Kavli Affiliate: Anna Frebel
| First 5 Authors: Kaitlin C. Rasmussen, Joseph Zepeda, Timothy C. Beers, Vinicius M. Placco, Eric Depagne
| Summary:
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 Angstrom. The elemental abundances of
C, Sr, Ba, and Eu are reported, as well as several alpha-elements (Mg, Ca, Sc,
Ti, V) and iron-peak elements (Mn, Co, Ni, 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.
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