Paradigm shifts in solar dynamo modeling

TL;DR

This paper discusses recent advances in solar dynamo modeling, emphasizing the role of magnetic helicity fluxes and shear effects in explaining solar magnetic phenomena and improving simulation accuracy.

Contribution

It highlights the importance of shear-mediated magnetic helicity fluxes in large-scale dynamo simulations and discusses their potential observational signatures.

Findings

Magnetic helicity fluxes help in magnetic field generation.

Shear layers influence magnetic helicity transport.

Coronal mass ejections may reflect helicity flux effects.

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.