Calibrating core overshooting parameters with two-dimensional hydrodynamical simulations

Vol. 646
7. Stellar structure and evolution

Calibrating core overshooting parameters with two-dimensional hydrodynamical simulations

The extent of mixed (overshooting) regions around convective zones is one of the biggest uncertainties in stellar evolution because they affect lifetimes and the shape of evolutionary tracks in the Hertzsprung-Russell diagram. Multi-dimensional hydrodynamics simulations can be used to study the size of these overshooting regions, and this is what the authors have done in this work. They performed 2D hydrodynamics simulations of zero-age main-sequence stars between 1.3 and 3.5 solar masses, which cover the convective cores and a large fraction of the surrounding radiative envelope, following the convective flow for at least 20 convective turnover times. Their results put strong quantitative constraints on the size of the overshooting regions in this mass range, and they help to identify a diffusive mixing component due to internal gravity waves.