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We present equivalent widths, improved model atmosphere parameters, and revised abundances for 14 species of 11 elements derived from high resolution optical spectroscopy of 311 metal-poor stars. All of these stars had their parameters…

Solar and Stellar Astrophysics · Physics 2025-02-27 Sanil Mittal , Ian U. Roederer

We present elemental abundance results from high resolution spectral analysis of three nitrogen-enhanced barium stars. The analysis is based on spectra obtained with the FEROS attached to 1.52m telescope at ESO, Chile. The spectral…

Solar and Stellar Astrophysics · Physics 2018-02-28 Drisya Karinkuzhi , Aruna Goswami , Navin Sridhar , Thomas Masseron , Meenakshi Purandardas , .

An abundance analysis for the carbon-enhanced, extremely iron-poor ([Fe/H] -3.5) star CS29498-043 has been obtained using new high-resolution, high signal-to-noise spectra from the Subaru Telescope. The [O I] forbidden line at 6300A and the…

Abundances for Fe, O, and the alpha-elements (Mg, Si, Ca, and Ti) have been derived from high resolution spectra of a sample of about one hundred dwarfs with high precision parallaxes measured by HIPPARCOS. The stars have metal abundances…

Astrophysics · Physics 2007-05-23 R. G. Gratton , E. Carretta , G. Clementini , C. Sneden

Context. We have recently investigated the origin of chemical signatures observed in Galactic halo stars by means of a stochastic chemical evolution model. We have found that rotating massive stars are a promising way to explain several…

Solar and Stellar Astrophysics · Physics 2016-11-03 G. Cescutti , M. Valentini , P. François , C. Chiappini , E. Depagne , N. Christlieb , C. Cortés

We present an analysis of the carbon dwarf G77-61, a known binary, based on high resolution Keck spectra. G77-61 has a very-low metallicity, although not as extreme as what was previously conjectured. This star is very carbon-enhanced, the…

Astrophysics · Physics 2009-11-10 Bertrand Plez , Judith G. Cohen

We present chemical abundances of the very bright metal-poor star HD~1936 based on high-resolution and high SNR spectra from AUKR. We obtain the abundances of 29 atomic species with atomic numbers between 3 and 63. In this context, the…

Solar and Stellar Astrophysics · Physics 2024-02-16 Şeyma Çalışkan , Jannat Mushreq Kamil Alazzawi , Yahya Nasolo

We present a Magellan/MIKE high-resolution (R ~ 35,000) spectrum of the ancient star SD 1313-0019 which has an iron abundance of [Fe/H] = -5.0, paired with a carbon enhancement of [C/Fe] ~ 3.0. The star was initially identified by Allende…

Solar and Stellar Astrophysics · Physics 2015-09-23 Anna Frebel , Anirudh Chiti , Alexander P. Ji , Heather R. Jacobson , Vinicius M. Placco

Metal-poor stars provide the fossil record of Galactic chemical evolution and the nucleosynthesis processes that took place at the earliest times in the history of our Galaxy. From detailed abundance studies of low mass, extremely…

Solar and Stellar Astrophysics · Physics 2015-03-11 T. Hansen , C. J. Hansen , N. Christlieb , D. Yong , T. C. Beers , J. Andersen

We present a chemical composition analysis of 36 giants in the nearby mildy metal-poor (<[Fe/H]> = -1.18) "CN-bimodal" globular cluster M4. Confronted with a cluster that has large and variable interstellar extinction across the cluster…

In this study we present abundances of 12^C, 13^C, N, O and up to 26 other chemical elements in two first ascent giants and two core-helium-burning 'clump' stars of the open cluster NGC 2506. Abundances of carbon were derived using the C_2…

Solar and Stellar Astrophysics · Physics 2015-05-28 Šarūnas Mikolaitis , Gražina Tautvaišienė , Raffaele Gratton , Angela Bragaglia , Eugenio Carretta

We present new high-resolution chemical-abundance analyses for the well-known high proper-motion subdwarfs G64-12 and G64-37, based on very high signal-to-noise spectra (S/N ~ 700/1) with resolving power R ~ 95,000. These high-quality data…

Solar and Stellar Astrophysics · Physics 2016-10-05 Vinicius M. Placco , Timothy C. Beers , Henrique Reggiani , Jorge Melendez

Elemental abundances of extrinsic carbon stars provide insight into the poorly understood origin and evolution of elements in the early Galaxy. In this work, we present the results of a detailed spectroscopic analysis of four potential…

Solar and Stellar Astrophysics · Physics 2022-08-22 Shejeelammal J. , Aruna Goswami

We present chemical abundances for 21 elements (from Li to Eu) in 150 metal-poor Galactic stars spanning $-$4.1 $<$ [Fe/H] $<$ $-$2.1. The targets were selected from the SkyMapper survey and include 90 objects with [Fe/H] $\le$ $-$3 of…

Carbon-enhanced metal-poor (CEMP) stars bear important imprints of the early chemical enrichment of any stellar system. While these stars are known to exist in copious amounts in the Milky Way halo, detailed chemical abundance data from the…

Solar and Stellar Astrophysics · Physics 2017-10-25 A. Susmitha , A. Koch , T. Sivarani

We report Zn abundances for 18 very metal-poor stars studied in our previous work, covering the metallicity range -3.2 < [Fe/H] < -2.5. The [Zn/Fe] values of most stars show an increasing trend with decreasing [Fe/H] in this metallicity…

Solar and Stellar Astrophysics · Physics 2015-05-27 Satoshi Honda , Wako Aoki , Timothy C. Beers , Masahide Takada-Hidai

Aims. The Chemical Evolution of R-process Elements in Stars (CERES) project aims to provide a homogeneous analysis of a sample of metal-poor stars ([Fe/H]<-1.5). We present the stellar parameters and the chemical abundances of elements up…

Ultra-faint dwarf galaxies recently discovered around the Milky Way (MW) contain extremely metal-poor stars, and might represent the building blocks of low-metallicity components of the MW. Among them, the Bo\"otes I dwarf spheroidal galaxy…

Astrophysics of Galaxies · Physics 2014-01-09 Miho N. Ishigaki , Wako Aoki , Nobuo Arimoto , Sakurako Okamoto

Based on high resolution, high signal-to-noise (S/N) ratio spectra from Keck/HIRES, we have determined abundances of 20 elements for 18 Ba candidates. The parameter space of these stars are in the range of 4880 $\leq$ $\rm{T_{eff}}$ $\leq$…

Solar and Stellar Astrophysics · Physics 2022-01-05 Shuai Liu , Liang Wang , Jian-Rong Shi , Zhen-Yu Wu , Hong-Liang Yan , Qi Gao , Chun-Qian Li

We have derived the stellar atmospheric parameters, the effective temperature T$_{eff}$, the microturbulent velocity $\zeta$, the surface gravity log g, and the metallicity [Fe/H] for HE 0017+0055, HE 2144-1832, HE 2339-0837, HD 145777, and…

Solar and Stellar Astrophysics · Physics 2021-05-12 Partha Pratim Goswami , Rajeev Singh Rathour , Aruna Goswami