MAGNETODYNAMIC INSTABILITY OF A ROTATING SELF-GRAVITATING FLUID LAYER SANDWICHED IN A FLUID OF DIFFERENT DENSITY

The magnetodynamic instability of a rotating self-gravitating fluid layer of finite thickness embedded in a fluid of different density is developed. A general eigenvalue relation valid for all perturbations is derived based on the linear perturbation technique. In absence of rotation and electromagnetic forces the model is gravitationally unstable if the resultant dimensionless wavenumber is less than 0.64 and vice versa and if it is equal to 0.64 the marginal stability arises. The magnetic field has a strong stabilizing effect that extends the region in which stable waves occur below 0.64 but the gravitational instability is not completely suppressed. For high values of the angular velocity OMEGA the rotating force is stabilizing and can suppress thc gravitating instability for symmetric perturbations in the absence of the magnetic field. Considering the combined effect of rotation and electromagnetic force simultaneously, it is found that the magnetic field would be able to suppress the instability influence of rotation and it appears that the stability criterion is unaffected by the rotation in this case.