Global-scale Simulations of Stellar Convection and their Observational Predictions

TL;DR

This paper uses 3D MHD simulations to predict observable signatures of stellar convection and differential rotation in solar-type stars, providing testable hypotheses for interferometric observations.

Contribution

It presents novel predictions of global-scale magnetic and flow structures in stars based on advanced simulations, linking interior dynamics to observable surface features.

Findings

Rapid rotators exhibit solar-like differential rotation with a prograde equator.

Slow rotators may have anti-solar rotation profiles with faster poles.

Magnetic wreaths in the convection zone could be observable near stellar surfaces.

Abstract

Stars on the lower main sequence (F-type through M-type) have substantial convective envelopes beneath their stellar photospheres. Convection in these regions can couple with rotation to build global-scale structures that may be observable by interferometers that can resolve stellar disks. Here I discuss predictions emerging from 3D MHD simulations for solar-type stars with the anelastic spherical harmonic (ASH) code and how these predictions may be observationally tested. The zonal flow of differential rotation is likely the most easily observable signature of dynamics occurring deep within the stellar interior. Generally, we find that rapidly rotating suns have a strong solar-like differential rotation with a prograde equator and retrograde poles while slowly spinning suns may have anti-solar rotation profiles with fast poles and slow equators. The thermal wind balance accompanying the differential rotation may lead to hot and bright poles in the rapid rotators and cooler, darker poles in slow rotators. The convection and differential rotation build global-scale magnetic structures in the bulk of the convection zone, and these wreaths of magnetism may be observable near the stellar surfaces.