INSIGHTS INTO THE ACCRETION FLOW IN QS TELESCOPII (RE1938-461) FROM HST OBSERVATIONS

We present HST/FOS observations of the polar QS Tel (RE1938-461) revea ling new details in its 140 min UV orbital variability. A colour-depen dent continuum orbital modulation as well as a narrow dip in its light curve, occurring at the same orbital phases as the one detected in th e EUVE band, are observed. Their spectral dependence allows us to iden tify the heated regions of the white dwarf surface with complex struct ure and temperature gradients as well as the accretion stream. The abs orption dip occurs during the minimum of UV emission line light curves and is interpreted as the occultation of the heated spot on the white dwarf surface by the accretion stream. We also confirm the strong UV modulation of the emission lines which, in these high time resolved sp ectroscopic data, is structured and consistent with X-ray irradiation of the stream material.