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The Frequency of Carbon-Enhanced Metal-Poor Stars Based on SDSS Spectroscopy

Published online by Cambridge University Press:  01 December 2006

B. Marsteller ,
T.C. Beers ,
T. Sivarani ,
S. Rossi ,
J. Knapp ,
B. Plez  and
J. Johnson
B. Marsteller
Affiliation:
Department of Physics and Astronomy, CSCE: Center for the Study of Cosmic Evolution, and JINA: Joint Institute for Nuclear Astrophysics, Michigan State University, East Lansing, MI 48824, USA
T.C. Beers
Affiliation:
Department of Physics and Astronomy, CSCE: Center for the Study of Cosmic Evolution, and JINA: Joint Institute for Nuclear Astrophysics, Michigan State University, East Lansing, MI 48824, USA
T. Sivarani
Affiliation:
Department of Physics and Astronomy, CSCE: Center for the Study of Cosmic Evolution, and JINA: Joint Institute for Nuclear Astrophysics, Michigan State University, East Lansing, MI 48824, USA
S. Rossi
Affiliation:
Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Departmento de Astronomia, Universidade de São Paulo, Rua do Matão 1226, 05508-900 São Paulo, Brazil
J. Knapp
Affiliation:
Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544
B. Plez
Affiliation:
GRAAL, UMR 5024 CNRS, Université de Montpellier-II, France
J. Johnson
Affiliation:
Department of Astronomy, Ohio State University, 140 W. 18th Avenue, Columbus, OH 43210
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Abstract

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The publicly available stellar database from SDSS contains many hundreds of metal-poor stars with large enhancements of carbon. The Galactic extension of SDSS, SEGUE, will identify several thousand more. Many of these Carbon-Enhanced Metal-Poor (CEMP) stars are likely to be enhanced in s-process elements created by AGB companions and dumped to the surviving member of a binary pair through either Roche-Lobe mass transfer or the operation of a stellar wind (CEMP-s stars). Based on previous high-resolution investigation of CEMP stars, an interesting subset of this sample is expected to show little or no s-process enhancement (CEMP-no stars).

Utilizing a novel technique of automatically fitting [Fe/H] and [C/Fe] for a large number of stars from SDSS through spectral synthesis methods, we are able to derive a new estimate of the frequency of CEMP stars as a function of metallicity for the largest sample of stars to date. Using this approach, we can also measure abundances (or limits) for species such as Sr and Ba, which can be used to roughly separate CEMP stars into the CEMP-s and CEMP-no classes.

Keywords

stars: abundancescarbonchemically peculiarGalaxy: structure
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 2 , Symposium S241: Stellar Populations as Building Blocks of Galaxies , December 2006 , pp. 252 - 253
Copyright
Copyright © International Astronomical Union 2007

References

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