Spindown of neutron stars in close binary systems - II

Abstract

The process is considered by which a rotating, magnetic, nonaccreting neutron star spins down by interacting with an external medium, for example, a weak stellar wind from a companion star. It is found that the spindown rate proposed by Illarionov and Sunyaev (1975) (the 'propeller' mechanism) is essentially correct, and reasons why various other rates proposed in the literature are likely to be overestimates are discussed. It is also pointed out that spindown can still occur even when the rotation is subsonic and accretion is no longer inhibited by a centrifugal barrier. Thus reasonable spindown time scales for the long-period pulsing X-ray sources may still be feasible.