H0538+608 (= BY CAMELOPARDALIS) - AN ASYNCHRONOUSLY ROTATING AM-HERCULIS BINARY

A concurrent X-ray/optical observing program was undertaken to study the anomalous AM Her-type cataclysmic variable H0538 + 608 (BY Cam). We found evidence that the orbital period differs from the rotational period by 1.3% +/- 0.1%. If confirmed, this would be the second AM Her system found to rotate asynchronously; this would explain much of the unusual behavior previously exhibited in optical photometry and polarimetry. The transition in the X-ray state that occurred on 1988 February 9.5 (Ishida et al.) was also evident in the behavior of the optical continuum and the H-alpha emission. We continue to develop the model proposed by Ishida et al. Before the transition, the accretion occurred onto two spots, one of which was periodically occulted by the body of the white dwarf. After the transition, all the accretion was funneled onto the noneclipsing spot. On 1988 February 8.065 both spots are shown to lie in the northern hemisphere and on the side of the white dwarf opposite from the companion star. The primary characteristics of the optical and X-ray light curves and the radial velocity measures of H-alpha are consistent with our geometric model. An optical quasi-periodic oscillation (QPO) with a period of approximately 30 minutes was seen on two nights and possible causes of the QPO are discussed. The short time scale variations in the X-rays and optical light were highly correlated. The X-ray-optical cross correlation is maximum at zero time lag but is clearly asymmetric in the sense that optical power lags X-ray power.