On convective and semiconvective mixing in massive stars

Abstract

The evolutionary sequence of a 15.57-solar mass star made with a simplified turbulence transport model demonstrates the importance of accurately modeling the turbulent convection in the stellar interior. The combination of the self-diffusion of turbulence and its finite decay time in a stable region extend the convective core by about 3 solar masses, profoundly affecting the evolution of the star. Among the important effects are the elimination of semiconvection and the increase in both the lifetime and luminosity in the hydrogen-burning phase.