Title:
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Convective Pumping of Magnetic Fields: On the Flux Storage 
Problem for Solar-like Dynamos

Authors:
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Bertil Dorch (ESMN, Royal Swedish Academy of Science, Stockholm)
Åke Nordlund (NBIfAFG, Copenhagen University, Denmark)

Abstract:
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A long standing issue in the theory of stellar dynamos is the
problem of keeping the magnetic field within the convection zone
long enough for the dynamo to operate: A magnetic flux rope is typically
assumed to escape the convection zone in a month
or so, while the dynamo is thought to operate on a longer time scale of
decades.

We present results from three-dimensional numerical simulations, of the
interaction of stratified over-turning solar-like convection with a
large-scale magnetic field: By the very topology of stellar
convection, even a formally super-equipartion field may be held down at
the bottom of the convection zone, rendering the storage problem
obsolete.
This effect might also explain the observations of magnetically
active but fully convective late type dwarf stars.

Several simulations have been performed, with both
open and closed upper boundary conditions, as well as including
differential
rotation: Inclusion of an open upper boundary may lead to a considerable
flux loss unless the boundary is placed close to the physical boundary.

Appeared in:
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``Recent Insights into the Physics of the Sun and Heliosphere - Highlights
from SoHO and Other Space Missions'', IAU Symp. 203 (P. Brekke, 
B. Fleck and J.B. Gurman Eds.) ASP Conf. Series, 2001, p. 186-189