Multidimensional hydrodynamic simulations of the core helium flash in low-mass stars

We investigate the hydrodynamics of the core helium flash near its peak in stars with a mass close to that of the Sun. Previous work indicated, that depending on initial conditions, employed turbulence models, grid resolution, and dimensionality of the simulation, the core helium flash leads either to the disruption of a star or to a quiescent quasi-hydrostatic evolution. We try to clarify this issue by simulating the evolution with advanced numerical methods and detailed microphysics. We find that the core helium flash neither rips the star apart, nor that it significantly alters its structure, as convection plays a crucial role in keeping the star in hydrostatic equilibrium. All our hydrodynamic simulations show the presence of turbulent entrainment, which results in a growth of the convection zone on dynamic time scales and implies new predictions concerning mixing of chemical species in red giant stars.