H.; Seager, S.; Torres, G.; Udry, S.; Villasenor, J. S.; Winn,
J. N.; Worden, S. P.
2009AAS...21340301R Altcode: 2009BAAS...41..193R
The Transiting Exoplanet Survey Satellite (TESS) is a low cost,
SMEX-class planet finder. In a two year all-sky survey, TESS will
observe more than two million bright, nearby stars, searching for
temporary drops in brightness that are caused by planetary transits,
which occur when a planet's orbit carries it directly in front of its
parent star. Such transits not only provide the means of identifying
the planet, but also provide knowledge of the planet's diameter, mass
density, surface gravity, temperature, and other key properties. <P
/>TESS is expected to catalog more than 1000 transiting exoplanet
candidates--20 times as many as are presently known, including a
sample of 'super Earths'. The TESS "wide-shallow" survey will be
complementary to the "narrow-deep" ones of the Corot and Kepler
missions: its sky coverage will exceed that of Corot by 1000 times,
and that of Kepler by 400 times. Because the TESS all-sky survey will
systematically examine every interesting bright star likely to harbor an
exoplanet, the resulting TESS Transit Catalog will constitute a unique
scientific legacy. High resolution, follow-up ground-based optical and
space-based IR spectroscopy of exoplanets demands bright targets. Thus,
TESS should identify those new exoplanets that are ideal for study
with the world's largest ground-based telescopes, as well as with
NASA's upcoming James Webb Space Telescope. <P />The TESS mission is a
collaborative effort led by researchers at MIT, the Harvard-Smithsonian
Center for Astrophysics, and the NASA Ames Research Center. Additional
TESS partners include the NASA Goddard Space Flight Center, the Harvard
Origins of Life Initiative, Lowell Observatory, Caltech's IPAC, the
SETI Institute, Geneva Observatory in Switzerland, Tokyo Institute
of Technology, SUPAERO in France, ATK Space, Espace Inc, and the Las
Cumbres Observatory Global Telescope Network. TESS has been accepted
for Phase A study by NASA, and is proposed for launch in late 2012.
---------------------------------------------------------
Title: NStED: Exo-Planet Transit Survey TrES Lyr1
Authors: O'Donovan, Francis T.; Charbonneau, David; Mandushev,
Georgi; Dunham, Edward W.; Latham, David W.; Torres, Guillermo;
Sozzetti, Alessandro; Brown, Timothy M.; Trauger, John T.; Belmonte,
Juan A.; Rabus, Markus; Almenara, José M.; Alonso, Roi; Deeg, Hans
J.; Esquerdo, Gilbert A.; Falco, Emilio E.; Hillenbrand, Lynne A.;
Roussanova, Anna; Stefanik, Robert P.; Winn, Joshua N.
2009nsted.cat....6O Altcode:
The Trans-atlantic Exoplanet Survey (TrES) attempts to find planetary
transits among bright stars. The two telescope used are the 10cm Sleuth
Telescope (Palomar Observatory, California) and the 10cm Planet Search
Survey Telescope (PSST) at Lowell Observatory, Arizona. The survey
area covers 5.7 degrees by 5.7 degrees and is centered on the star
16 Lyr (19h 01m 26.3713s +46d 56m 05.325s). NStED provides access to
high precision time-series photometry from stars observed by various
transit survey programs. The data presented here are the result of
the Lyra 1 campaign with TrES telescopes.
---------------------------------------------------------
Title: Research Science and Education: The NSF’s Astronomy and
Astrophysics Postdoctoral Fellowship
Authors: Norman, Dara; Agueros, Marcel; Brown, Timothy M.; Browning,
Matthew; Chakrabarti, Sukanya; Cobb, Bethany; Coble, Kim; Conselice,
Christopher; Cruz, Kelle; Danly, Laura; Frinchaboy, Peter M.; Gawiser,
Eric; Gelfand, Joseph; Gonzalez, Anthony; Hoffman, Jennifer L.;
Huterer, Dragan; Johnson, John; Johnson, Roberta M.; Kannappan,
Sheila; Kuzio de Naray, Rachel; Lai, David; Leonard, Douglas C.;
Lystrup, Makenzi; Markoff, Sera; Menendez-Delmestre, Karin; Muchovej,
Stephan; McSwain, M. Virginia; Rhode, Katherine; Smecker-Hane, Tammy;
Smith, Malcolm; Sokoloski, Jennifer; Tran, Kim-Vy
2009astro2010P..41N Altcode: 2009arXiv0903.4509N
The NSF's Astronomy and Astrophysics Postdoctoral Fellowship (AAPF)
is exceptional among the available postdoctoral awards in Astronomy and
Astrophysics. The fellowship is one of the few that allows postdoctoral
researchers to pursue an original research program, of their own design,
at the U.S. institution of their choice. However, what makes this
fellowship truly unique is the ability of Fellows to lead an equally
challenging, original educational program simultaneously. The legacy
of this singular fellowship has been to encourage and advance leaders
in the field who are equally as passionate about their own research as
they are about sharing that research and their passion for astronomy
with students and the public. In this positional paper we address the
importance of fellowships like the AAPF to the astronomical profession
by identifying the science and educational contributions that Fellows
have made to the community. Further, we recommend that fellowships that
encourage leading postdoctoral researchers to also become leaders in
Astronomy education be continued and expanded.
---------------------------------------------------------
Title: A cool starspot or a second transiting planet in the TrES-1
system?
Authors: Rabus, M.; Alonso, R.; Belmonte, J. A.; Deeg, H. J.;
Gilliland, R. L.; Almenara, J. M.; Brown, T. M.; Charbonneau, D.;
Mandushev, G.
2009A&A...494..391R Altcode: 2008arXiv0812.1799R
Aims: We investigate the origin of a flux increase found during a
transit of TrES-1, observed with the HST (Hubble Space Telescope). This
feature in the HST light curve cannot be attributed to noise and is
supposedly a dark area on the stellar surface of the host star eclipsed
by TrES-1 during its transit. We investigate the likelihood of two
possible hypotheses for its origin. A starspot or a second transiting
planet. <BR />Methods: We made use of several transit observations of
TrES-1 from space with the HST and from ground with the IAC 80-cm
telescope (IAC-80). On the basis of these observations we did a
statistical study of flux variations in each of the observed events to
investigate whether similar flux increases are present in other parts
of the data set. <BR />Results: The HST observation presents a single
clear flux rise during a transit, whereas the ground observations
lead to detecting two such events but with low significance. In the
case of having observed a starspot in the HST data, assuming a central
impact between the spot and TrES-1, we would obtain a lower limit for
the spot radius of 42 000 km. For this radius the spot temperature
would be 4690 K, 560 K lower then the stellar surface of 5250 K. For
a putative second transiting planet, we can set a lower limit for its
radius at 0.37 R<SUB>J</SUB> and for periods of less than 10.5 days,
we can set an upper limit at 0.72 R<SUB>J</SUB>. <BR />Conclusions:
Assuming a conventional interpretation, this HST observation then
constitutes the detection of a starspot. Alternatively, this flux rise
might also be caused by an additional transiting planet. The true nature
of the origin can be revealed if a wavelength dependency of the flux
rise can be shown or discarded with higher certainty. Additionally,
the presence of a second planet can be detected by radial velocity
measurements. <P />Based on observations made with the NASA/ESA Hubble
Space Telescope, obtained at the Space Telescope Science Institute,
which is operated by the Association of Universities for Research in
Astronomy, Inc., under NASA contract NAS 5-26555.
---------------------------------------------------------
Title: Asteroseismology: The Next Frontier in Stellar Astrophysics
Authors: Giampapa, Mark S.; Aerts, Conny; Bedding, Tim; Bonanno,
Alfio; Brown, Timothy M.; Christensen-Dalsgaard, Jorgen; Dominik,
Martin; Ge, Jian; Gilliland, Ronald L.; Harvey, J. W.; Hill, Frank;
Kawaler, Steven D.; Kjeldsen, Hans; Kurtz, D. W.; Marcy, Geoffrey W.;
Matthews, Jaymie M.; Monteiro, Mario Joao P. F. G.; Schou, Jesper
2009astro2010S..91G Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The Lyman Continuum Escape Fraction at z 0.7
Authors: Bridge, Carrie; Teplitz, H.; Siana, B.; Ferguson, H.;
Conselice, C.; Brown, T. M.; De Mello, D. F.; Dickinson, M.; Gardner,
J.; Giavalisco, M.; Claudia, S.; Colbert, J.
2009AAS...21334805B Altcode: 2009BAAS...41R.484B
Lyman continuum photons produced in massive starbursts likely played
an important role in the reionization of the Universe. However, their
contribution depends upon the fraction of ionizing radiation that
escapes from the intrinsic opacity of the galaxies below the Lyman
limit. We present the results of deep HST rest-frame, UV slitless
spectroscopy of 14 z 0.7 Lyman break galaxy (LBG) analogs in the COSMOS
field. While there are no <P />detections of the Lyman Continuum we
achieve individual limits of 5-21% and a stacked limit for the escape
fraction of <5%. These UV spectra from the ACS Solar Blind channel
have achieved the deepest limits to date of the escape fraction in
individual sources below z 1.
---------------------------------------------------------
Title: Temporal Variability of Stars and Stellar Systems
Authors: Lister, Tim; Metcalfe, Travis; Brown, Tim; Street, Rachel
2009astro2010S.184L Altcode: 2009arXiv0902.2966L
Although the Sun is our closest star by many orders of magnitude and
despite having sunspot records stretching back to ancient China, our
knowledge of the Sun's magnetic field is far from complete. Indeed,
even now, after decades of study, the most obvious manifestations of
magnetic fields in the Sun (e.g. sunspots, flares and the corona)
are scarcely understood at all. These failures in spite of intense
effort suggest that to improve our grasp of magnetic fields in stars
and of astrophysical dynamos in general, we must broaden our base of
examples beyond the Sun; we must study stars with a variety of ages,
masses, rotation rates, and other properties, so we can test models
against as broad a range of circumstances as possible. Over the next
decade, an array of indirect techniques will be supplemented by rapidly
maturing new capabilities such as gyrochronology, asteroseismology and
precision photometry from space, which will transform our understanding
of the temporal variability of stars and stellar systems. In this White
Paper we will outline some of the key science questions in this area
along with the techniques that could be used to bring new insights to
these questions.
---------------------------------------------------------
Title: Confirmation and Characterization of Kepler Mission Exoplanets:
The Era of Rock and Ice Exoplanets
Authors: Charbonneau, David; Borucki, William; Brown, Timothy; Deming,
Drake; Ford, Eric; Fortney, Jonathan; Gilliland, Ronald; Knutson,
Heather; Latham, David; Seager, Sara
2008sptz.prop60028C Altcode:
In the past 4 years, the combination of ground-based transit surveys
and the remarkable stability of the Spitzer Space Telescope permitted
the direct investigation of the atmospheres of one specific class
of exoplanet, namely the Hot Jupiters. The power of the NASA Kepler
Mission will be to discover dozens of transiting exoplanets that
are not detectable from the ground either due to the shallow transit
depth or the low transit frequency resulting from their longer orbital
periods. Kepler will find large numbers of transiting hot Neptunes
and hot SuperEarth exoplanets, as well as cooler Jupiters, each of
which are nonetheless amenable to direct study of their infrared
emission. We propose to use Spitzer to observe Kepler-detected
exoplanets and candidates to pursue two goals. First, we will measure
the two-color planetary emission for 20 representative members
of these previously inaccessible cexoplanets. Such observations
will permit the first opportunity to directly test theoretical
models of exoplanetary atmospheres of varying compositions (notably
SuperEarths and Neptunes) and under differing levels of irradiation
(cooler Jovian companions). The same data will permit an estimate of
the orbital eccentricities, thus providing a test of models of the
orbital migration, and tidal dissipation for these various types of
exoplanets. Second, we will use Spitzer to follow up Kepler-identified
candidate terrestrial exoplanets to prove that these signals are indeed
planetary in origin. By gathering single color time series spanning
times of primary transit, we will exclude a significant source of
astrophysical false positives (resulting from blends of triple stars
systems containing an eclipsing binary) that will precisely mimic an
exoplanetary signature in the Kepler data. These infrared data will
provide a crucial step in confirming the planetary nature of many of
the most exciting candidates, namely the planets with the smallest
radii that are likely rocky in composition.
---------------------------------------------------------
Title: Expected Planet and False Positive Detection Rates for the
Transiting Exoplanet Survey Satellite
Authors: Brown, Timothy M.; Latham, David W.
2008arXiv0812.1305B Altcode:
The proposed Transiting Exoplanet Survey Satellite (TESS) will survey
the entire sky to locate the nearest and brightest transiting extrasolar
planets with orbital periods up to about 36 days. Here we estimate
the number and kind of astrophysical false positives that TESS will
report, along with the number of extrasolar planets. These estimates
are then used to size the ground-based follow-up observing efforts
needed to confirm and characterize the planets. We estimate that the
needed observing resources will be about 1400 telescope-nights of
imaging with 0.5m to 1m-class telescopes, 300 telescope-nights with
1m to 2m-class telescopes for the classification of the host stars
and for radial velocity measurements with roughly 1 km/s precision,
and 380 telescope-nights with 2m to 4m-class telescopes for radial
velocity studies with precision of a few m/s. Follow-up spectroscopy of
the smallest planets discovered by TESS at the best possible velocity
precision will be limited by the number of telescope nights available
on 4m to 10m class telescopes with instruments such as HARPS and HIRES,
but the pay-off of such efforts will be the determination of masses
for Super Earths with sufficient accuracy to distinguish rocky desert
planets from water worlds.
---------------------------------------------------------
Title: Kepler
Authors: Christensen-Dalsgaard, J.; Arentoft, T.; Brown, T. M.;
Gilliland, R. L.; Kjeldsen, H.; Borucki, W. J.; Koch, D.
2008CoAst.157..266C Altcode:
Kepler is a NASA mission, scheduled for launch in April 2009, whose
principal purpose is to investigate extra-solar planetary systems,
through the detection of planetary transits across their parent
star. An important goal is to determine the prevalence of Earth-size
planets in Earth-like orbits. The required photometric precision also
makes the mission very well- suited for asteroseismology, with the
important purpose of characterizing the central stars in planetary
systems. An extensive asteroseismic programme is planned for Kepler,
organized in an international collaboration in the Kepler Asteroseismic
Science Consortium.
---------------------------------------------------------
Title: The Kepler asteroseismic investigation
Authors: Christensen-Dalsgaard, J.; Arentoft, T.; Brown, T. M.;
Gilliland, R. L.; Kjeldsen, H.; Borucki, W. J.; Koch, D.
2008JPhCS.118a2039C Altcode:
The NASA Kepler mission for studies of extra-solar planets, with
expected launch early in 2009, will provide a large set of excellent
data for asteroseismology. Here we provide a brief presentation of
the mission and discuss some aspects of the expected results of the
asteroseismic investigations and the organization of the effort in
the Kepler Asteroseismic Science Consortium (KASC).
---------------------------------------------------------
Title: Mutual Events of the Uranian Satellites Observed with the
Faulkes Telescopes
Authors: Christou, Apostolos; Lewis, F.; Hidas, M. G.; Brown, T. M.;
Roche, P.
2008DPS....40.4601C Altcode: 2008BAAS...40..480C
The 2007 Uranian Equinox allowed unique observations of the planet,
its rings and satellites, possible only twice during the planet's 84
year orbit. <P />Among these were mutual eclipses and occultations
between the 5 classical satellites Ariel, Umbriel, Titania, Oberon and
Miranda. These “mutual” events are extremely useful as reality checks
of satellite ephemerides. In addition, they provide an opportunity
to improve our knowledge of the satellite orbits and the system
constants. <P />We observed several mutual events in 2007 using the 2m
Faulkes Telescopes North (FTN) and South (FTS) located in Haleakala,
Maui and Siding Spring, Australia respectively, operated by the Las
Cumbres Observatory Global Telescope (LCOGT) network. To mitigate
against Uranus' glare, we utilized wide-band imaging in the near-IR,
a small image scale and a posteriori subtraction of the planet's
PSF. <P />We obtained positive detections of six mutual events, three
occultations and three eclipses, among these satellites. Three of
these events involved Miranda, a difficult target due to its proximity
to Uranus. Furthermore, we recorded at least two events that were
predicted to occur with high confidence but did not, in fact, occur. <P
/>During this presentation we will describe our observing strategy,
operational setup and data reduction techniques and present examples
of obtained lightcurves. Our observational results have been compared
with predictions based on ephemerides by Laskar and Jacobson (1987;
GUST86), by Lainey and Arlot (2006; LA06) and by Rush and Jacobson
(2007; RJ07). Offsets with respect to the Voyager-era GUST86 are quite
significant, of the order of minutes in the event midtimes. Smaller,
yet significant trends in the data also appear with respect to LA06
and RJ07. <P />We will discuss the nature of these trends and how they
can be interpreted in terms of potential improvements in our knowledge
of the Uranian system.
---------------------------------------------------------
Title: The Wide-Field Camera 3 detectors
Authors: Baggett, S. M.; Hill, R. J.; Kimble, R. A.; MacKenty, J. W.;
Waczynski, A.; Bushouse, H. A.; Boehm, N.; Bond, H. E.; Brown, T. M.;
Collins, N. R.; Delo, G.; Dressel, L.; Foltz, R.; Hartig, G.; Hilbert,
B.; Kan, E.; Kim-Quijano, J.; Malumuth, E.; Martel, A.; McCullough,
P.; Petro, L.; Robberto, M.; Wen, Y.
2008SPIE.7021E..1QB Altcode: 2008SPIE.7021E..50B
The Wide-field Camera 3 (WFC3) is a fourth-generation instrument
planned for installation in Hubble Space Telescope (HST). Designed as
a panchromatic camera, WFC3's UVIS and IR channels will complement the
other instruments onboard HST and enhance the observatory's scientific
performance. UVIS images are obtained via two 4096×2051 pixel e2v CCDs
while the IR images are taken with a 1024×1024 pixel HgCdTe focal plane
array from Teledyne Imaging Sensors. Based upon characterization tests
performed at NASA/GSFC, the final flight detectors have been chosen
and installed in the instrument. This paper summarizes the performance
characteristics of the WFC3 flight detectors based upon component and
instrument-level testing in ambient and thermal vacuum environments.
---------------------------------------------------------
Title: Parameters and Predictions for the Long-Period Transiting
Planet HD 17156b
Authors: Irwin, Jonathan; Charbonneau, David; Nutzman, Philip; Welsh,
William F.; Rajan, Abhijith; Hidas, Marton; Brown, Timothy M.; Lister,
Timothy A.; Davies, Donald; Laughlin, Gregory; Langton, Jonathan
2008ApJ...681..636I Altcode: 2008arXiv0801.1496I
We report high-cadence time series photometry of the recently
discovered transiting exoplanet system HD 17156, spanning the time of
transit on UT 2007 October 1, from three separate observatories. We
present a joint analysis of our photometry, previously published
radial velocity measurements, and times of transit center for three
additional events. Adopting the spectroscopically determined values
and uncertainties for the stellar mass and radius, we estimate a
planet radius of R<SUB>p</SUB> = 1.01 +/- 0.09 R<SUB>Jup</SUB> and an
inclination of i = 86.5<SUP>+ 1.1</SUP><SUB>-0.7</SUB> deg. We find a
time of transit center of T<SUB>c</SUB> = 2,454,374.8338 +/- 0.0020 HJD
and an orbital period of P = 21.21691 +/- 0.00071 days and note that
the four transits reported to date show no sign of timing variations
that would indicate the presence of a third body in the system. Our
results do not preclude the existence of a secondary eclipse, but
imply that there is only a 9.2% chance for this to be present and an
even lower probability (6.9%) that the secondary eclipse would be a
nongrazing event. Due to its eccentric orbit and long period, HD 17156b
is a fascinating object for the study of the dynamics of exoplanet
atmospheres. To aid such future studies, we present theoretical light
curves for the variable infrared emission from the visible hemisphere
of the planet throughout its orbit.
---------------------------------------------------------
Title: Stellar proper motions in the Galactic bulge with ACS/WFC
on HST
Authors: Clarkson, Will; Sahu, Kailash; Anderson, Jay; Smith, T. Ed;
Brown, Thomas M.; Casertano, Stefano; Rich, R. Michael; Bond, Howard
E.; Brown, Timothy; Livio, Mario; Minniti, Dante; Panagia, Nino;
Renzini, Alvio; Valenti, Jeff; Zoccali, Manuela
2008IAUS..245..361C Altcode:
In 2004 the Sagittarius Window Eclipsing Extrasolar Planet Search
(SWEEPS) project undertook a very deep ACS/WFC exposure-set of the Sgr-I
low-reddening window in the Galactic Bulge, with repeat observations
2.04 years later. The combination of superb first-epoch sampling,
wide field of view and high PSF stability of ACS/WFC on Hubble allows
proper motions to be extracted for more than 137,000 objects, over
85,000 to accuracy better than 0.3 mas yr<SUP>-1</SUP>. We present
these proper motions and outline some of the uses to which they have
been put, including the separation of a pure-Bulge sample and the
inner Galactic rotation curve.
---------------------------------------------------------
Title: Observations of the atmospheres of extrasolar planets
Authors: Brown, T. M.; Alonso, R.; Knölker, M.; Rauer, H.; Schmidt, W.
2008depn.conf...50B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Finding Earth-size planets in the habitable zone: the Kepler
Mission
Authors: Borucki, William; Koch, David; Basri, Gibor; Batalha, Natalie;
Brown, Timothy; Caldwell, Douglas; Christensen-Dalsgaard, Jørgen;
Cochran, William; Dunham, Edward; Gautier, Thomas N.; Geary, John;
Gilliland, Ronald; Jenkins, Jon; Kondo, Yoji; Latham, David; Lissauer,
Jack J.; Monet, David
2008IAUS..249...17B Altcode: 2007IAUS..249...17B
The Kepler Mission is a space-based mission whose primary goal is
to detect Earth-size and smaller planets in the habitable zone of
solar-like stars. The mission will monitor more than 100,000 stars
for transits with a differential photometric precision of 20 ppm
at V=12 for a 6.5 hour transit. It will also provide asteroseismic
results on several thousand dwarf stars. It is specifically designed
to continuously observe a single field of view of greater than 100
square degrees for 3.5 or more years. <P />This overview describes the
mission design, its goals and capabilities, the measured performance
for those photometer components that have now been tested, the Kepler
Input Catalog, an overview of the analysis pipeline, the plans for the
Follow-up Observing Program to validate the detections and characterize
the parent stars, and finally, the plans for the Guest Observer and
Astrophysical Data Program.
---------------------------------------------------------
Title: Las Cumbres Observatory Global Telescope: A homogeneous
telescope network
Authors: Hidas, M. G.; Hawkins, E.; Walker, Z.; Brown, T. M.; Rosing,
W. E.
2008AN....329..269H Altcode:
Las Cumbres Observatory Global Telescope is a research organisation in
the process of designing and building a network of robotic telescopes
to be used for research in time-domain astrophysics and education. The
network will have complete latitude coverage in both hemispheres to
allow continuous observations of any target. In other words, we will
keep you in the dark. We describe the current status of our facilities
and our vision for the full network.
---------------------------------------------------------
Title: An observation of a mutual event between two satellites
of Uranus
Authors: Hidas, M. G.; Christou, A. A.; Brown, T. M.
2008MNRAS.384L..38H Altcode: 2008MNRAS.tmpL...2H; 2007arXiv0711.2095H
We present observations of the occultation of Umbriel by Oberon on
2007 May 4. We believe this is the first observed mutual event between
satellites of Uranus. Fitting a simple geometric model to the light
curve, we measure the mid-event time with a precision of 4 s. We assume
previously measured values for the albedos of the two satellites, and
measure the impact parameter to be 500 +/- 80 km. These measurements
are more precise than estimates based on current ephemerides for these
satellites. Therefore observations of additional mutual events during
the 2007-2008 Uranian equinox will provide improved estimates of their
orbital and physical parameters.
---------------------------------------------------------
Title: Planets in the Galactic Bulge: Results from the SWEEPS Project
Authors: Sahu, K. C.; Casertano, S.; Valenti, J.; Bond, H. E.; Brown,
T. M.; Smith, T. E.; Clarkson, W.; Minniti, D.; Zoccali, M.; Livio,
M.; Renzini, A.; Rich, R. M.; Panagia, N.; Lubow, S.; Brown, T.;
Piskunov, N.
2008ASPC..398...93S Altcode: 2007arXiv0711.4059S
The exoplanets discovered so far have been mostly around relatively
nearby and bright stars. As a result, the host stars are mostly (i)
in the Galactic disk, (ii) relatively massive, and (iii) relatively
metal rich. The aim of the SWEEPS project is to extend our knowledge
to stars which (i) are in a different part of the Galaxy, (ii) have
low masses, and (iii) have a large range of metallicities. To achieve
this goal, we used the Hubble Space Telescope and its Advanced Camera
for Surveys to look for transiting planets around F, G, K, and and M
dwarfs in the Galactic bulge. We photometrically monitored ∼180,000
stars in a dense stellar field in the Galactic bulge continuously for
7 days. We discovered 16 candidate transiting extrasolar planets with
periods of 0.6 to 4.2 days, including a new class of ultra-short period
planets (USPPs) with P<1.2 days. Radial velocity observations of
two brightest candidates support the planetary nature. These results
suggest that planets are equally abundant in the Galactic bulge and
around low-mass stars (within a factor ∼2), and the metallicity
distribution holds even for the stars in the Galactic bulge. The USPPs
occur only around low-mass stars which suggest that close-in planets
around higher-mass stars are either irradiately evaporated, or that
the size of the inner disk hole decreases with decreasing mass of the
host stars.
---------------------------------------------------------
Title: Characterizing extrasolar planets
Authors: Brown, Timothy M.
2008expl.conf...65B Altcode:
Transiting extrasolar planets provide the best current opportunities
for characterizing the physical properties of extrasolar planets. In
this review, I first describe the geometry of planetary transits, and
methods for detecting and refining the observations of such transits. I
derive the methods by which transit light curves and radial velocity
data can be analyzed to yield estimates of the planetary radius,
mass, and orbital parameters. I also show how visible-light and
infrared spectroscopy can be valuable tools for understanding the
composition, temperature, and dynamics of the atmospheres of transiting
planets. Finally, I relate the outcome of a participatory lecture-hall
exercise relating to one term in the Drake equation, namely the lifetime
of technical civilizations.
---------------------------------------------------------
Title: The Lyman Continuum Escape Fraction at Moderate Redshift
Authors: Teplitz, Harry I.; Siana, B.; Bridge, C.; Ferguson, H.;
Giavalisco, M.; Dickinson, M.; Gardner, J. P.; de Mello, D.; Brown,
T. M.; Colbert, J.
2007AAS...21114306T Altcode: 2007BAAS...39..996T
Massive starbursts may have played a dominant role in the reionization
of the Universe. Their contribution depends in part upon the fraction of
ionizing radiation that escapes from the intrinsic opacity of galaxies
below the Lyman limit. Current surveys suggest that the escape fraction
is low in all but 15-25% of galaxies, even among young starbursts. We
present new HST ultraviolet imaging of moderate redshift starbursts
to constrain how close to zero the escape fraction is in galaxies
that are similar to those which may have reinoized the Universe. We
targeted 15 bright, blue galaxies at z 1.3 in the GOODS fields for 5
orbits each using the Solar Blind Channel of the ACS, achieving the
deepest limits to date on the escape fraction in individual sources.
---------------------------------------------------------
Title: Hubble Space Telescope time-series photometry of the planetary
transit of HD 189733: no moon, no rings, starspots
Authors: Pont, F.; Gilliland, R. L.; Moutou, C.; Charbonneau, D.;
Bouchy, F.; Brown, T. M.; Mayor, M.; Queloz, D.; Santos, N.; Udry, S.
2007A&A...476.1347P Altcode: 2007arXiv0707.1940P
We monitored three transits of the giant gas planet around the nearby K
dwarf HD 189733 with the ACS camera on the Hubble Space Telescope. The
resulting very-high accuracy lightcurve (signal-to-noise ratio near
15 000 on individual measurements, 35 000 on 10-min averages) allows a
direct geometric measurement of the orbital inclination, radius ratio
and scale of the system: i = 85.68 ± 0.04, R_pl/R<SUB>*</SUB> = 0.1572
± 0.0004, a/R<SUB>*</SUB> = 8.92 ± 0.09. We derive improved values
for the stellar and planetary radius, R<SUB>*</SUB> = 0.755 ± 0.011
R_⊙, R_pl = 1.154 ± 0.017 R_J, and the transit ephemerides, T_tr =
2453931.12048 ± 0.00002 + n\cdot2.218581 ± 0.000002. The HST data also
reveal clear evidence of the planet occulting spots on the surface of
the star. At least one large spot complex (>80 000 km) is required to
explain the observed flux residuals and their colour evolution. This
feature is compatible in amplitude and phase with the variability
observed simultaneously from the ground. No evidence for satellites
or rings around HD 189733b is seen in the HST lightcurve. This allows
us to exlude with a high probability the presence of Earth-sized
moons and Saturn-type debris rings around this planet. The timing of
the three transits sampled is stable to the level of a few seconds,
excluding a massive second planet in outer 2:1 resonance. <P />The
full version of Table ? 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/cgi-bin/qcat?J/A+A/476/1347
---------------------------------------------------------
Title: Selection and Prioritization of Targets for the Kepler Mission
Authors: Batalha, Natalie M.; Borucki, W. J.; Brown, T. M.; Bryson,
S. T.; Caldwell, D. A.; Everett, M. E.; Jenkins, J. M.; Koch, D. G.;
Latham, D. W.
2007AAS...21113516B Altcode: 2007BAAS...39R.974B
The Kepler mission is designed to detect and characterize Earth-size
planets in the habitable zone of their parent stars. This will be
possible for the brightest late-type Main Sequence stars (e.g. 12th
magnitude for sun-like stars, 15-16th magnitude for M-type stars). There
are nearly a half million stars brighter than 16th magnitude in the
Kepler field of view, most of which are too large or too faint for
detection of an Earth-like planet. The Kepler Stellar Classification
Program (SCP) is a pre-launch effort to characterize every star in the
field (with reasonable completeness down to m=20) using ground-based
multi-color photometry to determine the surface gravity and effective
temperature. The SCP products will allow us to pre-select and prioritize
targets based on the predicted SNR of an Earth-like transit. The
methodology is designed to maximize the science yield of the mission
by quantifying, for every potential target, the minimum detectable
planet radius as a function of semi-major axis. The metric considers
issues of crowding by quantifying the amount of contamination from
background stars that works to dilute the transit signal. We describe
the selection/prioritization methodology and present the magnitude
and spectral type distribution for a target list generated from a
preliminary release of the Kepler Input Catalog. <P />Support for this
work came from NASA's Discovery Program.
---------------------------------------------------------
Title: Towards A Scheduler For The LCOGT Multi-telescope Network
Authors: Brown, Timothy M.; Baliber, N.
2007AAS...211.4726B Altcode: 2007BAAS...39..807B
Las Cumbres Observatory Global Telescope (LCOGT) is building a
world-wide network of telescopes optimized for time-domain astronomy. A
key part of this effort is the scheduler, which converts allocations
of telescope time, judgments about scientific importance, and a
multitude of practical considerations into commands for the pointing
and instrument configuration of each network telescope. Among telescope
schedulers, this one will be unusual in two respects: it must deal
with multiple telescopes, and the mix of desired observations will
be dominated by lengthy observations of time-critical (but often
predictable) events. Here we describe the program BLOCKHEAD, intended
as a step toward the final scheduler. BLOCKHEAD uses a randomized
multi-pass procedure to distribute 30-minute blocks of observing time
among many observing projects and across multiple telescopes, for a
1-month planning interval. For automated scheduling of a full network,
BLOCKHEAD is intended to be preceded by a monthly time-allocation
process, and followed by a module that adapts the nominal schedule
to cope with weather, targets of opportunity, and other real-time
schedule-driving events. It does not attempt global optimization of the
schedule, but it is fast enough that many independent schedules may
easily be intercompared for optimization against any desired figure
of merit. BLOCKHEAD is now being tested using simulated observing
requests on telescope networks, and also as an element in scheduling
our existing telescopes on Haleakala and at Siding Spring.
---------------------------------------------------------
Title: Asteroseismology and interferometry
Authors: Cunha, M. S.; Aerts, C.; Christensen-Dalsgaard, J.;
Baglin, A.; Bigot, L.; Brown, T. M.; Catala, C.; Creevey, O. L.;
Domiciano de Souza, A.; Eggenberger, P.; Garcia, P. J. V.; Grundahl,
F.; Kervella, P.; Kurtz, D. W.; Mathias, P.; Miglio, A.; Monteiro,
M. J. P. F. G.; Perrin, G.; Pijpers, F. P.; Pourbaix, D.; Quirrenbach,
A.; Rousselet-Perraut, K.; Teixeira, T. C.; Thévenin, F.; Thompson,
M. J.
2007A&ARv..14..217C Altcode: 2007arXiv0709.4613C
Asteroseismology provides us with a unique opportunity to improve
our understanding of stellar structure and evolution. Recent
developments, including the first systematic studies of solar-like
pulsators, have boosted the impact of this field of research within
astrophysics and have led to a significant increase in the size of
the research community. In the present paper we start by reviewing
the basic observational and theoretical properties of classical and
solar-like pulsators and present results from some of the most recent
and outstanding studies of these stars. We centre our review on those
classes of pulsators for which interferometric studies are expected
to provide a significant input. We discuss current limitations to
asteroseismic studies, including difficulties in mode identification
and in the accurate determination of global parameters of pulsating
stars, and, after a brief review of those aspects of interferometry
that are most relevant in this context, anticipate how interferometric
observations may contribute to overcome these limitations. Moreover,
we present results of recent pilot studies of pulsating stars involving
both asteroseismic and interferometric constraints and look into the
future, summarizing ongoing efforts concerning the development of
future instruments and satellite missions which are expected to have
an impact in this field of research.
---------------------------------------------------------
Title: VizieR Online Data Catalog: HST/ACS flux time series for HD
189733 (Pont+, 2007)
Authors: Pont, F.; Gilliland, R. L.; Moutou, C.; Charbonneau, D.;
Bouchy, F.; Brown, T. M.; Mayor, M.; Queloz, D.; Santos, N.; Udry, S.
2007yCat..34761347P Altcode:
We monitored three transits of the giant gas planet around the nearby K
dwarf HD 189733 with the ACS camera on the Hubble Space Telescope. The
resulting very-high accuracy light-curve (signal-to-noise ratio near
15000 on individual measurements, 35000 on 10-min averages) allows
a direct geometric measurement of the orbital inclination, radius
ratio and scale of the system: i=85.68+/-0.04, Rpl/R*=0.1572+/-0.0004,
a/R*=8.92+/-0.09. <P />(1 data file).
---------------------------------------------------------
Title: TrES-4: A Transiting Hot Jupiter of Very Low Density
Authors: Mandushev, Georgi; O'Donovan, Francis T.; Charbonneau, David;
Torres, Guillermo; Latham, David W.; Bakos, Gáspár Á.; Dunham,
Edward W.; Sozzetti, Alessandro; Fernández, José M.; Esquerdo,
Gilbert A.; Everett, Mark E.; Brown, Timothy M.; Rabus, Markus;
Belmonte, Juan A.; Hillenbrand, Lynne A.
2007ApJ...667L.195M Altcode: 2007arXiv0708.0834M
We report the discovery of TrES-4, a hot Jupiter that transits
the star GSC 02620-00648 every 3.55 days. From high-resolution
spectroscopy of the star, we estimate a stellar effective temperature of
T<SUB>eff</SUB>=6100+/-150 K, and from high-precision z and B photometry
of the transit we constrain the ratio of the semimajor axis a and the
stellar radius R<SUB>*</SUB> to be a/R<SUB>*</SUB>=6.03+/-0.13. We
compare these values to model stellar isochrones to constrain the
stellar mass to be M<SUB>*</SUB>=1.22+/-0.17 M<SUB>solar</SUB>. Based
on this estimate and the photometric time series, we constrain the
stellar radius to be R<SUB>*</SUB>=1.738+/-0.092 R<SUB>solar</SUB> and
the planet radius to be R<SUB>p</SUB>=1.674+/-0.094 R<SUB>Jup</SUB>. We
model our radial velocity data assuming a circular orbit and find a
planetary mass of 0.84+/-0.10 M<SUB>Jup</SUB>. Our radial velocity
observations rule out line-bisector variations that would indicate
a specious detection resulting from a blend of an eclipsing binary
system. TrES-4 has the largest radius and lowest density of any of the
known transiting planets. It presents a challenge to current models of
the physical structure of hot Jupiters and indicates that the diversity
of physical properties among the members of this class of exoplanets
has yet to be fully explored.
---------------------------------------------------------
Title: Stellar Populations across the NGC 4244 Truncated Galactic Disk
Authors: de Jong, Roelof S.; Seth, A. C.; Radburn-Smith, D. J.; Bell,
E. F.; Brown, T. M.; Bullock, J. S.; Courteau, S.; Dalcanton, J. J.;
Ferguson, H. C.; Goudfrooij, P.; Holfeltz, S.; Holwerda, B. W.;
Purcell, C.; Sick, J.; Zucker, D. B.
2007ApJ...667L..49D Altcode: 2007arXiv0708.0826D
We use the Hubble Space Telescope ACS to study the resolved stellar
populations of the nearby, nearly edge-on galaxy NGC 4244 across its
outer disk surface density break. The stellar photometry allows us to
study the distribution of different stellar populations and reach very
low equivalent surface brightnesses. We find that the break occurs
at the same radius for young, intermediate-age, and old stars. The
stellar density beyond the break drops sharply by a factor of at least
600 in 5 kpc. The break occurs at the same radius independent of height
above the disk, but is sharpest in the midplane and nearly disappears
at large heights. These results make it unlikely that truncations are
caused by a star formation threshold alone: the threshold would have
to keep the same radial position from less than 100 Myr to 10 Gyr ago,
in spite of potential disturbances such as infall and redistribution
of gas by internal processes. A dynamical interpretation of truncation
formation is more likely, such as due to angular momentum redistribution
by bars or density waves, or heating and stripping of stars caused
by the bombardment of dark matter subhalos. The latter explanation
is also in quantitative agreement with the small diffuse component we
see around the galaxy.
---------------------------------------------------------
Title: GHOSTS: The Resolved Stellar Outskirts of Massive Disk Galaxies
Authors: de Jong, Roelof S.; Seth, A. C.; Bell, E. F.; Brown,
T. M.; Bullock, J. S.; Courteau, S.; Dalcanton, J. J.; Ferguson,
H. C.; Goudfrooij, P.; Holfeltz, S.; Purcell, C.; Radburn-Smith, D.;
Zucker, D.
2007IAUS..241..503D Altcode: 2007astro.ph..2168D
We show initial results from our ongoing HST GHOSTS survey of the
resolved stellar envelopes of 14 nearby, massive disk galaxies. In
hierarchical galaxy formation the stellar halos and thick disks of
galaxies are formed by accretion of minor satellites and therefore
contain valuable information about the (early) assembly process
of galaxies. We detect for the first time the very small halo of
NGC4244, a low mass edge-on galaxy. We find that massive galaxies
have very extended halos, with equivalent surface brightnesses of
28-29 V-mag/arcsec^2 at 20-30 kpc from the disk. The old RGB stars of
the thick disk in the NGC891 and NGC4244 edge-on galaxies truncate at
the same radius as the young thin disk stars, providing insights into
the formation of both disk truncations and thick disks. We furthermore
present the stellar populations of a very low surface brightness stream
around M83, the first such a stream resolved into stars beyond those
of the Milky Way and M31.
---------------------------------------------------------
Title: The Kepler Mission and Eclipsing Binaries
Authors: Koch, David; Borucki, William; Basri, Gibor; Brown, Timothy;
Caldwell, Douglas; Christensen-Dalsgaard, Jorgen; Cochran, William;
Devore, Edna; Dunham, Edward; Gautier, Thomas N.; Geary, John;
Gilliland, Ronald; Gould, Alan; Jenkins, Jon; Kondo, Yoji; Latham,
David; Lissauer, Jack; Monet, David
2007IAUS..240..236K Altcode: 2006IAUS..240E..21K
The Kepler Mission is a photometric mission with a precision of 14 ppm
( at R= 12) that is designed to continuously observe a single field of
view (FOV) of greater 100 sq deg in the Cygnus-Lyra region for four or
more years. The primary goal of the mission is to monitor >100,000
stars for transits of Earth-size and smaller planets in the habitable
zone of solar-like stars. In the process, many eclipsing binaries
(EB) will also be detected and light curves produced. To enhance and
optimize the mission results, the stellar characteristics for all
the stars in the FOV with R<16 will have been determined prior
to launch. As part of the verification process, stars with transit
candidates will have radial velocity follow-up observations performed to
determine the component masses and thereby separate eclipses caused by
stellar companions from transits caused by planets. The result will be
a rich database on EBs. The community will have access to the archive
for further analysis, such as, for EB modeling of the high-precision
light curves. A guest observer program is also planned to allow for
photometric observations of objects not on the target list but within
the FOV, since only the pixels of interest from those stars monitored
will be transmitted to the ground.
