The Binary X-Ray Stars – the Observational Picture

Abstract

When X-ray sources in the galaxy were discovered in 1962 (Giacconi et al., 1962) it was only possible to speculate on their nature, which centered on supernova and cosmic-ray phenomena since these were the only very energetic events known. In particular, the discovery of an X-ray source associated with the Crab Nebula led to the idea that the emission might be the thermal radiation from the surface of a hot, neutron star. However, it was soon demonstrated (Bowyer et al., 1964) that a neutron star could not be responsible for the bulk of the X-radiation from the Crab, and it was not possible to exclude highly pathological conditions in otherwise ordinary stellar systems as being responsible for the X-ray sources (cf. Hayakawa and Matsuoka, 1964).