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3D numerical MHD modeling of sunspots with radiation transport

Published online by Cambridge University Press:  26 August 2011

Matthias Rempel
Matthias Rempel*
Affiliation:
High Altitude Observatory, National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80307, USA email: rempel@ucar.edu
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Abstract

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Sunspot fine structure has been modeled in the past by a combination of idealized magneto-convection simulations and simplified models that prescribe the magnetic field and flow structure to a large degree. Advancement in numerical methods and computing power has enabled recently 3D radiative MHD simulations of entire sunspots with sufficient resolution to address details of umbral dots and penumbral filaments. After a brief review of recent developments we focus on the magneto-convective processes responsible for the complicated magnetic structure of the penumbra and the mechanisms leading to the driving of strong horizontal outflows in the penumbra (Evershed effect). The bulk of energy and mass is transported on scales smaller than the radial extent of the penumbra. Strong horizontal outflows in the sunspot penumbra result from a redistribution of kinetic energy preferring flows along the filaments. This redistribution is facilitated primarily through the Lorentz force, while horizontal pressure gradients play only a minor role. The Evershed flow is strongly magnetized: While we see a strong reduction of the vertical field, the horizontal field component is enhanced within filaments.

Keywords

MHDradiative transferSun: sunspotsSun: photosphereSun: magnetic fields
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 6 , Symposium S273: The Physics of Sun and Star Spots , August 2010 , pp. 8 - 14
Copyright
Copyright © International Astronomical Union 2011

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