---------------------------------------------------------
Title: The Transatlantic Exoplanet Survey (TrES): A Review
Authors: Alonso, R.; Brown, T. M.; Charbonneau, D.; Dunham, E. W.;
Belmonte, J. A.; Deeg, H. J.; Fernández, J. M.; Latham, D. W.;
Mandushev, G.; O'Donovan, F. T.; Rabus, M.; Torres, G.
2007ASPC..366...13A Altcode:
The TrES project is designed to search for exoplanetary transits
using three wide-field optical telescopes of 10-cm in diameter,
in three different observatories. We describe the instruments and
strategies used by the team, which has been working as a network since
2003. We summarize the major findings and difficulties faced during
these years, which include the discovery of two transiting planets,
a pair of eclipsing M stars, and many configurations of stars that
mimic the signal of transiting planets.
---------------------------------------------------------
Title: Precise Photometry of Extrasolar Planet Transits with SOFIA
Authors: Dunham, E. W.; Elliot, J. L.; Brown, T. M.; Charbonneau,
D.; McLean, I. S.
2007ASPC..366..256D Altcode:
Precise photometric observations of transiting extrasolar planets
can provide a wealth of data on the nature of these objects. Results
such as planetary radius, orbital inclination, stellar limb darkening,
evidence for planetary satellites or rings, and atmospheric composition
can be found from the transit observation alone. When combined with high
quality radial velocity data the mass and density of the planet can be
determined. Infrared observations of the secondary minimum provide a
means to determine the temperature of the planet and allow limits on
the orbital eccentricity to be defined. Perturbations by other planets
in the system can be found by variations in transit timing over a period
of years. <P />We anticipate that very high quality transit data can be
obtained with SOFIA using the HIPO and FLITECAM science instruments. At
present this work is limited to the nine brightest known transiting
planets, but the field is so active that many additional targets will
be found. The ongoing spectroscopic planet search programs and several
ongoing transit search programs designed specifically to find objects
bright enough for detailed follow-up work are expected to add numerous
objects to this list over SOFIA's lifetime. The Kepler mission will
be launched and complete its mission while SOFIA is flying, producing
numerous exciting opportunities for additional work.
---------------------------------------------------------
Title: Update and Recent Results of the STARE Instrument
Authors: Rabus, M.; Brown, T. M.; Deeg, H. J.; Belmonte Avilés,
J. A.; Almenara Villa, J. M.; Alonso, R.
2007ASPC..366...96R Altcode:
The STARE telescope of the High Altitude Observatory (HAO), Boulder
is maintained by the Instituto de Astrofísica de Canarias (IAC)
at the Observatorio del Teide (OT) on Tenerife. The STARE instrument
has been updated in spring 2006 and forms part of the TrES network,
which consists of two more telescopes located in the USA (PSST, Lowell
Observatory; Sleuth Mt. Palomar). In this paper an overview over
STARE's update and first results from recent observations are given.
---------------------------------------------------------
Title: TrES-3: A Nearby, Massive, Transiting Hot Jupiter in a 31
Hour Orbit
Authors: O'Donovan, Francis T.; Charbonneau, David; Bakos, Gáspár
Á.; Mandushev, Georgi; Dunham, Edward W.; Brown, Timothy M.; Latham,
David W.; Torres, Guillermo; Sozzetti, Alessandro; Kovács, Géza;
Everett, Mark E.; Baliber, Nairn; Hidas, Márton G.; Esquerdo, Gilbert
A.; Rabus, Markus; Deeg, Hans J.; Belmonte, Juan A.; Hillenbrand,
Lynne A.; Stefanik, Robert P.
2007ApJ...663L..37O Altcode: 2007arXiv0705.2004O
We describe the discovery of a massive transiting hot Jupiter
with a very short orbital period (1.30619 days), which we name
TrES-3. From spectroscopy of the host star GSC 03089-00929,
we measure T<SUB>eff</SUB>=5720+/-150 K, logg=4.6+/-0.3, and
vsini<2 km s<SUP>-1</SUP> and derive a stellar mass of 0.90+/-0.15
M<SUB>solar</SUB>. We estimate a planetary mass of 1.92+/-0.23
M<SUB>Jup</SUB>, based on the sinusoidal variation of our high-precision
radial velocity measurements. This variation has a period and phase
consistent with our transit photometry. Our spectra show no evidence of
line bisector variations that would indicate a blended eclipsing binary
star. From detailed modeling of our B and z photometry of the 2.5% deep
transits, we determine a stellar radius 0.802+/-0.046 R<SUB>solar</SUB>
and a planetary radius 1.295+/-0.081 R<SUB>Jup</SUB>. TrES-3 has one
of the shortest orbital periods of the known transiting exoplanets,
facilitating studies of orbital decay and mass loss due to evaporation,
and making it an excellent target for future studies of infrared
emission and reflected starlight. <P />Some of the data presented herein
were obtained at the W. M. Keck Observatory, which is operated as a
scientific partnership among Caltech, the University of California,
and NASA. The Observatory was made possible by the generous financial
support of the W. M. Keck Foundation.
---------------------------------------------------------
Title: Outcome of Six Candidate Transiting Planets from a TrES Field
in Andromeda
Authors: O'Donovan, Francis T.; Charbonneau, David; Alonso, Roi;
Brown, Timothy M.; Mandushev, Georgi; Dunham, Edward W.; Latham,
David W.; Stefanik, Robert P.; Torres, Guillermo; Everett, Mark E.
2007ApJ...662..658O Altcode: 2006astro.ph.10603O
Driven by the incomplete understanding of the formation of gas giant
extrasolar planets and of their mass-radius relationship, several
ground-based, wide-field photometric campaigns are searching the skies
for new transiting extrasolar gas giants. As part of the Trans-atlantic
Exoplanet Survey (TrES), in 2003/2004 we monitored approximately 30,000
stars (9.5<=V<=15.5) in a 5.7<SUP>deg</SUP>×5.7<SUP>deg</SUP>
field in Andromeda with three telescopes over 5 months. We identified
six candidate transiting planets from the stellar light curves. From
subsequent follow-up observations we rejected each of these as an
astrophysical false positive, i.e., a stellar system containing an
eclipsing binary, whose light curve mimics that of a Jupiter-sized
planet transiting a Sunlike star. We discuss here the procedures
followed by the TrES team to reject false positives from our list of
candidate transiting hot Jupiters. We present these candidates as early
examples of the various types of astrophysical false positives found
in the TrES campaign, and discuss what we learned from the analysis.
---------------------------------------------------------
Title: Asteroseismology with the Kepler mission
Authors: Christensen-Dalsgaard, J.; Arentoft, T.; Brown, T. M.;
Gilliland, R. L.; Kjeldsen, H.; Borucki, W. J.; Koch, D.
2007CoAst.150..350C Altcode: 2007astro.ph..1323C
NASA's Kepler mission will fly a photometer based on a wide-field
Schmidt camera with a 0.95 m aperture, staring at a single field
continuously for at least 4 years. Although the mission's principal
aim is to locate transiting extrasolar planets, it will provide an
unprecedented opportunity to make asteroseismic observations on a
wide variety of stars. Plans are now being developed to exploit this
opportunity to the fullest.
---------------------------------------------------------
Title: Surveys, Temporal Variability, and the Las Cumbres Observatory
Global Telescope
Authors: Brown, Tim; Rosing, W. E.; Baliber, N.; Hidas, M.; Street, R.
2007AAS...210.6601B Altcode: 2007BAAS...39..173B
Upcoming wide-field surveys such as Pan-STARRS, LSST, and Skymapper
will detect large numbers of objects that vary photometrically,
or that move. These objects will include small bodies in the solar
systema, eclipsing binary stars, transiting extrasolar planets,
pulsating stars, dwarf novae, novae, supernovae, active galactic
nuclei, and quite possibly other transient phenomena for which we
have no names as yet. Although they will be a fertile source of such
transient detections, wide-field surveys themselves ordinarily will
have neither the observing cadence nor the (e.g., spectroscopic)
observing capabilities to perform adequate follow-up observations of
these variable objects. The Las Cumbres Observatory Global Telescope
(LCOGT) will be a global network of moderate-aperture (2m and smaller)
telescopes, instrumented and interconnected so as to <P />facilitate
such in-depth variability studies. <P />The LCOGT now operates the
two 2m Faulkes Telescopes: FT North located on the island of Maui,
and FT South at the Siding Spring site in Australia. These telescopes
will anchor a network of about 7 clusters of 1m-class telescopes,
each cluster containing 4 telescopes. First-light instruments will
provide visible-light and NIR imaging; spectroscopic capabilities
will come later, and will likely include both low- and high-resolution
visible-light spectrographs. Scheduling and coordination of observations
will be provided from a central site, in pursuit of a single set of
scientific goals.
---------------------------------------------------------
Title: New Constraints on the Escape Fraction at z 1
Authors: Siana, Brian D.; Teplitz, H. I.; Colbert, J.; Ferguson,
H. C.; Brown, T. M.; Conselice, C. J.; de Mello, D. F.; Dickinson,
M.; Gardner, J. P.; Giavalisco, M.; Menantau, F.
2007AAS...20925205S Altcode: 2007BAAS...39Q.273S
We examine deep far-ultraviolet imaging (m_AB(1600 Å) < 29) of the
Hubble Deep Field-North (HDF-N) and the Hubble Ultra Deep Field (UDF)
to search for escaping Lyman continuum radiation from star-forming
galaxies at z 1.3. Of the 20 galaxies sufficiently bright for possible
detection in the far-UV, none are detected. Once the starburst age and
intergalactic HI absorption are accounted for, we derive 3σ limits
to the relative escape fractions between 0.16 < f_esc,rel < 1.0
and a stacked limit of f_esc,rel < 0.11. Our stacked limit is about
equal to the average detected relative escape fraction at z 3 so deeper
observations are required to determine if f_esc is evolving. We see no
indication of any galaxies with a relative escape fraction near unity,
as seen in individual z 3 galaxies in deep spectroscopic studies. The
difference may be attributed to luminosity differences in the samples
or due to the different regions of the Lyman continuum that are observed
(700 Å for our study and 900 Å with spectroscopy at z 3).
---------------------------------------------------------
Title: The Complementary Roles of Interferometry and Asteroseismology
in Determining the Mass of Solar-Type Stars
Authors: Creevey, O. L.; Monteiro, M. J. P. F. G.; Metcalfe, T. S.;
Brown, T. M.; Jiménez-Reyes, S. J.; Belmonte, J. A.
2007ApJ...659..616C Altcode: 2007astro.ph..2270C
How important is an independent diameter measurement for the
determination of stellar parameters of solar-type stars? When coupled
with seismic observables, how well can we determine the stellar mass? If
we can determine the radius of the star to between 1% and 4%, how does
this affect the theoretical uncertainties? Interferometry can provide
an independent radius determination, and it has been suggested that
we should expect at least a 4% precision on such a measurement for
nearby solar-type stars. This study aims to provide both qualitative
and quantitative answers to these questions for a star, such as our Sun,
where seismic information will be available. We show that the importance
of an independent radius measurement depends on the combination of
observables available and the size of the measurement errors. It is
important for determining all stellar parameters and in particular the
mass, where a good radius measurement can even allow us to determine
the mass with a precision better than 2%. Our results also show that
measuring the small frequency separation δν significantly improves
the determination of the evolutionary stage τ and the mixing-length
parameter α.
---------------------------------------------------------
Title: When Extrasolar Planets Transit Their Parent Stars
Authors: Charbonneau, D.; Brown, T. M.; Burrows, A.; Laughlin, G.
2007prpl.conf..701C Altcode: 2006astro.ph..3376C
When extrasolar planets are observed to transit their parent stars,
we are granted unprecedented access to their physical properties. It
is only for transiting planets that we are permitted direct estimates
of the planetary masses and radii, which provide the fundamental
constraints on models of their physical structure. In particular,
precise determination of the radius may indicate the presence (or
absence) of a core of solid material, which in turn would speak to the
canonical formation model of gas accretion onto a core of ice and rock
embedded in a protoplanetary disk. Furthermore, the radii of planets in
close proximity to their stars are affected by tidal effects and the
intense stellar radiation. As a result, some of these "hot Jupiters"
are significantly larger than Jupiter in radius. Precision follow-up
studies of such objects (notably with the spacebased platforms of the
Hubble and Spitzer Space Telescopes) have enabled direct observation
of their transmission spectra and emitted radiation. These data
provide the first observational constraints on atmospheric models of
these extrasolar gas giants, and permit a direct comparison with the
gas giants of the solar system. Despite significant observational
challenges, numerous transit surveys and quick-look radial velocity
surveys are active, and promise to deliver an ever-increasing number
of these precious objects. The detection of transits of short-period
Neptune-sized objects, whose existence was recently uncovered by the
radialvelocity surveys, is eagerly anticipated. Ultraprecise photometry
enabled by upcoming space missions offers the prospect of the first
detection of an extrasolar Earth-like planet in the habitable zone of
its parent star, just in time for Protostars and Planets VI.
---------------------------------------------------------
Title: Using Stellar Limb-Darkening to Refine the Properties of
HD 209458b
Authors: Knutson, Heather A.; Charbonneau, David; Noyes, Robert W.;
Brown, Timothy M.; Gilliland, Ronald L.
2007ApJ...655..564K Altcode: 2006astro.ph..3542K
We use multiband photometry to refine estimates for the planetary
radius and orbital inclination of the transiting planet system HD
209458. We gathered 1066 spectra over four distinct transits with the
STIS spectrometer on the Hubble Space Telescope using two gratings
with a resolution R=1500 and a combined wavelength range of 290-1030
nm. We divide the spectra into 10 spectrophotometric bandpasses,
five for each grating, of equal wavelength span within each grating,
and fit a transit curve over all bandpasses simultaneously. In our fit
we use theoretical values for the stellar limb-darkening to further
constrain the planetary radius. We find that the radius of HD 209458b is
(1.320+/-0.025)R<SUB>Jup</SUB>, which is a factor of 2 more precise
than current estimates. We also obtain improved estimates for the
orbital period P and time of center of transit T<SUB>C</SUB>. Although
in principle the photon-limited precision of the STIS data should allow
us to measure the timing of individual transits to a precision of 2-7 s,
we find that uncertainties in the stellar limb-darkening coefficients
and residual noise in the data degrade these measurements to a typical
precision of +/-14 s. Within this level of error, we find no significant
variations in the timing of the eight events examined in this work.
---------------------------------------------------------
Title: Report of the Working Group on Detection Methods
Authors: Brown, T. M.; de Medeiros, J. -R.
2006psps.conf..227B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Keck/Deimos Spectroscopy of Distant M31 fields with Deep
HST Imaging
Authors: Rich, Robert M.; Brown, T. M.; Reitzel, D. B.; Ferguson,
H.; Koch, A.; Smith, E.; Guhathakurta, P.; Kalirai, J.; Renzini, A.;
Kimble, R.; Sweigart, A.; Gilbert, K.; Chiba, M.; Iye, M.; Komiyama,
Y.; Tanaka, M.
2006AAS...20917708R Altcode: 2006BAAS...38.1155R
We are undertaking a program to obtain the radial velocities and
abundances of red giants in the vicinity of M31 fields with deep HST
imaging. Our goal is to obtain complementary spectroscopy for fields
at 22 and 35 kpc on the minor axis, where the M31 halo may be in a
transition in metallicity and surface brightness from relatively metal
rich and intermediate age, to metal poor and old. We will describe
existing deep M31 fields with Keck spectroscopy and HST imaging and
compare our findings with observations in other M31 deep fields.
---------------------------------------------------------
Title: Las Cumbres Observatory Global Telescope Network: Keeping
Education in the Dark
Authors: Ross, Rachel J.; Geibink, W.; Rosing, W. E.; Brown, T. M.
2006AAS...20921803R Altcode: 2006BAAS...38.1199R
The Las Cumbres Observatory Global Telescope Network is a privately
funded, non-profit organization that is constructing two overlapping
networks of robotic telescopes for scientific and educational uses. The
educational network will consist of at least thirty 0.4 1.0 meter
telescopes that will be longitudinally spaced around the world so
that there will always be at least one (more likely several) in the
dark at any given time. All will be equipped with high quality CCD
imagers, with the 1.0 meters having spectrographs and possible infrared
capabilities. All networked telescopes will have identical, completely
online interfaces that allow you to control the telescope and use
different imaging instruments in either real-time or queued modes. Any
registered school or group will have the capability to remotely observe
using a telescope that is currently in the dark from the comfort of
their classroom or science center, half a world away. Accompanying the
robotic observations will be a library of resources and activities that
will be usable in the formal classroom setting, informal groups and
clubs, and for public outreach in the community for all age-groups
and levels of science. Using the LCOGT network as a tool to enjoy
real astronomical research will not only create a new awareness for
science and technology, but also create connections between science
and humanities. We aim to always keep astronomy education in the dark.
---------------------------------------------------------
Title: LCOGT.net: A Global Telescope Network to Keep Astronomers in
the Dark
Authors: Taylor, Stuart F.; Brown, T. M.; Rosing, W.; Ross, R.;
Farrell, J.
2006AAS...209.2213T Altcode: 2006BAAS...38..930T
The Las Cumbres Observatory Global Telescope is a privately supported
planned network of medium-sized (2m) telescopes, longitudinally located
to "keep you in the dark all of the time”. The observatory is in
the process of completing major upgrades to its two 2m telescopes,
FTN and FTS. These are the two telescopes that have been completed,
among the nearly identical telescopes that will eventually form
a global network longitudinally distributed to provide continuous
night-time coverage. The upgrades of FTN and FTS are intended to
improve image quality and reduce noise from the CCD cameras. FTN and
FTS are being fitted with new CCD cameras, work on the enclosures will
provide improved thermal control, and a warping harness has been used
to reduce the astigmatism of the FTN secondary. We are in the process
of evaluating the impact of these improvements on the performance of
our telescopes.
---------------------------------------------------------
Title: TrES-2: The First Transiting Planet in the Kepler Field
Authors: O'Donovan, Francis T.; Charbonneau, David; Mandushev,
Georgi; Dunham, Edward W.; Latham, David W.; Torres, Guillermo;
Sozzetti, Alessandro; Brown, Timothy M.; Trauger, John T.; Belmonte,
Juan A.; Rabus, Markus; Almenara, José M.; Alonso, Roi; Deeg, Hans
J.; Esquerdo, Gilbert A.; Falco, Emilio E.; Hillenbrand, Lynne A.;
Roussanova, Anna; Stefanik, Robert P.; Winn, Joshua N.
2006ApJ...651L..61O Altcode: 2006astro.ph..9335O
We announce the discovery of the second transiting hot Jupiter
discovered by the Trans-atlantic Exoplanet Survey. The
planet, which we dub TrES-2, orbits the nearby star GSC
03549-02811 every 2.47063 days. From high-resolution spectra,
we determine that the star has T<SUB>eff</SUB>=5960+/-100 K and
logg=4.4+/-0.2, implying a spectral type of G0 V and a mass of
1.08<SUP>+0.11</SUP><SUB>-0.05</SUB> M<SUB>solar</SUB>. High-precision
radial velocity measurements confirm a sinusoidal variation with
the period and phase predicted by the photometry, and rule out the
presence of line bisector variations that would indicate that the
spectroscopic orbit is spurious. We estimate a planetary mass
of 1.28<SUP>+0.09</SUP><SUB>-0.04</SUB>M<SUB>Jup</SUB>. We
model B, r, R, and I photometric time series of
the 1.4% deep transits and find a planetary radius of
1.24<SUP>+0.09</SUP><SUB>-0.06</SUB>R<SUB>Jup</SUB>. This planet lies
within the field of view of the NASA Kepler mission, ensuring that
hundreds of upcoming transits will be monitored with exquisite precision
and permitting a host of unprecedented investigations. <P />Some of
the data presented herein were obtained at the W. M. Keck Observatory,
which is operated as a scientific partnership among Caltech, the
University of California, and NASA. The Observatory was made possible
by the generous financial support of the W. M. Keck Foundation.
---------------------------------------------------------
Title: Transiting extrasolar planetary candidates in the Galactic
bulge
Authors: Sahu, Kailash C.; Casertano, Stefano; Bond, Howard E.;
Valenti, Jeff; Ed Smith, T.; Minniti, Dante; Zoccali, Manuela;
Livio, Mario; Panagia, Nino; Piskunov, Nikolai; Brown, Thomas M.;
Brown, Timothy; Renzini, Alvio; Rich, R. Michael; Clarkson, Will;
Lubow, Stephen
2006Natur.443..534S Altcode: 2006astro.ph.10098S
More than 200 extrasolar planets have been discovered around relatively
nearby stars, primarily through the Doppler line shifts owing to reflex
motions of their host stars, and more recently through transits of
some planets across the faces of the host stars. The detection of
planets with the shortest known periods, 1.2-2.5 days, has mainly
resulted from transit surveys which have generally targeted stars
more massive than 0.75M<SUB>solar</SUB>, where M<SUB>solar</SUB>
is the mass of the Sun. Here we report the results from a planetary
transit search performed in a rich stellar field towards the Galactic
bulge. We discovered 16 candidates with orbital periods between
0.4 and 4.2 days, five of which orbit stars of masses in the range
0.44-0.75M<SUB>solar</SUB>. In two cases, radial-velocity measurements
support the planetary nature of the companions. Five candidates
have orbital periods below 1.0 day, constituting a new class of
ultra-short-period planets, which occur only around stars of less than
0.88M<SUB>solar</SUB>. This indicates that those orbiting very close
to more-luminous stars might be evaporatively destroyed or that jovian
planets around stars of lower mass might migrate to smaller radii.
---------------------------------------------------------
Title: The complementary roles of interferometry and asteroseismology
Authors: Creevey, O. L.; Monteiro, M. J. P. F. G.; Metcalfe, T. S.;
Brown, T. M.
2006ESASP.624E.114C Altcode: 2006soho...18E.114C
How important is an independent diameter measurement for the
determination of stellar parameters of a solar-type star? If we can
determine the radius of the star to between 1% and 4% how does this
effect the theoretical uncertainties? Interferometry can provide this
independent measurement and it has been suggested that we should expect
at least a 4% precision on this measurement for solartype stars. This
study aims to provide both qualitive and quantitive answers to the
posed questions for a star such as our sun, one to which seismology
can be applied. We find that the radius is fundamental for the
determination of all stellar parameters and in particular the mass
and the initial hydrogen abundance. Its influence depends not only
on the size of the error in the radius but also on the errors in the
seismic observables. The combination of observables available is also
important for determining how influential the radius measurement can be.
---------------------------------------------------------
Title: Kepler Mission: Mission Progress
Authors: Borucki, William J.; Koch, D. G.; Lissauer, J. J.; Basri,
G. S.; Caldwell, D. A.; DeVore, E.; Jenkins, J. M.; Caldwell, J. J.;
Christensen-Dalsgaard, J.; Cochran, W. D.; Dunham, E. W.; Gautier,
T. N.; Geary, J. C.; Latham, D. A.; Sasselov, D.; Gilliland, R. L.;
Gould, A.; Howell, S. B.; Brown, T. M.; Kondo, Y.; Monet, D. G.;
Batalha, N.
2006DPS....38.4501B Altcode: 2006BAAS...38..567B
Kepler is a Discovery-class mission designed to determine the
frequency of Earth-size planets in and near the habitable zone (HZ)
of solar-like stars. The instrument consists of a 0.95 m aperture
photometer designed to obtain high precision photometric measurements
of >100,000 stars to search for patterns of transits. The focal
plane of the Schmidt-telescope contains 42 CCDs with a total of 96
megapixels that cover 100 square degrees of sky. <P />Both the Schmidt
corrector and 1.4 m aperture primary mirror have been fabricated and
polished. All 50 CCD detectors have been delivered, tested and found to
perform better than required, and are now being mounted in modules to be
installed in the focal plane. Measurements of the ability of the first
module to detect transit amplitudes expected from Earth-size planets
are scheduled to start this month. A preliminary catalog classifying
11 million stars in the FOV has been produced. The science descope
that replaced the articulated antenna with a body-fixed antenna still
provides performance above the baseline design. A concise description of
the current mission design and expected science results are presented.
---------------------------------------------------------
Title: Far-Ultraviolet Imaging of the Hubble Deep Field-North:
Star Formation in Normal Galaxies at z<1
Authors: Teplitz, H. I.; Siana, B.; Brown, T. M.; Chary, R.; Colbert,
J. W.; Conselice, C. J.; de Mello, D. F.; Dickinson, M.; Ferguson,
H. C.; Gardner, Jonathan P.; Menanteau, F.
2006AJ....132..853T Altcode: 2006astro.ph..6244T
We present far-ultraviolet (FUV) imaging of the Hubble Deep Field-North
(HDF-N) taken with the Solar Blind Channel of the Advanced Camera for
Surveys (ACS SBC) and the FUV MAMA detector of the Space Telescope
Imaging Spectrograph onboard the Hubble Space Telescope. The full
WFPC2 deep field has been observed at 1600 Å. We detect 134 galaxies
and one star down to a limit of FUV<SUB>AB</SUB>~29. All sources
have counterparts in the WFPC2 image. Redshifts (spectroscopic or
photometric) for the detected sources are in the range 0<z<1. We
find that the FUV galaxy number counts are higher than those reported
by GALEX, which we attribute at least in part to cosmic variance in the
small HDF-N field of view. Six of the 13 Chandra sources at z<0.85
in the HDF-N are detected in the FUV, and those are consistent with
starbursts rather than active galactic nuclei. Cross-correlating with
Spitzer sources in the field, we find that the FUV detections show
general agreement with the expected L<SUB>IR</SUB>/L<SUB>UV</SUB>
versus β relationship. We infer star formation rates (SFRs),
corrected for extinction using the UV slope, and find a median value
of 0.3 M<SUB>solar</SUB> yr<SUP>-1</SUP> for FUV-detected galaxies,
with 75% of detected sources having SFR<1 M<SUB>solar</SUB>
yr<SUP>-1</SUP>. Examining the morphological distribution of sources,
we find that about half of all FUV-detected sources are identified as
spiral galaxies. Half of morphologically selected spheroid galaxies
at z<0.85 are detected in the FUV, suggesting that such sources
have had significant ongoing star formation in the epoch since z~1. <P
/>Based on observations made with the NASA/ESA Hubble Space Telescope,
obtained from the Space Telescope Science Institute, which is operated
by the Association of Universities for Research in Astronomy (AURA),
Inc., under NASA contract NAS5-26555. These observations are associated
with proposals 7410 and 9478.
---------------------------------------------------------
Title: Does the Line of Sight to M5 Intersect a Highly-Ionized
High-Velocity Cloud?
Authors: Dixon, W. V.; Brown, T. M.; Howk, J. C.; Landsman, W. B.
2006ASPC..348..218D Altcode:
FUSE and HST/STIS observations of the post-asymptotic giant branch
(PAGB) star ZNG 1 in the globular cluster M5 (NGC 5904) reveal
high-velocity absorption in O VI, C IV, Si IV, and other species. With
LSR velocities between -150 and -100 km s<SUP>-1</SUP>, this complex of
absorbing components is blue-shifted by roughly -180 km s<SUP>-1</SUP>
relative to the stellar photosphere. The absorption represents either
circumstellar material (e.g., gas ejected during the star's AGB
phase and now shock-heated by the fast PAGB wind) or a high-ionization
high-velocity cloud (HVC) along the line of sight to M5. If the latter,
it would be the first evidence that highly-ionized HVCs may be found
near the Galactic disk.
---------------------------------------------------------
Title: Rejecting Astrophysical False Positives from the TrES
Transiting Planet Survey: The Example of GSC 03885-00829
Authors: O'Donovan, Francis T.; Charbonneau, David; Torres, Guillermo;
Mandushev, Georgi; Dunham, Edward W.; Latham, David W.; Alonso, Roi;
Brown, Timothy M.; Esquerdo, Gilbert A.; Everett, Mark E.; Creevey,
Orlagh L.
2006ApJ...644.1237O Altcode: 2006astro.ph..3005O
Ground-based wide-field surveys for nearby transiting gas giants are
yielding far fewer true planets than astrophysical false positives, some
of which are difficult to reject. Recent experience has highlighted
the need for careful analysis to eliminate astronomical systems in
which light from a faint eclipsing binary is blended with that from a
bright star. During the course of the Transatlantic Exoplanet Survey,
we identified a system presenting a transit-like periodic signal. We
obtained the proper motion and infrared color of this target (GSC
03885-00829) from publicly available catalogs, which suggested this
star is an F dwarf, supporting our transit hypothesis. This spectral
classification was confirmed using spectroscopic observations from which
we determined the stellar radial velocity. The star did not exhibit
any signs of a stellar mass companion. However, subsequent multicolor
photometry displayed a color-dependent transit depth, indicating that a
blend was the likely source of the eclipse. We successfully modeled our
initial photometric observations of GSC 03885-00829 as the light from
a K dwarf binary system superimposed on the light from a late F dwarf
star. High-dispersion spectroscopy confirmed the presence of light from
a cool stellar photosphere in the spectrum of this system. With this
candidate, we demonstrate both the difficulty in identifying certain
types of false positives in a list of candidate transiting planets and
our procedure for rejecting these imposters, which may be useful to
other groups performing wide-field transit surveys. <P />Some of the
data presented herein were obtained at the W. M. Keck Observatory,
which is operated as a scientific partnership among the California
Institute of Technology, the University of California, and the National
Aeronautics and Space Administration. The Observatory was made possible
by the generous financial support of the W.M. Keck Foundation.
---------------------------------------------------------
Title: Keeping Astronomy in the Dark Around the Clock: Introducing
LCOGT.net
Authors: Brown, Timothy M.; Taylor, S. F.; Rosing, W.; Mann, R.;
Trimble, V.; Farrell, J. A.
2006AAS...208.5605B Altcode: 2006BAAS...38..136B
The Las Cumbres Observatory Global Telescope is a privately supported
planned network of medium-sized (2m) telescopes, longitudinally
located to "keep you in the dark all of the time". Since it will be
able to perform continuous optical observations unbroken by the usual
day/night cycle, LCOGT will have a capability to do astronomy in the
24+ hour time-domain, a function that does not currently exist in
a manner dedicated to doing time-varying astronomy. By having such
telescopes distributed in northern- and southern-hemisphere sets of
nearly-identical facilities, LCOGT will also have a uniqe ability to
perform target-of-opportunity observing. Finally, LCOGT will have
sufficient telescope time to address a small number of key science
questions that require large observing resources. A major educational
outreach effort will accompany LCOGT science, building upon the
educational work started by the Dill Faulkes Foundation.
---------------------------------------------------------
Title: Interested in observing TrES-Her0-07621?
Authors: Creevey, O. L.; Brown, T. M.; Jiménez-Reyes, S.; Belmonte,
J. A.
2006ASPC..349..387C Altcode: 2006astro.ph..5176C
TrES-Her0-07621 is a recently discovered detached M Dwarf eclipsing
binary system. We present some follow-up observations of this system
including new minima times and a refined orbital period. We have also
obtained better estimates of the stellar radii and inclination.
---------------------------------------------------------
Title: Understanding the Relationship between Observations and
Stellar Parameters in an Eclipsing Binary System
Authors: Creevey, O. L.; Brown, T. M.; Jiménez-Reyes, S.; Belmonte,
J. A.
2006ASPC..349..211C Altcode: 2006astro.ph..5177C
We investigate the information contained in observations and to what
extent each of them contributes individually to constraining the
physical parameters of the system we are investigating. To do this, we
present a study involving the technique of Singular Value Decomposition
using as a simple example a detached eclipsing binary system. We intend
to apply an extension of this technique to asteroseismic measurements
of Delta Scuti stars that are members of eclipsing binary systems.
---------------------------------------------------------
Title: The Kepler Mission: A Transit-Photometry Mission to Discover
Terrestrial Planets
Authors: Borucki, William J.; Koch, David; Basri, Gibor; Brown,
Timothy; Caldwell, Douglas; Devore, Edna; Dunham, Edward; Gautier,
Thomas; Geary, John; Gilliland, Ronald; Gould, Alan; Howell, Steve;
Jenkins, Jon
2006ISSIR...6..207B Altcode:
The Kepler Mission is a NASA Discovery-class mission designed to
continuously monitor the brightness of 100,000 main sequence stars
to detect the transit of Earth-size and larger planets. It is a wide
field of view photometer with a Schmidt-type telescope and an array
of 42 CCDs covering the 100 sq. degree field-of-view (FOV). It has
a 0.95 m aperture and a 1.4 m primary and is designed to attain a
photometric precision of 20 parts per million (ppm) for 12th magnitude
solar-like stars for a 6.5-hour transit duration. It will continuously
observe 100,000 main sequence stars from 9th to 15th magnitude in the
Cygnus constellation for a period of four years with a cadence of
4 measurements per hour. Kepler is Discovery Mission #10 and is on
schedule for launch in 2007 into heliocentric orbit. A ground-based
program to classify all 450,000 stars brighter than 15th magnitude
in the FOV and to conduct a detailed examination of a subset of
the stars that show planetary companions is also planned. Hundreds
of Earth-size planets should be detected if they are common around
solarlike stars. Ground-based spectrometric observations of those stars
with planetary companions will be made to determine the dependences of
the frequency and size of terrestrial planets on stellar characteristics
such as type and metallicity. A null result would imply that terrestrial
planets are rare.
---------------------------------------------------------
Title: Report of the Working Group on Detection Methods
Authors: Brown, T. M.; de Medeiros, J. -R.
2006ISSIR...6..227B Altcode:
A group of about fifteen interested scientists spent two long sessions
discussing issues related to detecting extrasolar planets, particularly
ones of roughly terrestrial size. We arrived at several recommendations,
principally: (1) Radial velocity measurement precision should be pushed
to its limits, presumably those set by the astrophysics of stars. (2)
Data policies for upcoming planet-finding space missions must be
written so they do not encourage premature or mistaken discovery
announcements. (3) Ground-based transit searches would benefit
enormously if some adequately-funded institution would take the lead in
fielding a coherent and well-engineered world-wide network of telescopes
for this purpose. We should attempt to build international consensus
and support for this idea.
---------------------------------------------------------
Title: Star Classification for the Kepler Input Catalog: From Images
to Stellar Parameters
Authors: Brown, T. M.; Everett, M.; Latham, D. W.; Monet, D. G.
2005AAS...20711012B Altcode: 2005BAAS...37.1340B
The Stellar Classification Project is a ground-based effort to
screen stars within the Kepler field of view, to allow removal
of stars with large radii (and small potential transit signals)
from the target list. Important components of this process are: (1)
An automated photometry pipeline estimates observed magnitudes both
for target stars and for stars in several calibration fields. (2)
Data from calibration fields yield extinction-corrected AB magnitudes
(with g, r, i, z magnitudes transformed to the SDSS system). We merge
these with 2MASS J, H, K magnitudes. (3) The Basel grid of stellar
atmosphere models yields synthetic colors, which are transformed to
our photometric system by calibration against observations of stars in
M67. (4) We combine the r magnitude and stellar galactic latitude with a
simple model of interstellar extinction to derive a relation connecting
{Teff, luminosity} to distance and reddening. For models satisfying
this relation, we compute a chi-squared statistic describing the match
between each model and the observed colors. (5) We create a merit
function based on the chi-squared statistic, and on a Bayesian prior
probability distribution which gives probability as a function of Teff,
luminosity, log(Z), and height above the galactic plane. The stellar
parameters ascribed to a star are those of the model that maximizes
this merit function. (6) Parameter estimates are merged with positional
and other information from extant catalogs to yield the Kepler Input
Catalog, from which targets will be chosen. Testing and validation of
this procedure are underway, with encouraging initial results.
---------------------------------------------------------
Title: Kepler Mission Design
Authors: Koch, D. G.; Borucki, W. J.; Lissauer, J. J.; Basri, G. S.;
Gould, A. D.; Brown, T. M.; Caldwell, D. A.; DeVore, E. K.; Jenkins,
J. M.; Christensen-Dalsgaard, J.; Cochran, W. D.; Dunham, E. W.;
Gautier, T. N.; Geary, J. C.; Latham, D. W.; Gilliland, R. L.; Kondo,
Y.; Monet, D. G.
2005AAS...20711009K Altcode: 2005BAAS...37.1339K
The Kepler Mission is in the development phase with launch planned for
2008. The mission goal is to reliably detect a significant number of
Earth-size and smaller planets in the habitable zone of solar-like
stars. (see W. Borucki, et al, this meeting.) The mission design
allows for exploring the diversity of planetary sizes and orbital
periods for a wide variety of stellar spectral types, (see posters by
D. Latham, et al and T. Brown, et al, this meeting on stellar catalog
preparation). In this poster we describe the technical approach taken
for the mission design; describing the flight and ground system, the
detection methodology, the photometer design and capabilities, the way
the data are taken and processed, the Guest Observer opportunity and
the EPO aspects (see paper by E. DeVore, et al). Finally the detection
capability in terms of planet size is presented as a function of
planetary orbital period, mission duration, stellar type and combined
differential photometric precision.
---------------------------------------------------------
Title: The Violent History of Andromeda
Authors: Brown, T. M.; Smith, E.; Guhathakurta, P.; Rich, R. M.;
Ferguson, H. C.; Renzini, A.; Sweigart, A. V.; Kimble, R. A.
2005AAS...20713505B Altcode: 2005BAAS...37R1387B
Using the Advanced Camera for Surveys on the Hubble Space Telescope,
Andromeda has now been imaged well below the main sequence turnoff
in three structures: the spheroid, the outer disk, and the tidal
stream. These data allow a complete reconstruction of the star formation
histories in these structures. Although the disk is significantly
different from the other two fields, the stream and spheroid look
remarkably similar. Each of the fields has an extended star formation
history that was largely finished approximately 5 Gyr ago. At the same
time, other observing programs are providing important constraints on
the spatial morphologies and kinematics of these structures. Taken
together, the extant data suggest a violent history in Andromeda,
with significant disruption of the disk population into the outskirts
of the galaxy.
---------------------------------------------------------
Title: HST Far-Ultraviolet Imaging of the Hubble Ultra Deep Field
Authors: Siana, B. D.; Teplitz, H. I.; Chary, R.; Colbert, J. W.;
Brown, T. M.; de Mello, D. F.; Ferguson, H. C.; Conselice, C.; Gardner,
J. P.; Menanteau, F.; Dickinson, M. E.
2005AAS...207.2205S Altcode: 2005BAAS...37.1193S
We present far-UV (1500Å) imaging of the Ultra Deep Field (UDF)
taken with the Solar Blind Channel of the Advanced Camera for Surveys
(ACS/SBC) on HST. Combined with data from a previous campaign covering
the Hubble Deep Field North (HDF-N), we detect more than 200 galaxies
over 12 arcmin<SUP>2</SUP> with Far-UV mags to m(AB)=29. The derived
number counts extend nearly four magnitudes fainter than the GALEX
ultra-deep fields. We use Spitzer infrared photometry from the GOODS
Legacy survey to examine the F(IR)/F(UV) vs. β relation. We find
that this relation, although derived with a local sample, holds
for starburst galaxies at moderate redshift between 0.3-0.9. We
detect about half of all morphologically selected ellipticals with
z<0.8, indicating significant ongoing star-formation at z<1 in
this population. Furthermore, our detection rate of ellipticals is
correlated with their dispersion in optical color across the galaxy
with nearly all of the "blue core" ellipticals (δ (V-I)>0.05)
detected in the far-UV.
---------------------------------------------------------
Title: A ∼7.5 Earth-Mass Planet Orbiting the Nearby Star, GJ 876
Authors: Rivera, E. J.; Lissauer, J. J.; Butler, R. P.; Marcy, G. W.;
Vogt, S. S.; Fischer, D. A.; Brown, T. M.; Laughlin, G.; Henry, G. W.
