The magnetic helicity driven solar-type dynamo

TL;DR

This paper investigates the role of the newly identified Visniac flux (NV flux) in enhancing solar-type dynamo processes, showing it can sustain large-scale magnetic fields even without the traditional alpha effect.

Contribution

The study introduces the NV flux as a new dynamo mechanism, demonstrating its impact on magnetic field concentration and dynamo efficiency in solar-like stars.

Findings

NV flux increases dynamo efficiency for large-scale magnetic field generation.

NV flux concentrates dynamo waves toward the equator.

Large-scale dynamo can be sustained without the kinetic alpha effect.

Abstract

(1)The previous theoretical studies showed that in the presence of the small-scale dynamo the large-scale vorticity can produce the the divergent-type helicity flux breaking the equatorial reflection symmetry of the magnetic fluctuations in the stellar convection zone. This effect was called the new Visniac flux (hereafter the NV flux). Similarly to the $\alpha$ effect, the NV flux is able to maintain the large-scale turbulent dynamo. 2) Methods:Using the mean-field dynamo model we study the effect of the NV flux on the solar type dynamos. We found that the NV flux results to a increase of the dynamo efficiency for the turbulent generation of the large-scale poloidal magnetic field of the Sun. The dynamic effect of the NV flux on the magnetic field evolution results into concentrating the dynamo waves toward the equator. Using the numerical simulations of the mean-field dynamo model we compare the helicity production rates by the turbulent dynamo effects, like the $\alpha$ effect and the NV flux. We found that the new dynamo source can produce the large-scale dynamo even if the kinetic $\alpha$ effect is zero.3) Conclusions:The new findings suggest the crucial role of the large-scale vorticity and fluctuating magnetic field in the large-scale dynamo inside the stellar convection zones.