On the power in intermediate polars

I review some of the more interesting recent results on Intermediate Polars, with an emphasis on the information content of their periodic intensity variations, as provided by power spectra. The current definitions of the class are discussed, and new contenders listed with their properties. Results of the X-ray periodicities seen in IPs and developments in interpreting their light curves and power spectra are discussed. Studies of the morphology of IP X-ray light curves seem to show a bifurcation into single- or double-maxima spin profiles. An explanation for this behaviour, involving faster, weaker field, rotators accreting over a larger area, is discussed. Significant polarization has: only been detected in three IPs, and the polarized Aux distributions have been used to infer magnetic field strength. The failure to detect any IR cyclotron spectral features in IPs, even for polarized systems, limits our possibilities of direct magnetic field measurements. Recent tomographic results qualitatively support the accretion curtain models for IPs and some progress has been made in modelling the line emission using realistic physics. (C) 2000 Elsevier Science B.V. All rights reserved.