ROSAT AND GINGA OBSERVATIONS OF THE MAGNETIC CATACLYSMIC VARIABLE QQ-VUL - EVIDENCE FOR 2-POLE ACCRETION

We report observations made in 1991 April of QQ Vul using the ROSAT an d Ginga satellites. We find a spectral variation in soft X-rays that c an be accounted for by an increase in the blackbody temperature by 3-5 eV, or by an increase in the intrinsic absorbing column density of (1 .8-3.6)x10(19) cm(-2), between phases 0.5 and 1.0. Together with evide nce for separated hard and soft X-ray emission regions, this suggests the presence of two-pole accretion. The emission region furthest from the secondary has a soft X-ray excess greater than or equal to 2.5, su ggesting buried shocks arising from the accretion of dense filaments. The other emission region, closer to the secondary, is the site of the hard X-ray component. The hard X-ray data show a 6.7-keV iron K line of large equivalent width.