2005AAS...20719103R Altcode: 2005BAAS...37Q1487R
High precision, high cadence radial velocity monitoring over the past
8 years at the W. M. Keck Observatory reveals evidence for a third
planet orbiting the nearby (4.69 pc) dM4 star GJ 876. The residuals
of three-body Newtonian fits, which include GJ 876 and Jupiter mass
companions b and c, show significant power at a periodicity of 1.9379
days. Self-consistently fitting the radial velocity data with a model
that includes an additional body with this period significantly
improves the quality of the fit. These four-body (three-planet)
Newtonian fits find that the minimum mass of companion “d” is m
sin {i}=5.89 ± 0.54 M<SUB>⊕ </SUB> and that its orbital period is
1.93776 (± 7×10<SUP>-5</SUP>) days. Assuming coplanar orbits, an
inclination of the GJ 876 planetary system to the plane of the sky of
∼50<SUP>o</SUP> gives the best fit. This inclination yields a mass
for companion d of m=7.53 ± 0.70 M<SUB>⊕ </SUB>, making it by far
the lowest mass companion yet found around a main sequence star other
than our Sun. Precise photometric observations at Fairborn Observatory
confirm low-level brightness variability in GJ 876 and provide the first
explicit determination of the star's 96.7-day rotation period. Even
higher precision short-term photometric measurements obtained at Las
Campanas imply that planet d does not transit GJ 876.
---------------------------------------------------------
Title: The Kepler Input Catalog
Authors: Latham, D. W.; Brown, T. M.; Monet, D. G.; Everett, M.;
Esquerdo, G. A.; Hergenrother, C. W.
2005AAS...20711013L Altcode: 2005BAAS...37.1340L
The Kepler mission will monitor 170,000 planet-search targets during
the first year, and 100,000 after that. The Kepler Input Catalog (KIC)
will be used to select optimum targets for the search for habitable
earth-like transiting planets. The KIC will include all known catalogued
stars in an area of about 177 square degrees centered at RA 19:22:40 and
Dec +44:30 (l=76.3 and b=+13.5). 2MASS photometry will be supplemented
with new ground-based photometry obtained in the SDSS g, r, i, and z
bands plus a custom filter centered on the Mg b lines, using KeplerCam
on the 48-inch telescope at the Whipple Observatory on Mount Hopkins,
Arizona. The photometry will be used to estimate stellar characteristics
for all stars brighter than K 14.5 mag. The KIC will include effective
temperature, surface gravity, metallicity, reddening, distance,
and radius estimates for these stars. The CCD images are pipeline
processed to produce instrumental magnitudes at PSI. The photometry
is then archived and transformed to the SDSS system at HAO, where
the astrophysical analysis of the stellar characteristics is carried
out. The results are then merged with catalogued data at the USNOFS to
produce the KIC. High dispersion spectroscopy with Hectochelle on the
MMT will be used to supplement the information for many of the most
interesting targets. The KIC will be released before launch for use by
the astronomical community and will be available for queries over the
internet. Support from the Kepler mission is gratefully acknowledged.
---------------------------------------------------------
Title: A ~7.5 M<SUB>⊕</SUB> Planet Orbiting the Nearby Star, GJ 876
Authors: Rivera, Eugenio J.; Lissauer, Jack J.; Butler, R. Paul; Marcy,
Geoffrey W.; Vogt, Steven S.; Fischer, Debra A.; Brown, Timothy M.;
Laughlin, Gregory; Henry, Gregory W.
2005ApJ...634..625R Altcode: 2005astro.ph.10508R
High-precision, high-cadence radial velocity monitoring over the
past 8 yr at the W. M. Keck Observatory reveals evidence for a third
planet orbiting the nearby (4.69 pc) dM4 star GJ 876. The residuals
of three-body Newtonian fits, which include GJ 876 and Jupiter-mass
companions b and c, show significant power at a periodicity of 1.9379
days. Self-consistently fitting the radial velocity data with a model
that includes an additional body with this period significantly
improves the quality of the fit. These four-body (three-planet)
Newtonian fits find that the minimum mass of companion “d” is
msini=5.89+/-0.54 M<SUB>⊕</SUB> and that its orbital period is
1.93776 (+/-7×10<SUP>-5</SUP>) days. Assuming coplanar orbits,
an inclination of the GJ 876 planetary system to the plane of the
sky of ~50° gives the best fit. This inclination yields a mass for
companion d of m=7.53+/-0.70 M<SUB>⊕</SUB>, making it by far the
lowest mass companion yet found around a main-sequence star other
than our Sun. Precise photometric observations at Fairborn Observatory
confirm low-level brightness variability in GJ 876 and provide the first
explicit determination of the star's 96.7 day rotation period. Even
higher precision short-term photometric measurements obtained at Las
Campanas imply that planet d does not transit GJ 876. <P />Based on
observations obtained at the W. M. Keck Observatory, which is operated
jointly by the University of California and the California Institute
of Technology.
---------------------------------------------------------
Title: Halos of Spiral Galaxies. II. Halo Metallicity-Luminosity
Relation
Authors: Mouhcine, M.; Ferguson, H. C.; Rich, R. M.; Brown, T. M.;
Smith, T. E.
2005ApJ...633..821M Altcode: 2005astro.ph.10254M
Using the Hubble Space Telescope, we have resolved individual red giant
branch stars in the halos of eight nearby spiral galaxies. The fields
lie at projected distances between 2 and 13 kpc along the galaxies'
minor axes. The data set allows a first look at the systematic trends
in halo stellar populations. We have found that bright galaxies tend to
have broad red giant branch star color distributions with redder mean
colors, suggesting that the heavy-element abundance spread increases
with the parent galaxy luminosity. The mean metallicity of the stellar
halo, estimated using the mean colors of red giant branch stars,
correlates with the parent galaxy luminosity. The metallicity of the
Milky Way halo falls nearly 1 dex below this luminosity-metallicity
relation, suggesting that the halo of the Galaxy is more the exception
than the rule for spiral galaxies; i.e., massive spirals with metal-poor
halos are unusual. The luminosity-halo stellar abundance relation
is consistent with the scaling relation expected for stellar systems
embedded in dominant halos, suggesting that the bulk of the halo stellar
population may have formed in situ. <P />Based on observations with
the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope
Science Institute, which is operated by the Association of Universities
for Research in Astronomy, Inc., under NASA contract NAS 5-26555.
---------------------------------------------------------
Title: Halos of Spiral Galaxies. III. Metallicity Distributions
Authors: Mouhcine, M.; Rich, R. M.; Ferguson, H. C.; Brown, T. M.;
Smith, T. E.
2005ApJ...633..828M Altcode: 2005astro.ph.10255M
We report results of a campaign to image the stellar populations
in the halos of highly inclined spiral galaxies, with the fields
roughly 10 kpc (projected) from the nuclei. We use the F814W (I) and
F606W (V) filters in the Wide Field Planetary Camera 2 on board the
Hubble Space Telescope. We unambiguously resolve the stellar halos
1 to 2 mag fainter than the tip of the red giant branch. Extended
halo populations are detected in all galaxies. The color-magnitude
diagrams appear to be completely dominated by giant branch stars,
with no evidence for the presence of young stellar populations in any
of the fields. The metallicity distribution function for the galaxy
sample is derived from interpolation within an extensive grid of red
giant branch loci. These loci are derived from theoretical sequences
that are calibrated using the Galactic globular clusters and from
empirical sequences for metal-rich stellar populations. We find that
the metallicity distribution functions are dominated by metal-rich
populations, with a tail extending toward the metal-poor end. To first
order, the overall shapes of the metallicity distribution functions
are similar to what is predicted by a simple, single-component model
of chemical evolution with the effective yields increasing with galaxy
luminosity. However, metallicity distributions significantly narrower
than the simple model are observed for a few of the most luminous
galaxies in the sample. The discrepancies are similar to those
previously observed for NGC 5128, the halo of M31, and the Galactic
bulge. Our observations can be used to help distinguish between
models for the formation of spiral galaxies. It appears that more
luminous spiral galaxies also have more metal-rich stellar halos. The
increasingly significant departures from the closed-box model for
the more luminous galaxies indicate that a parameter in addition
to a single yield is required to describe chemical evolution. This
parameter, which could be related to gas infall or outflow either
in situ or in progenitor dwarf galaxies that later merge to form the
stellar halo, tends to make the metallicity distributions narrower at
high metallicity. <P />Based on observations with the NASA/ESA Hubble
Space Telescope, obtained at the Space Telescope Science Institute,
which is operated by the Association of Universities for Research in
Astronomy, Inc., under NASA contract NAS 5-26555.
---------------------------------------------------------
Title: Halos of Spiral Galaxies. I. The Tip of the Red Giant Branch
as a Distance Indicator
Authors: Mouhcine, M.; Ferguson, H. C.; Rich, R. M.; Brown, T. M.;
Smith, T. E.
2005ApJ...633..810M Altcode: 2005astro.ph.10253M
We have imaged the halo populations of a sample of nearby spiral
galaxies using the Wide Field Planetary Camera 2 on board the Hubble
Space Telescope with the aim of studying the stellar population
properties and relating them to those of the host galaxies. In four
galaxies, the red giant branch is sufficiently well populated to measure
the magnitude of the tip of the red giant branch (TRGB), a well-known
distance indicator. Using both the Sobel edge-detection technique and
maximum likelihood analysis to measure the I-band magnitude of the TRGB,
we determine distances to four nearby galaxies: NGC 253, NGC 4244, NGC
4945, and NGC 4258. For the first three galaxies, the TRGB distance is
here determined more directly, and is likely to be more accurate, than
previous distance estimates. In the case of NGC 4258, our TRGB distance
is in good agreement with the geometrical maser distance, supporting the
Large Magellanic Cloud distance modulus (m-M)<SUB>0</SUB>=18.50 that
is generally adopted in recent estimates of the Hubble constant. <P
/>Based on observations with the NASA/ESA Hubble Space Telescope,
obtained at the Space Telescope Science Institute, which is operated
by the Association of Universities for Research in Astronomy, Inc.,
under NASA contract NAS 5-26555.
---------------------------------------------------------
Title: The Frequency of WFC3/IR Saturations
Authors: Brown, T. M.
2005wfc..rept...28B Altcode:
The WFC3/IR channel will combine sensitivity with a wide field of view,
such that all long exposures will contain some saturated stars, even
in sparse fields near the Galactic poles. Because such saturations in
IR detectors can result in persistence (particularly when a pixel is
over-saturated by factors of 10 to 100), I quantify here the frequency
of 1x, 10x, and 100x saturations, as a function of position on the
sky. I use the 2MASS and GSC2 catalogs for this analysis, although each
has its limitations for this purpose. Away from the Galactic plane,
the greater depth of the GSC2 is required to quantify the frequency of
moderate saturations (1-10x). If, however, one is only interested in
extreme saturations (>100x), the 2MASS catalog is more appropriate,
because it is sufficiently deep for such sources and it avoids the
large systematic errors (by factors of 200) that can arise due to an
incorrect assumption of spectral type and extinction when extrapolating
from the GSC2 optical bands into the IR. Both catalogs suffer from
serious incompleteness in the Galactic plane, especially toward the
Galactic center, but for such fields the 2MASS catalog would still be
preferred over the GSC2 when checking for saturating objects.
---------------------------------------------------------
Title: Thermal Emission from the Newest, Closest, and Brightest
Transiting Planet
Authors: Charbonneau, David; Allen, Lori; Barman, Travis; Bouchy,
Francois; Brown, Timothy; Mayor, Michel; Megeath, Tom; Moutou, Claire;
Queloz, Didier; Udry, Stephane
2005sptz.prop..261C Altcode:
We propose to observe the newly-discovered transiting-planet system
HD 189733 during two times of secondary eclipse, corresponding to
the passage of the planet behind the star. Of the 4 known transiting
planets accessible to Spitzer, this object offers by far the greatest
signal-to-noise ratio, owing to both the apparent brightness of the
system and the favorable ratio of the planetary flux to that of the
star. By measuring the planetary flux in 5 band passes (3.6, 4.5, 5.8,
8.0, & 24 um), we will directly constrain models of the planetary
emission, which in turn should allow identification of the molecules
that dominate its spectrum. Moreover, high-cadence observations with
IRAC during times of ingress and egress may permit us to spatially
resolve the planetary emission over the surface of the planet,
providing an unprecedented probe of the dynamics of these strongly
irradiated exoplanet atmospheres. These observations will firmly
establish Spitzer as the primary observatory in the nascent field of
comparative exoplanetology.
---------------------------------------------------------
Title: A New Detached M Dwarf Eclipsing Binary
Authors: Creevey, O. L.; Benedict, G. F.; Brown, T. M.; Alonso,
R.; Cargile, P.; Mandushev, G.; Charbonneau, D.; McArthur, B. E.;
Cochran, W.; O'Donovan, F. T.; Jiménez-Reyes, S. J.; Belmonte, J. A.;
Kolinski, D.
2005ApJ...625L.127C Altcode: 2005astro.ph..4490C
We describe a newly discovered detached M dwarf eclipsing binary
system. This system was first observed by the TrES network during a
long-term photometry campaign of 54 nights. Analysis of the folded
light curve indicates two very similar components orbiting each other
with a period of 1.12079 +/- 0.00001 days. Spectroscopic observations
with the Hobby-Eberly Telescope show the system to consist of two M3e
dwarfs in a near-circular orbit. Double-line radial velocity amplitudes,
combined with the orbital inclination derived from light-curve fitting,
yield M<SUB>total</SUB> = 0.983 +/- 0.007 M<SUB>solar</SUB>, with
component masses of M<SUB>1</SUB>=0.493+/-0.003 M<SUB>solar</SUB>
and M<SUB>2</SUB>=0.489+/-0.003 M<SUB>solar</SUB>. The light-curve fit
yields component radii of R<SUB>1</SUB>=0.453+/-0.060 R<SUB>solar</SUB>
and R<SUB>2</SUB>=0.452+/-0.050 R<SUB>solar</SUB>. Although a precise
parallax is lacking, broadband VJHK colors and spectral typing suggest
component absolute magnitudes of M<SUB>V</SUB>(1)=11.18+/-0.30 and
M<SUB>V</SUB>(2)=11.28+/-0.30.
---------------------------------------------------------
Title: Results of WFC3 Thermal Vacuum Testing - IR Channel Ghosts
& Baffle Scatter
Authors: Brown, T. M.
2005wfc..rept...22B Altcode:
During the Fall 2004 campaign of thermal-vacuum tests on WFC3, we looked
for optical ghosts in the IR channel by imaging a saturated point source
at various positions on the detector. For the F110W and F160W filters,
34 positions were checked on and off the detector, while the remaining
filters were checked at one position in each quadrant. Although the
primary image was 10x oversaturated in these checks, no signs of
optical ghosts were seen. In an additional test, we scanned a bright
point source across the baffle edges, immediately outside of the IR
field of view. These scans showed that strong scattering can occur from
the baffle edge, especially along the upper baffle edge. The strongest
glints from the baffle edge contained ~20% of the source flux and were
spread over a large area of the detector. The baffle installation is
under investigation.
---------------------------------------------------------
Title: Detection of Thermal Emission from an Extrasolar Planet
Authors: Charbonneau, David; Allen, Lori E.; Megeath, S. Thomas;
Torres, Guillermo; Alonso, Roi; Brown, Timothy M.; Gilliland, Ronald
L.; Latham, David W.; Mandushev, Georgi; O'Donovan, Francis T.;
Sozzetti, Alessandro
2005ApJ...626..523C Altcode: 2005astro.ph..3457C
We present Spitzer Space Telescope infrared photometric time series
of the transiting extrasolar planet system TrES-1. The data span a
predicted time of secondary eclipse, corresponding to the passage of the
planet behind the star. In both bands of our observations, we detect a
flux decrement with a timing, amplitude, and duration as predicted by
published parameters of the system. This signal represents the first
direct detection of (i.e., the observation of photons emitted by) a
planet orbiting another star. The observed eclipse depths (in units of
relative flux) are 0.00066+/-0.00013 at 4.5 μm and 0.00225+/-0.00036
at 8.0 μm. These estimates provide the first observational constraints
on models of the thermal emission of hot Jupiters. Assuming that the
planet emits as a blackbody, we estimate an effective temperature of
T<SUB>p</SUB>=1060+/-50 K. Under the additional assumptions that the
planet is in thermal equilibrium with the radiation from the star and
emits isotropically, we find a Bond albedo of A=0.31+/-0.14. This would
imply that the planet absorbs the majority of stellar radiation incident
upon it, a conclusion of significant impact to atmospheric models of
these objects. We also compare our data to a previously published
model of the planetary thermal emission, which predicts prominent
spectral features in our observational bands due to water and carbon
monoxide. This model adequately reproduces the observed planet-to-star
flux ratio at 8.0 μm however, it significantly overpredicts the ratio
at 4.5 μm. We also present an estimate of the timing of the secondary
eclipse, which we use to place a strong constraint on the expression
ecosω, where e is the orbital eccentricity and ω is the longitude of
periastron. The resulting upper limit on e is sufficiently small that
we conclude that tidal dissipation is unlikely to provide a significant
source of energy interior to the planet.
---------------------------------------------------------
Title: Results of WFC3 Thermal Vacuum Testing - Repeatability of
the Channel Select Mechanism
Authors: Brown, T. M.
2005wfc..rept...18B Altcode:
The channel select mechanism (CSM) on WFC3 is used to divert the optical
path of the incoming beam to the WFC3 IR channel. The contract end item
(CEI) specification for the CSM is that the position of point sources in
the IR channel should vary by less than 20 milliarcsec after movement
of the CSM. As part of the 2004 campaign of WFC3 thermal-vacuum tests,
the image stability of both WFC3 channels (UVIS & IR) was measured
over a wide range of environmental temperatures, simulating thermal
variations that could occur in flight due to orbital occultations and
slewing between hot and cold orientations. Some of these tests involved
rapid switching between the WFC3 channels to track the image stability
over large slews in temperature. These data imply that the CSM meets
its CEI specification for repeatability.
---------------------------------------------------------
Title: Far-Ultraviolet imaging of the Hubble Deep Field North
Authors: Teplitz, H. I.; Brown, T. M.; Conselice, C.; de Mello, D. F.;
Dickinson, M. E.; Ferguson, H. C.; Gardner, J. P.; Giavalisco, M.;
Menanteau, F.
2005ASSL..329P..79T Altcode: 2005sdlb.procP..79T
We present far-UV imaging of the Hubble Deep Field North (HDF-N)
taken with the Solar Blind Channel of the Advanced Camera for Surveys
(ACS/SBC) on board HST. Combined with archival STIS imaging, the
full WFPC2 deep field has now been observed at 1500 Å. We detect
111 objects, with redshifts 0.07 < z < 0.85. A high fraction
of galaxies previously identified as “blue-core ellipticals” show
significant UV flux, presumably due to star-formation activity. Number
counts to AB=29 have a surprisingly flat slope, consistent with a
larger-than-predicted population of starburst galaxies at intermediate
redshift. We examine the morphology of starburst galaxies as a function
of redshift, and compare FUV, optical and NIR properties.
---------------------------------------------------------
Title: A New Search for Carbon Monoxide Absorption in the Transmission
Spectrum of the Extrasolar Planet HD 209458b
Authors: Deming, Drake; Brown, Timothy M.; Charbonneau, David;
Harrington, Joseph; Richardson, L. Jeremy
2005ApJ...622.1149D Altcode: 2004astro.ph.12436D
We have revisited the search for carbon monoxide absorption features in
transmission during the transit of the extrasolar planet HD 209458b. In
2002 August-September we acquired a total of 1077 high-resolution
spectra (λ/δλ~25,000) in the K-band (2 μm) wavelength region using
NIRSPEC on the Keck II telescope during three transits. These data
are more numerous and of better quality than the data analyzed in an
initial search by Brown et al. Our analysis achieves a sensitivity
sufficient to test the degree of CO absorption in the first-overtone
bands during transit on the basis of plausible models of the planetary
atmosphere. We analyze our observations by comparison with theoretical
tangent geometry absorption spectra, computed by adding height-invariant
ad hoc temperature perturbations to the model atmosphere of Sudarsky
et al. and by treating cloud height as an adjustable parameter. We do
not detect CO absorption. The strong 2-0 R-branch lines between 4320
and 4330 cm<SUP>-1</SUP> have depths during transit less than 1.6 parts
in 10<SUP>4</SUP> in units of the stellar continuum (3 σ limit) at a
spectral resolving power of 25,000. Our analysis indicates a weakening
similar to that found in the case of sodium, suggesting that a general
masking mechanism is at work in the planetary atmosphere. Under
the interpretation that this masking is provided by high clouds,
our analysis defines the maximum cloud-top pressure (i.e., minimum
height) as a function of the model atmospheric temperature. For the
relatively hot model used by Charbonneau et al. to interpret their
sodium detection, our CO limit requires cloud tops at or above 3.3
mbar, and these clouds must be opaque at a wavelength of 2 μm. High
clouds comprised of submicron-sized particles are already present
in some models but may not provide sufficient opacity to account for
our CO result. Cooler model atmospheres, having smaller atmospheric
scale heights and lower CO mixing ratios, may alleviate this problem
to some extent. However, even models 500 K cooler than the Sudarsky et
al. model require clouds above the 100 mbar level to be consistent with
our observations. Our null result therefore requires clouds to exist at
an observable level in the atmosphere of HD 209458b, unless this planet
is dramatically colder than current belief. <P />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: The Challenge of Wide-Field Transit Surveys: The Case of
GSC 01944-02289
Authors: Mandushev, Georgi; Torres, Guillermo; Latham, David W.;
Charbonneau, David; Alonso, Roi; White, Russel J.; Stefanik, Robert
P.; Dunham, Edward W.; Brown, Timothy M.; O'Donovan, Francis T.
2005ApJ...621.1061M Altcode: 2005astro.ph..1554M
Wide-field searches for transiting extrasolar giant planets face
the difficult challenge of separating true transit events from the
numerous false positives caused by isolated or blended eclipsing
binary systems. We describe here the investigation of GSC 01944-02289,
a very promising candidate for a transiting brown dwarf detected by
the Trans-Atlantic Exoplanet Survey (TrES) network. The photometry
and radial velocity observations suggested that the candidate was an
object of substellar mass in orbit around an F star. However, careful
analysis of the spectral line shapes revealed a pattern of variations
consistent with the presence of another star whose motion produced
the asymmetries observed in the spectral lines of the brightest
star. Detailed simulations of blend models composed of an eclipsing
binary plus a third star diluting the eclipses were compared with
the observed light curve and used to derive the properties of the
three components. Using the predicted stellar parameters, we were
able to identify a second set of spectral lines corresponding to the
primary of the eclipsing binary and derive its spectroscopic orbit. Our
photometric and spectroscopic observations are fully consistent with
a blend model of a hierarchical triple system composed of an eclipsing
binary with G0 V and M3 V components in orbit around a slightly evolved
F5 dwarf. The rotational broadening of the spectral lines of the F5
primary (vsini~34 km s<SUP>-1</SUP>) and its brightness relative to
the eclipsing binary (~89% of the total light) made the discovery of
the true nature of the system particularly difficult. We believe that
this investigation will be helpful to other groups pursuing wide-field
transit searches as this type of false detection could be more common
than true transiting planets and difficult to identify.
---------------------------------------------------------
Title: Results of WFC3 Thermal Vacuum
Authors: Brown, T. M.; Reid, I. N.; Figer, D. F.
2005wfc..rept...12B Altcode:
The throughput measurements for the WFC3 IR channel, taken during
the Fall 2004 thermal-vacuum test, show that the IR throughput is
approximately 15% lower than expected at all wavelengths. These
measurements were obtained through all of the IR filters, scanning
a monochromatic source through the central wavelengths of each
filter, from 930 to 1670 nm. The source of this discrepancy is under
investigation.
---------------------------------------------------------
Title: Results of WFC3 Thermal Vacuum Testing - Image Stability
Authors: Brown, T. M.
2005wfc..rept...11B Altcode:
As part of the 2004 campaign of WFC3 thermal-vacuum tests, the image
stability of both WFC3 channels (UVIS & IR) was measured over a
wide range of environmental temperatures, simulating thermal variations
that could occur in flight due to orbital occultations and slewing
between hot and cold orientations. During orbital temperature cycles,
the drift in the UVIS channel slightly exceeded its specification
of 10 milliarcsec per 200 minutes, while the drift in the IR channel
met its specification of 20 milliarcsec per 200 minutes. During large
temperature slews, the UVIS channel drift exceeded its specification by
a factor of 6, while the IR channel drift exceeded its specification
by a factor of 3, and the alignment of the two channels diverged
significantly. Alternative versions of these tests showed that much of
this motion may be associated with the test apparatus instead of WFC3,
but this is still under investigation.
---------------------------------------------------------
Title: Results of WFC3 Thermal Vacuum Testing - UVIS Channel Ghosts
Authors: Brown, T. M.
2005wfc..rept....1B Altcode:
The optical ghosts in the WFC3 UVIS channel, measured during the Fall
2004 thermalvacuum test, show the same morphologies and strengths as
characterized previously while under ambient conditions. All filters
previously showing optical ghosts were tested: F225W, F280N, F606W,
F218W, F275W, F300X, F410M, F467M, F547M, F621M, F625M, F689M, F775W,
F814W, FQ232N, FQ243N, F656N, F658N, F665N, F673N, and F680N. F225W,
F280N, and F606W are representative of all ghost behavior, and were
tested at 8 field points; the remaining filters were tested at one
field point.
---------------------------------------------------------
Title: Results of WFC3 Thermal Vacuum Testing - UVIS Channel
Throughput
Authors: Brown, T. M.; Reid, I. N.
2005wfc..rept....2B Altcode:
The throughput measurements for the WFC3 UVIS channel, taken during
the Fall 2004 thermal-vacuum test, show that the UVIS throughput is
excellent, meeting or exceeding expectations at most wavelengths. These
measurements were obtained through both the "clear" aperture and
through a subset of the broad-band UVIS filters. The clear throughput
was obtained on each detector chip, scanning a monochromatic source from
the near- UV (200 nm) to the near-IR (1000 nm). The filtered throughput
was obtained at one field point using a monochromatic source at the
central wavelength of each tested filter.
---------------------------------------------------------
Title: High-Resolution Spectroscopy of the Transiting Planet Host
Star TrES-1
Authors: Sozzetti, Alessandro; Yong, David; Torres, Guillermo;
Charbonneau, David; Latham, David W.; Allende Prieto, Carlos; Brown,
Timothy M.; Carney, Bruce W.; Laird, John B.
2004ApJ...616L.167S Altcode: 2004astro.ph.10483S
We report on a spectroscopic determination of the stellar parameters
and chemical abundances for the parent star of the transiting planet
TrES-1. Based on a detailed analysis of iron lines in our Keck and
Hobby-Eberly Telescope spectra, we derive T<SUB>eff</SUB>=5250+/-75
K, logg=4.6+/-0.2, and [Fe/H]=0.00+/-0.09. By measuring the Ca
II activity indicator and by putting useful upper limits on the
Li abundance, we constrain the age of TrES-1 to be 2.5+/-1.5
Gyr. By comparing theoretical stellar evolution models with the
observational parameters, we obtain M<SUB>*</SUB>=0.89+/-0.05
M<SUB>solar</SUB> and R<SUB>*</SUB>=0.83+/-0.05 R<SUB>solar</SUB>. Our
improved estimates of the stellar parameters are utilized in
a new analysis of the transit photometry of TrES-1 to derive
a mass M<SUB>p</SUB>=(0.76+/-0.05)M<SUB>J</SUB>, a radius
R<SUB>p</SUB>=1.04<SUP>+0.08</SUP><SUB>-0.05</SUB>R<SUB>J</SUB>, and
an inclination i=89.5<SUP>+0.5</SUP><SUB>-1.3</SUB> deg. The improved
planetary mass and radius estimates provide the grounds for new crucial
tests of theoretical models of evolution and evaporation of irradiated
extrasolar giant planets.
---------------------------------------------------------
Title: FUSE and STIS Observations of the Post-AGB Star ZNG 1 in the
Globular Cluster M5
Authors: Dixon, W. V.; Brown, T. M.; Howk, J. C.; Landsman, W. B.
2004AAS...205.5309D Altcode: 2004BAAS...36.1426D
FUSE and HST/STIS observations of the UV-bright star ZNG 1 in
the globular cluster M5 (NGC 5904) reveal it to be a helium-rich,
post-asymptotic giant branch (PAGB) star enhanced in carbon, nitrogen,
and oxygen, with a high rotational velocity (170 km/s) and a fast
stellar wind (1000 km/s). Its spectrum exhibits high-velocity
absorption by both neutral and high-ionization (O VI, C IV, and
Si IV) species. Blue-shifted by approximately 180 km/s relative to
the stellar photosphere and by 100 to 150 km/s relative to the LSR,
the absorption represents either circumstellar material (e.g., gas
ejected during the star's AGB phase and now shock-heated by the fast
PAGB wind) or a high-ionization high-velocity cloud (HVC) along the
line of sight to M5. If the latter, it would be the first evidence
that highly-ionized HVCs may be found near the Galactic disk. In this
poster, we use these data to improve previous estimates of the stellar
parameters and test the possibility that the star is a merger remnant;
to determine the star's iron abundance and compare it to the cluster
mean; and to investigate the origin of the blue-shifted absorption. <P
/>This work is supported by NASA grant NNG04GC44G6.
---------------------------------------------------------
Title: FUSE Observations of the Hot Post-AGB Star ZNG 1 in the
Globular Cluster M5
Authors: Dixon, W. V.; Brown, T. M.; Landsman, W. B.
2004ASSL..315..382D Altcode: 2004hdgw.conf..382D
No abstract at ADS
---------------------------------------------------------
Title: STARE operations experience and its data quality control
Authors: Alonso, R.; Deeg, H. J.; Brown, T. M.; Belmonte, J. A.
2004AN....325..594A Altcode:
The STARE instrument was the first to detect the transits of an
extrasolar planet in 1999. To date it has performed one of the longest
running searches for transits, being in nearly continous operations
since July 2001 at Teide Observatory, Tenerife. We describe the
instrumental setup and the scheme that is used for data acquisition,
handling and analysis. To this end, we first review the conditions
under which we obtained data suggestive of transits, and we then
follow a chain of verification and follow-up measures, progressing
from fairly simple ones of low cost and effort towards more involved
ones, which may be needed to positively verify the existence of a true
planetary transit.
---------------------------------------------------------
Title: Asteroseismology of Sun-Like Stars
Authors: Metcalfe, T. S.; Brown, T. M.; Christensen-Dalsgaard, J.
2004ESASP.559..567M Altcode: 2004soho...14..567M; 2004astro.ph..8127M
In the past decade, helioseismology has revolutionized our
understanding of the interior structure of the Sun. In the next decade,
asteroseismology will place this knowledge into context, by providing
structural information for dozens of pulsating stars across the H-R
diagram. Solar-like oscillations have already been detected from
the ground in a few stars, and several current and planned satellite
missions will soon unleash a flood of stellar pulsation data. Deriving
reliable seismological constraints from these observations will
require a significant improvement to our current analysis methods. We
are adapting a computational method, based on a parallel genetic
algorithm, to help interpret forthcoming observations of Sun-like
stars. This approach was originally developed for white dwarfs and
ultimately led to several interesting tests of fundamental physics,
including a key astrophysical nuclear reaction rate and the theory of
stellar crystallization. The impact of this method on the analysis of
pulsating white dwarfs suggests that seismological modeling of Sun-like
stars will also benefit from this approach.
---------------------------------------------------------
Title: Solar site testing for the Advanced Technology Solar Telescope
Authors: Hill, Frank; Beckers, Jacques; Brandt, Peter; Briggs, John;
Brown, Timothy; Brown, W.; Collados, Manuel; Denker, Carsten; Fletcher,
Steven; Hegwer, Steven; Horst, T.; Komsa, Mark; Kuhn, Jeff; Lecinski,
Alice; Lin, Haosheng; Oncley, Steve; Penn, Matthew; Rimmele, Thomas
R.; Socas-Navarro, Hector; Streander, Kim
2004SPIE.5489..122H Altcode:
The location of the Advanced Technology Solar Telescope (ATST) is a
critical factor in the overall performance of the telescope. We have
developed a set of instrumentation to measure daytime seeing, sky
brightness, cloud cover, water vapor, dust levels, and weather. The
instruments have been located at six sites for periods of one to two
years. Here we describe the sites and instrumentation, discuss the
data reduction, and present some preliminary results. We demonstrate
that it is possible to estimate seeing as a function of height near the
ground with an array of scintillometers, and that there is a distinct
qualitative difference in daytime seeing between sites with or without
a nearby lake.
---------------------------------------------------------
Title: TrES-1: The Transiting Planet of a Bright K0 V Star
Authors: Alonso, Roi; Brown, Timothy M.; Torres, Guillermo; Latham,
David W.; Sozzetti, Alessandro; Mandushev, Georgi; Belmonte, Juan
A.; Charbonneau, David; Deeg, Hans J.; Dunham, Edward W.; O'Donovan,
Francis T.; Stefanik, Robert P.
2004ApJ...613L.153A Altcode: 2004astro.ph..8421A
We report the detection of a transiting Jupiter-sized planet
orbiting a relatively bright (V=11.79) K0 V star. We detected
the transit light-curve signature in the course of the TrES
multisite transiting planet survey and confirmed the planetary
nature of the companion via multicolor photometry and precise
radial velocity measurements. We designate the planet TrES-1
its inferred mass is (0.75+/-0.07)M<SUB>Jup</SUB>, its radius is
1.08<SUP>+0.18</SUP><SUB>-0.04</SUB>R<SUB>Jup</SUB>, and its orbital
period is 3.030065+/-0.000008 days. This planet has an orbital period
similar to that of HD 209458b but about twice as long as those of
the OGLE transiting planets. Its mass is indistinguishable from that
of HD 209458b, but its radius is significantly smaller and fits the
theoretical models without the need for an additional source of heat
deep in the atmosphere, as has been invoked by some investigators for
HD 209458b.
---------------------------------------------------------
Title: Taking the Temperature of the New Planet TrES-1
Authors: Charbonneau, David; Allen, Lori; Brown, Timothy; Gilliland,
Ronald; Latham, David; Mandushev, Georgi; Megeath, Tom; Torres,
Guillermo; Alonso Sobrino, Roi; O'Donovan, Francis; Sozzetti,
Alessandro
2004sptz.prop..227C Altcode:
We propose to observe the newly-discovered transiting planet TrES-1
during the time of secondary eclipse (when the planet passes behind
the star). A successful measurement of this eclipse would constitute
the first direct detection of emission from an extrasolar planet. The
secondary eclipse will reveal two key quantities of the planet: its
temperature (from the eclipse depth), and its orbital eccentricity
(from the eclipse timing). Moreover, these observations will enable
us to characterize the high-precision, rapid-cadence photometric
performance of IRAC. A successful demonstration of this innovative use
of IRAC would open a new observing mode for Spitzer with applications
extending well beyond the study of extrasolar planets.
---------------------------------------------------------
Title: Characterizing a Newly-Found Extrasolar Planet
Authors: Brown, Timothy
2004hst..prop10441B Altcode: 2004hst..prop.6754B
We propose to observe transits of the newly-discovered extrasolar planet
TRES-1 using {1} ACS/HRC to obtain precise time-series photometry of
the transit, and {2} NICMOS to measure the strength of water vapor
absorption in the planetary atmosphere. The visible light curve will
permit an accurate estimate of the planet's diameter by resolving
uncertainty concerning the diameter of the parent star, and the water
vapor observation can be used to test models of the structure, clouds
and composition in the planet's upper atmosphere.
---------------------------------------------------------
Title: Astrophysical False Positives Encountered in Wide-Field
Transit Searches
Authors: Charbonneau, David; Brown, Timothy M.; Dunham, Edward W.;
Latham, David W.; Looper, Dagny L.; Mandushev, Georgi
2004AIPC..713..151C Altcode: 2004astro.ph..1063C
Wide-field photometric transit surveys for Jupiter-sized planets
are inundated by astrophysical false positives, namely systems
that contain an eclipsing binary and mimic the desired photometric
signature. We discuss several examples of such false alarms. These
systems were initially identified as candidates by the PSST instrument
at Lowell Observatory. For three of the examples, we present follow-up
spectroscopy that demonstrates that these systems consist of (1) an
M-dwarf in eclipse in front of a larger star, (2) two main-sequence
stars presenting grazing-incidence eclipses, and (3) the blend of
an eclipsing binary with the light of a third, brighter star. For
an additional candidate, we present multi-color follow-up photometry
during a subsequent time of eclipse, which reveals that this candidate
consists of a blend of an eclipsing binary and a physically unassociated
star. We discuss a couple indicators from publicly-available catalogs
that can be used to identify which candidates are likely giant stars,
a large source of the contaminants in such surveys.
---------------------------------------------------------
Title: HST Photometry of 47 Tucanae: Time Series Analysis and Search
for Giant Planets
Authors: Brown, Timothy M.; Charbonneau, David; Gilliland, Ronald L.;
Albrow, M. D.; Burrows, A.; Cochran, W. D.; Baliber, N.; Edmonds,
P. D.; Frandsen, S.; Bruntt, S.; Guhathakurta, P.; Choi, P.; Lin,
D. N. C.; Vogt, S. S.; Marcy, G. W.; Mayor, M.; Naef, D.; Milone,
E. F.; Stagg, C. R.; Williams, M. D.; Sarajedini, A.; Sigurdsson,
S.; Vandenberg, D. A.
2004IAUS..202...66B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Probing the Outskirts of an Extrasolar Planet with HST
Time-Series Photometry
Authors: Charbonneau, David; Brown, Timothy M.; Gilliland, Ronald L.;
Noyes, Robert W.; Burrows, Adam
2004IAUS..202...72C Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Extrasolar Planet Transit Observations-Findings and Prospects
(Invited Review)
Authors: Brown, Timothy M.
2004IAUS..202...52B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Strategies to recognize false alarms in transit experiments:
experiences from the STARE project
Authors: Alonso, R.; Deeg, H. J.; Brown, T. M.; Belmonte, J. A.
2004ESASP.538..255A Altcode: 2004sshp.conf..255A
In this contribution, we study the different stellar configurations
that can produce signals resembling those produced by a transiting
planet. We list several strategies to recognize these false alarms. For
the most common configurations, we delineate which of these strategies
are able to detect them. The case of an eclipsing binary of similar
components, whose light is diluted by a third star, is discussed in
some detail. Multicolor photometry is considered as a useful tool
to recognize this common case. Two example of false alarms obtained
by the STARE project, the different techniques used to study them,
and the most probable configurations producing them are shown.
---------------------------------------------------------
Title: Far-Ultraviolet Imaging of the Hubble Deep Field North
Authors: Teplitz, H. I.; Brown, T. M.; de Mello, D. F.; Dickinson,
M. E.; Ferguson, H. C.; Gardner, J. P.; Giavalisco, M.; Heap, S. R.
2003AAS...203.9003T Altcode: 2003BAAS...35R1350T
We present far-UV imaging of the Hubble Deep Field North (HDF-N)
taken with the Solar Blind Channel of the Advanced Camera for Surveys
(ACS/SBC) onboard HST. Combined with archival STIS imaging, the full
WFPC2 deep field has now been observed at 1500 Angstroms. In the
mosaic of 14 ACS/SBC pointings, we detect more than 80 galaxies. No
sources are found without counterparts in the WFPC2 image. Redshifts
(spectroscopic or photometric) for the detected sources are in the
range z=0.07 to z=0.85. We compare morphological properties in the
FUV, optical, and near-IR. We investigate the population of UV-bright,
intermediate redshift starbursts by measuring the FUV number counts. The
galaxy counts reach fainter than AB=28, but dark current glow causes
the detection area and completeness to be a strong function of position
on the detector.
---------------------------------------------------------
Title: Iron Abundances of Hot Post-AGB Stars in Globular Clusters
Authors: Dixon, W. V.; Brown, T. M.; Landsman, W. B.
2003AAS...203.5214D Altcode: 2003BAAS...35Q1291D
Only two hot post-asymptotic giant branch (PAGB) stars in globular
clusters, Barnard 29 in M13 and ROA 5701 in Omega Cen, have
well-determined iron abundances, and in both cases [Fe/H] is more than
0.5 dex below the cluster mean. The stars apparently lost a significant
fraction of their photospheric iron while on the AGB, perhaps through
the selective condensation of iron onto dust grains. To determine
the frequency of iron depletion among cluster PAGB stars and to test
scenarios for this depletion, we have begun a project to re-analyze
archival spectra of cluster PAGB stars obtained with the Hopkins
Ultraviolet Telescope. (HUT flew on the Astro-1 and 2 Space Shuttle
missions in 1990 and 1995. Its first-order sensitivity ranged from 820
to 1840 Å with a resolution of about 3 Å.) Using state-of-the-art
non-LTE line-blanketed stellar atmosphere models, we determine the
effective temperature, surface gravity and iron abundance of each
star. In this poster, we present preliminary results for the stars
BS in 47 Tuc, vZ 1128 in M3, and UV5 in NGC 1851. <P />This work is
supported by NASA grant NAG 5-10916.
