On the oscillations of a composite stellar model with a weak magnetic field

Abstract

The unrestricted second-order virial tensor formalism has been used to calculate the characteristic frequencies of linear adiabatic oscillations of a composite stellar model having an isothermal core and a polytropic envelop in presence of a weak magnetic field. The frequencies of the transverse shear mode and the nonradial pulsation mode for both a radiative and a convective envelop (corresponding to polytropic index 3 and 1.5, res[ectively) alongwith that of the torodial mode for the radiative envelop get increased in presence of the magnetic field. However, the frequency of the toroidal mode for the convective envelop registers a decrease in presence of the field. The corrections to the various frequencies decrease with increasing values of the parameter characterizing the lowering of the core temperature in presence of the magnetic field.