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Metal-poor Stars Observed with the Southern African Large Telescope.

Authors :
Rasmussen, Kaitlin C.
Zepeda, Joseph
Beers, Timothy C.
Placco, Vinicius M.
Depagne, Éric
Frebel, Anna
Dietz, Sarah
Hartwig, Tilman
Source :
Astrophysical Journal; 12/10/2020, Vol. 905 Issue 1, p1-15, 15p
Publication Year :
2020

Abstract

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 ∼ 40,000 and S/N ∼ 20 per pixel at 4300 Å. The elemental abundances of C, Sr, Ba, and Eu are reported, as well as several α-elements (Mg, Ca, Sc, Ti, and V) and iron-peak elements (Mn, Co, Ni, and Zn). We find a diverse array of abundance patterns, including several consistent with the signatures of carbon-enhanced metal-poor CEMP-i and CEMP-r stars. We find that 15 of 50 (30%) are carbon enhanced (with [C/Fe] > +0.70), and that a large fraction (26 of 50, 52%) are enhanced in r-process elements. Among the r-process-enhanced stars, five are strongly enhanced r-II ([Eu/Fe] > +1.0) stars (two of which are newly discovered) and 21 are newly discovered moderately enhanced r-I (+0.3 ≤ [Eu/Fe] ≤ +1.0) stars. There are eight stars in our sample that, on the basis of their abundances and kinematics, are possible members of the metal-weak thick-disk population. We also compare our measured abundances to progenitor-enrichment models, and find that the abundance patterns for the majority of our stars can be attributed to a single (rather than multiple) enrichment event. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
0004637X
Volume :
905
Issue :
1
Database :
Complementary Index
Journal :
Astrophysical Journal
Publication Type :
Academic Journal
Accession number :
147617098
Full Text :
https://doi.org/10.3847/1538-4357/abc005