Convective Penetration in Early-type Stars

Abstract

Observations indicate that the convective cores of stars must ingest a substantial amount of material from the overlying radiative zone, but the extent of this mixing and the mechanism that causes it remain uncertain. Recently, Anders et al. developed a theory of convective penetration and calibrated it with 3D numerical hydrodynamics simulations. Here we employ that theory to predict the extent of convective boundary mixing (CBM) in early-type main-sequence stars. We find that convective penetration produces enough mixing to explain core masses inferred from asteroseismology and eclipsing binary studies, and matches observed trends in mass and age. While there are remaining uncertainties in the theory, this agreement suggests that most CBM in early-type main-sequence stars arises from convective penetration. Finally, we provide a fitting formula for the extent of core convective penetration for main-sequence stars in the mass range from 1.1–60 M ⊙ .