---------------------------------------------------------
Title: The ELODIE survey for northern extra-solar planets. II. A
Jovian planet on a long-period orbit around GJ 777 A
Authors: Naef, D.; Mayor, M.; Korzennik, S. G.; Queloz, D.; Udry,
S.; Nisenson, P.; Noyes, R. W.; Brown, T. M.; Beuzit, J. L.; Perrier,
C.; Sivan, J. P.
2003A&A...410.1051N Altcode: 2003astro.ph..6586N
We present radial-velocity measurements obtained with the ELODIE
and AFOE spectrographs for <ASTROBJ>GJ 777 A</ASTROBJ> (<ASTROBJ>HD
190360</ASTROBJ>), a metal-rich ([Fe/H] = 0.25) nearby (d = 15.9 pc)
star in a stellar binary system. A long-period low radial-velocity
amplitude variation is detected revealing the presence of a Jovian
planetary companion. Some of the orbital elements remain weakly
constrained because of the smallness of the signal compared to our
instrumental precision. The detailed orbital shape is therefore
not well established. We present our best fitted orbital solution:
an eccentric (e = 0.48) 10.7-year orbit. The minimum mass of the
companion is 1.33 M<SUB>Jup</SUB>. <P />Based on observations made
with the ELODIE echelle spectrograph mounted on the 1.93-m Telescope
at the Observatoire de Haute-Provence (CNRS) and with the AFOE
spectrograph mounted on the 1.5-m Telescope at the Fred Lawrence
Whipple Observatory (SAO). <P />The ELODIE and AFOE measurements
discussed in this paper 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/410/1051
---------------------------------------------------------
Title: Kepler Mission: a mission to find Earth-size planets in the
habitable zone
Authors: Borucki, William J.; Koch, David; Basri, Gibor; Brown,
Timothy; Caldwell, Douglas; Devore, Edna; Dunham, Edward; Gautier,
Thomas; Geary, John; Gilliland, Ronald; Gould, Alan; Howell, Steve;
Jenkins, Jon
2003ESASP.539...69B Altcode: 2003toed.conf...69B
The Kepler Mission is a NASA Discovery-class mission designed to
continuously monitor the brightness of 100,000 main sequence stars
to detect the transit of Earth-size and larger planets. It is a wide
field of view photometer with a Schmidt-type telescope and an array
of 42 CCDs covering the 100 sq. degree field-of-view (FOV). It has
a 0.95 m aperture and a 1.4 m primary and is designed to attain a
photometric precision of 20 parts per million (ppm) for 12th magnitude
solar-like stars for a 6.5-hour transit duration. It will continuously
observe 100,000 main sequence stars from 9th to 15th magnitude in the
Cygnus constellation for a period of four years with a cadence of 4
measurements per hour. The photometer is scheduled to be launched in
2007 into heliocentric orbit. A ground-based program to classify all
450,000 stars brighter than 15th magnitude in the FOV and to conduct
a detailed examination of a subset of the stars that show planetary
companions is also planned. Hundreds of Earth-size planets should
be detected if they are common around solar-like stars. Ground-based
spectrometric observations of those stars with planetary companions
will be made to determine the dependences of the frequency and size
of terrestrial planets on stellar characteristics such as type and
metallicity. A null result would imply that terrestrial planets
are rare.
---------------------------------------------------------
Title: VizieR Online Data Catalog: ELODIE survey for northern
extra-solar planets. II. (Naef+, 2003)
Authors: Naef, D.; Mayor, M.; Korzennik, S. G.; Queloz, D.; Udry,
S.; Nisenson, P.; Noyes, R. W.; Brown, T. M.; Beuzit, J. L.; Perrier,
C.; Sivan, J. P.
2003yCat..34101051N Altcode:
Here are the 69 radial-velocity measurements of GJ 777A (HD 190360)
used for deriving the orbital solution of this star. These velocities
were obtained using the ELODIE echelle spectrograph mounted on the
1.93-m Telescope at Observatoire de Haute-Provence (France) and the
AFOE spectrograph mounted on the 1.5-m Telescope at the Fred Lawrence
Whipple Observatory (USA). <P />(1 data file).
---------------------------------------------------------
Title: Expected Detection and False Alarm Rates for Transiting
Jovian Planets
Authors: Brown, Timothy M.
2003ApJ...593L.125B Altcode: 2003astro.ph..7256B
Ground-based searches for transiting Jupiter-sized planets have so far
produced few detections of planets but many of stellar systems with
eclipse depths, durations, and orbital periods that resemble those
expected from planets. The detection rates prove to be consistent
with our present knowledge of binary and multiple-star systems
and of Jovian-mass extrasolar planets. Space-based searches for
transiting Earth-sized planets will be largely unaffected by the
false alarm sources that afflict ground-based searches, except for
distant eclipsing binaries whose light is strongly diluted by that of
a foreground star. A by-product of the rate estimation is evidence
that the period distribution of extrasolar planets is depressed for
periods between 5 and 200 days.
---------------------------------------------------------
Title: A Search for Water Vapor in the Atmosphere of an Extrasolar
Planet
Authors: Brown, Timothy
2003hst..prop.9832B Altcode:
We propose to search for evidence of water vapor in the transmission
spectrum of the transiting planet of HD 209458. A successful detection
would not only establish the presence of this important atmospheric
constituent, but would also constrain other key properties of this
close-in, Jupiter-sized planet. Specifically, relating the absorption
caused by water to that already observed from atomic sodium would
help establish the height of the atmosphere's uppermost cloud layer
{if any}. Also, the abundance of water will provide information about
that of oxygen, and by extension, that of all heavy elements. To make
this measurement, we propose a doubly-differential procedure in which
we will use NICMOS in spectroscopic mode to detect the small spectral
changes that occur during planetary transits, and that result from
absorption of starlight as it passes through the outer parts of the
planet's atmosphere. We search for water because it is expected to
produce by far the strongest spectrum features within the wavelength
range accessible to HST.
---------------------------------------------------------
Title: Mapping the Star Formation History of the Local Group with NHST
Authors: Brown, T. M.
2003AAS...202.4903B Altcode: 2003BAAS...35..768B
The color-magnitude diagram (CMD) is the most fundamental
tool for studying the star formation history of nearby stellar
populations. Strong constraints on the ages of stellar populations
come from CMDs reaching the main sequence, and with the Hubble Space
Telescope (HST), it is possible to produce such a CMD for stars at
any distance within the Local Group. Unfortunately, resolving the
main sequence in old populations beyond the satellites of the Milky
Way requires an enormous investment of HST time, meaning that only a
few pencil beams can be explored within the remaining HST mission. In
strong contrast, an 8 meter UV-optical space telescope, diffraction
limited at 0.5 microns, could map the star formation history of all
galaxies in the Local Group: It would take only one hour to resolve
the main sequence in any Local Group galaxy, allowing the exploration
of hundreds of sight-lines in a reasonable program.
---------------------------------------------------------
Title: Flux Calibration of the STIS CCD: Correcting for Charge
Transfer Inefficiency and Time-Dependent Sensitivity
Authors: Davies, J.; Goudfrooij, P.; Bohlin, R. C.; Stys, D. J.;
Brown, T. M.; Walborn, N. R.; Proffitt, C. R.
2003AAS...202.0407D Altcode: 2003BAAS...35Q.704D; 2003AAS...202..407D
A variety of on-orbit imaging and spectroscopic observations have
been used to characterize the Charge Transfer Efficiency (CTE) of the
Charge-Coupled Device (CCD) of the Space Telescope Imaging Spectrograph
(STIS) aboard the Hubble Space Telescope. A set of formulae has been
developed to correct aperture photometry and spectrophotometry of
point sources for CTE-related loss, with dependencies on X and Y
positions, the source signal, the background counts, and the time
of observation. Application of the new formulae leads to a CCD flux
calibration that is accurate to within one percent, independent
of source signal. <P />The analysis of the STIS Sensitivity Monitor
observations from 1997 through January 2003 shows continuing sensitivity
trends correlated with time for all first-order, low- and medium
resolution spectroscopic modes as well as a temperature dependance
in the FUV and recently in the CCD detectors. The newly available
CTE corrections allow for the proper determination of time-dependent
sensitivity (TDS) trends in CCD modes. The wavelength-averaged rates
of sensitivity loss for the CCD modes range from 0%/yr (G750L grating)
to 1.5%/yr (G230LB grating). These sensitivity losses are wavelength
dependent and will be corrected for within the STIS data reduction
pipeline by means of the delivery of new reference files.
---------------------------------------------------------
Title: Hubble Space Telescope and Ground-based Optical and Ultraviolet
Observations of GRB 010222
Authors: Galama, T. J.; Reichart, D.; Brown, T. M.; Kimble, R. A.;
Price, P. A.; Berger, E.; Frail, D. A.; Kulkarni, S. R.; Yost,
S. A.; Gal-Yam, A.; Bloom, J. S.; Harrison, F. A.; Sari, R.; Fox,
D.; Djorgovski, S. G.
2003ApJ...587..135G Altcode: 2003astro.ph..1059G
We report on Hubble Space Telescope (HST) Wide Field Planetary Camera 2
optical and Space Telescope Imaging Spectrograph (STIS) near-ultraviolet
MAMA observations and ground-based optical observations of GRB 010222,
spanning 15 hr to 71 days. The observations are well described by a
relativistic blast wave model with a hard electron energy distribution,
p=1.57<SUP>+0.04</SUP><SUB>-0.03</SUB>, and a jet transition at
t<SUB>*</SUB>=0.93<SUP>+0.15</SUP><SUB>-0.06</SUB> days. These values
are slightly larger than previously found as a result of a correction
for the contribution from the host galaxy to the late-time ground-based
observations and the larger temporal baseline provided by the HST
observations. The host galaxy is found to contain a very compact core
(size <0.25"), which coincides with the position of the optical
transient. The STIS near-ultraviolet MAMA observations allow for an
investigation of the extinction properties along the line of sight
to GRB 010222. We find that the far-ultraviolet curvature component
c<SUB>4</SUB> is rather large. In combination with the low optical
extinction, A<SUB>V</SUB>=0.110<SUP>+0.010</SUP><SUB>-0.021</SUB> mag,
when compared with the hydrogen column inferred from X-ray observations,
we suggest that this is evidence for dust destruction.
---------------------------------------------------------
Title: FUSE Observations of the Post-AGB Star ZNG 1 in the Globular
Cluster M5 (NGC 5904)
Authors: Dixon, W. Van Dyke; Brown, T. M.; Landsman, W. B.
2003ASPC..296..236D Altcode: 2003ASPC..296..236V; 2002astro.ph..9344D; 2003nhgc.conf..236D
We report observations of the hot post-asymptotic giant branch
(PAGB) star ZNG 1 in the globular cluster M5 (NGC 5904) with the Far
Ultraviolet Spectroscopic Explorer (FUSE). From the resulting spectrum,
we derive an effective temperature T<SUB>eff</SUB> = 45 +/- 1 kK, a
surface gravity log g = 4.3 +/- 0.1, and a rotational velocity v sin i =
170 +/- 20 km/s. The star's luminosity, log (L/L<SUB>sun</SUB>) = 3.54
+/- 0.06, is consistent with its PAGB classification. The atmosphere is
helium-rich (Y = 0.92), with enhanced carbon (2.9% by mass), nitrogen
(0.43%), and oxygen (0.37%) abundances. The spectrum shows evidence for
a stellar wind with terminal velocity near 1000 km/s and an expanding
shell of carbon- and nitrogen-rich material. This work is supported
by NASA grant NAG 5-10405.
---------------------------------------------------------
Title: A New Formation Mechanism for the Hottest Horizontal-Branch
Stars
Authors: Sweigart, A. V.; Brown, T. M.; Lanz, T.; Landsman, W. B.;
Hubeny, I.
2003ASPC..296..313S Altcode: 2003nhgc.conf..313S; 2002astro.ph..7343S
Stars with very large mass loss on the red-giant branch can undergo
the helium flash while descending the white-dwarf cooling curve. Under
these conditions the flash convection zone will mix the hydrogen
envelope with the hot helium- burning core. Such “flash-mixed”
stars will arrive on the extreme horizontal branch (EHB) with helium-
and carbon-rich envelopes and will lie at higher temperatures than the
hottest canonical (i.e., unmixed) EHB stars. Flash mixing provides a
new evolutionary channel for populating the hot end of the EHB and may
explain the origin of the high gravity, helium-rich sdO and sdB stars.
---------------------------------------------------------
Title: Using M32 to Study Rapid Phases of Stellar Evolution
Authors: Brown, T. M.; Ferguson, H. C.
2003ASPC..296..199B Altcode: 2002astro.ph..7211B; 2003nhgc.conf..199B
The compact elliptical galaxy M32 offers a unique testing ground for
theories of stellar evolution. Because of its proximity, solar-blind
UV observations can resolve the hot evolved stars in its center. Some
of these late evolutionary phases are too rapid to study adequately
in globular clusters, and their study in the Galactic field is often
complicated by uncertainties in distance and reddening. Using the UV
cameras on the Space Telescope Imaging Spectrograph, we have obtained a
deep color-magnitude diagram (CMD) of the M32 center. Although the hot
horizontal branch is well-detected, our CMD shows a striking scarcity
of the brighter post-asymptotic giant branch (PAGB) and post-early AGB
stars expected for a population of this size. This dearth suggests
that the evolution to the white dwarf phase may be much more rapid
than that predicted by canonical evolutionary tracks for low-mass stars.
---------------------------------------------------------
Title: Recent Improvements to STIS Pipeline Calibration
Authors: Diaz-Miller, R. I.; Quijano, J. Kim; Valenti, J.; Proffitt,
C. R.; Sahu, K. C.; Bohlin, R. C.; Brown, T. M.; Lindler, D.
2003hstc.conf..189D Altcode:
In the last few months a number of improvements to the STIS pipeline
calibration have been developed and implemented, which include the
following. <P />We have released new low order flat files for use
with the G140L observations. These flats should reduce uncertainties
of the extracted flux with position from 12% to 2%. <P />To better
reflect the change with time in the overall shape of the NUV MAMA
dark current, new dark reference files were created for different
epochs. To further improve the dark subtraction, these darks are also
scaled using an improved algorithm, which takes into account long term
changes in the behavior of the NUV MAMA dark current. <P />Additional
improvements which have been implemented are described in the posters
by Stys et al., Valenti et al., Davies et al. and Lindler et al. Future
improvements include background smoothing for low signal spectroscopic
data, and updating the Pixel-to-Pixel flat library and the current
CCD bad pixel table.
---------------------------------------------------------
Title: STIS Status after the Switch to Side 2
Authors: Brown, T. M.; Davies, J. E.
2003hstc.conf..180B Altcode:
Since July 2001, STIS has been operating on its secondary (Side-2)
electronics, due to the failure of the primary (Side-1) system. The
change to Side 2 has required new calibration work. The dark rate of
the STIS CCD varies since the switch to Side 2, as it depends on the
temperature of the CCD (which cannot be regulated precisely using Side-2
electronics). We find that the dark rate is a linear function of the
housing temperature for pixels at a given dark rate, but the slope of
this relation varies for pixels with different dark rates. Scaling of
the darks as a function of the temperature has been incorporated into
the STIS pipeline. An additional feature of the switch to Side-2 is
that the STIS CCD read noise has increased by 1 e^{-} sec^{-1} for all
four amplifiers when using a gain of 1. This increased read noise is due
to electronic pick-up pattern noise (on Side 1 the noise was primarily
white noise). Although an algorithm exists for filtering this additional
pattern noise, it will not be incorporated into the STIS pipeline.
---------------------------------------------------------
Title: Astronomy: Distant planet is the hottest yet
Authors: Brown, Timothy M.
2003Natur.421..488B Altcode:
The first planet beyond our Solar System to be detected by means of
the transit method has now been found to orbit its star almost twenty
times closer than Mercury orbits the Sun.
---------------------------------------------------------
Title: Absolute Flux Calibration of STIS MAMA Imaging Modes
Authors: Proffitt, C. R.; Brown, T. M.; Mobasher, B.; Davies, J.
2003stis.rept....1P Altcode:
The absolute flux calibration of STIS MAMA imaging modes is tested
by comparison of observed and predicted count rates. As part of this
work, we have derived new, wavelength- dependent aperture corrections
for MAMA imaging, and have revised the NUVMAMA imaging throughput at
short wavelengths. FUV-MAMA imaging modes clearly show a time dependent
sensitivity loss that is consistent with the time dependent sensitivity
changes seen in G140L spectra. Once this time dependence is taken
into account, count rates measured using 1" apertures for FUV 25MAMA,
F25LYA, F25ND3, and F25SRF2 observations are within 5% of predictions
made using the prelaunch throughput determination. However, FUV F25QTZ
observations show a much larger scatter than expected from Poisson
statistics. NUV-MAMA imaging modes also appear to be consistent with
the time dependence observed for G230L spectra, although this effect
is not as large as for the FUV-MAMA. While most NUV-MAMA imaging
modes show adequate agreement with the tabulated sensitivity curve,
results for the F25CN182 mode are discrepant. We suggest a revision
of the short wavelength throughput of the NUV-MAMA imaging modes to
fix this problem. This revision brings the results for all NUV imaging
modes to within 5% of predictions.
---------------------------------------------------------
Title: Absolute Flux Calibration of STIS Imaging Modes
Authors: Proffitt, C. R.; Davies, J. E.; Brown, T. M.; Mobasher, B.
2003hstc.conf..201P Altcode:
The absolute flux calibration of STIS imaging photometry presents
a number of unique challenges. The very wide wavelength coverage
of most STIS imaging modes leads to significant color dependence in
both the throughputs and the aperture corrections, complicating the
determination of detector sensitivity. For CCD imaging modes, these
difficulties are further complicated by the very broad scattered light
halo at long wavelengths. For MAMA imaging modes, it is also necessary
to take the time and wavelength dependent sensitivity changes of the
detectors into account. We present deep imaging observations of a number
of stars with well measured spectral energy distributions. These data
have been used to derive improved color dependent aperture corrections
for all STIS imaging configurations, and to revise the wavelength
dependent detector sensitivities. These new aperture corrections and
sensitivity revisions should allow absolute flux calibration of imaging
observations with better than 5% accuracy for most STIS imaging modes.
---------------------------------------------------------
Title: 100 Times Faster and 3 Times Sharper: Background-Dominated
Observations of Stellar Populations with an 8-meter Optical-UV
Space Telescope
Authors: Brown, T. M.
2003ASPC..291..351B Altcode: 2002astro.ph..7212B; 2003hslf.conf..351B
An 8 m successor to the Hubble Space Telescope (HST) would make
incredible gains in the study of stellar populations, especially in
the Local Group. If diffraction-limited at 0.5 microns, the "Next HST"
could produce high-resolution imaging of faint sources over a wide field
in 1 percent of the time needed with the HST. With these capabilities,
photometry of the ancient main sequence could be obtained for many
sight-lines through Local Group galaxies, thus determining directly
the ages of their structures and providing a formation history for
the Local Group populations.
---------------------------------------------------------
Title: Possible Transiting Planet Candidates from the EXPLORE Project
Authors: Mallén-Ornelas, G.; Seager, S.; Yee, H. K. C.; Gladders,
M. D.; Brown, T. M.; Minniti, D.; Ellison, S. L.; Mallén-Fullerton,
G. M.
2003ASPC..294..391M Altcode: 2002astro.ph..9589M
The EXPLORE Project is a series of searches for transiting
extrasolar planets using large-format mosaic CCD cameras on 4-m class
telescopes. Radial velocity follow-up is done on transiting planet
candidates with 8--10m class telescopes. We present a summary of
transit candidates from the EXPLORE Project for which we have radial
velocity data.
---------------------------------------------------------
Title: The EXPLORE Project. I. A Deep Search for Transiting Extrasolar
Planets
Authors: Mallén-Ornelas, G.; Seager, S.; Yee, H. K. C.; Minniti,
D.; Gladders, Michael D.; Mallén-Fullerton, G. M.; Brown, T. M.
2003ApJ...582.1123M Altcode: 2002astro.ph..3218M
Planet transit searches promise to be the next breakthrough for
extrasolar planet detection and will bring the characterization of
short-period planets into a new era. Every transiting planet discovered
will have a measured radius, which will provide constraints on planet
composition, evolution, and migration history. Together with radial
velocity measurements, the absolute mass of every transiting planet
will be determined. In this paper we discuss the design considerations
of the Extrasolar Planet Occultation Research (EXPLORE) project,
a series of transiting planet searches using 4 m class telescopes to
continuously monitor a single field of stars in the Galactic plane in
each ~2 week observing campaign. We discuss the general factors that
determine the efficiency and the number of planets found by a transit
search, including time sampling strategy and field selection. The
primary goal is to select the most promising planet candidates for
radial velocity follow-up observations. We show that with very high
photometric precision light curves that have frequent time sampling and
at least two detected transits, it is possible to uniquely solve for
the main parameters of the eclipsing system (including planet radius),
based on several important assumptions about the central star. Together
with a measured spectral type for the star, this unique solution for
orbital parameters provides a powerful method for ruling out most
contaminants to transiting planet candidates. For the EXPLORE project,
radial velocity follow-up observations for companion mass determination
of the best candidates are done on 8 m class telescopes within 2 or
3 months of the photometric campaigns. This same-season follow-up is
made possible by the use of efficient pipelines to produce high-quality
light curves within weeks of the observations. We conclude by presenting
early results from our first search, EXPLORE I, in which we reached
better than 1% rms photometric precision (measured over a full night)
on ~37,000 stars with 14.5<=I<=18.2.
---------------------------------------------------------
Title: STARE Results on a Single Field: Tens of New Pulsating Stars
Authors: Alonso, Roi; Belmonte, Juan Antonio; Brown, Tim
2003Ap&SS.284...13A Altcode:
We present preliminary results on variable stars of a STARE's three
month observational run centered at the Cygnus constellation. A total
amount of aprox. 14000 stars with 9<R<12.5 magnitude, in STARE's
6.1×6.1<SUP>̂2</SUP> FOV, have been analyzed to obtain lightcurves
for each of these stars. The data spans for ~90 nights. In this single
field, we detect more that 40 stars with pulsation modes between 5
and 40 c/d, the vast mayority previously unknown to be variables.
---------------------------------------------------------
Title: STIS Calibration Status
Authors: Proffitt, C. R.; Goudfrooij, P.; Brown, T. M.; Davies, J. E.;
Diaz-Miller, R. I.; Dressel, L.; Quijano, J. Kim; Maíz-Apellániz,
J.; Mobasher, B.; Potter, M.; Sahu, K. C.; Stys, D. J.; Valenti, J.;
Walborn, N. R.; Bohlin, R. C.; Barrett, P.; Busko, I.; Hodge, P.
2003hstc.conf...97P Altcode:
Last year's failure of the STIS Side-1 electronics temporarily suspended
use of the instrument. The Side-1 electronics are not repairable, but
operations were resumed in August of 2001 using the redundant Side-2
electronics. STIS was fully returned to operation, with only minimal
impacts on scientific performance. <P />MAMA detector performance
continues to be very good, with sensitivity changes of 1 to 2 percent
per year. Although the detailed relation between the NUV MAMA detector
temperature and dark current has changed, typical NUV dark current
levels are similar to those in previous cycles. The FUV dark current
varies irregularly, and it is now usually significantly higher than
it had been during the first two years of STIS operations. <P />The
effects of radiation damage on the STIS CCD detector continue to follow
previous trends, with declining charge transfer efficiency, increasing
dark current, and increasing numbers of hot pixels. We also review the
use and calibration of the E1 aperture positions which can be used to
ameliorate CTE effects.
---------------------------------------------------------
Title: An Aluminum Secondary Mirror for the SOFIA Telescope
Authors: Erickson, E. F.; Kunz, N.; Brivkalns, C. A.; Brown, T. M.;
Honaker, M.
2002AAS...201.1808E Altcode: 2002BAAS...34.1131E
The secondary mirror for the SOFIA telescope is made from silicon
carbide. It is 352 mm in diameter, weighs 1.8 kg, and is finished to
good optical tolerances. The light weight is essential for chopping
with the secondary support mechanism to suppress low frequency "sky"
noise. To achieve the light weight, the back side of the mirror is
structured with thin-walled pockets; the face plate is 2.3 mm thick. The
material is stiff, has low density and high thermal conductance, but is
brittle. The latter is a concern because failure of this mirror would
render the telescope inoperable. For this reason we are designing a
spare secondary mirror. The spare must match the mass and moments of
inertia of the SiC mirror (to permit effective chopping), but should be
more robust and much cheaper. The spare should permit continuation of
much of the observing program, and since many of SOFIA's observations
will be made in the far-infrared, the optical quality of the spare
can be significantly lower than that of the SiC secondary. Currently
it appears that a bare aluminum secondary can be made to meet the
requirements, while achieving a diffraction-limited wavelength of 20
microns or less. The design details will be described and discussed
in the paper. We gratefully acknowledge NASA support of this work.
---------------------------------------------------------
Title: FUSE Observations of He-rich sdB Stars
Authors: Lanz, T.; Brown, T. M.; Sweigart, A. V.; Hubeny, I.; Landsman,
W. B.
2002AAS...20111308L Altcode: 2002BAAS...34.1285L
Subdwarf B stars all show significant abundance anomalies. Most are
extremely deficient in helium and selected light elements, but a
minority are helium-rich. Deficiencies in helium and heavier elements
have been attributed to gravitational settling, but the helium-enriched
members of the class present a puzzling exception, because radiative
levitation should be too weak to prevent gravitational settling. New
evolutionary calculations suggest that these helium-rich sdB stars are
the result of a delayed helium-core flash on the white dwarf cooling
curve. The convective zone produced by this flash will penetrate
the hydrogen envelope, mixing hydrogen into the hot helium-burning
interior, where it is rapidly consumed. The resulting star should show
greatly enhanced helium and carbon with respect to the other heavy
elements. This phenomenon is analogous to the born again scenario
for producing hydrogen-deficient R CrB stars following a very late
helium-shell flash. We have recently obtained FUSE spectra of two
helium-rich sdB stars, revealing huge C III lines at 977 and 1176
Å. Our preliminary analysis yields a surface composition of 97% He
and 3% C, in agreement with the new evolutionary scenario. This work
is supported in part by NASA grant NAG5-12383.
---------------------------------------------------------
Title: FUSE Observations of the Post-AGB Star ZNG 1 in the Globular
Cluster M5
Authors: Dixon, W. V.; Brown, T. M.; Landsman, W. B.
2002AAS...20111306D Altcode: 2002BAAS...34.1284D
We have observed the hot post-AGB star ZNG 1 in the globular
cluster M5 (NGC 5904) with the Far Ultraviolet Spectroscopic Explorer
(FUSE). From the resulting spectrum, we derive an effective temperature
T<SUB>eff</SUB> ~ 45,000K, a rotational velocity v<SUB>rot</SUB> ~
100km/s, carbon and nitrogen abundances approximately ten times solar,
a wind with terminal velocity near 1000 km/s, and evidence for an
expanding shell of material around the star. The carbon and nitrogen
enhancements suggest dredge-up of nuclear-processed material on the
AGB. The high rotational velocity may reflect a previous merger with
a binary companion. This research is supported by NASA grant NAG5-10405.
---------------------------------------------------------
Title: The EXPLORE Project: A Deep Search for Transiting Extrasolar
Planets at the KPNO and CTIO 4m Telescopes.
Authors: Mallen-Ornelas, G.; Seager, S.; Yee, H. K. C.; von Braun,
K.; Brown, T. M.; Gladders, M. D.; Lee, B.; Ellison, S. L.; Eyer,
L.; Blake, C.; Mallen-Fullerton, G.
2002AAS...20110410M Altcode: 2002BAAS...34.1273M
We present preliminary results of our October 2002 campaign at
the KPNO 4m telescope as part of an ongoing search for transiting
extrasolar planets. Our goal is to detect transiting planets and to
derive statistics of planet frequency, radius, and mass for stars
ranging from types early G to late K. Planet transits will be detected
via 1% photometric precision lightcurves with 4 minute time sampling
spanning 18 nights per run. Transit searches will mark a new era in
planetary discovery and characterization. Planet radii, which provide
constraints on composition, evolution, and migration history, can only
be measured for transiting planets. In addition absolute planet mass
can be determined with follow-up radial velocity measurements. Our
lightcurve database will have unprecedented time sampling and very
high photometric precision for hundreds of thousands of stars, enabling
new research on variable and binary stars, short microlensing events,
and moving objects such as asteroids.
---------------------------------------------------------
Title: Possible Transiting Planet Candidates from the Explore Project
Authors: Mallen-Ornelas, G.; Seager, S.; Yee, H. K. C.; Gladders,
M. D.; Brown, T. M.; von Braun, K.; Minniti, D.; Ellison, S. L.;
Mallen-Fullerton, G. M.
2002AAS...201.9604M Altcode: 2002BAAS...34.1263M
Planet transit searches promise to be the next big step forward in
short-period extrasolar planet detection and characterization. Every
transiting planet discovered will have a measured radius, and radial
velocity observations will lead to an absolute mass measurement (since
orbital inclination is known). Transiting planets can be discovered
around distant stars and in a variety of stellar environments. Many
transit searches are now ongoing. The EXPLORE Project is a series
of transit searches using wide-field CCD mosaic cameras on 4m-class
telescopes, with radial velocity follow-up of transit candidates done
using 8m-class telescopes. We continuously monitor a Galactic plane
field for as long as 18 consecutive nights with 3-minute time sampling,
and perform 0.2-1 tens of thousands of stars in our field. We have a
pipeline to completely reduce the data in a few weeks after the imaging
observations, which allows same-semester radial-velocity follow-up
observations. We present results from our 2001 and 2002 observing
campaigns at CTIO, CFHT, and KPNO, and show transit candidates for
which radial velocity follow-up has been done.
---------------------------------------------------------
Title: A Search for CO Absorption in the Transmission Spectrum of
HD 209458b
Authors: Brown, Timothy M.; Libbrecht, Kenneth G.; Charbonneau, David
2002PASP..114..826B Altcode: 2002astro.ph..5246B
We observed one transit of the extrasolar planet HD 209458b with the
NIRSPEC spectrograph on the Keck II telescope. Using time series of
low-noise observations in the wavelength range 2.0-2.5 μm, we searched
for extra absorption from the first-overtone rotation-vibration band
of CO near 2.3 μm. This was not detected with a detection limit that
fails to test simple models of the planetary atmosphere by a factor
of about 3. Great improvements in the detectability of the CO spectrum
features could be realized by observing a transit that is centered near
stellar meridian passage, and in better weather. Since it appears that
similar observations taken under better circumstances might succeed,
we describe our analysis procedures in detail.
---------------------------------------------------------
Title: Detection of an Extrasolar Planet Atmosphere
Authors: Charbonneau, David; Brown, Timothy M.; Noyes, Robert W.;
Gilliland, Ronald L.
2002ApJ...568..377C Altcode: 2001astro.ph.11544C
We report high-precision spectrophotometric observations of four
planetary transits of HD 209458, in the region of the sodium resonance
doublet at 589.3 nm. We find that the photometric dimming during
transit in a bandpass centered on the sodium feature is deeper by
(2.32+/-0.57)×10<SUP>-4</SUP> relative to simultaneous observations
of the transit in adjacent bands. We interpret this additional dimming
as absorption from sodium in the planetary atmosphere, as recently
predicted from several theoretical modeling efforts. Our model for
a cloudless planetary atmosphere with a solar abundance of sodium in
atomic form predicts more sodium absorption than we observe. There are
several possibilities that may account for this reduced amplitude,
including reaction of atomic sodium into molecular gases and/or
condensates, photoionization of sodium by the stellar flux, a low
primordial abundance of sodium, and the presence of clouds high in
the atmosphere. Based on observations with the NASA/ESA Hubble Space
Telescope (HST), obtained at the Space Telescope Science Institute,
which is operated by the Association of Universities for Research in
Astronomy, Inc. under NASA contract NAS 5-26555.
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Title: A Deep Search for Transiting Extrasolar Planets
Authors: Seager, Sara; Mallen-Ornelas, Gabriela; Yee, Howard; Minniti,
Dante; Gladders, Michael; Brown, Tim
2002noao.prop..336S Altcode:
We propose to continue our deep search for transiting close-in
extrasolar planets using the MOSAIC II wide-field imager on the CTIO 4m
telescope. We will take repeated short I-band exposures during 9 nights
(4 Chilean time and 5 USA time) of a single well-chosen field with
~100,000 stars with I≲18.2. Relative photometry accurate to 0.2-1%
rms will yield light curves which will allow the identification of
transiting planets. We have already analysed the best 37,000 lightcurves
(0.2%-1% rms) and found several planet candidates. However, due to
bad weather and seeing, we effectively had only 5-6 good nights out
of 11, and two nights were completely lost. The reduced time coverage
resulted in a loss of 3.5 times of planet-detection efficiency. We
are requesting additional time to compensate for this loss. Note
that the proposed observations - to be conducted a year after the
first run - will allow us to obtain a very accurate period and phase
measurement for those planet candidates for which we already have 2
transits detected, since we will have a large time baseline equivalent
to ~100 orbits of the planet. A detection of a second transit in a
light-curve with currently only one transit will result in new planet
candidates. Finally, there will be new candidates for which 2 transits
will be visible in the second run.
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Title: The Origin of Hot Subluminous Horizontal-Branch Stars in ω
Centauri and NGC 2808
Authors: Sweigart, A. V.; Brown, T. M.; Lanz, T.; Landsman, W. B.;
Hubeny, I.
2002ASPC..265..261S Altcode: 2002ocuw.conf..261S; 2002astro.ph..3063S
Hot subluminous stars lying up to 0.7 mag below the extreme horizontal
branch (EHB) are found in the UV color-magnitude diagrams of omega Cen
and NGC 2808. Such stars are unexplained by canonical HB theory. In
order to explore the origin of these subluminous stars, we evolved a
set of low-mass stars from the main sequence through the helium-core
flash to the HB for a wide range in the mass loss along the red-giant
branch (RGB). Stars with the largest mass loss evolve off the RGB to
high effective temperatures before igniting helium in their cores. Our
results indicate that the subluminous EHB stars, as well as the gap
within the EHB of NGC 2808, can be explained if these stars undergo
a late helium-core flash on the white-dwarf cooling curve. Under
these conditions the flash convection will penetrate into the stellar
envelope, thereby mixing most, if not all, of the envelope hydrogen
into the hot helium- burning interior. This phenomenon is analogous
to the "born-again" scenario for producing hydrogen-deficient stars
during a very late helium-shell flash. "Flash mixing" greatly enhances
the envelope helium and carbon abundances and, as a result, leads to
an abrupt increase in the HB effective temperature. We argue that
the EHB gap in NGC 2808 is caused by this theoretically predicted
dichotomy in the HB morphology. Using new helium- and carbon-rich
stellar atmospheres, we show that the flash-mixed stars have the same
reduced UV flux as the subluminous EHB stars. Moreover, we demonstrate
that models without flash mixing lie, at most, ~0.1 mag below the EHB
and hence fail to explain the observations. Flash mixing may also
provide a new evolutionary channel for producing the high gravity,
He-rich sdO and sdB stars.
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Title: δ Scuti stars with STARE: a project on planetary transits
and stellar variability
Authors: Alonso, R.; Brown, T. M.; Belmonte, J. A.; Charbonneau, D.;
Fox Machado, L.; Pallé, P. L.
2002ESASP.485..245A Altcode: 2002sshp.conf..245A
In this contribution, we show the capability of STARE to obtain
frequencies and amplitudes from high temporal resolution δ Scuti
spectra. Lightcurves of 13 new field δ Scuti stars are analyzed and a
total of 21 oscillation modes are found in a single field. Noise level
in the spectra falls bellow 3 mmag for stars fainter than magnitude
9. Subsequent analysis of the other observed fields, a new location
for STARE, as well as the sharing of data with similar projects will
provide higher-quality results and a valuable δ Scuti database,
which would be useful for follow-up observations.
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Title: The Origin of Hot Subluminous Horizontal-Branch Stars in ω
Cen and NGC 2808
Authors: Sweigart, A. V.; Brown, T. M.; Moehler, S.; Lanz, T.;
Landsman, W. B.; Hubeny, I.; Dreizler, S.; Napiwotzki, R.
2001AAS...19913704S Altcode: 2001BAAS...33.1512S
Ultraviolet (UV) observations of the globular clusters ω Cen and NGC
2808 have revealed an unexpected population of hot subluminous stars
lying up to 0.7 mag below the extreme horizontal branch (EHB) in the
UV, which are not explained by canonical stellar models. In order to
explore the evolutionary status of these stars, we have evolved a set
of low-mass stars from the main sequence through the helium flash to
the horizontal branch (HB) for a wide range in the mass loss along the
red-giant branch (RGB). Stars with the largest mass loss evolve off
the RGB to high effective temperatures before igniting helium in their
cores. Our results indicate that the subluminous stars can be explained
if these stars undergo a late helium flash while descending the white
dwarf cooling curve. Under these conditions the convection zone produced
by the helium flash will penetrate into the stellar envelope, thereby
mixing the envelope hydrogen into the hot helium-burning interior, where
it is rapidly consumed. Such “flash-mixed” stars will have helium-
and carbon-rich envelopes and will lie at higher effective temperatures
than the hottest canonical (i.e., unmixed) EHB stars. Using new stellar
atmospheres, we show that these changes in the envelope abundances
will suppress the UV flux in the spectra of the flash-mixed stars by
the amount needed to explain the hot subluminous stars in ω Cen and
NGC 2808. To test this evolutionary scenario, we have obtained medium
resolution spectra of a sample of the hottest HB stars in ω Cen. We
find that these stars are indeed helium-rich compared to classical
EHB stars and also considerably hotter than the hottest EHB models
without flash mixing.
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Title: Photospheric Abundances of the Hot Stars in NGC 1399
Authors: Brown, T. M.; Ferguson, H. C.; O'Connell, R. W.; Ohl, R. G.
2001AAS...199.2002B Altcode: 2001BAAS...33Q1339B
We present far-UV spectroscopy of the giant elliptical galaxy NGC1399,
obtained with the Far Ultraviolet Spectroscopic Explorer. Of all
quiescent ellipticals with measured UV emission, NGC1399 has the
strongest known “UV upturn” - a sharp rise in the spectrum shortward
of 2500 Å. It is now well-established that this emission comes from hot
horizontal branch (HB) stars and their progeny; however, the chemical
composition of these stars has been the subject of a long-standing
debate. Our spectra, covering 900 - 1200 Å, clearly show photospheric
absorption lines from the hot HB stars in this galaxy. The abundance
of N appears nearly solar, Si is at 30% of the solar value, and C is
at 4% of the solar value. Such abundances anomalies are a natural
consequence of gravitational diffusion, and are also observed in
subdwarf B stars of the Galactic field. Our spectra suggest that the
hot stars responsible for the UV upturn are drawn from a metal-rich
population. Although NGC1399 is at the center of the Fornax cluster,
we find no evidence for OVI cooling flow emission. The upper limit to
λ λ 1032,1038 emission is 3.6 x 10<SUP>-15</SUP> erg s<SUP>-1</SUP>
cm<SUP>-2</SUP>, equivalent to 0.1 M<SUB>sun</SUB> yr<SUP>-1</SUP>. This
OVI emission is far less than that predicted by cooling flow models
of the observed NGC1399 X-ray luminosity.
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Title: STIS Status after the Switch to Side-2, Calibration and
Time-Tag Fixes
Authors: Davies, J. E.; Brown, T. M.; Goudfrooij, P.; Proffitt, C.;
Sahu, K. C.; Stys, D.; Valenti, J.
