EXOSAT observations of X 1822 - 371: modelling of the accretion disc rim

We present X-ray data from three observations of X 1822 - 371 made using EXOSAT. The quasi-sinusoidal modulation dominating the X-ray light curve is not accompanied by spectral changes. We do, however, find a softening of the spectrum during eclipse and a hardening of the spectrum just prior to eclipse. The spectral change during eclipse indicates that the effective temperature of the ADC decreases with height. A similar energy dependence in the sinusoidal modulation may be masked by photo-electric absorption in the disc. We model the binary system with an X-ray emitting ADC partially obscured by an optically emitting disc whose height varies with azimuthal angle. (author)