Paradigm shifts in solar dynamo modeling

Abstract

Selected topics in solar dynamo theory are being highlighted. The possible relevance of the near-surface shear layer is discussed. The role of turbulent downward pumping is mentioned in connection with earlier concerns that a dynamo-generated magnetic field would be rapidly lost from the convection zone by magnetic buoyancy. It is argued that shear-mediated small-scale magnetic helicity fluxes are responsible for the success of some of the recent large-scale dynamo simulations. These fluxes help in disposing of excess small-scale magnetic helicity. This small-scale magnetic helicity, in turn, is generated in response to the production of an overall tilt in each Parker loop. Some preliminary calculations of this helicity flux are presented for a system with uniform shear. In the Sun the effects of magnetic helicity fluxes may be seen in coronal mass ejections shedding large amounts of magnetic helicity.

7 pages, 4 figures, final version

References in corpus (5)

• Global-Scale Turbulent Convection and Magnetic Dynamo Action in the Solar Envelope
• The case for a distributed solar dynamo shaped by near-surface shear
• Large-scale dynamos in turbulent convection with shear
• Turbulent magnetic Prandtl number and magnetic diffusivity quenching from simulations
• Nonlinear current helicity fluxes in turbulent dynamos and alpha quenching