Magneto-hydrodynamic modelling of solar envelope

A Standard Solar Model (SSM) excluding the magnetic field was used as reference in order to study the effect of the magnetic field in the solar envelope. For the linear case, a first order perturbation approximation was used in considering the effect of the magnetic field on the SSM. By a direct integration scheme (using Waterloo Maple 8), it was shown that perturbations in the magnetic field components become oscillatory. The ratio of the perturbed parameters to the equilibrium ones at a given radius was found to be about 10-6. The perturbation of the magnetic field at the base of the convective zone (r=0.713 R ) was approximately 0.8 μT. For the non linear case, the analytical solutions of the MHD equations were obtained as a function of time in the convective solar envelope. Resulting frequency shifts were also calculated and compared with the observed five-minute oscillations of the Sun