Diagnostic Studies for Excretion Be - Star Disc Evolution in Be/X-Ray Binary Systems Utilizing SALT Spectroscopy

Our study of the long-term superorbital variability in Be X-ray binaries using 22 yrs light curve from MACHO and OGLE databases, has revealed 200 - 3000d quasi-period variations in almost all of them with amplitudes ranging up to 1.2 mag. These variations are related to the formation and dissipation of the Be star circumstellar disc. We present the preliminary results of optical spectroscopic observations of a sample of Magellanic Clouds Be/X-ray binaries (BeX) taken throughout their superorbital cycle. These observations were carried out with the Southern African Large Telescope (SALT) using the Robert Stobie Spectrograph (RSS) in long-slit mode. For each observing night we obtained both wide wavelength and high-resolution spectra. This allows us to follow the evolution of the size and structure of the Be equatorial disc and to separate the various emitting components, in particular the spectrum of the Be disc. We used the high-resolution spectra for spectral classification of the underlying B star and determination of the rotational and radial velocities.