Volume 526, February 2011
|Number of page(s)||6|
|Published online||12 January 2011|
Alleviating α quenching by solar wind and meridional flows
NORDITA, AlbaNova University Center,
2 School of Mathematics, University of Manchester, Oxford Road, Manchester M13 9PL, UK
3 Astronomy Unit, School of Mathematical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, UK
4 Department of Astronomy, Stockholm University, 10691 Stockholm, Sweden
Accepted: 1 December 2010
Aims. We study the ability of magnetic helicity expulsion to alleviate catastrophic α-quenching in mean field dynamos in two–dimensional spherical wedge domains.
Methods. Motivated by the physical state of the outer regions of the Sun, we consider α2Ω mean field models with a dynamical α quenching. We include two mechanisms which have the potential to facilitate helicity expulsion, namely advection by a mean flow (“solar wind”) and meridional circulation.
Results. We find that a wind alone can prevent catastrophic quenching, with the field saturating at finite amplitude. In certain parameter ranges, the presence of a large-scale meridional circulation can reinforce this alleviation. However, the saturated field strengths are typically below the equipartition field strength. We discuss possible mechanisms that might increase the saturated field.
Key words: Sun: dynamo / magnetohydrodynamics (MHD)
© ESO, 2011
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