Hard X-Ray Observations of the Eclipsing Binary Ex-Hydrae

Abstract

The authors present light curves of EX Hydrae in the 1 - 10 keV range obtained with the medium energy experiment of EXOSAT. The 67-min modulation was observed with a peak-to-peak amplitude of 36% in the 1 - 4 keV range and of 24% in the 4 - 9 keV range. Newly discovered was a partial X-ray eclipse of ≡3 min full width which coincides with the optical eclipse and is seen at all energies. The results are interpreted in terms of an intermediate-polar (DQ Her star) model of EX Hydrae.