Projeto Observacional para 2007B - SO2007B-006

Autor: Sílvia Rossi
Instituição: IAG
e-mail: rossi@astro.iag.usp.br

Co-autores:
Timothy Beers
Thirupathi Sivarani
Vinicius Placco
Catherine Kennedy
Simon Schuler

Título: Near-IR SOAR/OSIRIS Spectroscopy of Carbon Enhanced Metal-Poor Stars

Resumo: We propose to complete a program of moderate resolution near-IR spectroscopy of a sample of ~50 Carbon-Enhanced Metal-Poor (CEMP) stars in order to measure their O content and 12C/13C ratios, and thereby constrain the nucleosynthetic histories of these stars. From previous studies, two primary categories of CEMP stars have emerged: those with enhanced neutron-capture elements (CEMP-s, CEMP-r, and CEMP-r/s), and those that do not show strong enhancements of neutron-capture elements (CEMP-no). While the atmospheres of CEMP-s stars have likely been polluted by intermediate-mass AGB companions, the source of the observed abundance patterns of the CEMP-no stars is not readily explained because existing samples of CEMP-no stars with available CNO measurements are too small to fully explore this connection. We hope to significantly expand the database of O abundances and the valuable 12C/13C ratio -- key tracers of both massive star and AGB nucleosynthesis -- for CEMP-no and CEMP-s stars with the proposed observations and as a result, dramatically increase our understanding of nucleosynthesis in the early Galaxy.