2001AAS...199.0803D Altcode: 2001BAAS...33.1316D
Since July 2001, STIS has been operating on its secondary (Side-2)
electronics due to the failure of the primary (Side-1) system. The
change to Side-2 has required new calibration work. The dark rate of
the STIS CCD varies after the switch to Side-2, as it depends on the
temperature of the CCD which cannot be regulated precisely using Side-2
electronics. By tracking the CCD housing temperature, the relation of
this dark rate to the housing temperature is found to be linear for
pixels at a fixed dark rate, but the relation also depends (slightly) on
the dark rate. The STIS CCD read noise has increased by 1 electron/sec
for all four amplifiers after the switch to Side-2. This increased
read noise is due to electronic pick-up noise, unlike before when it
was consistent with white noise. Work towards reducing or removing
this pattern noise is ongoing. The sensitivity of STIS in the imaging
modes has been recalibrated and updated. This has also resulted in new
aperature throughputs. Since the switch to Side-2, the sensitivity seems
to have remained the same based on initial data. MAMA TIME-TAG data
retrieved from the archive prior to 13 Sep 2001 may contain erroneous
temporal gaps and jumps, potentially affecting the flux calibration
of extracted spectra. New archive software installed on 13 Sep 2001
fixes all known problems with TIME-TAG data.
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Title: The Stellar Halos of Spiral Galaxies beyond the Local Group
Authors: Ferguson, H. C.; Rich, R. M.; Brown, T. M.; Smith, T. E.;
Mouhcine, M.
2001AAS...199.5212F Altcode: 2001BAAS...33.1380F
Were the extended stellar halos the first stellar populations to
form in spiral galaxies, or have they been accreted over time from
dwarf galaxies? What are the systematic relations between the disk,
the bulge and the halo? Does stellar mass of the halo scale with the
mass of the bulge or the mass of the entire galaxy? To begin to address
such questions we observed nine nearby spiral galaxies with WFPC2 and
resolved the top few magnitudes of the red-giant branch in the halo
population. Specifically, the WFPC2 fields were placed 2 to 13 kpc
off the minor-axis of the disks of NGC55, 247, 253, 300, 2903, 3031,
4244, 4258, and 4945. These observations allow the first systematic
study of the spatial distributions, metallicities and metallicity
distributions of halo stars in normal spiral galaxies outside of the
Local Group. We present a preliminary analysis of the color-magnitude
diagrams including: estimates of the mean metallicities and metallicity
distributions of each galaxy, estimates of the TRGB distances, estimates
of the radial density profiles and a search for metallicity gradients,
and first look at systematic trends within the sample of galaxies. This
work is supported by a grant from STScI which is operated by AURA
for NASA.
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Title: HST Studies of the Core of 47 Tucanae
Authors: Howell, J. H.; Warren, J. A.; Guhathakurta, P.; Gilliland,
R. L.; Albrow, M. D.; Sarajedini, A.; Brown, T. M.; Charbonneau, D.;
Burrows, A. S.; Cochran, W. D.; Baliber, N.; Edmonds, P. D.; Frandsen,
S.; Bruntt, H.; Lin, D. N. C.; Vogt, S. S.; Choi, P.; Marcy, G. W.;
Mayor, M.; Naef, D.; Milone, E. F.; Stagg, C. R.; Williams, M. D.;
Sigurdsson, S.; VandenBerg, D. A.
2001AAS...198.9505H Altcode: 2001BAAS...33.1182H
The 8.3 day HST experiment described by R. L. Gilliland, et al. 2000
is aimed at detecting planetary transits in the globular cluster
47 Tucanae. An important by-product is a set of extremely deep
WFPC2 images in F555W (V) and F814W (I) of the dense cluster core
region. The effective exposure times in each of these bands is over
100,000 s, and extensive sub-pixel dithers between individual exposures
supports the creation of 4x oversampled images in which the FWHM of
the point spread function is < ~70 mas (PC) and < ~140 mas
(WF CCDs). Limited use is made of the shorter exposure time F336W
(U) data. This poster describes several studies underway using this
outstanding data set. First is a study of mass segregation in the core
of 47 Tuc using this extremely deep WFPC2 data set. The degree of mass
segregation is characterized by the slope x of the best fitting stellar
mass function, where x=+1.35 is the Salpeter value. The mass function
slope is found to vary from x=-5 in the cluster center to x=-2 at the
edge of the WFPC2 field of view at a radius around 100”, indicating
extreme mass segregation in the core of 47 Tuc. We also examine nearly
100 blue stragglers in 47 Tuc's core. These include: a bright, strongly
centrally concentrated population, and a faint population whose radial
distribution is similar to that of the giants. The luminosity function
and photometric properties of these two kinds of 47 Tuc blue stragglers
are compared to predictions of blue straggler formation models. Blue
stragglers are also discussed in relation to millisecond pulsars and
other exotic objects in the cluster core. The binary sequence in 47
Tuc will be examined in future work. Funding has been provided via a
NASA/STScI grant for GO-8267.
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Title: The Frequency of Binary Stars in the Core of 47 Tucanae
Authors: Albrow, Michael D.; Gilliland, Ronald L.; Brown, Timothy M.;
Edmonds, Peter D.; Guhathakurta, Puragra; Sarajedini, Ata
2001ApJ...559.1060A Altcode: 2001astro.ph..5441A
Differential time series photometry has been derived for 46,422
main-sequence stars in the core of 47 Tucanae. The observations
consisted of near-continuous 160 s exposures alternating between the
F555W and F814W filters for 8.3 days in 1999 July with the Wide Field
Planetary Camera 2 on the Hubble Space Telescope. Using Fourier and
other search methods, 11 detached eclipsing binaries and 15 W Ursa
Majoris stars have been discovered plus an additional 10 contact or
near-contact noneclipsing systems. After correction for nonuniform area
coverage of the survey, the observed frequencies of detached eclipsing
binaries and W UMa stars within 90" of the cluster center are 0.022% and
0.031%, respectively. The observed detached eclipsing binary frequency,
the assumptions of a flat binary distribution with log period, and
assuming that the eclipsing binaries with periods longer than about 4
days have essentially their primordial periods imply an overall binary
frequency of 13%+/-6%. The observed W UMa frequency and the additional
assumptions that W UMa stars have evolved to contact according to
tidal circularization and angular momentum loss theory and that the
contact binary lifetime is 10<SUP>9</SUP> yr imply an overall binary
frequency of 14%+/-4%. An additional 71 variables with periods from 0.4
to 10 days have been found, which are likely to be BY Draconis stars in
binary systems. The radial distribution of these stars is the same as
that of the eclipsing binaries and W UMa stars and is more centrally
concentrated than average stars but less so than the blue straggler
stars. A distinct subset of six of these stars falls in an unexpected
domain of the color-magnitude diagram, comprising what we propose to
call red stragglers. Based on observations with the NASA/ESA Hubble
Space Telescope obtained at the Space Telescope Science Institute,
which is operated by AURA, Inc. under NASA contract NAS 5-26555.
---------------------------------------------------------
Title: Transmission Spectra as Diagnostics of Extrasolar Giant
Planet Atmospheres
Authors: Brown, Timothy M.
2001ApJ...553.1006B Altcode: 2001astro.ph..1307B
Atmospheres of transiting extrasolar giant planets (EGPs) such as
HD 209458b must impose features on the spectra of their parent stars
during transits; these features contain information about the physical
conditions and chemical composition of the atmospheres. The most
convenient observational index showing these features is the “spectrum
ratio” ℜ(λ), defined as the wavelength-dependent ratio of spectra
taken in and out of transit. The principal source of structure in ℜ is
the variation with wavelength of the height at which the EGP atmosphere
first becomes opaque to tangential rays-one may think of the planet
as having different radii, and hence different transit depths, at each
wavelength. The characteristic depth of absorption lines in ℜ scales
with the atmospheric scale height and with the logarithm of the opacity
ratio between continuum and strong lines. For close-in EGPs, line depths
of 10<SUP>-3</SUP> relative to the stellar continuum can occur. The
atmospheres of EGPs probably consist mostly of molecular species,
including H<SUB>2</SUB>, CO, H<SUB>2</SUB>O, and CH<SUB>4</SUB>, while
the illuminating flux is characteristic of a Sun-like star. Thus,
the most useful diagnostics are likely to be the near-infrared bands
of these molecules, and the visible/near-IR resonance lines of the
alkali metals. I describe a model that estimates ℜ(λ) for EGPs with
prescribed radius, mass, temperature structure, chemical composition,
and cloud properties. This model assumes hydrostatic and chemical
equilibrium in an atmosphere with chemistry involving only H, C, N,
and O. Other elements (He, Na, K, Si) are included as nonreacting
minor constituents. Opacity sources include Rayleigh scattering,
the strongest lines of Na and K, collision-induced absorption by
H<SUB>2</SUB>, scattering by cloud particles, and molecular lines of CO,
H<SUB>2</SUB>O, and CH<SUB>4</SUB>. The model simulates Doppler shifts
from height-dependent winds and from planetary rotation, and deals in
a schematic way with photoionization of Na and K by the stellar UV
flux. Using this model, I investigated the diagnostic potential of
various spectral features for planets similar to HD 209458b. Clouds
are the most important determinants of the depth of features in ℜ
they decrease the strength of all features as they reach higher in
the atmosphere. The relative strengths of molecular lines provide
diagnostics for the heavy-element abundance, temperature, and the
vertical temperature structure, although diagnostics for different
physical properties tend to be somewhat degenerate. Planetary rotation
with likely periods leaves a clear signature on the line profiles,
as do winds with speeds comparable to that of rotation. Successful
use of these diagnostics will require spectral observations with
signal-to-noise ratio (S/N) of 10<SUP>3</SUP> or better and resolving
power R=λ/δλ ranging from 10<SUP>3</SUP> to 10<SUP>6</SUP>,
depending on the application. Because of these stringent demands, it
will be important to evolve analysis methods that combine information
from many lines into a few definitive diagnostic indices.
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Title: Hubble Space Telescope Time-Series Photometry of the Transiting
Planet of HD 209458
Authors: Brown, Timothy M.; Charbonneau, David; Gilliland, Ronald L.;
Noyes, Robert W.; Burrows, Adam
2001ApJ...552..699B Altcode: 2001astro.ph..1336B
We have observed four transits of the planet of HD 209458 using
the STIS spectrograph on the Hubble Space Telescope (HST). Summing
the recorded counts over wavelength between 582 and 638 nm yields a
photometric time series with 80 s time sampling and relative precision
of about 1.1×10<SUP>-4</SUP> per sample. The folded light curve can
be fitted within observational errors using a model consisting of an
opaque circular planet transiting a limb-darkened stellar disk. In
this way we estimate the planetary radius R<SUB>p</SUB>=1.347+/-0.060
R<SUB>Jup</SUB>, the orbital inclination i=86.6d+/-0.14d, the stellar
radius R<SUB>*</SUB>=1.146+/-0.050 R<SUB>solar</SUB>, and one parameter
describing the stellar limb darkening. Our estimated radius is smaller
than those from earlier studies but is consistent within measurement
errors and also with theoretical estimates of the radii of irradiated
Jupiter-like planets. Satellites or rings orbiting the planet would, if
large enough, be apparent from distortions of the light curve or from
irregularities in the transit timings. We find no evidence for either
satellites or rings, with upper limits on satellite radius and mass
of 1.2 R<SUB>⊕</SUB> and 3 M<SUB>⊕</SUB>, respectively. Opaque
rings, if present, must be smaller than 1.8 planetary radii in
radial extent. The high level of photometric precision attained in
this experiment confirms the feasibility of photometric detection of
Earth-sized planets circling Sun-like stars. Based on observations with
the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope
Science Institute, which is operated by the Association of Universities
for Research in Astronomy, Inc. under NASA contract NAS 5-26555.
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Title: FUSE Observations of the UV-Bright Star ZNG 1 in M5 (NGC 5904)
Authors: Dixon, W. V.; Brown, T. M.; Landsman, W. B.
2001AAS...198.4505D Altcode: 2001BAAS...33Q.847D
Hot post-AGB stars in globular clusters typically exhibit Fe abundances
considerably lower than the cluster mean. This anomaly may reflect
selective condensation of metals onto dust grains at the end of the
AGB phase, a mechanism first suggested for cooler post-AGB stars
with peculiar Fe abundances. To investigate this phenomenon, we have
observed several UV-bright stars in globular clusters with FUSE, the
Far Ultraviolet Spectroscopic Explorer. In this poster, we present
first results for the post-AGB star ZNG 1 in M5 (NGC 5904). Previous
studies have shown the star to have an effective temperature of
about 41,000 K and a surface gravity of log g = 4.5. Using the TLUSTY
and SYNSPEC routines of Ivan Hubeny, we construct a set of non-LTE
stellar atmosphere models and synthetic spectra, with which we derive
the star's photospheric parameters and abundances. We present our
results and discuss their implications for AGB and post-AGB stellar
evolution. This research is supported by NASA grant NAG5-8962.
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Title: Understanding Horizontal Branch Anomalies in NGC 2808
Authors: Brown, T. M.; Sweigart, A. V.; Lanz, T.; Landsman, W. B.;
Hubeny, I.
2001AAS...198.4302B Altcode: 2001BAAS...33..844B
We present an ultraviolet color-magnitude diagram (CMD) spanning the hot
horizontal branch (HB), blue straggler, and white dwarf populations
of the globular cluster NGC 2808. These data, obtained with the
Space Telescope Imaging Spectrograph (STIS), demonstrate that NGC
2808 harbors a significant population of hot subluminous HB stars,
an anomaly only previously reported for the globular cluster Omega
Cen. Our theoretical modeling indicates that the location of these
subluminous stars in the CMD, as well as the high temperature gap along
the HB of NGC 2808, can be explained if these stars underwent a late
helium-core flash while descending the white dwarf cooling curve. We
show that the convective zone produced by such a late helium flash will
penetrate into the hydrogen envelope, thereby mixing hydrogen into
the hot helium-burning interior, where it is rapidly consumed. This
phenomenon is analogous to the "born again" scenario for producing
hydrogen-deficient stars following a late helium-shell flash. The flash
mixing of the envelope greatly enhances the envelope helium and carbon
abundances that, in turn, leads to a discontinuous increase in the HB
effective temperatures. We argue that the hot HB gap is associated with
this theoretically predicted dichotomy in the HB properties. Moreover,
the changes in the emergent spectral energy distribution caused by
these abundance changes are primarily responsible for explaining
the hot subluminous HB stars. Although further evidence is needed to
confirm that a late helium-core flash can account for the subluminous HB
stars and the hot HB gap, we demonstrate that an understanding of these
stars requires use of sophisticated models for the stellar evolution,
atmospheres, and synthetic spectra.
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Title: A Lack of Planets in 47 Tucanae from a Hubble Space Telescope
Search
Authors: Gilliland, Ronald L.; Brown, T. M.; Guhathakurta, P.;
Sarajedini, A.; Milone, E. F.; Albrow, M. D.; Baliber, N. R.; Bruntt,
H.; Burrows, A.; Charbonneau, D.; Choi, P.; Cochran, W. D.; Edmonds,
P. D.; Frandsen, S.; Howell, J. H.; Lin, D. N. C.; Marcy, G. W.; Mayor,
M.; Naef, D.; Sigurdsson, S.; Stagg, C. R.; Vandenberg, D. A.; Vogt,
S. S.; Williams, M. D.
2000ApJ...545L..47G Altcode:
We report results from a large Hubble Space Telescope project to observe
a significant (~34,000) ensemble of main-sequence stars in the globular
cluster 47 Tucanae with a goal of defining the frequency of inner
orbit, gas giant planets. Simulations based on the characteristics of
the 8.3 days of time series data in the F555W and F814W Wide Field
Planetary Camera 2 (WFPC2) filters show that ~17 planets should
be detected by photometric transit signals if the frequency of hot
Jupiters found in the solar neighborhood is assumed to hold for 47
Tuc. The experiment provided high-quality data sufficient to detect
planets. A full analysis of these WFPC2 data reveals ~75 variables,
but no light curves resulted for which a convincing interpretation as
a planet could be made. The planet frequency in 47 Tuc is at least
an order of magnitude below that for the solar neighborhood. The
cause of the absence of close-in planets in 47 Tuc is not yet known;
presumably the low metallicity and/or crowding of 47 Tuc interfered
with planet formation, with orbital evolution to close-in positions,
or with planet survival. Based on observations with the NASA/ESA Hubble
Space Telescope obtained at STScI, which is operated by AURA, Inc.,
under NASA contract NAS5-26555.
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Title: Seeking the Atmospheric Transmission Spectrum of HD209458b
Authors: Brown, T. M.; Butler, R. P.; Charbonneau, D.; Noyes, R. W.;
Sasselov, D.; Libbrecht, K. G.; Marcy, G. W.; Seager, S.; Vogt, S. S.
2000AAS...197.1105B Altcode: 2000BAAS...32Q1417B
Transiting extrasolar giant planets such as HD209458b should impress
a spectroscopic signature on the light that is transmitted through
the outer parts of their atmospheres. Theory suggests that the depths
of absorption features resulting from this effect may be as large as
about 10<SUP>-3</SUP> of the parent star's continuum intensity. Such
spectral features could provide important diagnostics concerning the
composition and physical state of the planetary atmosphere. Accordingly,
we have obtained low-noise spectra of HD209458 during two transits
of its planet, once in visible light using the HIRES spectrograph at
the Keck I telescope, and once in the near infrared using the NIRSPEC
spectrograph at Keck II. We describe the methods employed and the
results of searches for spectral signatures of neutral atomic sodium,
carbon monoxide, and other atomic and molecular species.
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Title: Searching for Shadows of Other Earths
Authors: Doyle, L. R.; Deeg, H. J.; Brown, T. M.
2000SciAm.283c..58D Altcode: 2000SciAm.283c..38D
No abstract at ADS
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Title: Multicolor Observations of a Planetary Transit of HD 209458
Authors: Jha, Saurabh; Charbonneau, David; Garnavich, Peter M.;
Sullivan, Denis J.; Sullivan, Tiri; Brown, Timothy M.; Tonry, John L.
2000ApJ...540L..45J Altcode: 2000astro.ph..7245J
We present BVRIZ photometric observations of HD 209458 during the
transit by its planetary companion on UT 1999 November 15 with the
University of Hawaii 0.6 and 2.2 m telescopes and the High Altitude
Observatory STARE telescope. The detailed shape of the transit
curve is predicted to vary with color primarily as a result of the
color-dependent limb darkening of the star but potentially due as well
to the effect of color-dependent opacity in the planetary atmosphere. We
model the light curves and present refined values for the transit timing
and orbital period, useful for planning future observations of the
planetary transit. We also derive significantly improved measurements
of the planetary radius, R<SUB>p</SUB>=1.55+/-0.10 R<SUB>Jup</SUB>,
stellar radius, R<SUB>s</SUB>=1.27+/-0.05 R<SUB>solar</SUB>, and
orbital inclination, i=85.9d+/-0.5d. The derived planetary radius
favors evolutionary models in which the planet has a low albedo.
---------------------------------------------------------
Title: A Lack of Planets in 47 Tucanae from an HST Search
Authors: Gilliland, Ronald L.; Brown, T. M.; Guhathakurta, P.;
Sarajedini, A.; Milone, E. F.; Albrow, M. D.; Baliber, N. R.; Bruntt,
H.; Burrows, A.; Charbonneau, D.; Choi, P.; Cochran, W. D.; Edmonds,
P. D.; Frandsen, S.; Howell, J. H.; Lin, D. N. C.; Marcy, G. W.; Mayor,
M.; Naef, D.; Sigurdsson, S.; Stagg, C. R.; VandenBerg, D. A.; Vogt,
S. S.; Williams, M. D.
2000astro.ph..9397G Altcode:
We report results from a large Hubble Space Telescope project to observe
a significant (~34,000) ensemble of main sequence stars in the globular
cluster 47 Tucanae with a goal of defining the frequency of inner-orbit,
gas-giant planets. Simulations based on the characteristics of the 8.3
days of time-series data in the F555W and F814W WFPC2 filters show
that ~17 planets should be detected by photometric transit signals
if the frequency of hot Jupiters found in the solar neighborhood is
assumed to hold for 47 Tuc. The experiment provided high-quality
data sufficient to detect planets. A full analysis of these WFPC2
data reveals ~75 variables, but NO light curves resulted for which
a convincing interpretation as a planet could be made. The planet
frequency in 47 Tuc is at least an order of magnitude below that for
the solar neighborhood. The cause of the absence of close-in planets in
47 Tuc is not yet known; presumably the low metallicity and/or crowding
of 47 Tuc interfered with planet formation, with orbital evolution to
close-in positions, or with planet survival.
---------------------------------------------------------
Title: Eclipsing Binaries in 47 Tuc: Bonus of an HST Planetary Search
Authors: Milone, E. F.; Stagg, C. R.; Williams, M. D.; Brown, T. M.;
Charbonneau, D.; Gilliland, R. L.; Albrow, M. D.; Burrows, A. S.;
Cochran, W. D.; Baliber, N.; Edmonds, P. D.; Frandsen, S.; Bruntt,
H.; Guhathakurta, P.; Choi, P.; Lin, D. N. C.; Vogt, S. S.; Howell,
J. H.; Marcy, G. W.; Mayor, M.; Naef, D.; Sarajedini, A.; Sigurdsson,
S.; VandenBerg, D. A.
2000AAS...196.4603M Altcode: 2000BAAS...32..746M
A direct benefit of the 8.3 d HST experiment described by
R. L. Gilliland, et al. (see their poster), is the opportunity to obtain
fundamental stellar data from an earlier generation of stars than are
found in the local field and in (relatively young) open clusters, the
sources of almost all our current knowledge of stellar parameters. Of 32
variables examined thus far from time-series detections (see the Brown,
et al., poster), 9 were previously known; of the 23 remaining, one
remains a possible (though unlikely) planetary transit candidate. At
present writing, 17 confirmed or potential eclipsing binary systems
have been closely examined: five contact/over-contact; two short-period
β Lyrae-type, four Algol-type; one asymmetric (O'Connell effect)
light curve-, but likely eclipsing, variable; one possible ellipsoidal
variable; and four others with asymmetric low-amplitude variation,
still under investigation. Preliminary modeling is nearly complete for
six binaries in this still incomplete sample, and is underway for the
others. Unadjusted and starting parameters are from VandenBerg's recent
isochrone models and from an eclipsing binary simulation database
of more than 8000 models created by Calgary students M. McClure,
and B. Desnoyers-Winmill. Kurucz limb-darkening and atmospheric
models straddling the metallicity range of the cluster are used in
conjunction with Calgary versions of the Wilson-Devinney code, WD98
& wd98k93; the time-based mode is used to improve the periods and
epochs. J Kallrath (BASF) developed and D. Terrell (SwRI) and W. Van
Hamme (FIU) contributed to the value of these tools. The eclipsing
binary modeling is funded by NSERC of Canada and by the Univ. of
Calgary Research Grants Committee through grants to EFM.
---------------------------------------------------------
Title: An HST Search for Planets in the Globular Cluster 47 Tucanae
Authors: Gilliland, R. L.; Albrow, M. D.; Brown, T. M.; Charbonneau,
D.; Burrows, A.; Cochran, W. D.; Baliber, N.; Edmonds, P. D.; Frandsen,
S.; Bruntt, H.; Guhathakurta, P.; Choi, P.; Howell, J. H.; Lin,
D. N. C.; Vogt, S. S.; Marcy, G. W.; Mayor, M.; Naef, D.; Milone,
E. F.; Stagg, C. R.; Williams, M. D.; Sarajedini, A.; Sigurdsson,
S.; VandenBerg, D. A.
2000AAS...196.0202G Altcode: 2000BAAS...32R.675G
HST was used for 8.3 days in July '99 to monitor over 30,000 stars on
the main sequence of 47 Tuc photometrically with a goal of detecting
planets via transit signals. Expected transit depths for 1.3 Jupiter
radii planets increase from 1% near main sequence turnoff to 6% at 4
magnitudes fainter due to decreasing stellar radii. Over this domain
realized time series rms, obtained with PSF fitting in difference
images, smoothly increases from 0.3% to 2.5%. With ~645 data points
in each of WFPC2 F555W and F814W filters any planet with P < 4.2
days should provide securely detectable transits lasting 2-4 hours
twice in each of V and I. Based on the frequency of inner-orbit,
gas-giant planets from solar neighborhood radial velocity surveys we
expect to detect 15 to 20 candidate planets, but see none (with 75%
search completion) in this low metalicity, crowded stellar system;
see also T.M. Brown poster. Many eclipsing binaries and variable
stars are detected; see also E.F. Milone poster. We provide a project
overview and details on: (1) reduction steps and resulting deep
(> 100,000s in V, I; 14,360s U) co-added, over-sampled images,
(2) key analysis steps that provide near-Poisson limited photometric
time-series precisions for dithered, under-sampled, crowded-field images
with significant focus variations in time, (3) global summaries of
time series precisions and sensitivity to detecting planets, and (4)
a few time series of particular interest. Funding has been provided
via a NASA/STScI grant for GO-8267.
---------------------------------------------------------
Title: Extreme Mass Segregation in the Core of 47 Tucanae (NGC 104):
Bonus of an HST Planetary Search
Authors: Howell, J. H.; Guhathakurta, P.; Sarajedini, A.; Gilliland,
R. L.; Albrow, M. D.; Brown, T. M.; Charbonneau, D.; Burrows, A. S.;
Cochran, W. D.; Baliber, N.; Edmonds, P. D.; Frandsen, S.; Bruntt,
H.; Lin, D. N. C.; Vogt, S. S.; Choi, P.; Marcy, G. W.; Mayor, M.;
Naef, D.; Milone, E. F.; Stagg, C. R.; Williams, M. D.; Sigurdsson,
S.; VandenBerg, D. A.
2000AAS...196.4108H Altcode: 2000BAAS...32..740H
The 8.3 d HST experiment described by R. L. Gilliland, et al. (see
their poster) is aimed at detecting planetary transits in the globular
cluster 47 Tucanae. An important by-product is a set of extremely
deep WFPC2 images in F555W (V) and F814W (I) of the dense cluster
core region. The effective exposure times in each of these bands is
over 100,000 s, and extensive sub-pixel dithers between individual
exposures supports the creation of 4x oversampled images in which the
FWHM of the point spread function is < ~70 mas (PC) and < ~140 mas
(WF CCDs). Limited use is made of the shorter exposure time F336W (U)
data. This poster describes a study of mass segregation in the core of
47 Tuc using this extremely deep WFPC2 data set. Luminosity functions
are constructed in a sequence of radial bins, and are compared with
theoretical luminosity functions (Bergbusch & VandenBerg 1992)
based on a variety of power-law stellar mass functions. The degree of
mass segregation is characterized by the slope x of the best fitting
stellar mass function, where x=+1.35 is the Salpeter value. The mass
function slope is found to vary from x ~-5 in the cluster center to x
~-2 at the edge of the WFPC2 field of view, r ~100”, indicating extreme
mass segregation in the core of 47 Tuc. The results are coupled with
image simulations and results derived from a set of archival short WFPC2
exposures to assess the effect of faint end incompleteness in the latter
data set. Funding has been provided via a NASA/STScI grant for GO-8267.
---------------------------------------------------------
Title: Ultraviolet Galaxy Counts from STIS Observations of the Hubble
Deep Fields
Authors: Gardner, J. P.; Brown, T. M.; Ferguson, H. C.
2000AAS...196.0607G Altcode: 2000BAAS...32..685G
We present galaxy counts in the near and far ultraviolet (NUV and FUV)
obtained from Space Telescope Imaging Spectrograph (STIS) observations
of portions of the Hubble Deep Field North, (HDFN), the Hubble Deep
Field South, (HDFS) and a parallel field near the HDFN. All three fields
have deep (AB>29) optical imaging, and we determine magnitudes
by taking the ultraviolet flux detected within the limiting optical
isophote. An analysis of the UV-optical colors of detected objects,
combined with a visual inspection of the UV images, indicates that
there are no detectable objects in the UV images which are not also
detected in the optical. We measure the detection area and completeness
as a function of magnitude by taking the size-magnitude distribution
of galaxies in the entire HDFN WFPC2 V+I image, applying the measured
UV-optical colors from the detected galaxies, and determining the
total area over which each galaxy would have been detected in the UV
images. The average area for the simulated galaxies in each UV magnitude
bin, (including galaxies which would not be detected at all), provides
the effective area and completeness for the bin. We test this procedure
with Monte Carlo simulations. The galaxy counts reach to AB=29 in
both the NUV and FUV; 1 magnitude fainter than the HDF F300W counts,
and 7 magnitudes fainter than balloon-based counts. We compare our
measured counts to various models.
---------------------------------------------------------
Title: Blue Stragglers in the Core of 47 Tucanae (NGC 104): Bonus
of an HST Planetary Search
Authors: Guhathakurta, P.; Howell, J. H.; Sarajedini, A.; Gilliland,
R. L.; Albrow, M. D.; Brown, T. M.; Charbonneau, D.; Burrows, A. S.;
Cochran, W. D.; Baliber, N.; Edmonds, P. D.; Frandsen, S.; Bruntt,
H.; Lin, D. N. C.; Vogt, S. S.; Choi, P.; Marcy, G. W.; Mayor, M.;
Naef, D.; Milone, E. F.; Stagg, C. R.; Williams, M. D.; Sigurdsson,
S.; VandenBerg, D. A.
2000AAS...196.4107G Altcode: 2000BAAS...32..740G
A secondary data product from the 8.3 d HST campaign to search
for planetary transits in 47 Tucanae is a set of coadded F555W (V),
F814W (I), and F336W (U) images with WFPC2 of unprecedented depth and
resolution (see the poster by R. L. Gilliland, et al.). The pointings
cover about 100 sub-pixel dither positions so that it is possible to
construct 4x oversampled images with FWHM< ~70 mas and < ~140
mas point spread functions in the PC and WF CCDs, respectively. This
poster uses this high quality data set to study ~100 blue stragglers in
47 Tuc's core. These include: a bright, strongly centrally concentrated
population, and a faint population whose radial distribution is similar
to that of the giants. The faint straggler region of the color-magnitude
diagram tends to be contaminated by subgiant/turnoff star blend
artifacts even in “normal resolution” (i.e., non-oversampled) WFPC2
images; this is illustrated using archival short WFPC2 images of 47
Tuc. A statistical technique is used to separate blend artifacts from
true faint blue stragglers---the ultra deep WFPC2 data set provides
a cross check. The technique should be useful for blue straggler
studies of other clusters for which only normal resolution WFPC2 data
are available. The luminosity function and photometric properties of
these two kinds of 47 Tuc blue stragglers are compared to predictions of
blue straggler formation models. Blue stragglers are also discussed in
relation to millisecond pulsars and other exotic objects in the cluster
core. Funding has been provided via a NASA/STScI grant for GO-8267.
---------------------------------------------------------
Title: HST Photometry of 47 Tucanae: Time Series Analysis and Search
for Giant Planets
Authors: Brown, T. M.; Charbonneau, D.; Gilliland, R. L.; Albrow,
M. D.; Burrows, A. S.; Cochran, W. D.; Baliber, N.; Edmonds, P. D.;
Frandsen, S.; Bruntt, H.; Guhathakurta, P.; Choi, P.; Howell, J. H.;
Lin, D. N. C.; Vogt, S. S.; Marcy, G. W.; Mayor, M.; Naef, D.; Milone,
E. F.; Stagg, C. R.; Williams, M. D.; Sarajedini, A.; Sigurdsson,
S.; VandenBerg, D. A.
2000AAS...196.0203B Altcode: 2000BAAS...32..676B
We have analyzed HST time series data of more than 34000 stars in the
globular cluster 47 Tuc in a search for transiting Jupiter-sized planets
in small orbits. The data consist of roughly 645 time samples each
in bands centered at 555 nm and 814 nm, with fairly uniform sampling
(except for orbital gaps) over an 8.3-day interval. They are described
in detail in a poster by Gilliland et al. We used a matched-filter
technique to search for periodic transit events in these time series
over a period range between 0.5 and 8.3 days. Blind tests with injected
artificial transits yielded recovery rates of about 85% for planets
of 1.3 Jupiter radii, and above 60% for planets of 1.0 Jupiter radii,
in a sample spanning 4 magnitudes below main sequence turnoff. At
abstract time, analysis was complete for 27000 stars. These data
reveal no convincing planet candidates; 15 to 20 detections would be
expected if the occurrence rate in 47 Tuc were the same as indicated
by radial velocity searches of stars in the solar neighborhood, and
if planet radii are indeed above 1 R<SUB>Jup</SUB>. This discrepancy
suggests that at least one of the processes of formation, migration,
or survival of close-in planets may be significantly altered in the
cluster environment. Many elipsing binaries and other variables were
found in this analysis. Some of them are described by Milone et al. in
an accompanying poster. Funding has been provided via a NASA/STScI
GO grant.
---------------------------------------------------------
Title: A High-Eccentricity Low-Mass Companion to HD 89744
Authors: Korzennik, Sylvain G.; Brown, Timothy M.; Fischer, Debra A.;
Nisenson, Peter; Noyes, Robert W.
2000ApJ...533L.147K Altcode: 2000astro.ph..3045K
HD 89744 is an F7 V star with a mass of 1.4 M<SUB>solar</SUB>, an
effective temperature of 6166 K, an age of 2.0 Gyr, and metallicity
[Fe/H]=0.18. The radial velocity of the star has been monitored
with the Advanced Fiber-Optic Echelle spectrograph at the Whipple
Observatory since 1996, and evidence has been found for a low-mass
companion. The data were complemented by additional data from the
Hamilton spectrograph at Lick Observatory during the companion's
periastron passage in the fall of 1999. As a result, we have
determined the star's orbital wobble to have a period P=256 days,
an orbital amplitude K=257 m s<SUP>-1</SUP>, and an eccentricity
e=0.7. From the stellar mass, we infer that the companion has a
minimum mass m<SUB>2</SUB>sini=7.2 M<SUB>J</SUB> in an orbit with a
semimajor axis a<SUB>2</SUB>=0.88 AU. The eccentricity of the orbit,
among the highest known for extrasolar planets, continues the trend
that extrasolar planets with semimajor axes greater than about 0.15 AU
tend to have much higher eccentricities than are found in our solar
system. The high metallicity of the parent star reinforces the trend
that parent stars of extrasolar planets tend to have high metallicity.
---------------------------------------------------------
Title: Progress in Observational Asteroseismology
Authors: Brown, T. M.
2000mons.proc....1B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Photometric Detection of Transits by Extrasolar Planets
Authors: Brown, T. M.
2000mons.proc...71B Altcode:
Transit photometry provides an efficient way to detect and to study
extrasolar planets. As the recent detection of transits in HD 209458
demonstrates, the intensity diminution as a giant planet crosses the
disk of its star is about 1%, a signal that is easily large enough to
detect using groundbased telescopes. With spaceborne photometers such as
MONS, planets of the Earth's size or smaller might be detected. Most
importantly, planets in transit can be studied in ways that other
extrasolar planets cannot; in some cases it should be possible to
derive fairly detailed information about the physical nature of the
planets from these follow-up studies.
---------------------------------------------------------
Title: The Spectroscopic Orbit of the Planetary Companion Transiting
HD 209458
Authors: Mazeh, Tsevi; Naef, Dominique; Torres, Guillermo; Latham,
David W.; Mayor, Michel; Beuzit, Jean-Luc; Brown, Timothy M.; Buchhave,
Lars; Burnet, Michel; Carney, Bruce W.; Charbonneau, David; Drukier,
Gordon A.; Laird, John B.; Pepe, Francesco; Perrier, Christian;
Queloz, Didier; Santos, Nuno C.; Sivan, Jean-Pierre; Udry, Stéphane;
Zucker, Shay
2000ApJ...532L..55M Altcode: 2000astro.ph..1284M
We report a spectroscopic orbit with period P=3.52433+/-0.00027 days
for the planetary companion that transits the solar-type star HD
209458. For the metallicity, mass, and radius of the star, we derive
[Fe/H]=0.00+/-0.02, M<SUB>*</SUB>=1.1+/-0.1 M<SUB>solar</SUB>, and
R<SUB>*</SUB>=1.2+/-0.1 R<SUB>solar</SUB>. This is based on a new
analysis of the iron lines in our HIRES template spectrum and also on
the absolute magnitude, effective temperature, and color of the star,
and it uses isochrones from four different sets of stellar evolution
models. Using these values for the stellar parameters, we reanalyze the
transit data and derive an orbital inclination of i=86.1d+/-1.6d. For
the planet, we derive a mass of M<SUB>p</SUB>=0.69+/-0.05
M<SUB>Jup</SUB>, a radius of R<SUB>p</SUB>=1.40+/-0.17 R<SUB>Jup</SUB>,
and a density of ρ=0.31+/-0.07 g cm<SUP>-3</SUP>. 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 the National Aeronautics
and Space Administration. The Observatory was made possible by the
generous financial support of the W. M. Keck Foundation. The other data
were obtained at Observatoire de Haute-Provence (France) and with the
1.2 m Euler Swiss telescope at La Silla Observatory, ESO Chile.
---------------------------------------------------------
Title: Detecting Planets Using Transit Observations (Invited Review)
Authors: Brown, T. M.
2000ASPC..219..557B Altcode: 2000dpp..conf..557B
No abstract at ADS
---------------------------------------------------------
Title: The STARE Project: a Transit Search for Hot Jupiters
Authors: Brown, T. M.; Charbonneau, D.
2000ASPC..219..584B Altcode: 2000dpp..conf..584B; 2000astro.ph..5009B
The STARE instrument is a small aperture, wide-field, CCD-based
telescope that delivers high cadence time series photometry on roughly
40,000 stars in a typical field centered on the galactic plane. In a
two-month observing run on a field, we obtain sufficient precision on
roughly 4,000 stars to detect a close-in Jupiter-sized companion in an
edge-on orbit. We also used this instrument to detect the planetary
transits across the Sun-like star HD209458. The project is now in
its third season, and we have acquired a large dataset on several
fields. Given the frequency of close-in extrasolar planets found by
the radial velocity surveys, and the recent confirmation that at least
some of these are indeed gas giants, the STARE project should be able
to detect roughly a dozen Jupiter-sized planets in its existing dataset.
---------------------------------------------------------
Title: Asteroseismology
Authors: Brown, T. M.
2000upse.conf..141B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Detection of Planetary Transits Across a Sun-like Star
Authors: Charbonneau, David; Brown, Timothy M.; Latham, David W.;
Mayor, Michel
2000ApJ...529L..45C Altcode: 1999astro.ph.11436C
We report high-precision, high-cadence photometric measurements of
the star HD 209458, which is known from radial velocity measurements
to have a planetary-mass companion in a close orbit. We detect two
separate transit events at times that are consistent with the radial
velocity measurements. In both cases, the detailed shape of the transit
curve due to both the limb darkening of the star and the finite size
of the planet is clearly evident. Assuming stellar parameters of 1.1
R<SUB>solar</SUB> and 1.1 M<SUB>solar</SUB>, we find that the data
are best interpreted as a gas giant with a radius of 1.27+/-0.02
R<SUB>Jup</SUB> in an orbit with an inclination of 87.1d+/-0.2d. We
present values for the planetary surface gravity, escape velocity, and
average density and discuss the numerous observations that are warranted
now that a planet is known to transit the disk of its parent star.
---------------------------------------------------------
Title: Evidence for Multiple Companions to υ Andromedae
Authors: Butler, R. Paul; Marcy, Geoffrey W.; Fischer, Debra A.;
Brown, Timothy M.; Contos, Adam R.; Korzennik, Sylvain G.; Nisenson,
Peter; Noyes, Robert W.
1999ApJ...526..916B Altcode:
The bright F8 V star υ Andromedae was previously reported to have
a 4.6 day Doppler velocity periodicity, consistent with having a
Jupiter-mass companion orbiting at 0.059 AU. Follow-up observations
by both the Lick and Advanced Fiber-Optic Echelle spectrometer (AFOE)
planet survey programs confirm this periodicity and reveal additional
periodicities at 241 and 1267 days. These periodicities are consistent
with Keplerian orbital motion and imply two additional companions
orbiting at 0.83 and 2.5 AU, with minimum (Msini) masses of 2.0 and
4.6 M<SUB>JUP</SUB>, respectively. Non-Keplerian explanations for the
observed Doppler velocity variations, including radial and nonradial
pulsations, rotational modulation of surface features, and stellar
magnetic cycles, are examined. These explanations seem unlikely
based on the observed photometric and chromospheric stability of the
star. This putative three-planet system is found to be dynamically
stable by both analytic techniques and numerical simulations. The
outer two companions both reside in eccentric orbits, as do all nine
known extrasolar planet candidates in distant orbits. If real, this
multiple-planet system is the first around a main-sequence star, and
its study should offer insights into planet formation, planet-planet
interactions, and the observed eccentricities of planetary orbits. <P
/>Based on observations obtained at Lick Observatory, operated by the
University of California, and at the Whipple Observatory, operated by
the Smithsonian Astrophysical Observatory.
