Metal-Poor Stars

TL;DR

This review discusses how metal-poor stars serve as key probes into the early universe's chemical evolution, nucleosynthesis, and the formation of the first stars, based on their abundance patterns.

Contribution

It provides a comprehensive overview of the history, observed abundance trends, and classifications of metal-poor stars, highlighting their significance in cosmology and galaxy formation.

Findings

Observed abundance trends at low metallicities.

Classification of metal-poor stars such as r-process and C-rich.

Implications for the early universe and first stars.

Abstract

The abundance patterns of metal-poor stars provide us a wealth of chemical information about various stages of the chemical evolution of the Galaxy. In particular, these stars allow us to study the formation and evolution of the elements and the involved nucleosynthesis processes. This knowledge is invaluable for our understanding of the cosmic chemical evolution and the onset of star- and galaxy formation. Metal-poor stars are the local equivalent of the high-redshift Universe, and offer crucial observational constraints on the nature of the first stars. This review presents the history of the first discoveries of metal-poor stars that laid the foundation to this field. Observed abundance trends at the lowest metallicities are described, as well as particular classes of metal-poor stars such as r-process and C-rich stars. Scenarios on the origins of the abundances of metal-poor stars and the application of large samples of metal-poor stars to cosmological questions are discussed.