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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

We discuss the origin of HE0107-5240 which is the most metal poor star yet observed ([Fe/H] = -5.3). Its discovery has an important bearing on the question of the observability of "first generation" stars. In common with other metal-poor…

Astrophysics · Physics 2009-11-10 T. Suda , M. Aikawa , M. N. Machida , M. Y. Fujimoto , I. Iben

The chemical compositions of 26 metal-poor stars that exhibit strong CH and/or C2 molecular bands are determined based on high-resolution spectroscopy. We define carbon-enhanced stars taking account of the carbon abundance ratio ([C/Fe])…

We present a chemical composition analysis of a sample of 20 giant branch stars in the "CN-bimodal" globular cluster M4 observed using high resolution echelle spectrographs at Lick & McDonald Observatories. M4, a mildly metal-poor ([Fe/H] ~…

Astrophysics · Physics 2009-10-31 I. I. Ivans , C. Sneden , R. P. Kraft

We report the serendipitous discovery of a nitrogen-rich, mildly metal-poor ([Fe/H]=-1.08) giant star in a single-lined spectroscopic binary system found in the SDSS-IV Apache Point Observatory Galactic Evolution Experiment (APOGEE-2)…

We report high-resolution, high-signal-to-noise, observations of the extremely metal-poor double-lined spectroscopic binary CS 22876-032. The system has a long period : P = 424.7 $\pm$ 0.6 days. It comprises two main sequence stars having…

Astrophysics · Physics 2009-10-31 John E. Norris , Timothy C. Beers , Sean G. Ryan

We present detailed chemical analyses for a sample of twelve stars selected from the CH star catalogue of Bartkevicius (1996). The sample includes two confirmed binaries, four objects that are known to show radial velocity variations and…

Solar and Stellar Astrophysics · Physics 2014-12-12 Drisya Karinkuzhi , Aruna Goswami

We present the first detailed chemical abundances for seven GD-1 stream stars from Subaru/HDS spectroscopy. Atmospheric parameters were derived via color calibrations ($T\rm_{eff}$) and iterative spectroscopic analysis. LTE abundances for…

Based on the high resolution and high signal-to-noise spectra, we derived the chemical abundances of 20 elements for 20 barium (Ba-) stars. For the first time, the detailed abundances of four sample stars, namely HD 92482, HD 150430, HD…

Solar and Stellar Astrophysics · Physics 2024-10-18 Guochao Yang , Jingkun Zhao , Yanchun Liang , Monique Spite , Francois Spite , Jianrong Shi , Shuai Liu , Nian Liu , Wenyuan Cui , Gang Zhao

We have derived new very accurate abundances of the Fe-group elements Sc through Zn (Z = 21-30) in the bright main-sequence turnoff star HD 84937, based on high-resolution spectra covering the visible and ultraviolet spectral regions. New…

Employing high resolution spectra obtained with the near-UV sensitive detector on the Keck I HIRES, supplemented by data obtained with the McDonald Observatory 2-d coude, we have performed a comprehensive chemical composition analysis of…

We report on the result of an ongoing campaign to determine chemical abundances in extremely metal poor (EMP) turn-off (TO) stars selected from the Sloan Digital Sky Survey (SDSS) low resolution spectra. This contribution focuses…

Astrophysics of Galaxies · Physics 2015-03-19 Luca Sbordone , Piercarlo Bonifacio , Elisabetta Caffau , Hans-Gunther Ludwig

We present the iron abundance and abundance ratios for 18 elements with respect to Fe in a sample of stars with a wide range in luminosity from luminous giants to stars near the turnoff in the globular cluster M5. The analyzed spectra,…

Astrophysics · Physics 2009-11-07 Solange V. Ramirez , Judith G. Cohen

We have gathered high resolution echelle spectra for more than two dozen high-velocity metal-poor field stars, including BD+80 245, a star previously known to have extremely low [alpha/Fe] abundances, as well as G4-36, a new low-alpha star…

Astrophysics · Physics 2007-05-23 Inese I. Ivans , Bruce Carney , Luisa de Almeida , Chris Sneden

We have performed a differential, line-by-line, chemical abundance analysis, ultimately relative to the Sun, of nine very metal-poor main sequence halo stars, near [Fe/H]=$-$2 dex. Our abundances range from…

Solar and Stellar Astrophysics · Physics 2017-04-05 Erin O'Malley , Andrew McWilliam , Brian Chaboyer , Ian Thompson

We present the first release of a large-scale study of relatively bright (V < 13.5) metal-poor stars observed with the Southern African Large Telescope (SALT), based on high-resolution spectra of 50 stars with a resolving power of R ~…

We present the results of analysis of ``snapshot'' spectra of 253 metal-poor halo stars -3.8 < [Fe/H] < -1.5 obtained in the HERES survey. The spectra are analysed using an automated line profile analysis method based on the Spectroscopy…

Results from high-resolution spectral analyses of a selected sample of CH stars are presented. Detailed chemical composition studies of these objects, which could reveal abundance patterns that in turn provide information regarding…

Solar and Stellar Astrophysics · Physics 2015-06-23 Drisya Karinkuzhi , Aruna Goswami

We present abundances for a sample of F,G,K dwarfs of the HR1614 moving group based on high resolution, high S/N ratio spectra from AAT/UCLES. Our sample includes stars from Feltzing & Holmberg (2000, A&A, 357, 153), as well as from Eggen…

Astrophysics · Physics 2009-11-11 G. M. De Silva , K. C. Freeman , J. Bland-Hawthorn , M. Asplund , M. S. Bessell

We present here the first abundance analysis of 44 late B, A and F-type members of the young open cluster M6 (NGC 6405, age about 75 Myrs). Spectra, covering the 4500 to 5800 \AA{} wavelength range, were obtained using the FLAMES/GIRAFFE…

Solar and Stellar Astrophysics · Physics 2016-02-16 Tolgahan Kılıçoğlu , Richard Monier , Jacques Richer , Luca Fossati , Berahitdin Albayrak
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