R-Mode Oscillations and Rocket Effect in Rotating Superfluid Neutron Stars. I. Formalism

Abstract

We derive the hydrodynamical equations of r-mode oscillations in neutron stars in the presence of a novel damping mechanism related to particle number changing processes. The change in the number densities of the various species leads to new dissipative terms in the equations that are responsible for the rocket effect. We employ a two-fluid model, with one fluid consisting of the charged components, while the second fluid consists of superfluid neutrons. We consider two different kinds of r-mode oscillations, one associated with comoving displacements, and the second associated with countermoving, out of phase, displacements.