Abstract

In this talk, we will review some aspects of the stellar magnetism and in particular what numerical simulations tell us about the physical processes underlying the observations.

In solar-like stars, a convective dynamo is thought to be responsible for the presence and evolution of magnetic fields. One step of this dynamo process is the emergence of magnetic flux from the interior where it is created and organised to the exterior where it emerges as sunspots. We will show the results of 3D numerical simulations of such a process.

Intermediate-mass stars have a probably different type of magnetism. Some A stars (Ap stars) possess strong large-scale magnetic fields which seem to remain rather stable in time. Some recent observations now tend to show that another class of A stars exists, which exhibit a more complex and weak magnetic field, organized at smaller scales at their surfaces. We try to understand such a magnetic dichotomy by numerically investigating the stability of magnetic fields created by differential rotation in the stellar radiative envelope.