Modeling of differential rotation in rapidly rotating solar-type stars

TL;DR

This study models differential rotation in rapidly rotating solar-type stars using a mean field approach, revealing how rotation speed influences the star's internal angular velocity distribution and matching observational data.

Contribution

It extends a solar mean field model to rapidly rotating stars, providing insights into their differential rotation profiles and underlying physical mechanisms.

Findings

Differential rotation approaches the Taylor-Proudman state at high rotation speeds.

Entropy gradient decreases with increasing stellar angular velocity.

Turbulent viscosity influences the spatial variation of angular velocity.

Abstract

We investigate differential rotation in rapidly rotating solar-type stars by means of an axisymmetric mean field model that was previously applied to the sun. This allows us to calculate the latitudinal entropy gradient with a rea- sonable physical basis. Our conclusions are as follows: (1) Differential rotation approaches the Taylor-Proudman state when stellar rotation is faster than so- lar rotation. (2) Entropy gradient generated by the attached subadiabatic layer beneath the convection zone becomes relatively small with a large stellar angu- lar velocity. (3) Turbulent viscosity and turbulent angular momentum transport determine the spatial difference of angular velocity $\Delta \Omega$. (4) The results of our mean field model can explain observations of stellar differential rotation.