The growth of helium burning cores

TL;DR

This paper investigates the process controlling the growth of helium burning cores in certain stars, identifying buoyancy as a key limiting factor that influences core size and matches observational data.

Contribution

It introduces a new model linking buoyancy effects to core growth rates, providing insights into stellar core evolution and matching asteroseismic constraints.

Findings

Growth rate scales with convective luminosity

Buoyancy limits helium ingestion into the core

Model aligns with asteroseismology data

Abstract

Helium burning in the convective cores of horizontal branch and `red clump' stars appears to involve a process of `ingestion' of unburnt helium into the core, the physics of which has not been identified yet. I show here that a limiting factor controlling the growth is the buoyancy of helium entering the denser C+O core. It yields a growth rate which scales directly with the convective luminosity of the core, and agrees with constraints on core size from current asteroseismology.