Buoyant Magnetic Flux Ropes and Convection:
Evolution Prior to Emergence
S.B.F. Dorch
Institute: The Royal Swedish Academy of Sciences
Contact Email: dorch@astro.su.se
Abstract:
We have performed detailed numerical 3-d simulations of the interaction of
buoyantly ascending twisted magnetic flux ropes and solar-like stratified
convection
(with surface cells similar to solar supergranules in size). Results are
presented for three different cases --- corresponding to different amounts
of initial field line twist --- that represents fundamentally different types
of instabilities: the magnetic Rayleigh-Taylor instability in which case the
flux rope disrupts and network patches are formed at surface cell boundaries;
the kink instability that has been proposed as a mechanism for forming
tightly packed $\delta$-type spots; a stable flux rope where neither of the
former instabilities arise, and the behavior of which is similar to
classical text book flux tubes, except from a flux-loss due to
the advective action of the convective flows.
The simulations thus support the idea that the magnetic flux observed at
the surface in
bipolar regions are smaller, ceteris paribus, than that of the
dynamo generated flux ropes near the bottom of the convection zone.
Please note that this material is also available as an online
as a web talk.
Index Keywords: magnetism -- instabilities ; 3-D Simulations ; Sun
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Manuscript submitted: 2001-Aug-15
"The Future of Cool-Star Astrophysics", 2003, Eds. A. Brown,
G. M. Harper, & T. R. Ayres.
Proceedings of 12th Cambridge Workshop on Cool Stars, Stellar Systems,
& The Sun,
© 2003 University of Colorado.