Convective Differential Rotation in Stars and Planets II: Observational and Numerical Tests

TL;DR

This paper compares theoretical predictions of differential rotation in stars and planets with observations and simulations, confirming the models' validity and providing insights into stellar and planetary interior dynamics.

Contribution

It validates the scaling laws of differential rotation and related flows through observational and numerical comparisons, extending the understanding of rotation in various astrophysical objects.

Findings

Predictions are consistent with observations and simulations in most cases.

Core-envelope shear in red giants can be explained by the models.

Rotation affects gravity wave frequencies and gravity darkening deviations.

Abstract

Differential rotation is central to a great many mysteries in stars and planets. In Part I we predicted the order of magnitude and scaling of the differential rotation in both hydrodynamic and magnetohydrodynamic convection zones. Our results apply to both slowly- and rapidly-rotating systems, and provide a general picture of differential rotation in stars and fluid planets. We further calculated the scalings of the meridional circulation, entropy gradient and baroclinicity. In this companion paper we compare these predictions with a variety of observations and numerical simulations. With a few exceptions we find that these are consistent in both the slowly-rotating and rapidly-rotating limits. Our results help to localize core-envelope shear in red~giant stars, suggest a rotation-dependent frequency shift in the internal gravity waves of massive stars and potentially explain observed deviations from von Zeipel's gravity darkening in late-type stars.