On the potential of Carbon-Enhanced Metal-poor Stars for Galactic Archaeology

Abstract

The low-mass metal-poor stars in the Galaxy that preserve in their atmosphere, the chemical imprints of the gas clouds from which they were formed can be used as probes to get insight into the origin and evolution of elements in the early galaxy, early star formation and nucleosynthesis. Among the metal-poor stars, a large fraction, the so-called carbon-enhanced metal-poor (CEMP) stars exhibits high abundance of carbon. These stars exhibit diverse abundance patterns, particularly for heavy elements, based on which they are classified into different groups. The diversity of abundance patterns points at different formation scenarios. Hence, accurate classification of CEMP stars and knowledge of their distribution is essential to understand the role and contribution of each group. While CEMP-s and CEMP-r/s stars can be used to get insight into binary interactions at very low metallicity, CEMP-no stars can be used to probe the properties of the first stars and early nucleosynthesis. To exploit the full potential of CEMP stars for Galactic archaeology a homogeneous analysis of each class is extremely important. Our efforts towards, and contributions to providing an improved classification scheme for accurate classification of CEMP-s and CEMP-r/s stars and in characterizing the companion asymptotic giant branch (AGB) stars of CH, CEMP-no, CEMP-s and CEMP-r/s binary systems are discussed. Some recent results obtained based on low- and high-resolution spectroscopic analysis of a large number of potential CH and CEMP star candidates are highlighted.