Relative Importance of Convective Uncertainties

TL;DR

This paper investigates how different treatments of convection boundaries and mixing in stellar models affect the early evolution of massive stars, highlighting the convergence of models and changes in stellar evolution outcomes.

Contribution

It compares two key convective uncertainties in stellar models and shows how their variation influences stellar evolution predictions.

Findings

Convergence of boundary location with increased mixing.

Decreased blue to red supergiant ratio.

Reduced significance of semiconvection.

Abstract

Convection plays a key role in the evolution of stars due to energy transport and mixing of composition. Despite its importance, this process is still not well understood. One longstanding conundrum in all 1D stellar evolution codes is the treatment of convective boundaries. In this study we compare two convective uncertainties, the boundary location (Ledoux versus Schwarzschild) and the amount of extra mixing, and their impact on the early evolution of massive stars. With increasing convective boundary mixing (CBM), we find a convergence of the two different boundary locations, a decreasing blue to red super giant ratio and a reduced importance of semiconvection.