Abstract
Flux-transport dynamos have proven to be successful for modeling the evolution of the large scale solar magnetic field. However, these studies addressed the transport of magnetic field by the meridional circulation in a purely kinematic regime. The toroidal field strength at the base of the solar convection zone inferred from studies of rising magnetic flux tubes is around 100 KG and thus orders of magnitude larger than the equipartition field strength estimated from a meridional flow velocity of a few m/s. Therefore it is crucial for flux-transport dynamos to address the feedback of the j×B on the meridional flow. In this paper we present two approaches: 1) A kinematic approach in which we parametrize this feed-back in terms of a non-linear quenching of the meridional flow in regions exceeding a certain field strength. 2) A MHD approach in which we solve the full set of hydrodynamic equations together with the dynamo equations. Since we focus in this approach only on the large scale flow field, the anisotropic turbulent transport of angular momentum responsible for the differential rotation has been parametrized. From both studies we conclude that Babcock-Leighton flux-transport dynamos work even with strong feedback of the j×B force for mainly two reasons: 1) The transport of the weak poloidal magnetic field is not affected strongly. 2) The meridional flow results from a small difference between large forces, so that the transport capability is much larger than a simple estimate based on equipartition field strengths suggests.
| Original language | English |
|---|---|
| Pages (from-to) | 913-916 |
| Number of pages | 4 |
| Journal | European Space Agency, (Special Publication) ESA SP |
| Issue number | 560 II |
| State | Published - 2005 |
| Event | 13th Cambridge Workshop on Cool Stars, Stellar Systems and the Sun - Hamburg, Germany Duration: Jul 5 2004 → Jul 9 2004 |
Keywords
- Differential rotation
- Dynamo -
- Sun: Magnetic field -