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Symposium 241

Abstract details

The Frequency of Carbon-Enhanced Metal-Poor Stars in SDSS and SEGUE
B. Marsteller, T.C. Beers, T. Sivarani (Michigan State \& JINA), S. Rossi (Univ. of Sao Paulo, Brazil), J. Knapp (Princeton), B. Plez (U. Montpellier, France), J. Johnson (Ohio State)

The publicly available stellar database from SDSS contains many hundreds of metal-poor stars with large enhancements of carbon. The stellar extension of SDSS, The Sloan Extension for Galactic Understanding and Exploration (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). Using a novel technique of automatic spectral synthesis for the estimation of [Fe/H] and [C/Fe] for stars from SDSS and SEGUE, 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 analyzed to date. With the ability to fit other lines with this approach, we can also detect the presence of Sr and Ba, and thereby roughly separate CEMP stars into the CEMP-s and CEMP-no classes.

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