The growth of helium-burning cores

¹ Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, 85748 Garching, Germany
e-mail: henk@mpa-garching.mpg.de
² Monash Center for Astrophysics, Monash University, Clayton VIC 3800, Australia

Received: 11 August 2015
Accepted: 1 September 2015

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 clearly 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 that scales directly with the convective luminosity of the core and agrees with constraints on core size from current asteroseismology.