X-RAY ORBITAL MODULATIONS IN INTERMEDIATE POLARS

A systematic search of the EXOSAT observations of intermediate polars has revealed that a majority of systems show orbital-cycle X-ray modulations. The modulations are irregular, have the characteristic energy dependence of photoelectric absorption and, where it can be determined, have minima preferentially at orbital phase approximately 0.8. We remark on their similarity to the dips seen in high-inclination low-mass X-ray binaries. Similar causes (obscuration of the compact star by the accretion flow) may operate in both types of binary.