Magnetic field generation in celestial bodies

Abstract

This article presents a review of various possible mechanisms of magnetic field generation in celestial bodies. We shall avoid analysing problems that have been considered in the review literature. Many authors believe that the dynamo theory can explain almost all magnetic effects in cosmic bodies, with a few exceptions connected with magnetic fields of neutron stars and white dwarfs, which are thought to be explained by the fossil field theory. We shall discuss briefly the advantages and weak points of the dynamo theory and shall try to show that various mechanisms may be responsible for the field generation. The thermomagnetic instability may be efficient for the field generation in white dwarfs and neutron stars. Meridional circulations may be important for the dynamo process in hot O and B stars. The field amplification in close binary stellar systems may be due to the inductive interaction of the stars. The “battery” effect, connected with the observed local chemical inhomogeneities in Cp stars, may be the cause of the field generation. Chemical and temperature inhomogeneities at the Earth's core-mantle boundary may be important for the terrestrial magnetisma. A brief discussion is also given of related problems, for example, the processes in stellar magnetospheres. The role of tidal circulations in binary systems is considered. New data about the solar oscillations and the solar magnetic field are discussed.