Publication date: Dec 2005
Abstract:
Properties of the gravitational perturbation force caused by a small
inhomogeneity located on the surface of a neutron star are studied. The
oscillating perturbation force in both the accretion disc rotating
around the star and in the interior of a differentially rotating star is
determined. Both vertical and radial components of the force are given
and their relations are discussed. The frequency of the oscillations is
given by the difference of the frequency of the rotation of the star
surface, and the orbital frequency in the disc (the frequency of
rotation of matter in the star interior). Outside the star, in the disc,
the vertical and radial forces vary with the same phase. Inside a
differentially rotating star, the variations of the forces are in the
opposite phase in an internal part of the star, while they are in the
same phase in an external layer of the star. In an intermediate part of
the star, an additional oscillatory change appears. Is is shown that the
anharmonic character of the oscillatory forces is limited to the seventh
non-negligible harmonics. For completeness, we present the perturbation
force generated by a symmetric accretion column.
Authors:
Stuchlík, Zdeněk; Hledík, Stanislav;