The Solar Dynamo: Old, Recent, and New Problems
Abstract
There are a number of fundamental uncertainties in our understanding of the solar dynamo. What is the significance of the lower overshoot layer, does the dynamo work in the entire convection zone, why is the field oscillatory, migratory, and dipole-like? Although some of those properties can be understood in the framework of α-Ω dynamo theory, there are some basic questions whether this theory can actually work. In my talk I will present a model of helically forced turbulence that allows us to address the question what generates the large scale field (e.g. α-effect and/or inverse cascade). Next, a simulation of a convective dynamo with shear will be presented, where a large scale magnetic field is found to develop near the lower overshoot layer. Finally, comparisons will be made with dynamo action in galaxies and accretion discs. In all cases the effects of noise are rather strong, and it is the presence of large scale shear which is crucial in producing a well-defined large scale field. The importance of magnetic instabilities will be highlighted in connection with stellar dynamos, where the observed cycle periods point toward the existence of different branches of activity.
- Publication:
-
Recent Insights into the Physics of the Sun and Heliosphere: Highlights from SOHO and Other Space Missions
- Pub Date:
- 2001
- DOI:
- 10.48550/arXiv.astro-ph/0011579
- arXiv:
- arXiv:astro-ph/0011579
- Bibcode:
- 2001IAUS..203..144B
- Keywords:
-
- Astrophysics
- E-Print:
- 8 pages, 4 figs, IAU 203 proceedings (Recent Insights into the Physics of the Sun and Heliosphere: Highlights from SOHO and Other Space Missions)