Continuum optical pulsation from the companions of binary X-ray pulsars

Observations of continuum optical pulsation reprocessed from X-ray pulsation by the companions of binary X-ray pulsars are valuable in deducing several properties of the systems. These include the X-ray luminosity, the masses of the two stars, the shape and size of the stellar surface, and whether the pulsar rotates in a prograde or retrograde sense. A general description of how this optical pulsation depends on various quantities is followed by predictions for the optical pulsation expected from the known binary X-ray pulsar systems. In many cases, the optical pulsation is much stronger than is predicted by less detailed estimates.