Nonradial g-mode oscillations of warm neutron stars

Journal Article · Sun May 15 04:00:00 EDT 1983 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/161006· OSTI ID:5651269

McDermott, P N; Van Horn, H M; Scholl, J F

We have computed adiabatic l = 1 and 2, p-, f-, and g-mode fluid oscillations of finite-temperature neutron star models. We use the ''relativistic Cowling approximation,'' defined in this paper, in which all perturbations of the gravitational potentials are neglected. This approximation is expected to be adequate for the g-modes and even gives reasonable results for the periods of p- and f-modes. For example, in agreement with previous calculations, we find the p-mode periods to be approximately Pi/sub p/approx.0.5(M*/M/sub X/)/sup -1/2/R/sup 3/2//sub 6/ ms, where R/sub 6/ is the neutron star radius in units of 10/sup 6/ cm. For the g-modes, the periods from our numerical calculations are > or approx. =400 ms for a neutron star with T/sub 7/roughly-equal1.0 and vary roughly as the inverse of T/sub 7/, where T/sub 7/ is the core temperature in units of 10/sup 7/ K. We have also estimated the gravitational radiation damping times, tau, of the l = 2 oscillation modes. For the p- and f-modes we find, again in rough agreement with previous calculations, tauapprox.(10/sup 2/--10/sup 3/)Pi. For the fluid g-mode oscillations we have studied, however, gravitational radiation damping is exceedingly weak, with typical values of tau greatly exceeding the age of the universe. These very long gravitational radiation damping times are a consequence of the much longer g-mode periods, which greatly reduce the relative power radiated, and of the concentration of the oscillatory motions to the outermost several meters of the neutron star, which reduces the effective quadrupole moment of the oscillations. Damping of neutron star g-mode oscillations will thus be dominated by other processes. The confinement of the g-mode eigenfunctions to the crust suggests that the effects of the nonzero shear modulus (which we have not included) may be quite important.

• Research Organization: Department of Physics and Astronomy and C. E. Kenneth Mees Observatory, University of Rochester
• OSTI ID: 5651269
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 268:2; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640102* -- Astrophysics & Cosmology-- Stars & Quasi-Stellar
Radio & X-Ray Sources
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
DAMPING
DISPERSION RELATIONS
EIGENVALUES
FIELD THEORIES
GENERAL RELATIVITY THEORY
GRAVITATIONAL RADIATION
MATHEMATICAL MODELS
NEUTRON STARS
NUMERICAL SOLUTION
OSCILLATION MODES
OSCILLATIONS
PULSATIONS
RADIATIONS
STAR MODELS
STARS