Generation of large-scale magnetic fields and flows in fully convective stars
Wolfgang Dobler (Kiepenheuer-Institut für Sonnenphysik/University of Calgary)
Axel Brandenburg (NORDITA, Copenhagen)
Michael Stix (Kiepenheuer-Institut, Freiburg)
We present results of numerical simulations of convection and magnetic field
evolution in fully convective stars like M-dwarfs. The model consists of a
rotating gas sphere in a spherically symmetric gravity potential, with heating
near the centre and cooling at the surface.
While magnetic fields can grow even in the absence of rotation, the growth is
faster if rotation is present. For inverse Rossby numbers considerably larger
than unity, the magnetic spectrum peaks at moderate wave number during the
kinematic dynamo phase, but after saturation, the magnetic field is dominated by
large scales.
We also discuss the pattern of differential rotation and meridional circulation
that is generated by convection and influenced by the magnetic field.