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What can simulations tell us about convection in the surface layers of stars?

Frank Robinson
Astronomy Department, Yale University, USA

Numerical simulations can be used to model very different types of convective phenomena such as laboratory convection experiments, mesoscale atmospheric processes (clouds) and solar and stellar convection. In each case one numerically solves essentially the same governing equations (the Navier-Stokes equations) but with different input physics, boundary conditions and equations of state. The solar and stellar simulations provide data that in the case of the sun can be directly compared to observed quantities such as granule sizes and can explain the discrepancy between observed and computed p-mode frequencies. As well as reproducing observable features like solar granulation, 3D simulations can provide useful information for stellar modeling. Examples include testing out mixing length theory in the surface layers, providing the turbulent correction for stellar models of p-mode frequencies in other stars, testing models of tidal dissipation and testing higher order moment closures.

In addition to explaining the aforementioned material in full detail, in this talk I will show the latest results of a detailed comparison between our simulations and those of the other solar simulation groups. Even though the groups use different input physics, different boundary conditions and a different treatment of radiation transfer in the optically thin layer, provided the grid resolution is adequate, the results are surprisingly similar.

2008 May 14, 13:30

Centro de Astrofísica da Universidade do Porto (Auditorium)
Rua das Estrelas, 4150-762 Porto

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