THE BE STAR GAMMA CASSIOPEIAE - X-RAY, FAR-UV, AND OPTICAL OBSERVATIONS IN EARLY 1989

The state of gamma Cas in early 1989 is presented as the result of joi nt observations in the X-ray, far-UV, and optical regions, Particular attention has been paid to short- and long-term variations within thes e spectral ranges. In X-ray observations with the Ginga satellite we h ave found no specific periodic variabilities in the 64 to 13,000 s ran ge, although a highly variable nature with no appreciable changes in t he hardness ratios has been confirmed. The X-ray spectrum has been fit ted with that of a thin thermal plasma (16-17 keV) with an iron emissi on line centered at 6.7 keV. For the resonance lines of Si IV, C IV, a nd N V observed with the IUE satellite in the far-UV region, no high-v elocity narrow absorption components were detected. The presence of ve ry broad wings in their profiles extending to expansion velocities (gr eater than or similar to 1,000 km s-1) much larger than the photospher ic escape velocity provides evidence for the existence of high-velocit y mass-loss processes from the star. The optical spectrum shows that g amma Cas is still in the state of V/R > 1 for Halpha, Hbeta, and Hgamm a. A series of high-resolution, high-S/N, He I lambda4471 and Mg II la mbda4481 line profiles indicates evidence of nonradial pulsation (\m\ congruent-to 8-10) of the star. The UBV photometric observations show that gamma Cas was in a rather stable state in early 1989, although so me fluctuation was recorded on time scales of minutes and hours. We ca nnot find any correlation between the time variations of the X-ray and other wavelength regions. We discuss the X-ray characteristics of gam ma Cas, which is uncommon among Be star X-ray sources regarding its sp ectral feature and variability.