Second-order rotational effects on the r-modes of neutron stars - art. no.064006

Techniques an developed here for evaluating the r-modes of rotating neutron stars through second order in the angular velocity of the star. Second-ord er corrections to the frequencies and eigenfunctions for these modes are ev aluated for neutron star models. The second-order eigenfunctions for these modes are determined here by solving an unusual inhomogeneous hyperbolic bo undary-value problem. The numerical techniques developed to solve this unus ual problem are somewhat non-standard and may well be of interest beyond th e particular application here. The bulk-viscosity coupling to the r-modes, which appears first at second order, is evaluated. The bulk-viscosity time scales are found here to be longer than previous estimates for normal neutr on stars, but shorter than previous estimates for strange stars. These new time scales do not substantially affect the current picture of the gravitat ional radiation driven instability of the r-modes either for neutron stars or for strange stars. [S0556-2821(99)01518-0].