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 › Conference 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
Event	11th Symposium on Nuclei in the Cosmos, NIC 2010 - Heidelberg, Germany Duration: 19 Jul 2010 → 23 Jul 2010

Cite this

@article{49fbd50e960f4027b67448be5649da04,

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",

note = "11th Symposium on Nuclei in the Cosmos, NIC 2010 ; Conference date: 19-07-2010 Through 23-07-2010",

}

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 - https://www.scopus.com/pages/publications/84887470775

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 -

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

Abstract

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