Near-Field Cosmology with Metal-Poor Stars

TL;DR

This paper reviews how studying the chemical compositions of the oldest, most metal-poor stars in the Milky Way and dwarf galaxies sheds light on early star formation, galaxy evolution, and the Universe's initial chemical enrichment.

Contribution

It synthesizes stellar and dwarf galaxy archaeology with near-field cosmology, highlighting insights into Population III stars and early star formation channels.

Findings

Evidence for two distinct early star formation channels.

Chemical abundance patterns inform on Population III progenitors.

Metal-poor stars help constrain early Universe chemical evolution.

Abstract

The oldest, most metal-poor stars in the Galactic halo and satellite dwarf galaxies present an opportunity to explore the chemical and physical conditions of the earliest star forming environments in the Universe. We review the fields of stellar archaeology and dwarf galaxy archaeology by examining the chemical abundance measurements of various elements in extremely metal-poor stars. Focus on the carbon-rich and carbon-normal halo star populations illustrates how these provide insight into the Population III star progenitors responsible for the first metal enrichment events. We extend the discussion to near-field cosmology, which is concerned with the formation of the first stars and galaxies and how metal-poor stars can be used to constrain these processes. Complementary abundance measurements in high-redshift gas clouds further help to establish the early chemical evolution of the Universe. The data appear consistent with the existence of two distinct channels of star formation at the earliest times.