Abstract
In the thesis, several issues of asteroseimology of pulsars and magnetars are considered from the view point of a model of a solid star capable of sustaining the quake-induced shear vibrations. A brief review is given of magneto-solid-mechanical theory of node-free torsional seismic vibrations of a quaking neutron star with homogeneous internal and dipolar external magnetic field. This theory has been developed to explain quasi-periodic oscillations (QPOs) in the outburst X-ray flux from SGR 1806-20 and SGR 1900+14. The main task of presented work is to investigate the model of torsional nodeless vibrations of neutron star with inhomogeneous internal and dipolar external magnetic field which has been taken in Ferraro’s form. Based on the energy variational method. the frequency spectrum for the frequency of Alfv’en toroidal vibrational mode is obtained and applied to modal identification of the QPOs in X-ray outburst of above magnetars. It is shown that the model provide fairly good description of detected frequencies and lead one’s to conclude that it is the Lorentz force of magnetic field stresses plays decisive part in post-quake vibrational relaxation of above magnetars in which the magnetic field is non- homogeneous. The work is a part of running pro jects of Institute of Astronomy, National Tsing Hua University, on the study of sources of high-energy emission.