Cool Stars 14 - Submitted Abstract # 20
This version created on 05 October 2006

Magnetic flux emergence in the solar photosphere


Mark Chun Ming Cheung, Lockheed Martin Solar and Astrophysics Laboratory
Manfred Schuessler, Max Planck Institute for Solar System Research
Fernando Moreno-Insertis, Instituto de Astrofisica de Canarias

The most prominent magnetic structures on the surface of the Sun are
bipolar active regions.  These magnetic complexes are comprised of a
hierarchy of magnetic structures of different sizes, the largest of
which are sunspots.  Observations indicate that the appearance of
active regions on the solar surface result from the emergence of
bundles of magnetic flux from the underlying convection zone.  We
study the emergence process by means of 3D radiation MHD simulations.
In the simulations, an initially buoyant magnetic flux tube is
introduced into the near-surface layers of the convection zone.
Subject to the buoyancy force, the flux tube rises towards the
photosphere.  Our simulations highlight the importance of
magneto-convection on the evolution of the magnetic flux tube.  The
external convective flow field has an important influence on the
emergence morphology of the emerging magnetic field.  Depending on the
initial properties of the magnetic flux tube (e.g.  field strength,
twist, entropy etc.), flux emergence may lead to a disturbance of the
local granulation pattern.  The observational signatures associated
with emerging magnetic flux in our simulations are in qualitative and
quantitative agreement with observational studies of emerging flux
regions on the Sun.

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