Solar dynamo cycle variations with a rotational period

Abstract

ABSTRACT Using non-linear mean-field dynamo models, we calculate magnetic cycle parameters, such as the dynamo cycle period, the amplitude of the total magnetic energy and the Poynting flux luminosity from the surface, for solar analogues with rotation periods in the range of 1–30 d. We perform simulations for both kinematic and non-kinematic dynamo models. The kinematic dynamo models, which take into account the non-linear α-effect and the loss of the magnetic flux due to magnetic buoyancy, show a decrease of the magnetic cycle with the decrease of the stellar rotation period. Stars with a rotational period of fewer than 10 d show non-stationary long-term variations of magnetic activity. The non-kinematic dynamo models take into account the magnetic field feedback on the large-scale flow and heat transport inside the convection zone. They show the non-monotonic variation of the dynamo period with the rotation rate. The models for rotational periods fewer than 10 d show non-stationary evolution with a slight increase in the primary dynamo period with the increase of the rotation rate. The non-kinematic models show the growth of the dynamo-generated magnetic flux with the increase of the rotation rate. There is a dynamo saturation for a star rotating with a period of 2 d or less. The saturation of the magnetic activity parameters is accompanied by a depression of the differential rotation.