Observations of binary X-ray sources with Ariel 5

Ariel 5 observations of the established X-ray binary sources are presented. Most of the results are from the Leicester Sky Survey Experiment, which made extended observations of the Milky Way in November 1974 and again in July-August 1975. The light curves of Cen X-3 and Vel X-1 are found to have attenuation features which are attributed to shocks near the secondary star and which provide evidence in support of stellar-wind-driven accretion in these sources. An extended observation of Cyg X-1 is described in which there is evidence of the 5.6-day period of the associated optical binary. A systematic variation of spectral hardness (temperature) with the intensity of the Cyg X-3 source is found, and further spectral observations by the MSSL proportional-counter spectrometer reveal the presence of a strong monochromatic feature near 6.5 keV, probably attributable to line radiation from highly ionized iron.