Carbon-enhanced metal-poor stars in SDSS/SEGUE. II. comparison of CEMP-star frequencies with binary population-synthesis models

Abstract

We present a comparison of the frequencies of carbon-enhanced metal-poor (CEMP) giant and main-sequence turnoff (MSTO) stars with predictions from binary population-synthesis models involving asymptotic giant-branch (AGB) mass transfer. The giant and MSTO stars are selected from the Sloan Digital Sky Survey and the Sloan Extension for Galactic Understanding and Exploration. We consider two initial mass functions (IMFs) - a Salpeter IMF, and a mass function with a characteristic mass of 10 M. For giant stars, the comparison indicates a good agreement between the observed CEMP frequencies and the AGB binary model using a Salpeter IMF for [Fe/H] >-1.5, and a characteristic mass of 10 M for [Fe/H]