TY - JOUR
T1 - AN ELEMENTAL ASSAY of VERY, EXTREMELY, and ULTRA-METAL-POOR STARS
AU - Hansen, T.
AU - Hansen, C. J.
AU - Christlieb, N.
AU - Beers, T. C.
AU - Yong, D.
AU - Bessell, M. S.
AU - Frebel, A.
AU - Pérez, A. E.García
AU - Placco, V. M.
AU - Norris, J. E.
AU - Asplund, M.
PY - 2015/7/10
Y1 - 2015/7/10
N2 - We present a high-resolution elemental-abundance analysis for a sample of 23 very metal-poor ([Fe/H] < -2.0) stars, 12 of which are extremely metal-poor ([Fe/H] < -3.0), and 4 of which are ultra-metal-poor ([Fe/H] < -4.0). These stars were targeted to explore differences in the abundance ratios for elements that constrain the possible astrophysical sites of element production, including Li, C, N, O, the α-elements, the iron-peak elements, and a number of neutron-capture elements. This sample substantially increases the number of known carbon-enhanced metal-poor (CEMP) and nitrogen-enhanced metal-poor (NEMP) stars - our program stars include eight that are considered "normal" metal-poor stars, six CEMP-no stars, five CEMP-s stars, two CEMP-r stars, and two CEMP-r/s stars. One of the CEMP-r stars and one of the CEMP-r/s stars are possible NEMP stars. We detect lithium for three of the six CEMP-no stars, all of which are Li.
AB - We present a high-resolution elemental-abundance analysis for a sample of 23 very metal-poor ([Fe/H] < -2.0) stars, 12 of which are extremely metal-poor ([Fe/H] < -3.0), and 4 of which are ultra-metal-poor ([Fe/H] < -4.0). These stars were targeted to explore differences in the abundance ratios for elements that constrain the possible astrophysical sites of element production, including Li, C, N, O, the α-elements, the iron-peak elements, and a number of neutron-capture elements. This sample substantially increases the number of known carbon-enhanced metal-poor (CEMP) and nitrogen-enhanced metal-poor (NEMP) stars - our program stars include eight that are considered "normal" metal-poor stars, six CEMP-no stars, five CEMP-s stars, two CEMP-r stars, and two CEMP-r/s stars. One of the CEMP-r stars and one of the CEMP-r/s stars are possible NEMP stars. We detect lithium for three of the six CEMP-no stars, all of which are Li.
KW - Galaxy: formation
KW - Galaxy: halo
KW - Galaxy: stellar content
KW - nuclear reactions nucleosynthesis abundances
KW - stars: abundances
UR - http://www.scopus.com/inward/record.url?scp=84936993982&partnerID=8YFLogxK
U2 - 10.1088/0004-637X/807/2/173
DO - 10.1088/0004-637X/807/2/173
M3 - Article
SN - 0004-637X
VL - 807
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 2
M1 - 173
ER -