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Revised spectroscopic parameters for the HF molecule and a new CN line list in the 2.3 mu region have been recently available, allowing a revision of the F content in AGB stars. AGB carbon stars are the only observationally confirmed…

Solar and Stellar Astrophysics · Physics 2015-09-16 C. Abia , K. Cunha , S. Cristallo , P. de Laverny

We present an abundance analysis of the far-ultraviolet (905--1187 A) spectrum of the subdwarf B star PG0749+658, obtained by the Far Ultraviolet Spectroscopic Explorer (FUSE). The data have a resolution of about R = lambda / Delta lambda =…

Astrophysics · Physics 2007-05-23 R. G. Ohl , P. Chayer , H. W. Moos

We report the discovery of one extremely metal-poor (EMP; [Fe/H]<-3) and one ultra metal-poor (UMP; [Fe/H]<-4) star selected from the SDSS/SEGUE survey. These stars were identified as EMP candidates based on their medium-resolution…

We present a sample of 1777 bright (9<B<14) metal-poor candidates selected from the Hamburg/ESO Survey (HES). Despite saturation effects present in the red portion of the HES objective-prism spectra, the data were recoverable and…

We present a homogeneous chemical abundance analysis of 16 elements in 190 metal-poor Galactic halo stars (38 program and 152 literature objects). The sample includes 171 stars with [Fe/H] < -2.5, of which 86 are extremely metal poor,…

We report the discovery of SMSS J160540.18-144323.1, a new ultra-metal poor halo star discovered with the SkyMapper telescope. We measure [Fe/H] = -6.2 +- 0.2 (1D LTE), the lowest ever detected abundance of iron in a star. The star is…

Open clusters are ideal tools for tracing the abundances of different elements because their stars are expected to have the same age, distance, and metallicity. Therefore, they serve as very powerful tracers for investigating the cosmic…

We present elemental abundance results for HE 2148-2039 and HE 2155-2043 based on a detailed high-resolution spectroscopic analysis. The high-resolution SUBARU/HDS spectra used for our analysis have a resolution of R~60 000. Although…

Solar and Stellar Astrophysics · Physics 2021-05-12 Meenakshi Purandardas , Aruna Goswami

We have compiled composition, luminosity, and binarity information for carbon-enhanced, metal-poor (CEMP) stars reported by recent studies. We divided the CEMP star sample into two classes, having high and low abundances, respectively, of…

Astrophysics · Physics 2009-11-13 S. G. Ryan , W. Aoki , J. E. Norris , T. C. Beers

This work describes a study of elemental abundances for 30 metal-poor stars whose chemical abundances provide excellent information for setting constraints on models of neutron-capture processes. Based on the abundances of main r- and weak…

Solar and Stellar Astrophysics · Physics 2015-06-12 Hongjie Li , Xiaojing Shen , Shuai Liang , Wenyuan Cui , Bo Zhang

Based on high-resolution spectra obtained with Magellan/MIKE, we present a chemo-dynamical analysis for 27 near main-sequence turnoff metal-poor stars, including 20 stars analyzed for the first time. The sample spans a range in [Fe/H] from…

Astrophysics of Galaxies · Physics 2023-05-10 Mohammad K. Mardini , Anna Frebel , Leyatt Betre , Heather Jacobson , John E. Norris , Norbert Christlieb

We use detailed nucleosynthesis calculations and a realistic prescription for the environment of the first stars to explore the first episodes of chemical enrichment that occurred during the dark ages. Based on these calculations, we…

Astrophysics of Galaxies · Physics 2015-06-19 Ryan Cooke , Piero Madau

We present a detailed analysis of the composition and nucleosynthetic origins of the heavy elements in the metal-poor ([Fe/H]=-1.62+/-0.09) star HD94028. Previous studies revealed that this star is mildly enhanced in elements produced by…

Solar and Stellar Astrophysics · Physics 2016-04-20 Ian U. Roederer , Amanda I. Karakas , Marco Pignatari , Falk Herwig

We report estimated carbon-abundance ratios, [C/Fe], for seven newly-discovered carbon-enhanced metal-poor (CEMP) RR Lyrae stars. These are well-studied RRab stars that had previously been selected as CEMP candidates based on low-resolution…

We present $\gtrsim 15,000$ metal-rich (${\rm [Fe/H]}>-0.2$dex) A and F stars whose surface abundances deviate strongly from Solar abundance ratios and cannot plausibly reflect their birth material composition. These stars are identified by…

The known Mega and Hyper Metal-Poor (MMP-HMP) stars with [Fe/H]<-6.0 and <-5.0, respectively, likely belong to the CEMP-no class, i.e. carbon-enhanced stars with low or absent second peak neutron capture elements. They are likely second…

The primary objective of this study is to accurately determine the abundances of Cu, Sr, Y, Zr, Ba, La, and Ce in selected solar-type stars. This will allow us to establish observational abundance-metallicity and abundance-age relations and…

Solar and Stellar Astrophysics · Physics 2024-07-23 Valentina Sheminova , Martina Baratella , Valentina D'Orazi

We present a comparison of the frequencies of carbon-enhanced metal-poor (CEMP) giant and main-sequence turnoff stars, selected from the Sloan Digital Sky Survey and the Sloan Extension for Galactic Understanding and Exploration, with…

Solar and Stellar Astrophysics · Physics 2015-06-17 Young Sun Lee , Takuma Suda , Timothy C. Beers , Sara Lucatello

We present our chemical abundance investigation of the metal-poor ([Fe/H]=-1.60 dex), r-process-enriched ([Eu/Fe]=0.73 dex) halo star HD 20 using novel and archival high-resolution spectra at outstanding signal-to-noise ratios. By combining…

We present a double-blind analysis of high-dispersion spectra of seven red giant members of the Bo\"{o}tes I ultra-faint dwarf spheroidal galaxy, complemented with re-analysis of a similar spectrum of an eighth member star. The stars cover…

Astrophysics of Galaxies · Physics 2015-06-12 Gerard Gilmore , John E. Norris , Lorenzo Monaco , David Yong , Rosemary F. G. Wyse , D. Geisler