Neutron star wobble in binary x-ray sources

Calculations of the influence of accreting-matter torques on the free precession of neutron stars in close binary systems are summarized. To the extent that the flow of accreting matter is modulated by the wobble motion of the neutron star, there will be components of the accretion torque locked in phase with this motion. Such components can be very effective in exciting of damping stellar wobble. It is suggested that large-amplitude stellar wobble, which can result from certain matter flow patterns and types of accretion gate, may be responsible for some of the high-low X-ray states observed in binary X-ray sources, including the 35/sup d/ cycle in Her X-1