NOAO >   Observing Info >   Approved Programs >   2009B-0099

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Proposal Information for 2009B-0099


PI: Simon C. Schuler, NOAO, sschuler@noao.edu
Address: 950 N Cherry Ave, Tucson, AZ 85719, USA

CoI: Martin Asplund, MPA
CoI: Thirupathi Sivarani, Univ. of Florida
CoI: Verne V. Smith, NOAO
CoI: Katia Cunha, NOAO
CoI: Timothy C. Beers, MSU/JINA
CoI: Steven J. Margheim, Gemini Observatory

Title: How Carbon Enhanced are Carbon-Enhanced Metal-Poor Stars?

Abstract: Carbon-Enhanced Metal-Poor (CEMP) stars make up a large fraction of very metal-poor (VMP) stars in the Galactic halo, and they are proving to be important to our understanding of a wide range of astrophysical phenomena. Accurate abundance determinations of these stars are needed to both fully delineate their formation and evolution, and to firmly place them into a greater astrophysical context. Our group has recently demonstrated that CEMP star C abundances derived from the blue bands of CH and the C_2 Swan system, the principal features used for this purpose, may be systematically overestimated at \mathrm[Fe/H] <=- 3.0. We have also shown that the (lambda) 8727 forbidden [C \small I] line is an accurate abundance indicator for CEMP stars. Here we propose an observational program to obtain Keck/HIRES spectra of six CEMP stars, four of which have Fe abundances ranging from -4.0 <=\mathrm[Fe/H] <=-3.12, in order to derive accurate C abundances of the targets from the [C \small I] line. With the proposed observations we will determine if indeed molecular line-based C abundances of CEMP stars are too high at very low metallicities and if so, provide empirically determined corrections for those abundances.


National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360



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