TY - JOUR
T1 - A systematic study of extremely metal-poor stars with SDSS/Subaru
AU - Aoki, Wako
AU - Beers, Timothy C.
AU - Honda, Satoshi
AU - Carollo, Daniela
AU - Ito, Hiroko
AU - Lee, Young Sun
PY - 2010
Y1 - 2010
N2 - We have conducted follow-up high-resolution spectroscopy with the Subaru Telescope High Dispersion Spectrograph (HDS) of extremely metal-poor (EMP) star candidates discovered by the Sloan Digital Sky Survey (SDSS), in particular the sub-survey SEGUE, in order to determine accurate metallicities and elemental abundance ratios. Here we report first results for 115 objects, among which 70 stars have [Fe/H]< -3, doubling the known samples of such stars. We clearly confirm the rapid decrease of the number of stars below [Fe/H]= -3.5, although the low-metallicity cutoff is not as sharp as that found by previous studies based on medium-resolution spectra. We identified two cool (5000 K) main-sequence stars with [Fe/H]< -3, the first example of this class of stars studied based on high-resolution spectra. One of them exhibits an extremely large enhancement of r-process elements (e.g., [Eu/Fe]= +1.9). The metallicity of this object ([Fe/H] = -3.4) is the lowest yet found for such r-process-enhanced stars.
AB - We have conducted follow-up high-resolution spectroscopy with the Subaru Telescope High Dispersion Spectrograph (HDS) of extremely metal-poor (EMP) star candidates discovered by the Sloan Digital Sky Survey (SDSS), in particular the sub-survey SEGUE, in order to determine accurate metallicities and elemental abundance ratios. Here we report first results for 115 objects, among which 70 stars have [Fe/H]< -3, doubling the known samples of such stars. We clearly confirm the rapid decrease of the number of stars below [Fe/H]= -3.5, although the low-metallicity cutoff is not as sharp as that found by previous studies based on medium-resolution spectra. We identified two cool (5000 K) main-sequence stars with [Fe/H]< -3, the first example of this class of stars studied based on high-resolution spectra. One of them exhibits an extremely large enhancement of r-process elements (e.g., [Eu/Fe]= +1.9). The metallicity of this object ([Fe/H] = -3.4) is the lowest yet found for such r-process-enhanced stars.
UR - http://www.scopus.com/inward/record.url?scp=84887470775&partnerID=8YFLogxK
M3 - Conference article
AN - SCOPUS:84887470775
SN - 1824-8039
JO - Proceedings of Science
JF - Proceedings of Science
T2 - 11th Symposium on Nuclei in the Cosmos, NIC 2010
Y2 - 19 July 2010 through 23 July 2010
ER -