The most metal-poor stars. III. the metallicity distribution function and carbon-enhanced metal-poor fraction

David Yong; John E. Norris; M. S. Bessell; N. Christlieb; M. Asplund; Timothy C. Beers; P. S. Barklem; Anna Frebel; S. G. Ryan

doi:10.1088/0004-637X/762/1/27

The most metal-poor stars. III. the metallicity distribution function and carbon-enhanced metal-poor fraction

David Yong^*, John E. Norris, M. S. Bessell, N. Christlieb, M. Asplund, Timothy C. Beers, P. S. Barklem, Anna Frebel, S. G. Ryan

^*Corresponding author for this work

Research output: Contribution to journal › Review article › peer-review

100 Citations (Scopus)

Abstract

We examine the metallicity distribution function (MDF) and fraction of carbon-enhanced metal-poor (CEMP) stars in a sample that includes 86 stars with [Fe/H] ≤ -3.0, based on high-resolution, high signal-to-noise spectroscopy, of which some 32 objects lie below [Fe/H] = -3.5. After accounting for the completeness function, the "corrected" MDF does not exhibit the sudden drop at [Fe/H] = -3.6 that was found in recent samples of dwarfs and giants from the Hamburg/ESO survey. Rather, the MDF decreases smoothly down to [Fe/H] = -4.1. Similar results are obtained from the "raw" MDF. We find that the fraction of CEMP objects below [Fe/H] = -3.0 is 23% ± 6% and 32% ± 8% when adopting the Beers & Christlieb and Aoki et al. CEMP definitions, respectively. The former value is in fair agreement with some previous measurements, which adopt the Beers & Christlieb criterion.

Original language	English
Article number	27
Journal	Astrophysical Journal
Volume	762
Issue number	1
DOIs	https://doi.org/10.1088/0004-637X/762/1/27
Publication status	Published - 1 Jan 2013

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title = "The most metal-poor stars. III. the metallicity distribution function and carbon-enhanced metal-poor fraction",

abstract = "We examine the metallicity distribution function (MDF) and fraction of carbon-enhanced metal-poor (CEMP) stars in a sample that includes 86 stars with [Fe/H] ≤ -3.0, based on high-resolution, high signal-to-noise spectroscopy, of which some 32 objects lie below [Fe/H] = -3.5. After accounting for the completeness function, the {"}corrected{"} MDF does not exhibit the sudden drop at [Fe/H] = -3.6 that was found in recent samples of dwarfs and giants from the Hamburg/ESO survey. Rather, the MDF decreases smoothly down to [Fe/H] = -4.1. Similar results are obtained from the {"}raw{"} MDF. We find that the fraction of CEMP objects below [Fe/H] = -3.0 is 23% ± 6% and 32% ± 8% when adopting the Beers & Christlieb and Aoki et al. CEMP definitions, respectively. The former value is in fair agreement with some previous measurements, which adopt the Beers & Christlieb criterion.",

keywords = "Galaxy: formation, Galaxy: halo, early universe, nuclear reactions, nucleosynthesis, abundances, stars: abundances",

author = "David Yong and Norris, {John E.} and Bessell, {M. S.} and N. Christlieb and M. Asplund and Beers, {Timothy C.} and Barklem, {P. S.} and Anna Frebel and Ryan, {S. G.}",

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doi = "10.1088/0004-637X/762/1/27",

language = "English",

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T1 - The most metal-poor stars. III. the metallicity distribution function and carbon-enhanced metal-poor fraction

AU - Yong, David

AU - Norris, John E.

AU - Bessell, M. S.

AU - Christlieb, N.

AU - Asplund, M.

AU - Beers, Timothy C.

AU - Barklem, P. S.

AU - Frebel, Anna

AU - Ryan, S. G.

PY - 2013/1/1

Y1 - 2013/1/1

N2 - We examine the metallicity distribution function (MDF) and fraction of carbon-enhanced metal-poor (CEMP) stars in a sample that includes 86 stars with [Fe/H] ≤ -3.0, based on high-resolution, high signal-to-noise spectroscopy, of which some 32 objects lie below [Fe/H] = -3.5. After accounting for the completeness function, the "corrected" MDF does not exhibit the sudden drop at [Fe/H] = -3.6 that was found in recent samples of dwarfs and giants from the Hamburg/ESO survey. Rather, the MDF decreases smoothly down to [Fe/H] = -4.1. Similar results are obtained from the "raw" MDF. We find that the fraction of CEMP objects below [Fe/H] = -3.0 is 23% ± 6% and 32% ± 8% when adopting the Beers & Christlieb and Aoki et al. CEMP definitions, respectively. The former value is in fair agreement with some previous measurements, which adopt the Beers & Christlieb criterion.

AB - We examine the metallicity distribution function (MDF) and fraction of carbon-enhanced metal-poor (CEMP) stars in a sample that includes 86 stars with [Fe/H] ≤ -3.0, based on high-resolution, high signal-to-noise spectroscopy, of which some 32 objects lie below [Fe/H] = -3.5. After accounting for the completeness function, the "corrected" MDF does not exhibit the sudden drop at [Fe/H] = -3.6 that was found in recent samples of dwarfs and giants from the Hamburg/ESO survey. Rather, the MDF decreases smoothly down to [Fe/H] = -4.1. Similar results are obtained from the "raw" MDF. We find that the fraction of CEMP objects below [Fe/H] = -3.0 is 23% ± 6% and 32% ± 8% when adopting the Beers & Christlieb and Aoki et al. CEMP definitions, respectively. The former value is in fair agreement with some previous measurements, which adopt the Beers & Christlieb criterion.

KW - Galaxy: formation

KW - Galaxy: halo

KW - early universe

KW - nuclear reactions, nucleosynthesis, abundances

KW - stars: abundances

UR - http://www.scopus.com/inward/record.url?scp=84871328839&partnerID=8YFLogxK

U2 - 10.1088/0004-637X/762/1/27

DO - 10.1088/0004-637X/762/1/27

M3 - Review article

SN - 0004-637X

VL - 762

JO - Astrophysical Journal

JF - Astrophysical Journal

IS - 1

M1 - 27

ER -

The most metal-poor stars. III. the metallicity distribution function and carbon-enhanced metal-poor fraction

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