---------------------------------------------------------
Title: The Evolution of Far-UV Emission in Elliptical Galaxies
Authors: Brown, T. M.; Bowers, C. W.; Kimble, R. A.; Ferguson, H. C.
1999AAS...195.0912B Altcode: 1999BAAS...31.1385B
The restframe UV-to-optical flux ratio, characterizing the “UV
upturn” phenomenon, is potentially the most sensitive tracer of age
in elliptical galaxies; models predict that it may change by orders
of magnitude over the course of a few Gyr. In order to trace the
evolution of the UV upturn as a function of redshift, we have used the
far-UV camera on the Space Telescope Imaging Spectrograph to image the
galaxy cluster CL0016+16 at z=0.55. Our 25 " x 25 " field includes four
bright elliptical galaxies, spectroscopically confirmed to be passively
evolving cluster members. The weak UV emission from the galaxies in our
image demonstrates that the UV upturn is very weak at a lookback time
5.6 Gyr earlier than our own, as compared to measurements of the UV
upturn in cluster E and S0 galaxies at z=0 and z=0.375. These images
are the first with sufficient depth to demonstrate the fading of the
UV upturn expected at moderate redshifts. We discuss these observations
and the implications for the formation history of galaxies.
---------------------------------------------------------
Title: Stellar and Planetary Explorer (SPEX)
Authors: Schou, J.; Bogart, R. S.; Bush, R. I.; Hoeksema, J. T.;
Scherrer, P. H.; Brown, T. M.; Buzasi, D. L.; Horner, S. D.; Korzennik,
S. G.
1999AAS...195.8808S Altcode: 1999BAAS...31.1506S
The Stellar and Planetary Explorer (SPEX) mission will search for
terrestrial inner planets around Sun-like (FGK, main sequence) stars
using photometric techniques as well as provide very long time series
for asteroseismology. If every Sun-like star had a planetary system
similar to ours, the proposed instrumentation would detect at least
100 terrestrial planets similar to the Earth or Venus and be able to
provide statistics on their diameters and orbital periods. SPEX will
accomplish this by continuously observing a large number of field stars
to detect planetary transits. The instrument consists of a fast Schmidt
camera with a mosaic of large CCD detectors. SPEX will observe a field
near the galactic plane from a geosynchronous orbit for a minimum of 3
years. The very long asteroseismic time series will allow inferences
on the interiors of more than 100 Sun-like stars with a variety of
masses and ages. This will allow us to substantially refine stellar
model calculations and in particular improve on the age estimates of
stars. This in turn is of considerable interest for the understanding
of the evolution of our galaxy and the universe as a whole. SPEX will
also provide new data for stellar activity and will be able to detect
the reflected light from large inner planets, such as those detected
using ground based Doppler velocity searches.
---------------------------------------------------------
Title: The STARE Project; A Transit Search for Hot Jupiters
Authors: Brown, T. M.; Charbonneau, D.
1999AAS...19510907B Altcode: 1999BAAS...31.1534B
Radial velocity surveys of nearby, solar-type stars have revealed
nine planets that orbit their parent stars with a separation of a
≲ 0.1 A.U. Close-in, extrasolar giant planets such as these will
produce a measurable photometric dimming of the star as the planet
transits the stellar disk. The motivation to undertake a transit
search is strong: It may be the first detection of extrasolar planets
by a method other than the radial velocity technique. Furthermore,
it would be the first survey of planets that is not strongly biased
toward solar-type stars. In combination with follow-up radial velocity
observations, transit measurements will yield a direct measurement
of the planetary radius and mass, which can be combined to calculate
the average density and surface gravity. These would provide the
first measurements of the physical characteristics of the planet,
and provide the first constraints on the structural models. The
STARE instrument is a small aperture (10 cm), wide-field (6 degree
square), CCD-based telescope that delivers high cadence (2 minute)
time series photometry on roughly 40,000 stars (9 < V < 14) in a
typical field centered on the galactic plane. In a typical two-month
observing run on a single field, sufficient precision is obtained
on roughly 4,000 stars to detect a close-in Jupiter-sized companion
in a near edge-on orbit. The project is now in its third season, and
has acquired a large dataset on several fields. Based on the results
of the radial velocity projects, roughly one star in 1,500 surveyed
should show transits due to a hot Jupiter. Thus, the STARE project
should either detect numerous Jupiter-sized planets, or, in the event
of a non-detection, establish that the radial velocity signatures are
not due to large-radius, planetary-mass orbital companions. The STARE
project is funded by the NASA Origins of Solar Systems program.
---------------------------------------------------------
Title: HD 209458
Authors: Latham, D. W.; Charbonneau, D.; Brown, T. M.; Mayor, M.;
Mazeh, T.; Torres, G.; Beuzit, J. L.; Burnet, M.; Druckier, G. A.;
Naef, D.; Pepe, F.; Perrier, C.; Queloz, D.; Santos, N.; Sivan, J. P.;
Udry, S.; Zucker, S.
1999IAUC.7315....1L Altcode: 1999IAUC.7315A...1L; 1999IAUC.7315Q...1L
In response to a request from the Central Bureau, D. W. Latham,
Harvard-Smithsonian Center for Astrophysics, communicates on behalf
also of D. Charbonneau, T. M. Brown, M. Mayor, and T. Mazeh: "We
have prepared an updated ephemeris for the transits of HD 209458. This
ephemeris is based on 150 velocity observations dating back to Aug. 1997
(made with HIRES on Keck I, as part of the G Dwarf Planet Search under
NASA time, with ELODIE on the 1.93-m telescope at Observatoire de Haute
Provence, and with CORALIE on the new Swiss 1.2-m telescope at La Silla;
a paper describing the spectroscopic results is in preparation) and
on two complete transit observations obtained on 1999 Sept. 8 and 15
(made by Charbonneau and Brown with the STARE instrument at the High
Altitude Observatory, National Center for Atmospheric Research, Boulder,
and reported in a paper submitted to Ap.J. Lett. by Charbonneau, Brown,
Latham, and Mayor). G. Torres has carried out a simultaneous solution
of the radial velocities and the transit observations and provided the
following orbital period and epoch of transit center: P = 3.52433 +/-
0.00027 days, T_c = 2451430.8238 +/- 0.0033 (HJD). Predictions for
the center of the transits through the end of Dec. 1999 are: HJD
2451508.3590 +/- 0.0080, 2451511.8833 +/- 0.0083, 2451515.4077 +/-
0.0086, 2451518.9320 +/- 0.0089, 2451522.4563 +/- 0.0091, 2451525.9806
+/- 0.0094, 2451529.5050 +/- 0.0097, 2451533.0293 +/- 0.010, 2451536.554
+/- 0.010, 2451540.078 +/- 0.011, 2451543.602 +/- 0.011. Observers
should plan to monitor the star for at least 2 hr before and after
these times of transit center. Our identification of HD 209458 as a
prime target for transit observations was made possible by the many
contributions of the G Dwarf Planet Search, ELODIE, and CORALIE teams:
J. L. Beuzit, M. Burnet, G. A. Druckier, D. Naef, F. Pepe, C. Perrier,
D. Queloz, N. Santos, J. P. Sivan, G. Torres, S. Udry, and S. Zucker."
---------------------------------------------------------
Title: Evidence for a system of planets orbiting Upsilon Andromedae.
Authors: Noyes, R. W.; Korzennik, S. G.; Nisenson, P.; Holman, M. J.;
Contos, A.; Brown, T. M.
1999BAAS...31.1236N Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Evidence for a System of Planets Orbiting Upsilon Andromedae
Authors: Noyes, R. W.; Korzennik, S. G.; Nisenson, P.; Holman, M. J.;
Contos, A.; Brown, T. M.
1999AAS...194.1404N Altcode: 1999BAAS...31..847N
Using the Advanced Fiber Optic Echelle (AFOE) spectrograph at SAO's
Whipple Observatory, we have monitored the radial velocity of Upsilon
Andromedae since September 1994. Similar observations were made by the
"Lick" group (P. Butler, G. Marcy, D. Fischer; see Paper 14.02).The AFOE
data show, in addition to the already known close-in “hot Jupiter”
in a 4.6-day circular orbit, two additional companions. The middle
companion has a well-defined orbit, with semi-major axis about
0.83 AU, period 243.5 days, eccentricity 0.22, and minimum mass
(M sin i) of 2 Jupiter masses. This is in very close agreement with
independent findings by the Lick group. The AFOE data alone do not
yield well-determined orbital parameters for the outer companion,
because the total observing span encompasses only about one period of
its orbit. However, the data are consistent with parameters derived
for that companion by the Lick group from data with a longer time span,
and when combined with the Lick data yield a semi-major axis of 2.5 AU,
orbital period of 1267 days, eccentricity of 0.41, and minimum mass
about 4.6 Jupiter masses. These results, independently obtained by two
different groups with different instruments and analysis methodologies,
together give strong indications that a true planetary “system” has
now been discovered around a star like our own. We have carried out
numerical integrations which show that this system can be stable, but
only for certain combinations of periods, masses, and eccentricities
of the outer two companions. The stability requirement thus provides
a prediction that can be tested as the orbital elements of the outer
companion are refined. In addition, it imposes an upper limit on the
actual planetary masses, and on the difference in orbital inclination of
the two outer planets. Finally, the numerical integrations imply that
the longitudes of periastron of the two outer companions are locked to
nearly the same value, in accord with the present observations. This
work was supported by NASA, NSF, and the Smithsonian Institution.
---------------------------------------------------------
Title: Probing the Outskirts of an Extrasolar Planet: Photometry
and Spectroscopy
Authors: Brown, Timothy
1999hst..prop.8789B Altcode: 1999hst..prop.4860B
HD 209458 is the first extrasolar planet known to transit the disk
of its parent star. HST can provide unique probes of this system
for moons, rings and atmospheric composition that are unlikely to be
feasible with ground-based observations. Furthermore, we note that
since HD 209458 will come out of the solar avoidance zone in mid-
April 2000, it will be observable to HST several months before the
first decent transits can be followed from the ground. The field of
extrasolar planets is one that proceeds with breakneck speed {the
entire field is only four years old}, and next fall HD 209458 will
no doubt be the subject of intensive study. The analysis of the data
acquired by this project may be critically important in its own right,
and should help significantly to define optimum follow-on observations
during the coming year. Timely analysis and publication of the data
will clearly be a top priority to the authors of this proposal. HST
is thus in a unique position to deliver a wealth of science on this
first transiting extrasolar planet early next year.
---------------------------------------------------------
Title: A Deep UV STIS Image of Hot Horizontal Branch Stars in M32
Authors: Brown, T. M.; Bowers, C. W.; Kimble, R. A.; Sweigart, A. V.;
Ferguson, H. C.
1999AAS...194.0713B Altcode: 1999BAAS...31Q.833B
We present the deepest near-UV image of M32, which for the first time
resolves hot horizontal branch (HB) stars in an elliptical galaxy. Given
the near-solar metallicity of M32, much larger than that of globular
clusters, the existence of an extended horizontal branch is a striking
example of the second parameter effect, and, most importantly,
provides direct evidence that hot HB stars are the major contributors
to the UV upturn phenomenon observed in elliptical galaxies. Our image,
obtained with the Space Telescope Imaging Spectrograph (STIS), detects
approximately 8000 stars in a 25x25 arcsec field, centered 7.7 arcsec
from the galaxy core. These stars span a range of 21-28 mag in the
STMAG system, and in the deepest parts of the image, our catalog is
reasonably complete (> 25%) to a magnitude of 27. The hot HB spans
a magnitude range of 25-27 at effective temperatures hotter than 8500
K. We interpret the luminosity function with an extensive set of HB
and post-HB evolutionary tracks.
---------------------------------------------------------
Title: The Lyα Forest of the Quasar in the Hubble Deep Field South
Authors: Savaglio, S.; Ferguson, H. C.; Brown, T. M.; Espey, B. R.;
Sahu, K. C.; Baum, S. A.; Carollo, C. M.; Kaiser, M. E.; Stiavelli,
M.; Williams, R. E.; Wilson, J.
1999ApJ...515L...5S Altcode: 1999astro.ph..1022S
The quasar in the Hubble Deep Field South (HDF-S), J2233-606
(z<SUB>em</SUB>=2.23), has been observed exhaustively by ground-based
telescopes and by the Space Telescope Imaging Spectrograph on board
the Hubble Space Telescope at low, medium, and high resolution in
the spectral interval from 1120 to 10000 Å. The combined data give
continuous coverage of the Lyα forest from redshift 0.9 to 2.24. This
very large baseline represents a unique opportunity to study in detail
the distribution of clouds associated with emitting structures in the
field of the quasar and in nearby fields already observed as part of
the HDF-S campaign. Here we report on the main properties obtained from
the large spectroscopic data set that is available for the Lyα clouds
in the intermediate-redshift range of 1.20-2.20, where our present
knowledge has been complicated by the difficulty in producing good
data. The number density is shown to be higher than what is expected
by extrapolating the results from both lower and higher redshifts:
63+/-8 lines with logN<SUB>HI</SUB>>=14.0 are found (including
metal systems) at =1.7, compared with the ~40 lines predicted by
extrapolating from previous studies. The redshift distribution of the
Lyα clouds shows a region spanning z~=1.383-1.460 (comoving size of 94
h<SUP>-1</SUP><SUB>65</SUB> Mpc, Ω<SUB>0</SUB>=1) with a low density
of absorption lines; we detect five lines in this region, compared with
the 16 expected from an average density along the line of sight. The
two-point correlation function shows a positive signal up to scales
of about 3 h<SUP>-1</SUP><SUB>65</SUB> Mpc and an amplitude that is
larger for larger H I column densities. The average Doppler parameter
is about 27 km s<SUP>-1</SUP>, which is comparable to the mean value
found at z>3, thus casting doubts on the temperature evolution of
the Lyα clouds. <P />Based on observations made with the NASA/ESA
Hubble Space Telescope by the Space Telescope Science Institute,
which is operated by AURA, Inc., under NASA contract NAS5-26555.
---------------------------------------------------------
Title: Doppler Imaging of Stellar Oscillations: Multi-Site
Observations of Epsilon Cephei
Authors: Kennelly, E. J.; Brown, T. M.; Ehrenfreund, P.; Foing,
B.; Hao, J.; Horner, S.; Korzennik, S.; Nisenson, P.; Noyes, R.;
Sonnentrucker, P.
1999ASPC..185..264K Altcode: 1999IAUCo.170..264K; 1999psrv.conf..264K
We investigate the oscillation properties of ɛ Cep using a series of
specialized techniques designed to extract and analyze time variations
in absorption line profiles. To obtain the necessary temporal coverage
for this investigation, multi-site observations were collected at
3 sites (China, France, Arizona) all equipped with high-resolution
echelle spectrographs. From these observations, we find evidence for
a very rich spectrum of modes in ɛ Cep.
---------------------------------------------------------
Title: Dating intermediate-age populations with main-sequence A and
F-type stars
Authors: Lanz, T.; Heap, S.; Brown, T. M.; Hubeny, I.; Yi, S.
1999ASPC..192..106L Altcode: 1999sdsg.conf..106L
No abstract at ADS
---------------------------------------------------------
Title: On the Age Estimation of High Redshift Galaxies
Authors: Yi, S.; Brown, T. M.; Heap, S.; Hubeny, I.; Landsman, W.;
Lanz, T.; Sweigart, A.
1999ASPC..192..126Y Altcode: 1999sdsg.conf..126Y
No abstract at ADS
---------------------------------------------------------
Title: Measurements of the UV Upturn in Local and
Intermediate-Redshift Ellipticals
Authors: Brown, T. M.
1999ASPC..192..315B Altcode: 1999sdsg.conf..315B; 1999astro.ph..5377B
The rest-frame UV contains the most sensitive indicators of age for
elliptical galaxies. While the near-UV flux from young ellipticals
isolates the main sequence turnoff, the far-UV flux in old ellipticals
is dominated by hot horizontal branch (HB) stars. This evolved
population was first revealed by early UV observations showing a sharp
flux increase shortward of rest-frame 2500 A, subsequently dubbed the
"UV upturn." The phenomenon has since been characterized in many
local ellipticals, and measurements at intermediate redshifts are
now underway. Once ellipticals reach ages of 5-10 Gyr, stellar and
galactic evolution theories predict that the UV-to-optical flux ratio
can increase by orders of magnitude over timescales of a few Gyr, making
the UV upturn the most rapidly evolving feature of these galaxies. It is
thus expected to fade dramatically with increasing redshift. I review
the imaging and spectroscopic evidence for the nature of the UV upturn
in nearby ellipticals, and then present observations that measure the
UV upturn at an epoch significantly earlier than our own. Far-UV data
from the HUT demonstrate that the spectra of nearby ellipticals are
dominated by hot HB stars. FOC UV imaging of M32 and the M31 bulge
detected the UV-bright phases of post-HB stars, but did not reach the
HB itself. Recent STIS observations were the first to image the hot
HB and post-HB stars in the center of the nearest elliptical galaxy,
M32; these observations also show a striking lack of UV-bright post-AGB
stars. FOC observations of Abell 370, a rich galaxy cluster at z=0.375,
show that giant ellipticals at a lookback time of 4 Gyr can exhibit
strong UV luminosity, with no evidence of evolution in the UV upturn
between this epoch and our own, thus implying a high redshift of
formation (z_f > 4).
---------------------------------------------------------
Title: Color-Luminosity Relations for the Resolved Hot Stellar
Populations in the Centers of M31 and M32
Authors: Brown, T. M.; Ferguson, H. C.; Stanford, S. A.; Deharveng, J.
1999IAUS..192..195B Altcode:
We present Faint Object Camera (FOC) ultraviolet images of the central
14 x 14” of Messier 31 and Messier 32. The hot stellar population
detected in the composite UV spectra of these nearby galaxies is
partially resolved into individual stars, and their individual colors
and apparent magnitudes are measured. We detect 433 stars in M31
and 138 stars in M32, down to detection limits of m<SUB>F275W</SUB>
= 25.5 mag and m<SUB>F175W</SUB> = 24.5 mag. We investigate the
luminosity functions of the sources, their spatial distribution,
their color-magnitude diagrams, and their total integrated far-UV
flux. Although M32 has a weaker UV upturn than M31, the luminosity
functions and color-magnitude diagrams of M31 and M32 are surprisingly
similar, and are inconsistent with a majority contribution from any
of the following: PAGB stars more massive than 0.56 M<SUB>odot</SUB>,
main sequence stars, or blue stragglers. Both the luminosity functions
and color-magnitude diagrams are consistent with a dominant population
of stars that have evolved from the extreme horizontal branch (EHB)
along tracks with masses between 0.47 and 0.53 M<SUB>odot</SUB>. These
stars are well below the detection limits of our images while on the
zero-age EHB, but become detectable while in the more luminous (but
shorter) AGB-Manque and post-early asymptotic giant branch (PEAGB)
phases. The FOC observations require that only a very small fraction of
the main sequence population (2% in M31 and 0.5% in M32) in these two
galaxies evolve though the EHB and post-EHB phases, with the remainder
evolving through bright PAGB evolution that is so rapid that few if
any stars are expected in the small field of view covered by the FOC.
---------------------------------------------------------
Title: The Planet Orbiting ρ Coronae Borealis
Authors: Noyes, R. W.; Contos, A. R.; Korzennik, S. G.; Nisenson,
P.; Brown, T. M.; Horner, S. D.
1999ASPC..185..162N Altcode: 1999IAUCo.170..162N; 1999psrv.conf..162N
Continuing precise radial velocity observations of ρ Coronae Borealis
have allowed the determination of updated parameters of the 40-day
orbit of its Jupiter-mass companion. This confirms the near-zero
eccentricity of the orbit, and provides improved predictions for the
times of possible transit of the companion in front of the star. The
new data provide more stringent upper limits to the mass of a possible
second companion to the system. The orbital parameters are discussed in
the light of several different scenarios for the origin and migration
of extra-solar giant planets.
---------------------------------------------------------
Title: Age and Metallicity of F-type Stars
Authors: Lanz, T.; Heap, S. R.; Brown, T. M.; Hubeny, I.; Yi, S.
1998AAS...193.0302L Altcode: 1998BAAS...30.1246L
The rest-frame ultraviolet spectrum of intermediate-age stellar
populations (1 to few Gyr) is dominated by the UV flux of F-type
stars at the main sequence turn-off. We have obtained high-resolution
spectra of four well-studied F stars with STIS aboard HST to calibrate
ultraviolet spectral features in terms of age and metallicity. The UV
spectrum is mostly degenerate in terms of effective temperature and
metallicity, but we found that two spectral indices, [2850/2770] and
[2310/3040], allow a discrimination between these two parameters. The
first index measures mainly the strength of Mg I 2852, while the second
index is the mid-UV color. We find that the Mg I index is sensitive
to the effective temperature, but insensitive to metallicity; the
UV color is sensitive to both metallicity and T_eff. We discuss the
importance of departures from LTE and chromospheric activity on these
two spectral indices. We apply our results to estimate the time since
the last major star formation episode in the early-type galaxy LBDS
53W091 at redshift z=1.55.
---------------------------------------------------------
Title: Measurements of Far-UV Emission from Elliptical Galaxies
at z=0.375
Authors: Brown, T. M.; Ferguson, H. C.; Deharveng, J. -M.;
Jedrzejewski, R. I.
1998AAS...193.0907B Altcode: 1998BAAS...30R1261B
The “UV upturn” is a sharp rise in spectra of elliptical galaxies
shortward of rest-frame 2500 Angstroms. It is a ubiquitous phenomenon
in nearby giant ellipticals, and is thought to arise primarily
from low-mass evolved stars on the extreme horizontal branch and
beyond. Models suggest that the UV upturn is a very strong function of
age for these old stellar populations, increasing as the galaxy gets
older. In some models the change in UV/optical flux ratio is a factor
of 25 over timescales of less than 3 Gyr. To test the predictions
for rapid evolution of the UV upturn, we have observed a sample of
normal elliptical galaxies in the z=0.375 cluster Abell 370 with the
Faint Object Camera aboard the Hubble Space Telescope. A combination
of two long-pass filters was used to isolate wavelengths shortward of
rest-frame 2700 Angstroms, providing a measurement of the UV upturn at a
lookback time of approximately 4 Gyr. Surprisingly, the four ellipticals
observed show a range of UV upturn strength that is similar to that
seen in nearby ellipticals, with an equivalent m<SUB>1550</SUB>-V
color ranging from 2.9--3.4 mag. Our result is inconsistent with some
models for the UV upturn; other models are consistent only for a high
redshift of formation (z_f >= 4).
---------------------------------------------------------
Title: The Hubble Deep Field South: Flanking Fields
Authors: Lucas, R. A.; Baum, S. A.; Casertano, S.; de Mello, D.;
Dickinson, M.; Ferguson, H. C.; Fruchter, A. S.; Gonzalez-Lopezlira,
R.; Heyer, I.; Mack, J.; Makidon, R.; Martin, C. L.; Mutchler, M.;
Smith, E.; Stiavelli, M.; Teplitz, H. I.; Wiggs, M. S.; Williams,
R.; Zurek, D.; Brown, T. M.; Gardner, J. P.; Kaiser, M. E.; Hook, R. N.
1998AAS...193.7506L Altcode: 1998BAAS...30.1367L
Due to the availability of the STIS and NICMOS instruments at the time
of the observations, the Hubble Deep Field - South Flanking Fields
are more complex and varied than those of the Hubble Deep Field -
North. In addition to the WFPC2 Flanking Fields, there are parallel
observations in STIS and NICMOS for each, and there are also a series
of STIS observations of the NICMOS deep field, and associated WFPC2 and
NICMOS parallels as well. In this paper, we will present the data and
describe the data reduction process used for the HDF-S Flanking Fields.
---------------------------------------------------------
Title: The Hubble Deep Field South: UV Spectroscopy of QSO J2233-606
Authors: Ferguson, H. C.; Baum, S. A.; Busko, I.; Espey, B. R.;
Gonnella, A.; Hayes, J.; Hodge, P.; Martin, C. L.; Sahu, K. C.;
Savaglio, S.; Smith, E.; Williams, R.; Wilson, J.; Brown, T. M.;
Gardner, J. P.; Carollo, C. M.; Kaiser, M. E.
1998AAS...193.7502F Altcode: 1998BAAS...30Q1366F
QSO J2233-606 was observed with the Space Telescope Imaging Spectrograph
during the HDF-South campaign. The spectroscopic observations
covered wavelengths from 1150 to 3560 { Angstroms} at a range of
resolutions. The QSO spectrum is attenuated by a Lyman-limit absorption
line system at z ~ 1.9, but the flux recovers in the far-UV. Most of
the spectroscopic observing time (155 ks) was devoted to obtaining
observations with the medium-resolution echelle grating at a resolution
of 10 km/s. The spectra show a rich forest of absorption lines, some
arising from Lyman alpha in the redshift range 1.2 to 1.5, and others
from higher order Lyman series lines of higher-redshift systems. At
shorter wavelengths, some strong absorption line systems are seen
at the 250-400 km/s resolution with the low-resolution gratings. The
higher-redshift Lyman alpha forest is detected at 50 km/s resolution
in the 3100-3560 { Angstroms} region.
---------------------------------------------------------
Title: The Hubble Deep Field -- South: STIS Imaging
Authors: Gardner, J. P.; Brown, T. M.; Teplitz, H. I.; Baum, S. A.;
Espey, B. R.; Ferguson, H. C.; Fruchter, A. S.; Gonnella, A.; Hayes,
J.; Martin, C. L.; Sahu, K. C.; Savaglio, S.; Smith, E.; Williams,
R.; Wilson, J.; Carollo, C. M.; Kaiser, M. E.; Hook, R. N.
1998AAS...193.7503G Altcode: 1998BAAS...30.1366G
We present the imaging observations made with the Space Telescope
Imaging Spectrograph of the Hubble Deep Field -- South. The field was
imaged in 4 bandpasses, a clear CCD bandpass for 156 ksec, a long-pass
filter for 25 ksec, a Near-UV bandpass for 23 ksec and a Far-UV bandpass
for 52 ksec. The clear visible image is the deepest observation ever
made in the UV-NIR wavelength region. The field contains QSO J2233-606,
the target of the STIS spectroscopy, and extends 50arcsec x 50arcsec
for the visible images, and 25arcsec x 25arcsec for the ultraviolet
images. We present the images, catalog of objects, and galaxy counts
obtained in the field.
---------------------------------------------------------
Title: The Southern Hubble Deep Field: HDF-S
Authors: Williams, R.; Baum, S. A.; Bergeron, L. E.; Blacker, B.;
Boyle, B. J.; Brown, T. M.; Bernstein, N.; Carollo, C. M.; Casertano,
S.; de Mello, D.; Dickinson, M.; Espey, B. R.; Ferguson, H. C.;
Fruchter, A. S.; Gardner, J. P.; Gonnella, A.; Gonzalez, R.; Hayes, J.;
Hewett, P.; Heyer, I.; Hook, R. N.; Jones, D.; Kaiser, M. E.; Lubenow,
A.; Lucas, R. A.; Mack, J.; MacKenty, J. W.; Madau, P.; Makidon, R.;
Martin, C. L.; Mazzuca, L.; Mutchler, M.; Norris, R. P.; Perriello,
B.; Postman, M.; Royle, P.; Sahu, K. C.; Savaglio, S.; Sherwin, A.;
Smith, E.; Stiavelli, M.; Teplitz, H. I.; van der Marel, R.; Weymann,
R. J.; Wiggs, M. S.; Williger, G. M.; Wilson, J.; Zurek, D.
1998AAS...193.7501W Altcode: 1998BAAS...30.1366W
177 orbits of HST imaging and spectroscopy were devoted to three
adjacent fields plus flanking fields in the southern CVZ in October
1998, in an observing program similar to the original northern HDF. Two
important features of the HDF-S make it distinct from the HDF-N: (1)
simultaneous observations with WFPC2, STIS, and NICMOS in parallel
observing modes, leading to imaging of three separate fields, and (2)
the inclusion of a z<SUB>em</SUB>=2.2 quasar in the line of sight for
the STIS field. The HDF-S observations produced WFPC2 images in U,
B, V, and I; a deep STIS image of the field surrounding the quasar;
spectroscopy of the quasar with STIS from 1150-3560 Angstroms; and deep
imaging of an adjacent field with NICMOS in the J, H, and K bands. All
of the data, both raw and reduced, have been made public on 23 November
1998 and are available from the HST archive for analysis.
---------------------------------------------------------
Title: The Hubble Deep Field South: Deep uBVRI Imaging of 1/2
Square Degree
Authors: Teplitz, H. I.; Gardner, J. P.; Palunas, P.; Sahu, M. S.;
Malumuth, E. M.; Woodgate, B. E.; Heap, S. R.; Williger, G. M.; Danks,
A. C.; Smette, A.; Brown, T. M.; Kaiser, M. E.; Gull, T. R.
1998AAS...193.7507T Altcode: 1998BAAS...30.1367T
We present 1/2 square degree uBVRI imaging around the Hubble Deep Field
-- South. The images were obtained with the Big Throughput Camera at
CTIO in 1998 September. We will discuss the broad-band photometry of
this field and present the statistics of ~ 50000 galaxies, including
number-magnitude counts and clustering properties. The deep field was
chosen for the presence of the z=2.25 QSO J2233-606, which has multiple
absorption systems that may mark large scale structures. We also discuss
the color distribution of galaxies and u-band dropouts. We compare our
photometric measurements with the high resolution images available from
the HST observations. We will make the images and catalogs presented
here available over the WWW.
---------------------------------------------------------
Title: Acoustic Power Maps of Solar Active Regions
Authors: Hindman, Bradley W.; Brown, Timothy M.
1998ApJ...504.1029H Altcode:
Using observations made by the Michelson Doppler Imager (MDI), we find
that within solar active regions the spatial distributions of Doppler
velocity power and continuum intensity power differ. The oscillation
power within any pixel is a strong function of the magnetic field
strength within that pixel. The amplitudes of oscillations with
frequencies less than 5.2 mHz decrease with field strength for both
velocity and continuum intensity measurements. However, within active
regions oscillations with frequencies between 5.2 and 7.0 mHz have
suppressed continuum intensity amplitudes but enhanced velocity
amplitudes. The enhancement of the high-frequency velocity signal
is largest in pixels with intermediate field strength (50-250 G)
and is a manifestation of the high-frequency acoustic halos. We find
that the high-frequency halos are absent in MDI observations of the
continuum intensity.
---------------------------------------------------------
Title: Exoplanets or Dynamic Atmospheres? The Radial Velocity and
Line Shape Variations of 51 Pegasi and τ Bootis
Authors: Brown, Timothy M.; Kotak, Rubina; Horner, Scott D.;
J. Kennelly, Edward; Korzennik, Sylvain; Nisenson, P.; Noyes, Robert W.
1998ApJS..117..563B Altcode: 1998astro.ph..1166B
The stars 51 Pegasi and τ Bootis show radial velocity variations that
have been interpreted as resulting from companions with roughly Jovian
mass and orbital periods of a few days. Gray and Gray & Hatzes
reported that the radial velocity signal of 51 Peg is synchronous with
variations in the shape of the line λ6253 Fe I; thus, they argue that
the velocity signal arises not from a companion of planetary mass but
from dynamic processes in the atmosphere of the star, possibly nonradial
pulsations. Here we seek confirming evidence for line shape or strength
variations in both 51 Peg and τ Boo, using R = 50,000 observations
taken with the Advanced Fiber Optic Echelle. Because of our relatively
low spectral resolution, we compare our observations with Gray's line
bisector data by fitting observed line profiles to an expansion in terms
of orthogonal (Hermite) functions. To obtain an accurate comparison,
we model the emergent line profiles from rotating and pulsating stars,
taking the instrumental point-spread function into account. We describe
this modeling process in detail. We find no evidence for line profile or
strength variations at the radial velocity period in either 51 Peg or in
τ Boo. For 51 Peg, our upper limit for line shape variations with 4.23
day periodicity is small enough to exclude with 10 σ confidence the
bisector curvature signal reported by Gray & Hatzes; the bisector
span and relative line depth signals reported by Gray are also not seen,
but in this case with marginal (2 σ) confidence. We cannot, however,
exclude pulsations as the source of 51 Peg's radial velocity variation
because our models imply that line shape variations associated with
pulsations should be much smaller than those computed by Gray &
Hatzes; these smaller signals are below the detection limits both for
Gray & Hatzes's data and for our own. τ Boo's large radial velocity
amplitude and v sin i make it easier to test for pulsations in this
star. Again we find no evidence for periodic line shape changes, at a
level that rules out pulsations as the source of the radial velocity
variability. We conclude that the planet hypothesis remains the most
likely explanation for the existing data.
---------------------------------------------------------
Title: Accurate Determination of the Solar Photospheric Radius
Authors: Brown, T. M.; Christensen-Dalsgaard, J.
1998ApJ...500L.195B Altcode: 1998astro.ph..3131B
The Solar Diameter Monitor measured the duration of solar meridian
transits during the 6 years 1981-1987, spanning the declining half of
solar cycle 21. We have combined these photoelectric measurements with
models of the solar limb-darkening function, deriving a mean value for
the solar near-equatorial radius of 695.508+/-0.026 Mm. Annual averages
of the radius are identical within the measurement error of +/-0.037 Mm.
---------------------------------------------------------
Title: Detection of Extrasolar Planets by Transit Photometry in
the Antarctic
Authors: Borucki, William J.; Koch, David G.; Lissauer, Jack J.;
Brown, Timothy M.; Jenkins, Jon M.; Dunham, Edward T.
1998AAS...192.6223B Altcode: 1998BAAS...30R.909B
The recent discovery by the Doppler velocity technique that
approximately 2% to 3% of the solar-like stars possess giant planets
demonstrates that ground-based detection of extrasolar planets is
feasible. Photometric detection of transits can provide the size of
planetary companions and determine both orbital period and inclination
angle. Subsequent Doppler velocity measurements can then estimate the
mass since the inclination angle is known. The combination of mass
and size allows the density of these objects to be determined. These
data can then be used to compare with theoretical predictions of
the inflation of a planet's atmosphere as a function of its distance
from the primary. Follow on observations at major observatories using
high resolution spectrographs can be made to determine the spectral
class and metallicity of the stars found to have planets so that
correlations with these quantities and the frequency of planets and
their orbital radii can be investigated. Only a small aperture (i.e.,
10 cm to 30 cm), wide-field-of-view telescope with a CCD detector and
several weeks of continuous observation are required to detect planets
around a variety of stars. By observing approximately 4,000 stars
continuously, approximately four giant inner planets (like 51 Peg b)
with orbital periods near 4 days should be discovered each month;
i.e. approximately 16 planets during the four month winter period in
Antarctica. The availability of continuous observing would dramatically
improve the yield of searches now being conducted at other locations
in the presence of day/night cycles.
---------------------------------------------------------
Title: The Oscillations of Tau Pegasi
Authors: Kennelly, E. J.; Brown, T. M.; Kotak, R.; Sigut, T. A. A.;
Horner, S. D.; Korzennik, S. G.; Nisenson, P.; Noyes, R. W.; Walker,
A.; Yang, S.
1998ApJ...495..440K Altcode:
We present extensive spectroscopic time series observations of the
multiperiodic, rapidly rotating, δ Scuti star τ Pegasi. Information
about the oscillations is contained within the patterns of line-profile
variation of the star's blended absorption-line spectrum. We introduce
the new technique of Doppler deconvolution with which to extract these
patterns by modeling the intrinsic stellar spectrum and the broadening
functions for each spectrum in the time series. Frequencies and modes
of oscillation are identified from the variations using the technique
of Fourier-Doppler imaging and a two-dimensional least-squares cleaning
algorithm. We find a rich mode spectrum with degrees up to l = 20 and
with frequencies below about 35 cycles day<SUP>-1</SUP>. Those modes
with the largest amplitudes have frequencies that lie within a narrow
band. We conclude that the observed spectrum can be explained if the
modes of τ Peg propagate in the prograde direction with l ~= |m| and
with frequencies that are about equal in the corotating frame of the
star. We discuss the implications of these results for the prospect
of δ Scuti seismology.
---------------------------------------------------------
Title: A Search for Line Shape and Depth Variations in 51 Pegasi
and τ Bootis
Authors: Brown, Timothy M.; Kotak, Rubina; Horner, Scott D.; Kennelly,
Edward J.; Korzennik, Sylvain; Nisenson, P.; Noyes, Robert W.
1998ApJ...494L..85B Altcode: 1997astro.ph.12279B
Spectroscopic observations of 51 Pegasi and τ Bootis show no periodic
changes in the shapes of their line profiles; these results for 51
Peg are in significant conflict with those reported by Gray &
Hatzes. Our detection limits are small enough to rule out nonradial
pulsations as the cause of the variability in τ Boo, but not in 51
Peg. The absence of line shape changes is consistent with these stars'
radial velocity variability arising from planetary mass companions.
---------------------------------------------------------
Title: The Stellar and Planetary Explorer (SPEX) Mission
Authors: Schou, J.; Scherrer, P. H.; Brown, T. M.; Frandsen, S.;
Horner, S. D.; Korzennik, S. G.; Noyes, R. W.; Tarbell, T. D.; Title,
A. M.; Walker, A. B. C., II; Weiss, W. W.; Bogart, R. S.; Bush, R. I.;
Christensen-Dalsgaard, J.; Hoeksema, J. T.; Jones, A.; Kjeldsen, H.
1998ESASP.418..401S Altcode: 1998soho....6..401S
The Stellar and Planetary Explorer (SPEX) is a mission designed
to search for terrestrial sized planets around sun-like stars using
precise photometry. The planets will be detected by searching for the
decrease in brightness associated with transits of the planets in front
of their parent stars. One of the secondary scientific objective of
SPEX is to do asteroseismology on a number of sun-like stars. SPEX
is designed as a secondary payload on a commercial communications
satellite and will have a design life time of three years. We will
provide an overview of the SPEX scientific objectives and design,
with particular emphasis on the prospects for doing asteroseismology.
---------------------------------------------------------
Title: Observational Challenges in Asteroseismology
Authors: Brown, Timothy M.
1998ASPC..154..289B Altcode: 1998csss...10..289B
Asteroseismology of Sun-like stars will probably be done best by means
of CCD photometry from space. However, making this happen is going to
take hard work and organization. In the meantime, significant progress
is being made on spectroscopic studies of F- and G-type subgiants,
and important advances are being made in techniques for measuring
modes in delta Scuti stars.
---------------------------------------------------------
Title: Ultraviolet Spectral Dating of Stars and Galaxies
Authors: Heap, S. R.; Brown, T. M.; Hubeny, I.; Landsman, W.; Yi,
S.; Fanelli, M.; Gardner, J. P.; Lanz, T.; Maran, S. P.; Sweigart,
A.; Kaiser, M. E.; Linsky, J.; Timothy, J. G.; Lindler, D.; Beck,
T.; Bohlin, R. C.; Clampin, M.; Grady, J.; Loiacono, J.; Krebs, C.
1998ApJ...492L.131H Altcode:
An echelle spectrogram (R = 30,000) of the 2300-3100 Å region in
the ultraviolet spectrum of the F8 V star 9 Comae is presented. The
observation is used to calibrate features in the mid-ultraviolet spectra
of similar stars according to age and metal content. In particular, the
spectral break at 2640 Å is interpreted using the spectral synthesis
code SYNSPEC. We use this feature to estimate the time since the last
major star formation episode in the early-type galaxy LBDS 53W091 at
redshift z=1.55, whose rest-frame mid-ultraviolet spectrum, observed
with the Keck Telescope, is dominated by the flux from similar stars
that are at or near the main-sequence turnoff in that system (Spinrad
et al.). Our result, 1 Gyr if the flux-dominating stellar population
has a metallicity twice solar, or 2 Gyr for a more plausible solar
metallicity, is significantly lower than the previous estimate and
thereby relaxes constraints on cosmological parameters that were implied
by the earlier work. <P />Based on observations with the NASA/ESA Hubble
Space Telescope, obtained at the Space Telescope Science Institute,
which is operated by the Association of Universities for Research in
Astronomy, Inc., under NASA contract NAS5-2655.
---------------------------------------------------------
Title: Exoplanet Research with the Advanced Fiber Optic Echelle
Authors: Korzennik, S. G.; Brown, T. M.; Contos, A. R.; Horner, S.;
Jha, S.; Kennelly, T.; Krockenberger, M.; Nisenson, P.; Noyes, R. W.
