Global 3D radiation-hydrodynamical models of AGB stars with dust-driven winds

Vol. 669
8. Stellar atmospheres

Global 3D radiation-hydrodynamical models of AGB stars with dust-driven winds

Convection and mass loss by stellar winds are two dynamical processes that shape asymptotic giant branch (AGB) stars and their evolution. We model the dynamical stellar interiors, atmospheres, and wind-acceleration zones of two M-type AGB stars with the CO5BOLD code. These first global 3D simulations are based on frequency-dependent gas opacities, and they feature time-dependent condensation and evaporation of silicate grains. Convection and pulsations emerge self-consistently, allowing us to derive wind properties without relying on parameterized descriptions of these processes. In contrast to 1D models with purely radial pulsations, the shocks induced by convection and pulsations in the 3D models cover large parts but not the entirety of the sphere, leading to a patchy, nonspherical structure of the atmosphere.