SIMBAD references

2018ApJ...859...18P - Astrophys. J., 859, 18-18 (2018/May-3)

Generation of a large-scale magnetic field in a convective full-sphere cross-helicity dynamo.

PIPIN V.V. and YOKOI N.

Abstract (from CDS):

We study the effects of the cross-helicity in the full-sphere large-scale mean-field dynamo models of a 0.3 M star rotating with a period of 10 days. In exploring several dynamo scenarios that stem from magnetic field generation by the cross-helicity effect, we found that the cross-helicity provides the natural generation mechanisms for the large-scale scale axisymmetric and nonaxisymmetric magnetic field. Therefore, the rotating stars with convective envelopes can produce a large-scale magnetic field generated solely due to the turbulent cross-helicity effect (we call it γ2-dynamo). Using mean-field models we compare the properties of the large-scale magnetic field organization that stems from dynamo mechanisms based on the kinetic helicity (associated with the α2 dynamos) and cross-helicity. For the fully convective stars, both generation mechanisms can maintain large-scale dynamos even for the solid body rotation law inside the star. The nonaxisymmetric magnetic configurations become preferable when the cross-helicity and the α-effect operate independently of each other. This corresponds to situations with purely γ2 or α2 dynamos. The combination of these scenarios, i.e., the γ2α2 dynamo, can generate preferably axisymmetric, dipole-like magnetic fields at strengths of several kGs. Thus, we found a new dynamo scenario that is able to generate an axisymmetric magnetic field even in the case of a solid body rotation of the star. We discuss the possible applications of our findings to stellar observations.

Abstract Copyright: © 2018. The American Astronomical Society. All rights reserved.

Journal keyword(s): dynamo - magnetic fields - stars: activity - stars: low-mass

Simbad objects: 2

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