1998ASPC..154.1876K Altcode: 1998csss...10.1876K
The AFOE is a fiber-fed bench-top echelle spectrometer installed
at the Mt. Hopkins 1.5 m telescope for research in exoplanets,
asteroseismology, and other topics requiring precise radial velocity
measurements. Here we describe the instrumentation, observing programs,
and data reduction techniques for exoplanet research with the AFOE. We
also summarize recent results of our search for and characterization
of exoplanets. Further information on the AFOE can be found on the
Web at http://cfa-www.harvard.edu/afoe.
---------------------------------------------------------
Title: 51 Pegasi and Tau Bootis: Planets or Pulsations?
Authors: Horner, S. D.; Brown, T. M.; Kennelly, E. J.; Kotak, R.; Jha,
S.; Korzennik, S. G.; Krockenberger, M.; Nisenson, P.; Noyes, R. W.
1998ASPC..135..206H Altcode: 1998hcsp.conf..206H
It has recently been suggested (Gray 1997) that the radial velocity
variations observed in the spectra of 51 Pegasi are the result of
stellar pulsations as opposed to the reflex motion due to an orbital
companion. The AFOE group has confirmed the radial velocity variations
in 51 Pegasi and t Bootis. Here we discuss the results of a search for
evidence of pulsations in the AFOE data for these two stars, as well
as attempt to clear up misconceptions regarding pulsations circulated
as a result of the current debate about the nature of the 51 Pegasi
radial velocity variations.
---------------------------------------------------------
Title: 51 Pegasi and Tau Bootis: Planets or Pulsations?
Authors: Horner, S. D.; Brown, T. M.; Kennedy, E. J.; Kotak, R.; Jha,
S.; Korzennik, S. G.; Krockenberger, M.; Nisenson, P.; Noyes, R. W.
1998ASPC..154.1860H Altcode: 1998csss...10.1860H
Using data from the AFOE and simulations of pulsating stars, we are able
to rule out pulsations as the cause of the radial velocity variations
seen in tau Bootis and conclude that it is unlikely that pulsations
are the cause of radial velocity variations seen in 51 Pegasi. Orbital
companions are still the most probable causes of the radial velocity
variations observed in these systems.
---------------------------------------------------------
Title: Asteroseismology of Procyon with the AFOE
Authors: Horner, S. D.; Brown, T. M.; Kennelly, E. J.; Korzennik,
S.; Nisenson, P.; Noyes, R. W.
1997AAS...191.4310H Altcode: 1997BAAS...29R1276H
The Advanced Fiber Optic Echelle (AFOE) is a bench-mounted,
fiber-fed echelle spectrograph designed for precision radial velocity
observations. Located at the 1.5m Tillinghast telescope at Whipple
Observatory, the AFOE is used to detect exoplanets and is involved in
several projects in asteroseismology, including asteroseismology of
Sun-like stars. Procyon has been a prime target for asteroseismology
of Sun-like stars due to its proximity and its spectral type
(F5 IV-V). Theory predicts that due to its low surface gravity
and inefficient surface convection, the amplitudes of its p-mode
pulsation modes should be relatively large, though still less than 1
m\ s(-1) . While the velocity of individual modes is extremely small,
observations of Procyon with the AFOE show excess power in the frequency
range between 0.5 to 1.5 MHz. This power may be the result of p-mode
oscillations on Procyon, and is consistent with previous results (Brown
et al. 1991). However, mode identification is required to interpret
the ramifications of the observations for the star's structure, which
is the goal of asteroseismology. These single-site data are limited
in frequency resolution, which may prevent clear identification of
individual modes.
---------------------------------------------------------
Title: Color--Luminosity Relations for the Resolved Hot Stellar
Populations in the Centers of M31 and M32
Authors: Brown, T. M.; Ferguson, H. C.; Stanford, S. A.; Deharveng,
J. -M.; Davidsen, A. F.
1997AAS...191.8219B Altcode: 1997BAAS...29R1345B
We present Faint Object Camera ultraviolet images of Messier 31 and
Messier 32. The hot stellar population detected in the composite
UV spectra of these nearby galaxies is partially resolved into
individual stars, and their individual colors and luminosities are
measured. Although our photometry does not extend to the horizontal
branch (HB) itself, we can detect and characterize stars that are
in the bright phases of post-HB evolution for the entire range of
mass on the HB. Many of our detected stars imply the existence of an
extended HB in the cores of these galaxies. These hot stars are the
extragalactic counterparts to the hot subdwarfs in our own Galactic
field, and their confirmed existence in neighboring galaxies supplies
an important validation to explanations of the ultraviolet upturn
phenomenon found in ellipticals and spiral bulges.
---------------------------------------------------------
Title: STIS Ultraviolet Imagery of the Globular Cluster NGC 6681
Authors: Landsman, W.; Bowers, C.; Heap, S.; Kimble, R.; Sweigart,
A.; Brown, T. M.; Catelan, M.; Yi, S.
1997AAS...191.8003L Altcode: 1997BAAS...29.1338L
The post--core-collapse globular cluster NGC 6681 (M70) is characterized
by an intermediate metallicity ([Fe/H] = --1.5), a low reddening
(E(B--V) = 0.06), and a blue horizontal branch (HB). STIS ultraviolet
images of NGC 6681 have recently been obtained as part of the
Servicing Mission Observatory Verification (SMOV) testing. The images
were obtained in five ultraviolet filters (25MAMA, F25QTZ, F25SRF2,
F25CN182, and F25CN270), and reach a typical limiting monochromatic
magnitude of m(UV) ~ 22. Photometry of the blue HB stars in the
far-ultraviolet ( ~ 1600 Angstroms) images is in good agreement with
the WFPC2 Woods filter photometry of Watson et al. (1994, ApJL, 435,
L55). The F25CN182 -- F25CN270 color-magnitude diagram shows a tight
cluster of blue HB stars, a pronounced blue straggler sequence, and
several white dwarf candidates.
---------------------------------------------------------
Title: Erratum: A Planet Orbiting the Star Rho Coronae Borealis:
Authors: Noyes, Robert W.; Jha, Saurabh; Korzennik, Sylvain G.;
Krockenberger, Martin; Nisenson, Peter; Brown, Timothy M.; Kennelly,
Edward J.; Horner, Scott D.
1997ApJ...487L.195N Altcode:
In the Letter, “A Planet Orbiting the Star ρ Coronae Borealis”
by Robert W. Noyes, Saurabh Jha, Sylvain G. Korzennik, Martin
Krockenberger, Peter Nisenson, Timothy M. Brown, Edward J. Kennelly,
and Scott D. Horner (ApJ, 483, L111 [1997]), a software error caused
the sign of the reported radial velocity variations of ρ Coronae
Borealis to be reversed. This error has no effect on the period,
amplitude, or eccentricity of the derived orbit and thus does not
affect the main conclusion of the paper. However, the longitude ω
of periastron reported in Table 1 is off by 180°, and the predicted
time of a possible planetary transit T<SUB>transit</SUB> is off by
approximately 1/2 period. The correct values are ω = 30° +/- 74°
and T<SUB>transit</SUB> = 2,450,657.88 +/- 0.54 HJD.
---------------------------------------------------------
Title: A Planet Orbiting the Star ρ Coronae Borealis
Authors: Noyes, Robert W.; Jha, Saurabh; Korzennik, Sylvain G.;
Krockenberger, Martin; Nisenson, Peter; Brown, Timothy M.; Kennelly,
Edward J.; Horner, Scott D.
1997ApJ...483L.111N Altcode: 1997astro.ph..4248N
We report the discovery of near-sinusoidal radial velocity variations
of the G0V star ρ CrB, with period 39.6 days and amplitude 67 m
s<SUP>-1</SUP>. These variations are consistent with the existence
of an orbital companion in a circular orbit. Adopting a mass of 1.0
M<SUB>solar</SUB> for the primary, the companion has minimum mass
about 1.1 Jupiter masses and orbital radius about 0.23 AU. Such an
orbital radius is too large for tidal circularization of an initially
eccentric orbit during the lifetime of the star, and hence we suggest
that the low eccentricity is primordial, as would be expected for a
planet formed in a dissipative circumstellar disk.
---------------------------------------------------------
Title: Hot Evolved Stars in the Centers of M31 and M32
Authors: Brown, T. M.; Ferguson, H. C.; Standford, S. A.; Deharveng,
J. -M.; Davidsen, A. F.
1997AAS...190.0303B Altcode: 1997BAAS...29Q.781B
We present UV images of M31 and M32, as observed by HST with the
refurbished FOC. The galaxies were observed through the F175W and F275W
filters, allowing the construction of color magnitude diagrams (CMDs)
for the hundreds of detected sources found in each image. Comparison of
these data with the stellar evolutionary tracks of horizontal branch
stars and their progeny shows that for the first time outside of our
own Galaxy, we are measuring the colors of individual stars that are
evolving along post asymptotic giant branch (PAGB), post-early AGB,
and AGB-Manque' paths. Searching to the 6-sigma detection limit,
we find 986 sources in M31 and 183 sources in M32. We compare the
distribution of stars in the CMDs with the expectations from theory.
---------------------------------------------------------
Title: A Radial Velocity Search for p-Mode Pulsations in η Bootis
Authors: Brown, Timothy M.; Kennelly, Edward J.; Korzennik, Sylvain
G.; Nisenson, Peter; Noyes, Robert W.; Horner, Scott D.
1997ApJ...475..322B Altcode:
The subgiant η Boo (G5 IV) has been reported to show p-mode pulsations,
as evidenced by variations in the equivalent width of its hydrogen
Balmer lines (reported by Kjeldsen et al.). In an attempt to confirm
this report, we observed η Boo's radial velocity with the AFOE
spectrograph for a total of 22 hours spread over seven successive
nights in 1995 March. We find no evidence for the presence of excess
power at the frequencies reported by Kjeldsen et al.; our upper limit
corresponds to typical mode amplitudes of 0.5 m s<SUP>-1</SUP>, about 3
times smaller than the velocity amplitudes they inferred. Signals with
amplitudes larger than 0.5 m s<SUP>-1</SUP> may be present at other
frequencies within the 0-1000 μHz range, but evidence for such signals
is scanty, and typical mode amplitudes greater than 1.5 m s<SUP>-1</SUP>
are clearly inconsistent with our observations.
---------------------------------------------------------
Title: A Far Ultraviolet Analysis of the Stellar Populations in
Elliptical and S0 Galaxies
Authors: Brown, T. M.
1996AAS...189.6204B Altcode: 1996BAAS...28.1351B
We have analyzed the far-ultraviolet (FUV) spectra of six elliptical and
S0 galaxies in order to characterize their hot stellar populations. The
spectra were obtained using the Hopkins Ultraviolet Telescope (HUT)
in March 1995. These data, together with the spectra of two galaxies
observed with HUT in 1990, represent the only FUV spectra of early type
galaxies that extend to the Lyman limit at 912 Angstroms and therefore
include the “turnover” in the spectral energy distribution below
Lyman alpha. Using an extensive new grid of synthetic spectra which
match the HUT resolution and cover the relevant parameter space of
temperature and gravity, we have constructed synthetic spectral energy
distributions by integrating over predicted stellar evolutionary tracks
for horizontal branch stars and their progeny. When the models are
compared with the HUT data, we find that those with supersolar metal
abundances and helium best reproduce the flux across the entire HUT
wavelength range, while those with subsolar Z & Y fit less well,
partly because of a significant flux deficit shortward of 970 Angstroms
in the models. We find that AGB-Manquacutee evolution is required in
all fits to the HUT spectra, suggesting that all of the galaxies have
some subdwarf B star population. At any Z & Y, the models that
best match the HUT flux are dominated by stars evolving from a narrow
range of envelope mass on the blue end of the horizontal branch. We
find that most absorption features in the spectra are consistent with
Z = 0.1 Z_⊙, significantly lower than the abundances implied by the
best-fitting spectral energy distributions. However, given the strong
observational and theoretical evidence for diffusion processes in the
atmospheres of evolved stars, the observed atmospheric abundances may
not reflect the interior abundances in the population producing the
ultraviolet flux in elliptical galaxies.
---------------------------------------------------------
Title: Asteroseismological calibration of open clusters
Authors: Audard, N.; Brown, T. M.; Christensen-Dalsgaard, J.; Frandsen,
S.; Kjeldsen, H.
1996BASI...24..305A Altcode:
No abstract at ADS
---------------------------------------------------------
Title: A radial velocity search for p-modes in Procyon.
Authors: Brown, T. M.; Kennelly, E. J.; Noyes, R. W.; Korzennik,
S. G.; Nisenson, P.; Horner, S. D.; Catala, C.
1996BAAS...28..917B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The oscillation modes of ɛ Cep and τ Peg.
Authors: Horner, S. D.; Kennelly, E. J.; Brown, T. M.; Noyes, R. W.;
Korzennik, S. G.; Nisenson, P.; Yang, S.; Walker, A. R.
1996BAAS...28..916H Altcode:
No abstract at ADS
---------------------------------------------------------
Title: A Grid of Model Atmospheres and Synthetic Spectra for the
Far Ultraviolet Analysis of Old Stellar Populations
Authors: Brown, T. M.; Davidsen, A. F.; Ferguson, H. C.
1996AAS...188.1106B Altcode: 1996BAAS...28..840B
We present a grid of stellar synthetic spectra suitable for detailed
comparison to far-ultraviolet (FUV) observations obtained with the
Hopkins Ultraviolet Telescope, IUE, and HST. Our specific application
is to study the hot stellar populations in elliptical galaxies, but we
anticipate that the models will be useful for other purposes. The 1,497
spectra span a range of 10,000 K <= T<SUB>eff</SUB> <= 250,000 K
and 2 <= log g <= 8.5, with three metallicities: Z = Z_⊙, Z =
0.1 Z_⊙, and Z = 0.01 Z_⊙. A variety of simplifying assumptions
have been made to reduce computer time and improve convergence, at
the inevitable expense of some accuracy. Nevertheless, models in the
grid reproduce the overall continuum shape and most of the absorption
features seen in HUT spectra of four evolved stars at temperatures
of 17000, 29900, 36100, and 55000 K. The most serious discrepancy is
in the cores of the Lyman series lines, where the observed lines are
not as deep as those obtained from the models. Until this problem is
resolved, the Lyman series lines will not provide a reliable measure of
T<SUB>eff</SUB> or log g. While the synthetic spectra in this grid may
not be appropriate for detailed analysis of high S/N stellar spectra,
they are sufficiently similar to the observed stars to provide a
considerable advantage over existing models for the analysis of the FUV
spectra of composite systems, such as elliptical galaxies and globular
clusters, where the advantages of having a large, well-sampled grid
of models tend to outweigh the known inadequacies of the individual
grid points.
---------------------------------------------------------
Title: The Oscillation Modes of epsilon CEP and tau Peg
Authors: Horner, S. D.; Kennelly, E. J.; Brown, T. M.; Noyes, R. W.;
Korzennik, S. G.; Nisenson, P.; Yang, S.; Walker, A.
1996AAS...188.5901H Altcode: 1996BAAS...28Q.917H
Asteroseismology of delta Scuti stars offers an attractive prospect for
determining the interior properties of main sequence and slightly more
evolved A- and F-type stars. Here we present detailed identifications
of oscillation modes in the rapidly rotating delta Scuti stars epsilon
Cep and tau Peg based on extensive observations carried out at two
North American sites. Using cross-correlation and Fourier techniques
we analyze the line-profile variations and the variations in the
line-profile moments. A solution to the mode spectrum is sought using
a genetic-based search algorithm and a line profile simulation model
to reproduce the observed variations.
---------------------------------------------------------
Title: The Solar Acoustic Spectrum and Eigenmode Parameters
Authors: Hill, F.; Stark, P. B.; Stebbins, R. T.; Anderson, E. R.;
Antia, H. M.; Brown, T. M.; Duvall, T. L., Jr.; Haber, D. A.;
Harvey, J. W.; Hathaway, D. H.; Howe, R.; Hubbard, R. P.; Jones,
H. P.; Kennedy, J. R.; Korzennik, S. G.; Kosovichev, A. G.; Leibacher,
J. W.; Libbrecht, K. G.; Pintar, J. A.; Rhodes, E. J., Jr.; Schou, J.;
Thompson, M. J.; Tomczyk, S.; Toner, C. G.; Toussaint, R.; Williams,
W. E.
1996Sci...272.1292H Altcode:
The Global Oscillation Network Group (GONG) project estimates
the frequencies, amplitudes, and linewidths of more than 250,000
acoustic resonances of the sun from data sets lasting 36 days. The
frequency resolution of a single data set is 0.321 microhertz. For
frequencies averaged over the azimuthal order m, the median formal
error is 0.044 microhertz, and the associated median fractional error
is 1.6 x 10<SUP>-5</SUP>. For a 3-year data set, the fractional error
is expected to be 3 x 10<SUP>-6</SUP>. The GONG m-averaged frequency
measurements differ from other helioseismic data sets by 0.03 to 0.08
microhertz. The differences arise from a combination of systematic
errors, random errors, and possible changes in solar structure.
---------------------------------------------------------
Title: A Radial Velocity Search for p-modes in Procyon
Authors: Brown, T. M.; Kennelly, E. J.; Noyes, R. W.; Korzennik,
S. G.; Nisenson, P.; Horner, S. D.; Catala, C.
1996AAS...188.5902B Altcode: 1996BAAS...28R.917B
Procyon (alpha CMi F5 IV) has long been a promising candidate for
detection of solar-like p-modes. Although several authors have reported
evidence for low-amplitude (<= 10) m/s pulsations in this star,
none of the existing observations are conclusive. A clear detection
of such pulsations would be a significant step for asteroseismology
of Sun-like stars, allowing refined estimates of the star's properties
and paving the way for the study of fainter stars of similar spectral
type. Identification of oscillation modes in subgiants like Procyon is
expected to be difficult, however, because both the amplitudes and the
frequency separations of the modes are expected to be small. To address
these difficulties, we organized a joint observing campaign involving
the AFOE spectrograph located at the Whipple Observatory (Mt. Hopkins,
AZ) and the MUSICOS spectrograph located at Pic du Midi. Both
instruments are capable of providing Doppler measurements with the
required precision of a few m/s, and the 7 hour longitude separation
between them allows the acquisition of relatively long uninterrupted
data strings. In the event, bad weather prevented more than sporadic
observations from Pic du Midi. At Mt. Hopkins, however, we obtained
good observations on each of 6 consecutive nights 3-8 Feb 1996, for
a total of 47 h of observing time. We discuss here the interpretation
of this data set in terms of possible p-mode oscillations.
---------------------------------------------------------
Title: Techniques for observing solar oscillations.
Authors: Brown, T. M.
1996stsu.conf....1B Altcode:
The following topics were dealt with: analysis tools and the solar
noise background; instrumentation for measuring solar p-modes; analysis
tools for helioseismology; local analysis methods.
---------------------------------------------------------
Title: Far-UV Line Strengths in Elliptical Galaxies
Authors: Ferguson, H. C.; Brown, T. M.; Davidsen, A. F.
1996ASPC...98..486F Altcode: 1996fstg.conf..486F; 1996astro.ph..4008F
Much of the far-UV emission from elliptical galaxies is thought to
arise from extreme horizontal branch stars and related objects. Only
about 10% of the stellar population needs to evolve through this phase
even in galaxies with the strongest UV upturn. However it is not yet
clear if this population represents the extreme low-metallicity or
high-metallicty tail of the distribution, or rather arises from the
overall population through some metallicity-insensitive mechanism
that causes increased mass loss in a small fraction of RGB stars. We
investigate the utility of far-UV line strengths for deciding between
these possiblities. Complications include the fact that the line
strengths reflect both the temperature distribution and the metallicity
distribution of the stars, that there may be abundance anomalies
introduced on the RGB, and that metals are likely to be redistributed
by gravitational settling and radiative diffusion in the atmospheres
of hot high-gravity stars. Line-strength measurements from Astro-2
HUT spectra are considered in this context.
---------------------------------------------------------
Title: A Radial Velocity Search for p-mode Pulsations in eta Bootis
Authors: Noyes, R. W.; Korzennik, S. G.; Nisenson, P.; Brown, T. M.;
Kennelly, E. J.; Horner, S. D.
1995AAS...18710211N Altcode: 1995BAAS...27.1429N
Kjeldsen et al. 1994 (Astron. J 109, 1313 ) have reported the presence
of p-mode pulsations in Balmer line equivalent widths measured in
the spectrum of eta Boo (G5 IV); they give accurate frequencies for
13 modes of oscillation, and estimate velocity amplitudes for these
modes of typically 1.6 m/s. We report here time-series observations of
the radial velocity of eta Boo obtained with the Advanced Fiber Optic
Echelle (AFOE) spectrograph. In March 1995 we obtained 555 spectra
of eta Boo for a total of 21.6 hours of observing time spread over
7 consecutive nights. The radial velocity time series clearly shows
the night-to-night orbital motion of eta Boo; the residual velocities
after removing this motion are typically 10 m/s for single spectra,
a value that is roughly consistent with shot noise limits. The power
spectrum of the time series shows no evidence for Kjeldsen et al.'s
frequencies. With 95 % confidence, we can rule out the presence of these
13 frequencies with typical amplitudes of 0.5 m/s or more. The spectrum
is consistent with pure photon noise, but also with the presence of
pulsations having other frequencies (not those given by Kjeldsen et
al.) and with typical amplitudes as large as about 1.5 m/s. Possible
explanations for the discrepancy between the two results are (a) an
incorrect conversion between the amplitudes of equivalent width and
Doppler pulsations, and (b) a fluke in the noise behavior of one or
both observations.
---------------------------------------------------------
Title: Determining the AFOE's Radial Velocity Precision with Solar
Observations
Authors: Horner, S. D.; Brown, T. M.; Kennelly, E. J.; Noyes, R. W.;
Korzennik, S. G.; Nisenson, P.; Krockenberger, M.
1995AAS...187.7006H Altcode: 1995BAAS...27.1380H
The Advanced Fiber Optic Echelle (AFOE) is an instrument designed
for high precision radial velocity observations to detect extra-solar
planets and study stellar structure through asteroseismology. A 320 mu
m optical fiber is used to obtain solar observations during the day to
determine the precision of the instrument, and to study the relationship
between stellar activity and measured radial velocities. Here we
present the results of our analysis of solar data to determine the
short and long term radial velocity precision of the AFOE.
---------------------------------------------------------
Title: Precise Photometry Mission -- Measuring Stellar
Microvariability from Space
Authors: Brown, T. M.; Borucki, W.; Frandsen, S.; Gilliland, R. L.;
Jones, A.; Noyes, R. W.; Tarbell, T.; Title, A.; Ulrich, R. K.
1995AAS...187.7111B Altcode: 1995BAAS...27R1385B
Atmospheric scintillation limits the precision attainable by
ground-based photometry; this limitation is a major obstacle to
progress in several fields, notably asteroseismology of Sun-like
stars. A space-borne photometric telescope could operate near the shot
noise limit, removing this obstacle and providing new opportunities
for inquiry. As part of the program for New Mission Concepts in
Astrophysics, we are studying the scientific rewards and technological
challenges associated with a Precise Photometry Mission (PPM). The
baseline performance goal for the PPM is to measure solar-like
pulsations (amplitude 3 mu mag) in G stars in the Hyades with a S/N
ratio of 4 in 10 days of observing time. This performance would also
allow detection of transits of Earth-sized planets of main-sequence
stars, extremely precise characterization of the light curves of
micro-lensing events, and other novel applications. The technical
approach envisioned for the PPM is wide-band CCD photometry. The study
that is underway focuses on two aspects of the required technology: (1)
Are CCD detectors able to provide the necessary very high S/N within
the spacecraft operating environment? (2) Can new lightweight mirror
and telescope structure technology be applied to yield significant
reductions in mission cost? We are addressing both questions with
laboratory tests, including time-series performance tests of suitable
CCDs, and thermal and mechanical tests of a SiC telescope mirror. In
addition to describing PPM's scientific aims and technical rationale,
we report preliminary results of the CCD tests.
---------------------------------------------------------
Title: Hopkins Ultraviolet Telescope Observations of Six E and
S0 Galaxies
Authors: Brown, T. M.; Ferguson, H. C.; Davidsen, A. F.
1995AAS...186.2004B Altcode: 1995BAAS...27..834B
In order to better understand the hot stellar populations of E and
S0 galaxies, we observed six objects using the Hopkins Ultraviolet
Telescope. Through our 11” times 60” aperture, we obtained one
observation each of M 49 (1346 s), M 87 (950 s), M 89 (1682 s), and
NGC 3115 (1634 s), two observations of NGC 3379 (3074 s), and four
observations of M 60 (5824 s). The far-ultraviolet (FUV) spectra
were obtained during orbital night as part of the Astro-2 mission
on the space shuttle Endeavor in March 1995, and cover the spectral
range of 912 Angstroms to 1850 Angstroms with a resolution of 2--4
Angstroms. This sample quadruples the number of early-type galaxies
studied to the Lyman limit. After correcting for geocoronal emission
and interstellar extinction in our own Galaxy, all the spectra are
similar, even though the “UV upturn” strength, as characterized by
the parameter m<SUB>1550</SUB>-V, varies over the range of 2.04 mag to
3.86 mag for these galaxies. Comparison with models of evolved stellar
populations confirms the conclusion from Astro-1 data that the FUV
flux can be explained by stars with a narrow range of temperature and
envelope mass on the extreme horizontal branch (EHB). This work was
supported by NASA contract NAS 5-27000 to the Johns Hopkins University.
---------------------------------------------------------
Title: Asteroseismology
Authors: Brown, T. M.
1995ESASP.376a.177B Altcode: 1995heli.conf..177B; 1995soho....1..177B
Asteroseismology is already being successfully practiced on white
dwarfs. To make progress applying it to stars that are more like the
Sun, advances are needed in both observation and theory. Observations of
the subgiant η Boo may point the way to a new low-noise spectroscopic
technique for studying the very small-amplitude pulsations in stars
with surface temperatures similar to that of the Sun. In the longer
term, photometric observations from spacecraft probably hold the most
promise for studying such stars. Several such missions are now being
studied or actively pursued.
---------------------------------------------------------
Title: The AFOE: A Spectrograph for Precision Doppler Studies
Authors: Brown, Timothy M.; Noyes, Robert W.; Nisenson, Peter;
Korzennik, Sylvain G.; Horner, Scott
1994PASP..106.1285B Altcode:
The Advanced Fiber Optic Echelle (AFOE) is a fiber-fed echelle
spectrograph designed for the measurement of stellar Doppler
shifts. Using a 2k x 2k CCD detector, it samples about 55% of the
wavelength range between 450 nm and 700 nm (20 echelle orders) at a
single shot, with spectral resolution R = 32000 to 70000 at 500 nm,
depending on the slit width employed. The AFOE employs a number of
devices to assure that the calibrations necessary for accurate Doppler
measurements can be properly performed. The most important of these
are: (1) coupling to the telescope via a double-scrambling optical
fiber system; (2) continuous calibration of the wavelength scale and
point-spread function by means of an atomic emission lamp entering the
spectrograph via a separate fiber and/or a molecular iodine absorption
cell; (3) availability of fiber-coupled sunlight for regular calibration
against the solar spectrum; (4) appropriate mechanical design and active
thermal control, yielding good mechanical stability. The AFOE is coupled
to the Tillinghast 1.5-m telescope at the F. L. Whipple Observatory. It
presently achieves S/N = 500 in the continuum near 500 nm in 60s when
observing Arcturus (alpha-Boo, m_V = -0.04). This noise level sets
a limit of about 0.7 ms^-1 to the Doppler precision attainable in
this length of observing time. Currently, our actual frame-to-frame
repeatability is worse than the photon noise limited value by about a
factor of 3 for this bright star, and about 1.5 for stars with m_V =
4. Work is continuing to refine data processing methods so that the
ultimate noise limit may be approached more closely, and to improve
the spectrograph's relatively low efficiency. (SECTION: Astronomical
Instrumentation )
---------------------------------------------------------
Title: Generation of artificial helioseismic time-series.
Authors: Schou, J.; Brown, T. M.
1994A&AS..107..541S Altcode:
We present an outline of an algorithm to generate artificial
helioseismic time-series, taking into account as much as possible of
the knowledge we have on solar oscillations. The hope is that it will
be possible to find the causes of some of the systematic errors in
analysis algorithms by testing them with such artificial time-series.
---------------------------------------------------------
Title: On the Rotation Rate in the Solar Convection Zone
Authors: Schou, Jesper; Brown, Timothy M.
1994ApJ...434..378S Altcode:
Recently Gough et al. (1993) have argued that the rotation rate in parts
of the solar convection zone may be constant on cylinders as predicted
by models of the convection zone, contrary to the inferences generally
made from helioseismology. Here we consider models similar to those
suggested by Gough et al. and show that they are either inconsistent
with observations made by Fourier Tachometer or require unphysical
rotation rates in other parts of the Sun. These observations use a more
detailed model of the effects of the solar rotation on the observed
frequencies than that used in reducing previous observations. We
also show the results of an inversion of the Fourier Tachometer
observations and compare it with an inversion of data similar to that
used previously. The result of this inversion generally confirms the
conclusions from previous inversions.
---------------------------------------------------------
Title: Asteroseismology: Theory and phenomenology
Authors: Brown, Timothy M.
1994spmt.nasa...17B Altcode:
Seismic studies of the Sun have succeeded in mapping the variation of
sound speed with depth in the Sun, and variation of angular velocity
with both depth and latitude. Many stars besides the Sun may also be
amenable to asteroseismic analysis. Stars of roughly solar type should
of course behave in ways similar to the sun, and stars of this sort form
a large fraction of the potential targets for asteroseismology. But
several other types of stars (delta scuti stars, roAP stars,
and the pulsating white dwarfs) also have the desired pulsation
characteristics. Pulsations in some of these stars are, for various
reasons, much easier to observe than in the Sun-like stars. Virtually
all unambiguous observations of multi-mode pulsators relate to these
other categories of stars. Since oscillation mode frequencies are
arguably the most precise measurement relating to a star that we can
make, a few tens of such frequencies may still be of great importance
to our understanding of the stellar structure and evolution.
---------------------------------------------------------
Title: The Effectiveness of Oscillation Frequencies in Constraining
Stellar Model Parameters
Authors: Brown, Timothy M.; Christensen-Dalsgaard, J.; Weibel-Mihalas,
Barbara; Gilliland, Ronald L.
1994ApJ...427.1013B Altcode:
Recent observational advances suggest that it may soon be possible to
measure the frequencies of p-mode oscillations on distant Sun-like
stars. We investigate the potential utility of such oscillation
frequencies in determining the fundamental stellar structure parameters
of these stars, in the case in which frequencies may be measured
for both members of a visual binary system. To utilize all of the
observations presumed to be available in an optimal way, we develop a
formalism based on singular value decomposition (SVD) to relate errors
in observed quantities to those in model parameters. As a particularly
interesting example, we consider the alpha Cen system as it would
be seen from distances between 1.3 pc (its true distance) and 100
pc. We find that for the nearest case, adding oscillation frequency
separations with plausible errors to the available astrometric,
photometric, and spectroscopic data allows one to reduce the formal
errors in estimates of the helium abundance, heavy-element abundance,
and mixing length by roughly a factor of 2. Estimates of the stellar
masses and the system's age and distance are not markedly improved,
mostly because of the very high quality astrometric data that can
be obtained on such a nearby object. If the system were located at a
signifcantly larger distance, the addition of oscillation information
would allow drastic reductions in the formal error applicable to all
of the stellar parameters except the helium abundance. These results
suggest that accurately measured oscillation frequencies for visual
binaries might allow tests of stellar structure theory at a level of
precision that has hitherto been obtainable only for a few eclipsing
binaries. Reducing the observational errors in photometry or astrometry
by a factor of 3 does not provide the same level of improvement,
especially for relatively distant systems. We show that the extra
information contained in the oscillation frequencies for a reasonable
set of modes would easily allow one to distinguish between models using
opacity laws obtained from the Los Alamos Opacity Library and from
the more recent Livermore OPAL tables. Different formulations of the
equation of state (without and with Coulomb effects) lead to models
that are marginally distinguishable, while models with and without
helium settling from the convection zone are not distinguishable,
given observations with errors as large as we assume.
---------------------------------------------------------
Title: Asteroseismology
Authors: Brown, Timothy M.; Gilliland, Ronald L.
1994ARA&A..32...37B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: A Search for Solar-Like Oscillations in the Stars of M67 With
CCD Ensemble Photometry on a Network of 4m Telescopes
Authors: Gilliland, R. L.; Brown, T. M.; Kjeldsen, H.; McCarthy,
J. K.; Peri, M. L.; Belmonte, J. A.; Vidal, I.; Cram, L. E.; Palmer,
J.; Frandsen, S.; Parthasarathy, M.; Petro, L.; Schneider, H.; Stetson,
P. B.; Weiss, W. W.
1993AJ....106.2441G Altcode:
Results are presented from a large observational project directed
toward the detection of solar-like oscillations in an ensemble of
open cluster stars. Seven groups collaborated in 1992 January to
observe twelve stars in M67 with 4 m class telescopes for a one week
period. High quality time series were collected on 22 telescope nights
for a total of 156 h. The technique of CCD ensemble photometry allowed
precisions of about 250 micro-mag per minute to be reached in the best
cases, and provided robust results in conditions that sometimes were
far from 'photometric.' The longitude-distributed network, coupled
with generally low noise levels, provided a good window function and
yielded detection thresholds of about 20 micro-mag (five times solar)
for solar-like oscillations in the best ensembled stars. Sensitivity
to solar-like oscillations over our twelve ensemble stars ranges
from 30% to a factor of three better than obtained previously by any
group. When our simulations results for 12 stars is taken into account
this project provides a (multiplexed) factor of 20 to 30 gain over
previous experiments. For two stars we derive interesting upper limits
for oscillation amplitudes that are near the lower range predicted by
theory. Over half the stars in the ensemble show suggestive evidence for
oscillations; we develop the evidence for, and the cautions against,
claiming detections in these cases. We argue that a more aggressive
network campaign could provide a factor of two sensitivity gain with
a resulting high probability of attaining unambiguous oscillation
detections on most of the stars in the M67 ensemble.
---------------------------------------------------------
Title: Generation of artificial helioseismic time-series
Authors: Schou, J.; Brown, T. M.
1993STIN...9415968S Altcode:
We present an outline of an algorithm to generate artificial
helioseismic time-series, taking into account as much as possible of
the knowledge we have on solar oscillations. The hope is that it will
be possible to find the causes of some of the systematic errors in
analysis algorithms by testing them with such artificial time-series.
---------------------------------------------------------
Title: Observations of Intermediate Degree Solar Oscillations:
1989 April--June
Authors: Bachmann, Kurt T.; Schou, Jesper; Brown, Timothy M.
1993ApJ...412..870B Altcode:
Frequencies, splittings, and line widths from 85 d of full disk
Doppler observations of solar p-modes taken between April 4 and June
30, 1989 are presented. Comparison of the present mode parameters
with published Big Bear Solar Observatory (BBSO) results yields good
agreement in general and is thus a confirmation of their work using an
independent instrument and set of analysis routines. Average differences
in p-mode frequencies measured by the two experiments in spring-summer
1989 are explained as a result of differences in the exact periods of
data collection during a time of rapidly changing solar activity. It
is shown that the present a(1) splitting coefficients for p-modes
with nu/L less than 45 micro-Hz suffer from a significant systematic
error. Evidence is presented to the effect that a detector distortion
or alignment problem, not a problem with the power spectra analysis,
is the most likely explanation of this a(1) anomaly.
---------------------------------------------------------
Title: P-Mode Frequency Variation in Relation to Global Solar Activity
Authors: Bachmann, Kurt T.; Brown, Timothy M.
1993ApJ...411L..45B Altcode:
We show that p-mode frequency variations correlate remarkably well with
the variations of six solar activity indices over a 6 yr period from
1984 October to 1990 November, including both the large variation from
solar minimum to solar maximum and smaller variations observed over
approximately 1 month intervals during solar maximum. The quality of
correlation as seen visually and as measured by two statistical tests
differs significantly among the six activity indices, and we briefly
speculate on possible reasons for this. Observations used in this
study come from the HAO/NSO Fourier tachometer (FTACH) and include
the spherical harmonic degree range l greater than 20 and equal to 60
or less and frequency range between 2600 and 3200 micro-Hz. The data
are divided into 18 separate epochs with time string duration ranging
from a minimum of 18 days to a maximum of 45 days. We have particularly
good coverage during the early part of solar maximum of cycle 22.
---------------------------------------------------------
Title: The Absorption of p-Modes by Sunspots: Variations with Degree
and Order
Authors: Bogdan, Thomas J.; Brown, Timothy M.; Lites, Bruce W.;
Thomas, John H.
1993ApJ...406..723B Altcode:
A spherical harmonic decomposition of the p-modes into inward and
outward propagating waves is employed to investigate the absorption
of solar p-modes by an isolated sunspot. The absorption coefficient
(averaged over frequency and azimuthal order) is found to increase
with increasing horizontal wavenumber k over the range 0-0.8/Mm. For
larger horizontal wavenumbers, in the range 0.8-1.5/Mm, the absorption
coefficient decreases with increasing k. The absorption along each
individual p-mode ridge tends to peak at an intermediate value of the
spherical harmonic degree in the range 200-400. The highest absorption
is found along the p(1) ridge, and the absorption decreases with
increasing radial order.
---------------------------------------------------------
Title: A search for solar-like oscillations in the stars of M67
Authors: Gilliland, R. L.; Brown, T. M.; Kjeldsen, H.; Belmonte,
J. A.; Cram, L. E.; Frandsen, S.; McCarthy, J. K.; Parthasarathy,
M.; Peri, M. L.; Petro, L.; Schneider, H.; Stetson, P. B.; Vidal,
I.; Weiss, W. W.
1993prph.conf..145G Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The Search for Pulsations in Late-Type Giants - Preliminary
Results
Authors: Horner, S. D.; Brown, T. M.
1993ASPC...42..391H Altcode: 1993gong.conf..391H
No abstract at ADS
---------------------------------------------------------
Title: Ring Diagram Analysis of MT.WILSON Data
Authors: Patron, J.; Hill, F.; Rhodes, E. J., Jr.; Korzennik, S. G.;
Cacciani, A.; Brown, T. M.
1993ASPC...42..437P Altcode: 1993gong.conf..437P
No abstract at ADS
---------------------------------------------------------
Title: How may seismological measurements constrain parameters of
stellar structure?
Authors: Brown, T. M.; Christensen-Dalsgaard, J.; Mihalas, B. W.
1993ASPC...40..554B Altcode: 1993IAUCo.137..554B; 1993ist..proc..554B
No abstract at ADS
---------------------------------------------------------
Title: Observations of Intermediate Degree Solar Oscillations -
1989APR-JUN
Authors: Bachmann, K. T.; Schou, J.; Brown, T. M.
1993ASPC...42..197B Altcode: 1993gong.conf..197B
No abstract at ADS
---------------------------------------------------------
Title: GONG 1992 : seismic investigation of the sun and stars :
proceedings of a conference held in Boulder, Colorado, August
11-14, 1993
Authors: Brown, Timothy M.
1993ASPC...42.....B Altcode: 1993gong.conf.....B; 1993QB539.O83G66...
Various papers on the seismic investigation of the sun and stars are
presented. Individual topics addressed include: excitation of solar
p-modes, cause of cycle-related global solar changes, ionization effects
on solar granulation dynamics, turbulent compressible convection with
rotation, convective overshooting in stars, local helioseismology of
subsurface structure, observations of high-frequency solar oscillations,
high-frequency P-mode spectrum, high-frequency solar velocity noise,
isothermal waves in solar atmosphere, detection of convective overshoot,
2D helioseismic inversions, seismic limits on the sun's internal
toroidal field, faster formulations of the OLA method, torsional
oscillations and internal rotation. Also discussed are: solar g-mode
signatures in p-mode signals, theory of Delta Scuti stars, the Whole
Earth Telescope, phase function for solar-like stars, asteroseismic
HR diagram, seismic analysis of stellar P-mode spectra, asteroseismic
calibration of stellar clusters, observations of Delta Scuti stars from
Arhus, seismology of Procyon, seismological modeling of PG1159-035, GONG
Project update, ring diagram analysis of Mt. Wilson data, gap filling
the GONG data set, helioseismic prospects in the MIR, multicolor CCD
photometer, new echelle spectrograph for asteroseismology.
---------------------------------------------------------
Title: Preliminary results from observations with the Fourier
tachometer.
Authors: Schou, J.; Brown, T. M.; Bachman, K. T.
