Breaking Taylor-Proudman balance by magnetic field in stellar convection zone

TL;DR

This study uses high-resolution simulations to show that small-scale dynamos significantly influence stellar differential rotation by disrupting the Taylor-Proudman balance through multiple mechanisms.

Contribution

It reveals the roles of small-scale dynamos in breaking the Taylor-Proudman state in stellar convection zones, highlighting their impact on differential rotation.

Findings

Small-scale dynamo suppresses angular velocity shear.

It increases the latitudinal entropy gradient.

Convection velocity is reduced, enhancing rotational effects.

Abstract

We carry out high-resolution calculations for the stellar convection zone. The main purpose of this study is to investigate the effect of a small-scale dynamo on the differential rotation. The solar differential rotation deviates from the Taylor-Proudman state in which the angular velocity does not change along the rotational axis. To break the Taylor-Proudman state deep in the convection zone, it is thought that a latitudinal entropy gradient is required. In this study, we find that the small-scale dynamo has three roles in the deviation of the stellar differential rotation from the Taylor-Proudman state. 1. The shear of the angular velocity is suppressed. This leads to a situation where the latitudinal entropy gradient efficiently breaks the Taylor-Proudman state. 2. The perturbation of the entropy is increased with suppressing the turbulent velocity between up- and downflows. 3. The convection velocity is reduced. This increases the effect of the rotation on the convection. The second and third factors increase the latitudinal entropy gradient and break the Taylor-Proudman state. We find that the efficient small-scale dynamo has a significant impact on the stellar differential rotation.