Dynamo and Fossil Magnetic Field in Young Stars

Abstract

The theory of fossil magnetic fields shows that new born stars may have internal magnetic fields of more than 1 million gauss. Convection inside young solar type stars will tangle any strong fossil magnetic field. The small scale magnetic field rises to the surface and determines the young stars activity attenuating with their age. When a fossil field is diminished a turbulent dynamo may begin to work in the condition of nonlinear stabilization. The scaling relations for the turbulent αω dynamo show that the strength of the generated “fossil” magnetic field inside the main sequence stars is stabilized on the level one tenth — 10 millions gauss, depending on the mass of the stars.