1993ASPC...40...90S Altcode: 1993IAUCo.137...90S; 1993ist..proc...90S
The authors present preliminary results from an analysis of two ≍3
month observation runs with the Fourier Tachometer (which was operated
by HAO and NSO) from 1987 and 1989. The analysis was done with two
different methods in order to test for systematic errors. It is shown
that the mode frequencies change in a manner similar to that reported
by Libbrecht and Woodard. The authors also present results for the
frequency splittings caused by the solar rotation.
---------------------------------------------------------
Title: An Advanced Fiber Optic Echelle Spectrograph for
Asteroseismology
Authors: Noyes, R. W.; Brown, T. M.; Horner, S.; Korzennik, S.;
Nisenson, P.
1993ASPC...42..485N Altcode: 1993gong.conf..485N
No abstract at ADS
---------------------------------------------------------
Title: The AFOE - a new instrument for asteroseismology
Authors: Noyes, R. W.; Brown, T. M.; Horner, S.; Korzennik, S.;
Nisenson, P.
1993ASPC...40..752N Altcode: 1993IAUCo.137..752N; 1993ist..proc..752N
No abstract at ADS
---------------------------------------------------------
Title: Data analysis techniques for determining high precision
doppler shifts using Iodine absorption cells
Authors: Horner, S. D.; Brown, T. M.
1993ASPC...40..764H Altcode: 1993ist..proc..764H; 1993IAUCo.137..764H
No abstract at ADS
---------------------------------------------------------
Title: Key issues - A round table discussion
Authors: Brown, T. M.; Demarque, P.; Noyes, R.; Praderie, F.; Roxburgh,
I. W.; Schatzman, E.
1993ASPC...40..776B Altcode: 1993ist..proc..776B; 1993IAUCo.137..776B
An overview of a round table discussion on the internal dynamics of
stars, some problems in stellar structure and evolution, a study of
stellar activity mechanisms using PRISMA, the seismology of sunlike
stars, and directions of future research is presented. It is concluded
that models that take into account just one physical process generally
do not agree with the observations. This provides evidence for the
presence of other physical processes. In each phenomenon which is
considered, a variety of physical processes are involved. All physical
processes should be taken into account simultaneously. Stars need to
be considered globally. It is recommended that attention be given to
such unsolved problems as the helium content of the sun, the abundance
of lithium in fast rotating stars, and the origin and evolution of
stellar magnetic fields.
---------------------------------------------------------
Title: Tests of a Simple GONG P-Mode Merging Algorithm
Authors: Williams, W.; Hill, F.; Toner, C.; Brown, T. M.
1993ASPC...42..441W Altcode: 1993gong.conf..441W
No abstract at ADS
---------------------------------------------------------
Title: Localized Sources of Propagating Acoustic Waves in the Solar
Photosphere
Authors: Brown, Timothy M.; Bogdan, Thomas J.; Lites, Bruce W.;
Thomas, John H.
1992ApJ...394L..65B Altcode:
A time series of Doppler measurements of the solar photosphere with
moderate spatial resolution is described which covers a portion of the
solar disk surrounding a small sunspot group. At temporal frequencies
above 5.5 mHz, the Doppler field probes the spatial and temporal
distribution of regions that emit acoustic energy. In the frequency
range between 5.5 and 7.5 mHz, inclusive, a small fraction of the
surface area emits a disproportionate amount of acoustic energy. The
regions with excess emission are characterized by a patchy structure
at spatial scales of a few arcseconds and by association (but not
exact co-location) with regions having substantial magnetic field
strength. These observations bear on the conjecture that most of the
acoustic energy driving solar p-modes is created in localized regions
occupying a small fraction of the solar surface area.
---------------------------------------------------------
Title: Limits to CCD Ensemble Photometry Precision, and Prospects
for Asteroseismology
Authors: Gilliland, Ronald L.; Brown, Timothy M.
1992PASP..104..582G Altcode:
We report results of CCD ensemble, time-resolved photometry with
the KPNO 2.1-m telescope yielding precision of 400 umag per minute
of integration. Previous experience on 1-m class telescopes and
well-known scaling laws for the limiting noise sources indicate
that current 4-m class telescopes and existing detectors, operated
as a network for about five days, would allow detection of coherent
(solar-like) oscillations at an amplitude of 15 umag. We provide
detailed stellar-evolution modeling and eigenfrequency-analysis results
for the stars of the old open cluster M67. Using observed amplitudes
of solar p-mode oscillations, and published scaling laws with spectral
type, we show that direct detection of solar-analog oscillations on
13th-magnitude M67 stars is possible with a several-night 4-m network
campaign. Asteroseismology on a substantial ensemble of cluster stars
promises to allow fundamental new tests of stellar structure and
evolution theory. (SECTION: Instrumentation and Data Analysis)
---------------------------------------------------------
Title: The Oscillating Blue Stragglers in the Open Cluster M67
Authors: Gilliland, Ronald L.; Brown, Timothy M.
1992AJ....103.1945G Altcode:
Results from high-precision, time-resolved CCD photometry of two
oscillating blue stragglers in M67 are presented. By comparing similar
observations obtained two years apart, ten independent modes in one
of these Delta Scuti stars, and five modes in the other have been
detected. Results from stellar evolution computations and theoretical
eigenfrequency analyses are discussed in attempts to make definitive
mode identifications. For both oscillating blue stragglers, nonradial
p modes are present that carry information on internal structure,
rotation, and inclination of the stars. The implications of oscillation
frequency analyses for theories of the origin of blue stragglers
are discussed.
---------------------------------------------------------
Title: Wide-field f /3.5 Rosin camera
Authors: Brown, Timothy M.
1992ApOpt..31.2314B Altcode:
A relatively fast wide-field f/3.5 camera with an aperture of 15 cm and
a focal length of 52 cm was constructed by modifying wide-field Rosin's
(1961) design. The camera yields 2.5-arcsec resolution over a 5-deg-diam
flat field. No ghost images arising from multiple reflections were
detected within the antireflection-coated corrector system or from
light reflected backward from the focal plane.
---------------------------------------------------------
Title: On the Analysis of Helioseismic Time-Series
Authors: Schou, J.; Brown, T. M.
1991BAAS...23.1390S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: High Precision Doppler Measurements Using Iodine Absorption
Cells
Authors: Horner, S. D.; Brown, T. M.
1991BAAS...23.1315H Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The Source of Solar High-Frequency Acoustic Modes: Theoretical
Expectations
Authors: Brown, Timothy M.
1991ApJ...371..396B Altcode:
The source exciting the solar p-modes is likely to be acoustic noise
generated in the top part of the sun's convection zone. If so, then
simple arguments suggest that most of the emitted energy may come
from rare localized events that are well separated from one another in
space and time. This note describes the acoustic emission that would
be expected from such events, based on a ray-theory analysis. Most
of the acoustic energy is found to emerge very close to the source,
so that observations to identify emission events will require high
spatial resolution.
---------------------------------------------------------
Title: Detection of Possible p-Mode Oscillations on Procyon
Authors: Brown, Timothy M.; Gilliland, Ronald L.; Noyes, Robert W.;
Ramsey, Lawrence W.
1991ApJ...368..599B Altcode:
In the course of a search for solar-like oscillations in bright
late-type stars, Doppler variability was observed in the F5 subgiant
Procyon. The variations have frequencies within a 1.1 mHz range
centered at 0.9 mHz, and a total rms amplitude within that range
of 2.5 m/s. Observations of Arcturus and scattered sunlight made
with the same equipment during the same time interval show no such
variation, indicating that the variations seen on Procyon are of stellar
origin. The Doppler signal seen is entirely consistent with solar-like
p-modes on Procyon, with maximum mode amplitudes of about 50 cm/s
and periods around 20 minutes. Several statistical tests support the
identification for the signal with narrow-band oscillations, but none
does so conclusively. Assuming that the signal does arise from p-modes,
there is evidence that the frequency splitting nu(0) is 71 micro-Hz. The
data do not permit a definite estimate of this quantity, and other
values of nu(0) fit the observations about equally well. In order to
clarify the sources of ambiguity in this and similar observations,
the data acquisition, reduction, and interpretation are described.
---------------------------------------------------------
Title: Time-Resolved CCD Photometry of an Ensemble of Stars in the
Open Cluster M67
Authors: Gilliland, Ronald L.; Brown, Timothy M.; Duncan, Douglas K.;
Suntzeff, Nicholas B.; Lockwood, G. Wesley; Thompson, Don T.; Schild,
Rudolph E.; Jeffrey, William A.; Penprase, Bryan E.
1991AJ....101..541G Altcode:
Stars in the central region of the old open cluster M67 were monitored
for stability using CCD, time-resolved photometry. Five sites
with 1 m class telescopes participated in an intensive monitoring
effort, yielding contiguous 14 night coverage with 1 min temporal
resolution. Noise levels to 0.0008 mag variation relative to an
ensemble mean were attained at 13th mag over 9 hr time series. Limits
to detection of coherent oscillations with periods of 3-20 min,
assuming a solarlike spectrum of frequencies, are 100 micromag
(30 times solar amplitude) for the best cases. Evidence suggestive
of p-mode oscillations is shown for a few stars, but an unambiguous
detection is not claimed. Serendipitous detection was made of two new
W UMa stars in M67, two oscillating blue stragglers (with multiple
modes) a likely AM Her cataclysmic variable with a 2.091 hr period,
and several stars with low-amplitude intensity changes over timescales
of 1-10 days, that presumably result from rotation or orbital motion.
---------------------------------------------------------
Title: Solar Oscillation Ring Diagrams from Mt. Wilson Full-Disk
Magneto-Optical Dopplergrams
Authors: Hill, Frank; Rhodes, Edward J.; Korzennik, Sylvain G.;
Cacciani, Alessandro; Brown, Timothy M.
1991LNP...388..271H Altcode: 1991ctsm.conf..271H
Three-dimensional power spectra of solar oscillations have been
computed from moderate-resolution full disk Doppler images obtained
with the Magneto-Optical Filter at Mt. Wilson. Slices of the spectra
at constant frequency reveal the ring structures that are analogous
to the ridges in two-dimensional spectra. Ring diagrams obtained
at different heliographic positions show large differences in the
structure of the rings. These variations can be attributed to the
changing effective spatial resolution of the observations across the
disk. After correction for this effect, and .for terrestrial seeing,
the rings will be used to map the horizontal flows in the convection
zone as a function of position and depth.
---------------------------------------------------------
Title: Improvements to solar oscillations time series analysis
methods.
Authors: Brown, T. M.
1991dsoo.conf....3B Altcode:
At HAO, one is in the process of performing a comprehensive and
critical evaluation of several methods for analyzing time series
data related to helioseismology. The purpose is to understand the
random and systematic errors that may be introduced into estimates
of p-mode frequencies, amplitudes, and linewidths by the time series
analysis, and, where possible, to devise means for minimizing these
errors. The methods will be directly applicable to data obtained by
extant experiments, as well as to that expected from the GONG network,
and from the helioseismology instruments on the SOHO spacecraft.
---------------------------------------------------------
Title: Measurements of Intermediate- and High-Degree (20<1<600)
p-Mode Solar Oscillation Power and Energy
Authors: Rhodes, Edward J.; Brown, Timothy M.; Cacciani, Alessandro;
Korzennik, Sylvain G.; Ulrich, Roger K.
1991LNP...388..277R Altcode: 1991ctsm.conf..277R
We present measurements of the total modal power and energy of
both intermediate- and high-degree (20< l <600) solar p-mode
oscillations which have been corrected to first order for the combined
effects of atmospheric seeing, image motion due to imperfect tracking,
and the point spread function of our optics. These power and energy
estimates have been obtained from an average of 20 separate zonal l -
n power spectra, which were obtained from observations obtained at the
60-Foot Solar Tower of the Mt. Wilson Observatory between July 1 and 20,
1988. The raw total power values were obtained from a least-squares
fitting of Lorentzian profiles to the p-mode ridges in the average
zonal power spectrum. As an initial method of correcting the observed
power levels, we adopted the procedure described by Kaufman (1988)
and deconvolved measurements of the observed limb profiles from one
of our images using two slightly different theoretical unblurred limb
profiles in order to obtain two estimates of the modulation transfer
function (mtf) of our experiment. The corrected power values which
resulted show systematic variations with both frequency and degree
which are similar to those obtained by Kaufman. For example, between
l = 100 and 600 our corrected power values drop by a factor of at
least 4.5, although the magnitude of our correction becomes less
certain as the degree is increased above 300. We also convert these
power values into estimates of the total energy of the modes to show
that the modal energies decrease by a factor of at least 15 over the
same range in l. Even given the uncertainty of our correction at the
higher degrees, the consistency of the l-dependent decrease in the
modal energies with similar results by Kaufman (1990) suggests that,
at least above l = 100, the modes are not in energy equipartition with
turbulent convective eddies.
---------------------------------------------------------
Title: The Sun and Asteroseismology
Authors: Brown, Timothy M.
1991ASPC...20..139B Altcode:
Helioseismological studies of the p-mode solar oscillations can
be extended to similar oscillations on more distant stars, thereby
constituting the field of asteroseismology. An evaluation is presented
of the current and future prospects for such studies in the cases of
stars of approximately solar type; general agreement has not yet been
reached as to the detection of p-modes in stars other than the sun,
but such detections appear likely in the near future through powerful
new telescopic techniques. There are also suggestive theoretical
indications as to how much would be learned about stellar interiors
through detailed studies of stellar oscillation.
---------------------------------------------------------
Title: The Variability of the Solar Diameter
Authors: Ribes, E.; Beardsley, B.; Brown, T. M.; Delache, Ph.; Laclare,
F.; Kuhn, J. R.; Leister, N. V.
1991suti.conf...59R Altcode:
It is argued here that most of the variation in observations of
the solar radius of over three centuries measure properties of the
sun's limb darkening function and are affected by many sources of
degradation of the solar image. They do not directly measure a true
solar radius. From a long series of visual observations made by a
single observer as well as recent photoelectric observations, evidence
is found for periodicities in the apparent radius that occur in both
modern and historical records. The magnitude of the observed variations
is quite different in visual and photoelectric observations, suggesting
that the process responsible for the periodicities is either one that
modifies the solar limb darkening function or one that causes systematic
variations in image blurring by the earth's atmosphere. A connection
between solar magnetic activity an apparent radius seems likely, with
evidence for such a relation dating back as fast as the Maunder minimum.
---------------------------------------------------------
Title: A Computer Model of Echelle Spectrograph Efficiency
Authors: Horner, S. D.; Brown, T. M.; Ramsey, L. W.
1990BAAS...22.1260H Altcode:
No abstract at ADS
---------------------------------------------------------
Title: An Inverse Method for P-Mode Scattering Measurements
Authors: Brown, Timothy M.
1990SoPh..128..133B Altcode: 1990IAUCo.121P.133B
Observations of acoustic waves propagating into and out of solar active
regions (Braun, Duvall, and LaBonte, 1987a, b) show that for moderately
large horizontal wavenumbers, sunspots may absorb as much as 50% of
the acoustic energy incident on them. If the absorption process can be
parameterized adequately, it should be possible to use such observations
to learn something about the subsurface structure of magnetized
regions. One way to do this is to treat the inhomogeneities seen by the
propagating sound waves as a collection of point scatterers. Starting
from this approximation, and assuming that multiple scattering is
unimportant, it is possible to use the ingoing and outgoing wave
fields observed at the solar surface to infer a 3-dimensional map of
the active region structure. The inversion technique used to do this is
a departure from usual practice in helioseismology, in that the input
data it requires are mode amplitudes and phases, not frequencies. An
advantage resulting from this difference is that one can attain high
spatial resolution (comparable to the local acoustic wavelength)
with small noise amplification.
---------------------------------------------------------
Title: A Search for Solar-like Oscillations in alpha Centauri A
Authors: Brown, Timothy M.; Gilliland, Ronald L.
1990ApJ...350..839B Altcode:
Spectrographic observations made in the course of a search for
solar-like acoustic oscillations in Alpha Cen A are described. The
observational method was to search for periodic Doppler-shift variations
in all of the spectrum lines within the wavelength range accessible
to a high-dispersion echelle spectrograph - about 30 nm centered on
427.5 nm, in this case. A search was also conducted for variations in
the ratio of line core to continuum intensity, again averaged over all
the available lines. No convincing oscillations were found in either
case, with upper limits for typical single oscillation modes of 70
cm/s in Doppler shift and 4 x 10 to the -5th for continuum intensity
variations inferred from line core intensities.
---------------------------------------------------------
Title: A Technique for Estimating Complicated Power Spectra from
Time Series with Gaps
Authors: Brown, Timothy M.; Christensen-Dalsgaard, Jorgen
1990ApJ...349..667B Altcode:
Fahlman and Ulrych (1982) describe a method for estimating the power
and phase spectra of gapped time series, using a maximum-entropy
reconstruction of the data in the gaps. It has proved difficult to
apply this technique to solar oscillations data, because of the great
complexity of the solar oscillations spectrum. A means for avoiding
this difficulty is described, and the results of a series of blind
tests of the modified technique are reported. The main results of
these tests are: (1) gap filling gives good results, provided that
the signal-to-noise ratio in the original data is large enough, and
provided the gaps are short enough. For low-noise data, the duty cycle
of the observations should not be less than about 50 percent. (2) the
frequencies and widths of narrow spectrum features are well reproduced
by the technique. (3) The technique systematically reduces the apparent
amplitudes of small features in the spectrum relative to large ones.
---------------------------------------------------------
Title: High precision Doppler measurements via echelle spectroscopy.
Authors: Brown, Timothy M.
1990ASPC....8..335B Altcode: 1990ccd1.proc..335B; 1990LDP....13..335B; 1990ccda.proc..335B
With modern echelle spectrographs and CCD detectors, photon noise
permits one to measure the radial velocity of bright stars with
precision as good as 1 m/s in 60 s of observing time. In order to
achieve this precision in practice, one must take measures to control
several sources of instrumental noise. Two distinct methods have evolved
to do this: (1) one may use a molecular absorption cell to impress lines
of constant wavelength on the incoming starlight, or (2) one may use a
fiber optic feed for the starlight, in conjunction with a second fiber
carrying light from a stable wavelength source. At the current state of
development, the first method yields better long-term stability (useful,
e.g., for planetary detection), while the second method provides better
S/N per unit time in circumstances where low-frequency stability is
not required (such as observation of stellar oscillations). For both
methods, details of instrument setup, data acquisition, and data
analysis are important for getting the best results.
---------------------------------------------------------
Title: Oscillating Blue Stragglers in the Old open Cluster M67
Authors: Gilliland, R. L.; Brown, T. M.; Duncan, D. K.; Suntzeff,
N. B.; Lockwood, G. W.; Schild, R. E.; Jeffrey, W. A.; Penprase, B. E.
1989BAAS...21.1119G Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Inferring the Sun's Internal Angular Velocity from Observed
p-Mode Frequency Splittings
Authors: Brown, Timothy M.; Christensen-Dalsgaard, Jorgen; Dziembowski,
Wojciech A.; Goode, Philip; Gough, Douglas O.; Morrow, Cherilynn A.
1989ApJ...343..526B Altcode:
The sun's internal solar velocity Omega is studied as a function of
latitude and radius using the solar oscillation data of Brown and
Morrow (1987). An attempt is made to separate robust inferences about
the sun from artifacts of the analysis. It is found that a latitudinal
variation of Omega similar to that observed at the solar surface exists
throughout the sun's convection zone and that the variation of Omega
with latitude persists to some extent even beneath the convection zone.
---------------------------------------------------------
Title: The GONG data reduction and analysis system.
Authors: Pintar, J. A.; Andersen, B.; Anderson, E. R.; Armet, D. B.;
Brown, T. M.; Hathaway, D. H.; Hill, F.; Jones, H. P.; GONG Data Team
1988ESASP.286..217P Altcode:
Each of the six GONG observing stations will produce three, 16-bit,
256×256 images of the Sun every 60 seconds of sunlight. These
data will be transferred from the observing sites to the GONG Data
Management and Analysis Center (DMAC), in Tucson, on high-density tapes
at a combined rate of over 1 gigabyte per day. The contemporaneous
processing of these data will produce several standard data products
and will require a sustained throughput in excess of 7 megaflops. Peak
rates may exceed 50 megaflops. Archives will accumulate at the rate
of approximately 1 terabyte per year, reaching nearly 3 terabytes in
three years of observing. Researchers will access the data products
with a machine-independent GONG Reduction and Analysis Software
Package (GRASP). Based on the Image Reduction and Analysis Facility
(IRAF), this package will include database facilities and helioseismic
analysis tools. Users may access the data as visitors in Tucson, or
may access DMAC remotely through networks, or may process subsets of
the data at their local institutions using GRASP or other systems of
their choice. Elements of the system will reach the prototype stage
by the end of 1988. Full operation is expected in 1992 when data
acquisition begins.
---------------------------------------------------------
Title: Time-Resolved CCD Photometry of an Ensemble of Stars
Authors: Gilliland, Ronald L.; Brown, Timothy M.
1988PASP..100..754G Altcode:
A technique for obtaining CCD photometry of a large ensemble of
stars, with precision limited by atmospheric scintillation and photon
statistics is presented. Under bright-sky conditions with a 0.9-m
telescope, a precision of about 0.0015 mag relative to an ensemble
average standard was obtained for 12th-13th mag stars in M 67 with
exposure times of 1 min. The increase in noise level due to variable
cirrus clouds is minimal. Effective noise levels for the detection of
coherent oscillations with periods of 5-20 min could thus be reduced
to about 30 micromag over ten nights of observing for stars of this
brightness. A much larger ensemble of faint stars could be followed at
lower precision with sky background and photon statistics as dominant
error sources. Four probable-cluster DA white dwarfs were detected in
the old galactic cluster M 67, using B, V calibration photometry.
---------------------------------------------------------
Title: A Bayesian Approach to Ridge Fitting in the Omega-K Diagram
of the Solar 5-MINUTE Oscillations
Authors: Morrow, C. A.; Brown, T. M.
1988IAUS..123..485M Altcode:
The acoustic oscillation modes of the Sun cluster along ridges of power
in the frequency (ω), horizontal wave number (k) plane. Fitting curves
to these ridges provides input for methods that reveal information
about the Sun's interior. The Bayesian approach allows one to make
systematic use of prior physical and phenomenological information to
assign a prior probability that a candidate curve gives the best fit
to a ridge. Bayes' rule then permits one to update this probability
using the new ridge power data. The maximally probable candidate curve
giving both new and prior information is chosen as the best fit.
---------------------------------------------------------
Title: Automated P-Mode Identification Using Bayes' Theorem
Authors: Brown, T. M.
1988IAUS..123..491B Altcode:
The task of interpreting p-mode spectra is complicated by the
presence of a very large number of oscillation modes, each of which
may appear in the power spectra corresponding to several values of l
and m. Identifying peaks in a power spectrum with particular modes in
an interactive fashion thus quickly becomes impractical. The author
describes an automated method for doing this identification. The
method is based on an application of Bayes' theorem. The method takes
as input the observed power spectra, and a model of the amplitudes
and frequencies one expects to see.
---------------------------------------------------------
Title: Techniques for Observing Solar Oscillations
Authors: Brown, T. M.
1988IAUS..123..453B Altcode:
The author discusses first the instrumental techniques used to observe
solar p-modes, with attention given both to low- and no-resolution
systems, and to systems with spatial resolution. Then he describes
the reduction techniques that are used to convert the raw observations
into useful form.
---------------------------------------------------------
Title: Depth and Latitude Dependence of Solar Rotation
Authors: Brown, Timothy M.; Morrow, Cherilynn A.
1987ApJ...314L..21B Altcode:
A 15-day time series of spatially resolved full-disk Doppler
observations is used to measure the dependence of p-mode oscillation
frequencies on the mode azimuthal order m. This dependence may be used
to infer the depth and latitude variation of the solar rotation. The
results are consistent with solar models that have approximately the
surface latitudinal differential rotation within the convection zone,
but no latitudinal differential rotation in the radiative interior. The
data do not make it possible to distinguish between models for which
the angular rotation rate within the convection zone is a function
of latitude alone, and those for which it is constant on cylindrical
surfaces. Weak evidence for a pole-equator asymmetry in the sound
speed is found.
---------------------------------------------------------
Title: Observations of Solar P-Mode Rotational Splittings
Authors: Brown, Timothy M.; Morrow, Cherilynn A.
1987ASSL..137....7B Altcode: 1987isav.symp....7B
The results of a new set of observations of solar p-mode rotational
splittings obtained with the Fourier Tachometer at NSO/Sunspot (Brown
and Morrow, 1986) are described. The rotational splittings from
these observations fall between those of Brown (1985) and Duvall et
al. (1986). They are apparently consistent with a model in which the
differential rotation resembles that seen at the surface throughout
the convective zone, but becomes constant on spherical surfaces within
the radiative interior.
---------------------------------------------------------
Title: Some current problems in helioseismology
Authors: Brown, Timothy M.
1987LNP...274..298B Altcode: 1987stpu.conf..298B
Helioseismology is enjoying a tremendous surge of activity, spurred
by the combination of reliable data and effective interpretation
methods. Since I cannot do justice to the entire field, I attempt in
this review to describe two current topics that I find interesting. (1)
Several workers have now made measurements relating to the variation
of rotation with depth and latitude inside the Sun. Most of the
observations agree fairly well on the depth dependence, but not so
well on the latitude dependence. I explain how such measurements
are made, and discuss the current state of this controversy. (2)
The driving mechanism for solar p-modes remains a mystery. The best
(in my view) explanation involves stochastic driving of the modes by
turbulent convection. This theory (proposed by Goldreich and Keeley)
has recently been extended by Goldreich and Kumar in a way that
illuminates some issues and obscures others. I attempt to provide a
simple introduction to these ideas.
---------------------------------------------------------
Title: An Asteroseismology Explorer
Authors: Brown, Timothy M.; Cox, Arthur N.
1987LNP...274..415B Altcode: 1987stpu.conf..415B
In response to a NASA opportunity, a proposal has been made to study
the concept of an Asteroseismology Explorer (ASE). The goal of the
ASE would be to measure solar-like oscillations on many (perhaps
hundreds) of stars during a 1-year mission, including many members
of open clusters. We describe this proposal's observational goals,
a strawman technical approach, and likely scientific rewards.
---------------------------------------------------------
Title: Phase recovery with dual nonredundant arrays
Authors: Zirker, J. B.; Brown, T. M.
1986JOSAA...3.2077Z Altcode: 1986OSAJ....3.2077Z
Nonredundant arrays inserted at the pupil plane of a telescope permit
recovery of both amplitude and phase of numerous Fourier components of a
small target. A single array, however, yields insufficient information
with which to solve for all the Fourier components to which that array
responds. A method is proposed here for selecting pairs of arrays that
yield complete information within some passband of spatial frequencies.
---------------------------------------------------------
Title: Solar waves and oscillations.
Authors: Brown, T. M.; Mihalas, B. W.; Rhodes, E. J., Jr.
1986psun....1..177B Altcode:
Contents: Theory of waves and oscillations (basic equations: full
hydromagnetic equations, linearized equations; waves: nonmagnetic waves,
magnetohydrodynamic waves; general properties of solar oscillations:
equations and spheroidal mode solutions, Cowling approximation,
asymptotic behavior of p- and g-mode frequencies, radial oscillations,
properties of nonadiabatic solutions, toroidal oscillations; excitation
and damping of solar pulsations: excitation and damping mechanisms,
mode lifetimes, stability of solar pulsation modes; detailed solutions
for frequencies and frequency splitting: effects of structure on
unperturbed frequencies, effects of rotation, effects of internal
magnetic fields; future theoretical needs). Observations (observational
techniques: diagnostics of spectrum lines, techniques for observing
oscillations and trapped waves; oscillations observed: observations
of 5 minute period p-mode oscillations, the 160 minute oscillation,
torsional oscillations, localized brightness oscillations; wave
observations; waves and oscillations in sunspots; future observational
needs). Oscillations as probes of the solar interior (direct method:
technique and results; inversion methods: technique and applications).
---------------------------------------------------------
Title: Measuring the Sun's internal rotation using solar p-mode
oscillations.
Authors: Brown, Timothy M.
1986ASIC..169..199B Altcode: 1986ssds.proc..199B
2-dimensional velocity images of the Sun were obtained for 5 days in
June, 1984. This time series of images has been analyzed to obtain
frequencies of solar p-mode oscillations with degrees between 8 and 50,
with all azimuthal orders for each degree. The principal results of the
analysis are measurements of the frequency splitting between modes with
the same degree and radial order; these are related to the latitudinal
variation of solar rotation. The observed splittings suggest that for
0.3 R_sun; ≤ r ≤ 0.7 R_sun;, the solar latitudinal differential
rotation is much smaller than at the surface, and moreover than the
rotation rate is close to the surface equatorial value.
---------------------------------------------------------
Title: Solar rotation as a function of depth and latitude
Authors: Brown, T. M.
1985Natur.317..591B Altcode:
A 5-day series of two-dimensional velocity images of the Sun
is analysed to yield frequencies of solar p-mode oscillations
with degrees between 8 and 50, with all azimuthal orders for each
degree. The frequency splitting between modes with the same degree
and radial order is related to the latitudinal variation of rotation,
averaged over a depth range that depends on the degree. The observed
splittings indicate that for 0.3Rsolar <~r<~0.7Rsolar the solar
latitudinal differential rotation is much smaller than at the surface
(rotation roughly constant on spheres), and moreover that the rotation
rate is close to the surface equatorial value.
---------------------------------------------------------
Title: Analysis and interpretation of synthetic time strings of
oscillation data.
Authors: Mihalas, B. W.; Christensen-Dalsgaard, J.; Brown, T. M.
1984sses.nasa..279M Altcode: 1984sss..conf..279M
Artificial strings of solar oscillation data with gaps and noise,
corresponding to the output of different spatial filter functions,
were analyzed. Peaks in the power spectrum are identified for values of
the degree l from 0 to 18, and rotational splitting is estimated. The
filters prove effective in facilitating identification of essentially
all the real peaks in the power spectrum. Estimates of peak frequencies
and amplitudes and rotational splitting frequencies are in reasonably
good agreement with the input values. Spurious peaks in autocorrelation
spectra correspond to the frequency spacing between power peaks with
the same order n, differing by one or two in the degree l.
---------------------------------------------------------
Title: The Fourier Tachometer II - an instrument for measuring global
solar velocity fields.
Authors: Brown, T. M.
1984sses.nasa..157B Altcode: 1984sss..conf..157B
The High Altitude Observatory and Sacramento Peak Observatory have
jointly constructed a second version of the Fourier Tachometer,
which is now undergoing final integration and testing. This is an
interferometric instrument for measuring the Doppler shift of solar
spectrum lines. The principal features and performance goals of this
instrument are: simultaneous velocity observations over a 2-dimensional,
100 x 100 pixel field of view; measurement of absolute Doppler shifts
with 1 m/s accuracy; noise level for moderate-1 oscillation modes of
1 cm/s for a 1-day observing run; flexibility and ease of use. Early
(though incomplete) testing suggests that these goals should be
attainable with the current instrument.
---------------------------------------------------------
Title: Solar p-Mode Eigenfrequencies are Decreased by Turbulent
Convection
Authors: Brown, T. M.
1984Sci...226..687B Altcode:
Average solar p-mode eigenfrequencies are decreased by large fluctuating
velocity fields in the upper convection zone. This effect is greatest
for modes with large horizontal wave numbers and frequencies. It
is large enough to affect estimates of the depth of the convection
zone and may carry useful information about the structure of solar
convective turbulence.
---------------------------------------------------------
Title: Techniques for detecting giant cells using spatially resolved
solar velocity data
Authors: Brown, T. M.; Gilman, P. A.
1984ApJ...286..804B Altcode:
Whether giant cells exist in the convection zone of the sun, and what
their properties might be, are matters of great importance for the
understanding of the dynamics of the solar interior. So far, such cells
have escaped detection, probably because of the small amplitude of their
associated velocity fields and the large amplitudes of shorter-lived
flows. Techniques for improving the detectability of giant cells are
presented. These methods are based on the spatial extent and symmetry
properties of giant cells as seen in self-consistent dynamical models
of the solar convection zone. Simulations suggest that these techniques
allow detection of giant cells with photospheric rms velocities of 2
m/s (0.4 m/s per longitudinal wavenumber), given observations spanning
about one year.
---------------------------------------------------------
Title: Solar Oscillations Observations with the Fourier Tachometer II
Authors: Brown, T. M.
1984BAAS...16..978B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Life history of a fossil: An introduction to taphonomy and
paleoecology
Authors: Brown, T. M.
1983ESRv...19..356B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Seeing-independent definitions of the solar limb position
Authors: Brown, T. M.
1982A&A...116..260B Altcode:
The most important of the advantages of the finite Fourier transform
definition (FFTD) is a low sensitivity to changes in the width of
the atmospheric point spread function. This paper describes a class
of similar edge definitions which share the advantages of the FFTD
and which may be tailored to any desired limb darkening function or
set of observing conditions. For some limb darkening functions, edge
definitions may be obtained which are substantially less sensitive to
seeing than the FFTD.
---------------------------------------------------------
Title: Solar diameter monitor: an instrument to measure long-term
changes
Authors: Brown, Timothy M.; Elmore, D. F.; Lacey, L.; Hull, H.
1982ApOpt..21.3588B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Information theory and the spectrum of isotropic turbulence
Authors: Brown, T. M.
1982JPhA...15.2285B Altcode:
A method of closing the equation set describing turbulent flows is
presented in which the flow behaves in such a way that an entropy
defined in terms suggested by information theory is maximized. The
relevant constraints are taken to be the Reynolds number and energy
dissipation rate of the flow, energy balance at every point in
wavenumber space, and adherence to the Navier-Stokes equations. It is
shown that the maximum entropy formalism leads to a pair of coupled
equations describing the distribution of energy in the turbulent
spectrum, and the correlations between the amplitudes of velocity
components with nearly identical wavenumbers. It develops that if
a power-law solution exists, it can only be the Kolmogorov law. The
turbulent temperature, defined as the reciprocal of the derivative
of the entropy with respect to the local energy dissipation rate,
is virtually constant within the spectrum's inertial subrange.
---------------------------------------------------------
Title: The HAO Solar Diameter Monitor
Authors: Brown, T. M.
1981BAAS...13..878B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Evidence for trapped gravity waves in the solar atmosphere
Authors: Brown, T. M.; Harrison, R. L.
1980ApJ...236L.169B Altcode:
Observations of disk-center solar continuum brightness fluctuations are
reported. These observations show features that may be interpreted
as internal gravity waves trapped in the solar photosphere and
chromosphere. The reasons for this interpretation, and some of its
implications are discussed.
---------------------------------------------------------
Title: Are Gravity Waves Trapped in the Solar Photosphere?
Authors: Brown, T. M.
1980BAAS...12..475B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The Opportunities Offered by SCADM for the Study of Surface
Phenomena Related to Interior Structure and Dynamics
Authors: Brown, T. M.
1980NASCP2098..101B Altcode: 1980sscs.nasa..101B
The physical processes to be probed by experiments may be grouped
as large scale flows, oscillations, and chromospheric/coronal
diagnostics. While the fundamental concerns and observational equipments
are similar within each class, different investigations may tell
different things about the Sun. Observational requirements are listed
for experiments to study (1) plasma-magnetic field interactions; (2)
interior structure via oscillations; (3) chromospheric and coronal
tracers; (4) rotation, meridional flows, and giant cells; (5) the depth
dependence of rotation; (6) EUV luminosity; (7) intensity fluctuations
and tracers; and (8) diameter oscillations, the effects of noise and
time-string on experiment results are assessed.
---------------------------------------------------------
Title: Solar circulation measurements: consideration and plans
Authors: Beckers, J. M.; Brown, T. M.
1980fsoo.conf..189B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Solar continuum brightness oscillations - A progress report
Authors: Brown, T. M.; Harrison, R. L.
1980LNP...125..200B Altcode: 1980nnsp.work..200B
Solar brightness oscillations were observed in the continuum, and
results achieved to date are summarized for two distinct groups of
data. One deals with oscillations at the extreme solar limb, while
the other involves oscillations at the disk center. Some preliminary
interpretations are offered pending further data collection.
---------------------------------------------------------
Title: Observed brightness oscillations at the solar limb.
Authors: Brown, T. M.
1979ApJ...230..255B Altcode:
Observations of the continuum intensity near the solar limb are used to
estimate the power in fluctuating brightness as a function of spatial
and temporal frequency and distance from the limb. This presentation of
the data clearly discriminates between atmospheric and solar effects,
and shows that brightness oscillations are indeed present on the
sun. Most power lies below 1.5 mHz or betweeen 3.0 and 5.0 mHz, and
at wavelengths longer than 5 Mm. Amplitudes per frequency-wavenumber
resolution element range downward from one thousandth the disk-center
intensity. The oscillation amplitude apparently increases with distance
inward from the limb, indicating that the contribution from a high,
optically thin shell cannot be very important.
---------------------------------------------------------
Title: Solar circulation measurements: considerations and plans.
Authors: Beckers, J. M.; Brown, T. M.
1979MmArc.106..189B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Solar limb brightness oscillations.
Authors: Brown, T. M.
1978BAAS...10..729B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Long-period oscillations of the apparent solar diameter:
observations.
Authors: Brown, T. M.; Stebbins, R. T.; Hill, H. A.
1978ApJ...223..324B Altcode:
New observations of the time-varying component of the apparent solar
diameter are reported. Power spectra derived from these observations
reveal narrow-band oscillations at frequencies consistent with the
normal mode frequencies of a standard solar model. The amplitudes of
these oscillations are discussed and related to the observations of
other investigators. A detailed analysis of the experiment and its
associated sources of error is presented and used to show that there
is a very small likelihood that the power spectrum peaks are due to
nonsolar causes.
---------------------------------------------------------
Title: Solar circulation measurements: consideration and plans
Authors: Beckers, J. M.; Brown, T. M.
1978fsoo.conf..189B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Performance of image-plane sharpness criteria in image
reconstruction
Authors: Brown, T. M.
1978JOSA...68..890B Altcode: 1978OSAJ...68..890B
The performance of image-plane sharpness criteria for purposes of image
reconstruction is discussed in terms of a probabilistic model. This
model provides a general framework for understanding sharpness criteria
and predicts that the accuracy of the phase compensation process is
proportional to the number of discrete phase correcting elements.
---------------------------------------------------------
Title: Reconstruction of turbulence-degraded images using nonredundant
aperture arrays
Authors: Brown, T. M.
1978JOSA...68..883B Altcode: 1978OSAJ...68..883B
A technique is described which allows the removal of seeing distortions
from a single frame of speckle-type imagery, provided that this frame
is obtained using an aperture consisting of a nonredundant array of
subapertures, each smaller than the seeing correlation length. Although
performed a posteriori, the method is related to those already proposed
for use with active optical systems. Computer simulations are described
which verify the basic features of this technique. The simulations
indicate that reconstructed images of diffraction-limited quality should
be obtainable for starlike objects as dim as eighth magnitude. For
more extended objects, the limiting magnitude depends somewhat on the
object structure. The technique described is immediately applicable to
any large telescope, and because the processing is done after the fact,
a frame containing many isoplanatic patches may be processed piecewise,
allowing the reconstruction of large areas
---------------------------------------------------------
Title: An Observational Investigation of Long-Period Oscillations
in the Apparent Solar Diameter.
Authors: Brown, T. M.
1977PhDT.........5B Altcode:
A power spectrum analysis of eleven individual time series observations
of the apparent solar diameter reveals oscillations throughout the
three minute to 70 minute period range, with typical amplitudes of
.000002 of the solar diameter. Many of the long period peaks in the
power spectrum appear to be narrow-band features, with damping times
long compared to the length of a typical time series. At least ten of
the observed peaks show repeatable power levels that are significant
at the 0.999 confidence level, and two of them appear to show good
phase coherence over the entire 30 day observation period.
---------------------------------------------------------
Title: Observed Oscillations of the Apparent Solar Diameter
Authors: Brown, T. M.; Stebbins, R. T.; Hill, H. A.
1976ssp..conf....1B Altcode:
No abstract at ADS
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Title: INVITED PAPER - Recent Progress in Solar Oblateness Studies
Authors: Hill, H. A.; Stebbins, R. T.; Brown, T. M.
1975BAAS....7R.478H Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The Dispersal of the Shell of Zeta Ophiuchi
Authors: Barker, Paul K.; Brown, Timothy
1974ApJ...192L..11B Altcode:
Observations are presented showing that the shell recently ejected by
Oph has now disappeared. Spectral changes, including the disappearance
of Ha emission, are described. Subject headings: circumstellar shells -
early-type stars - line profiles
