Solar Dynamo and Toroidal Field Instabilities
Abstract
The possibility of non-axisymmetric (kink) instabilities of a toroidal field seated in the tachocline is much discussed in the literature. In this work, the basic properties of kink and quasi-interchange instabilities, produced by mixed toroidal and poloidal configuration, will be briefly reviewed. In particular, it will be shown that the unstable modes are strongly localized near the Equator and not near the Poles as often claimed in the literature. Based on the results of recent numerical simulations, it is argued that a non-zero helicity can already be produced at a non-linear level. A mean-field solar dynamo is then constructed with a positiveα-effect in the overshoot layer localized near the Equator, and a meridional circulation with deep return flow. Finally, the possibility that the solar cycle is driven by an αΩ dynamo generated by the negative subsurface shear in the supergranulation layer will also be discussed.
- Publication:
-
Solar Physics
- Pub Date:
- October 2013
- DOI:
- 10.1007/s11207-012-0198-z
- arXiv:
- arXiv:1211.5431
- Bibcode:
- 2013SoPh..287..185B
- Keywords:
-
- Solar dynamo;
- Magnetic fields;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- to appear in Solar Physics