A systematic study of extremely metal-poor stars with SDSS/Subaru

Wako Aoki; Timothy C. Beers; Satoshi Honda; Daniela Carollo; Hiroko Ito; Young Sun Lee

A systematic study of extremely metal-poor stars with SDSS/Subaru

Wako Aoki, Timothy C. Beers, Satoshi Honda, Daniela Carollo, Hiroko Ito, Young Sun Lee

Research output: Contribution to journal › Article › peer-review

Abstract

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.

Original language	English
Journal	Proceedings of Science
Publication status	Published - 2010

Cite this

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title = "A systematic study of extremely metal-poor stars with SDSS/Subaru",

abstract = "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.",

author = "Wako Aoki and Beers, {Timothy C.} and Satoshi Honda and Daniela Carollo and Hiroko Ito and Lee, {Young Sun}",

year = "2010",

language = "English",

journal = "Proceedings of Science",

issn = "1824-8039",

publisher = "Sissa Medialab Srl",

}

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 - Article

AN - SCOPUS:84887470775

SN - 1824-8039

JO - Proceedings of Science

JF - Proceedings of Science

ER -

A systematic study of extremely metal-poor stars with SDSS/Subaru

Abstract

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