Simulations of Turbulent, Active and Rotating Stars (Suns)

Abstract

The STARS project aims at modelling in a self-consistent and three-dimensional way the complex, time dependent and nonlinear dynamics present in the Sun and stars. In particular we wish to understand stellar magnetic activity, that depending on the spectral type of the star considered can be cyclic (solar type stars) irregular (very low mass stars, with spectral type later than M3), or even for stars with stellar mass greater than 2 solar mass, without any activity or simply possessing a modulated signal (probably due to the presence of a fossil field in their stably stratified, radiative envelope). The mecanism thought to be at the origin of the magnetism seen in solar type stars or in low mass stars is likely to be linked to dynamo action in the upper convective layers of such stars. The simultaneous existence of convective turbulent motions (that could even possess helicity), of rotation and its associated differential rotation and shear layers in stars, favour the emergence of a small and/or large scale magnetic field through induction. For more massive stars, possessing a convective core, understanding the interaction between the dynamo generated magnetic field and the probable fossil magnetic field of their radiative envelope constitute a major challenge in stellar fluid dynamics.

To study in great details the interaction between convection, rotation and magnetic field in stars IS the main scientific goal of this project.