Dresden 2017 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 16: Focus: Fundamental aspects of turbulent convection

DY 16.3: Vortrag

Dienstag, 21. März 2017, 10:15–10:30, ZEU 118

Stellar convection models with Kramers-type opacity law — •Petri Käpylä — Leibniz-Institut für Astrophysik, Potsdam, Germany — ReSoLVE Centre of Excellence, Department of Computer Science, Aalto University, Finland

We present first results from three-dimensional hydrodynamic simulations of stratified convection in a slab geometry applying a Kramers-type opacity law. We show that in such models the depth of the convection zone is not a priori fixed as the opacity law is sensitive to temperature and density. This is in contrast to the overwhelming majority of models presented in the literature where either a fixed profile of the heat conductivity or the boundary conditions dictate the depth of the convective layer.

Furthermore, we also show that a substantial portion of the mixed layer is stably stratified according to the Schwarzschild criterion. In particular, we find an extended layer where both the enthalpy flux and the vertical gradient of specific entropy are positive which cannot be explained by the usual counter-gradient parametrization. Such weakly sub-adiabatic layers are also potentially crucial for solving some of the current issues in stellar differential rotation and dynamo modeling.