Element Diffusion and Accretion in Metal Poor Stars

TL;DR

This paper reviews how atomic diffusion and accretion processes affect the surface abundances of elements in metal-poor stars, highlighting their impact on interpreting stellar compositions.

Contribution

It emphasizes the significance of diffusion and accretion in altering surface abundances, providing insights into stellar evolution and observational interpretations.

Findings

Diffusion can significantly modify surface element abundances.

Accretion processes may induce thermohaline instabilities.

Surface abundances may not reflect initial stellar compositions.

Abstract

The abundances of the chemical elements observed at the surface of metal-poor stars are not always representative of their initial values. During stellar evolution, various physical processes modify their internal composition. In this short paper, in honor of George W. Preston, I remind the importance of atomic diffusion, and the possible effects of accretion processes which may lead to double-diffusive (thermohaline) instabilities. I discuss the consequences of these processes and compare them to current observations.