MAGNETOHYDRODYNAMIC DYNAMO IN DISC-LIKE ASTROPHYSICAL BODIES.

Abstract

Magnetohydrodynamic dynamo in disc-like astrophysical bodies has been considered for some time. Important astrophysical objects like accretion discs, protostellar and protoplanetary nebulae and galaxies are thought to regenerate a magnetic field through a dynamo mechanism. Although there is a well developed theory for describing the regeneration of magnetic field in these objects, there are not any specific methods how to calculate such magnetic fields in general case. In this work, after a description of the dynamo theory, the specific method for solving the nonspherical dynamo is introduced. The unique feature of this method is accommodation of variable magnetic diffusivity in order to model the shape of a disc-like body. The detailed construction of the method is presented, as well as description of mathematical and numerical methods used for obtaining the solution. The method of checking the model with respect to well established spherical models is also presented. Finally, some examples are calculated and discussion is given on the behaviour of calculated magnetic field and possible astrophysical implications.