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We improve the identification and isolation of individual stellar populations in the Galactic halo based on an updated set of empirically calibrated stellar isochrones in the Sloan Digital Sky Survey (SDSS) and Pan-STARRS 1 (PS1)…

Astrophysics of Galaxies · Physics 2021-02-10 Deokkeun An , Timothy C. Beers

We present results from a medium-resolution (R ~ 2, 000) spectroscopic follow-up campaign of 1,694 bright (V < 13.5), very metal-poor star candidates from the RAdial Velocity Experiment (RAVE). Initial selection of the low-metallicity…

Gaia Data Release 3 contains a wealth of new data products for the community. Astrophysical parameters are a major component of this release. They were produced by the Astrophysical parameters inference system (Apsis) within the Gaia Data…

Gaia/DR3 has provided a large sample of new g-mode pulsators, among which~11,600 are Gam Dor stars. This work present the spectroscopic parameters of these Gam Dor pulsators estimated by the GSP-spec module that analysed millions of Gaia…

Solar and Stellar Astrophysics · Physics 2024-11-13 P. de Laverny , A. Recio-Blanco , C. Aerts , P. A. Palicio

We present a Bayesian method to cross-match 5,827,988 high proper motion Gaia sources ($\mu>40 \ mas \ yr^{-1}$) to various photometric surveys: 2MASS, AllWISE, GALEX, RAVE, SDSS and Pan-STARRS. To efficiently associate these objects across…

Solar and Stellar Astrophysics · Physics 2021-05-07 Ilija Medan , Sébastien Lépine , Zachary Hartman

We present the metallicities and carbon abundances of four newly discovered metal-poor stars with $ -2.2 <$ [Fe/H] $< -1.6$ in the Sagittarius dwarf spheroidal galaxy. These stars were selected as metal-poor member candidates using a…

Astrophysics of Galaxies · Physics 2019-05-01 Anirudh Chiti , Anna Frebel

The Edinburgh-Cape Blue Object Survey is an ongoing project to identify and analyse a large sample of hot stars selected initially on the basis of photographic colours (down to a magnitude limit B~18.0) over the entire…

Astrophysics · Physics 2019-08-17 T. C. Beers , S. Rossi , D. O'Donoghue , D. Kilkenny , R. S. Stobie , C. Koen , R. Wilhelm

We present carbon and strontium abundances for 100 metal-poor stars measured from R$\sim $7000 spectra obtained with the Echellette Spectrograph and Imager at the Keck Observatory. Using spectral synthesis of the G-band region, we have…

Astrophysics · Physics 2009-11-13 David K. Lai , Jennifer A. Johnson , Michael Bolte , Sara Lucatello

In early type stars the ultraviolet spectral region is important for several reasons. Firstly, since the majority of the total flux is emitted here, it provides a rather sensitive indicator of a photospheric temperature and luminosity.…

Astrophysics · Physics 2007-05-23 Jadwiga Daszy{ń}ska-Daszkiewicz , Ewa Niemczura

We develop and test a method for the estimation of metallicities ([Fe/H]) and carbon abundance ratios ([C/Fe]) for carbon-enhanced metal-poor (CEMP) stars, based on application of artificial neural networks, regressions, and synthesis…

We present a comprehensive chemical abundance analysis of five red giants and two horizontal branch (HB) stars towards the southern Galactic bulge, at (l,b)$\sim$(0$^{\rm o}$,-11$^{\rm o}$). Based on high-resolution spectroscopy obtained…

Astrophysics of Galaxies · Physics 2016-03-16 Andreas Koch , Andrew McWilliam , George W. Preston , Ian B. Thompson

We present the results of an analysis for 107 extremely metal-poor (EMP) stars with metallicities less than [Fe/H] = -3.0, identified from medium-resolution spectra in SDSS. We follow a methodology based on comparisons of the observed…

Solar and Stellar Astrophysics · Physics 2016-09-07 E. Fernandez-Alvar , C. Allende Prieto , T. C. Beers , Y. S. Lee , T. Masseron , D. P. Schneider

Orbital characteristics based on Gaia Early Data Release 3 astrometric parameters are analyzed for ${\sim} 4000$ metal-poor stars ([Fe/H] $\leq -0.8$) compiled from the Best $\&$ Brightest survey. Selected as metal-poor candidates based on…

In this paper, we explore the feasibility of using machine learning regression as a method of extracting basic stellar parameters and line-of-sight extinctions from spectro-photometric data. We built a stable gradient-boosted random-forest…

Metal-poor stars play an import role in the understanding of Galaxy formation and evolution. Evidence of the early mergers that built up the Galaxy might remain in the distributions of abundances, kinematics, and orbital parameters of the…

Astrophysics of Galaxies · Physics 2020-12-09 André R. da Silva , Rodolfo Smiljanic , Riano E. Giribaldi

Very metal-poor stars are of obvious importance for many problems in chemical evolution, star formation, and galaxy evolution. Finding complete samples of such stars which are also bright enough to allow high-precision individual analyses…

The origin of very metal-poor (VMP; [Fe/H] $\leq -2.0$) stars on planar orbits has been the subject of great attention since their first discovery. However, prior to the release of the Gaia BP/RP (XP) spectra, and large photometric samples…

Astrophysics of Galaxies · Physics 2025-07-15 Shuai Xu , Haibo Yuan , Bowen Huang , Timothy C. Beers , Yang Huang , Maosheng Xiang , Kai Xiao , Jihye Hong , Young Sun Lee , Wuming Yang

We used the spectroscopic and astrometric data provided from the GALAH DR2 and Gaia DR2, respectively, for a large sample of stars to investigate the behaviour of the [$\alpha$/Fe] abundances via two procedures, i.e. kinematically and…

Astrophysics of Galaxies · Physics 2019-11-13 S. Karaali , S. Bilir , E. Yaz Gokce , O. Plevne

We carried out a homogeneous abundance study for various elements, including $\alpha$-elements, iron peak elements and $n$-capture elements for 35 metal-poor stars with a wide metallicity range ($-3.0\lesssim$[Fe/H]$\lesssim-0.5$).…

Astrophysics · Physics 2008-06-02 Jeong-Deok Lee , Sang-Gak Lee , Kang-Min Kim

We search for an optimal filter design for the estimation of stellar metallicity, based on synthetic photometry from Gaia XP spectra convolved with a series of filter-transmission curves defined by different central wavelengths and…