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Seismology of the Sun and the Distant Stars 2016
Using Today’s Successes to Prepare the Future
Joint TASC2 & KASC9 Workshop – SPACEINN & HELAS8 Conference

Improving 1D Stellar Models with 3D Atmospheres
Jakob Mosumgaard (Aarhus University), Victor Silva Aguirre (Aarhus University), Achim Weiss (Max Planck Institute for Astrophysics), Jørgen Christensen-Dalsgaard (Aarhus University), et al.

One of the basic ingredients in astrophysics is the understanding of stellar structure and evolution. This understanding is primarily based on one-dimensional numerical models and the comparison of these with observations. Many of today's stellar models share common issues; amongst these are the use of an artificial grey atmosphere to describe the outer layers of the star and the use of the mixing-length formulation to describe convection. I am working on using the results from three-dimensional radiation-coupled hydrodynamics (3D-RHD) simulations in one-dimensional stucture models; I have implemented 3D-RHD results into the GARching STellar Evolution Code (GARSTEC). My implementation substitutes the non-physical grey atmosphere with more appropriate T-tau-relations, depending on the physical properties of the star (i.e. position in the HR-diagram), to set up more realistic outer boundary conditions. Furthermore, the mixing-length parameter changes as the star moves in the HR-diagram (calibrated from the 3D atmospheres) to refine the treatment of convection. Moreover, my implementation is consistent and takes modification of the thermal gradients properly into account, as well as correctly scaling the mixing-length parameter to the solar calibrated value. Finally, I have generated custom opacity tables to fully match the microphysics of the atmospheric simulations.

Faculdade de Ciências da Universidade de Lisboa Universidade do Porto Faculdade de Ciências e Tecnologia da Universidade de Coimbra
Fundação para a Ciência e a Tecnologia COMPETE 2020 PORTUGAL 2020 União Europeia