TY - JOUR
T1 - The ubiquity of the rapid neutron-capture process
AU - Roederer, Ian U
AU - Cowan, John J
AU - Karakas, Amanda Irene
AU - Kratz, Karl-Ludwig
AU - Lugaro, Maria Anna
AU - Simmerer, Jennifer
AU - Farouqi, Khalil
AU - Sneden, Chris
PY - 2010
Y1 - 2010
N2 - To better characterize the abundance patterns produced by the r-process, we have derived new abundances or upper limits for the heavy elements zinc (Zn, Z= 30), yttrium (Y, Z= 39), lanthanum (La, Z= 57), europium (Eu, Z= 63), and lead (Pb, Z= 82). Our sample of 161 metal-poor stars includes new measurements from 88 high-resolution and high signal-to-noise spectra obtained with the Tull Spectrograph on the 2.7 m Smith Telescope at the McDonald Observatory, and other abundances are adopted from the literature. We use models of the s-process in asymptotic giant branch stars to characterize the high Pb/Eu ratios produced in the s-process at low metallicity, and our new observations then allow us to identify a sample of stars with no detectable s-process material. In these stars, we find no significant increase in the Pb/Eu ratios with increasing metallicity.
AB - To better characterize the abundance patterns produced by the r-process, we have derived new abundances or upper limits for the heavy elements zinc (Zn, Z= 30), yttrium (Y, Z= 39), lanthanum (La, Z= 57), europium (Eu, Z= 63), and lead (Pb, Z= 82). Our sample of 161 metal-poor stars includes new measurements from 88 high-resolution and high signal-to-noise spectra obtained with the Tull Spectrograph on the 2.7 m Smith Telescope at the McDonald Observatory, and other abundances are adopted from the literature. We use models of the s-process in asymptotic giant branch stars to characterize the high Pb/Eu ratios produced in the s-process at low metallicity, and our new observations then allow us to identify a sample of stars with no detectable s-process material. In these stars, we find no significant increase in the Pb/Eu ratios with increasing metallicity.
UR - http://stacks.iop.org/0004-637X/724/975
U2 - 10.1088/0004-637X/724/2/975
DO - 10.1088/0004-637X/724/2/975
M3 - Article
VL - 724
SP - 975
EP - 993
JO - The Astrophysical Journal
JF - The Astrophysical Journal
SN - 1538-4357
IS - 2
ER -