Nordita Astrophysics Seminars

Dynamo transitions in simulations of solar-like stars: the effect of heat conduction treatment

by Mariangela Viviani

Europe/Stockholm
Description

https://stockholmuniversity.zoom.us/j/530682073

.Results from global magnetoconvection simulations of solar-like stars show discrepancies with observations: a surplus of energy in the kinetic power spectrum at large scales, anti-solar differential rotation profiles for the solar rotation rate, and a transition from axi- to non-axisymmetric dynamos at a much lower rotation rate than what is observed. Even though the simulations reproduce the observed active longitudes in fast rotators, their motion in the rotational frame (the so-called azimuthal dynamo wave, ADW) is retrograde, in contrast to the prevalent prograde motion in observations. In an attempt to alleviate these inconsistencies, we employ a physically-motivated heat conduction prescription, based on Kramers opacity law, on a semi-global spherical setup describing convective envelopes of solar-like stars, and compare with the results from a previous setup using a prescribed heat conduction profile from mixing-length arguments. Although a Kramers-based heat conduction does not help in reproducing the solar rotation profile, it does help in the faster rotation regime, where the dynamo solutions now match better with observations.