UBC Theses and Dissertations
Magnetohydrodynamics of neutron star interiors Easson, Ian Whiteman
The dynamics of the charged particles in the fluid interior of rotating magnetized neutron stars (pulsars) is investigated. It is shown that a magnetohydrodynamic approach is valid under a wide variety of conditions. The small amplitude waves that can propagate in the "charged" fluid are sound waves (period ~< 10⁻⁴ sec), inertial waves (≈ 1 sec) and hydromagnetic-inertial waves (~< months). Generally, the most effective damping mechanism is viscosity. Viscous damping times for hydromagnetic-inertial waves can be as long as hundreds of years. Several normal sound mode and normal inertial mode calculations are performed. The motion of the charged fluid over the time scales of inertial waves and hydromagnetic-inertial waves is simulated on a computer. Mode-mode coupling, boundary layers, and the acceleration of the crust due to charged fluid motion are also studied. The most important conclusion in this thesis is that the time the charged fluid as a whole takes to respond to a sudden disturbance such as a change in the angular velocity or acceleration of the crust is the time for a long wavelength hydromagnetic-inertial wave to cross the star. Contrary to an assumption which has been made in models of pulsar post-glitch behaviour, the charged fluid response time is not necessarily small compared to post-glitch relaxation times. In view of this, models of post-glitch behaviour which assume that the charged fluid response time is small compared to post-glitch relaxation times should be re-examined.
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