Issue |
A&A
Volume 374, Number 1, July IV 2001
|
|
---|---|---|
Page(s) | 301 - 308 | |
Section | Planets and planetary systems | |
DOI | https://doi.org/10.1051/0004-6361:20010686 | |
Published online | 15 July 2001 |
Circulation-dominated solar shell dynamo models with positive alpha-effect
Astrophysikalisches Institut Potsdam, An der Sternwarte 16, 14482 Potsdam, Germany
Corresponding author: M. Küker, kueker@astro.uni-jena.de
Received:
7
November
2000
Accepted:
9
May
2001
We present shell dynamo models for the solar convection zone with
positive
α-effect in the northern hemisphere
and a meridional circulation which is
directed equatorward at the bottom and poleward at the top of the
convection zone. Two different rotation patterns are used: a simple
variation of the rotation rate with depth and
the rotation law as derived by helioseismology.
Depending on the Reynolds number associated with the meridional flow,
the dynamo shows a whole "zoo" of solutions.
For sufficiently small values of the eddy magnetic diffusivity
(1011 cm2/s), field advection by the meridional flow
becomes dominant and even changes the character of the butterfly diagram.
Flow amplitudes of a few m/s are then sufficient to turn the originally "wrong"
butterfly diagram into a "solar-type" butterfly diagram,
i.e. with activity belts drifting equatorward.
This effect can easily be demonstrated with a super-rotation law
( 0) with Ω independent of the
latitude. The situation is much more complicated for the "real" rotation
law with the observed strong negative shear at high latitudes.
With zero meridional flow, oscillating solutions are found
without any latitudinal migration of the toroidal field belts,
neither poleward nor equatorward.
Small but finite flow amplitudes cause the magnetic field belts to
drift poleward while in case of fast flow they move equatorward.
Key words: magnetohydrodynamics / Sun: interior / Sun: magnetic field
© ESO, 2001
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.