Optical and X-Ray Variability of Gamma Cas Analogs

γ Cas analogs is an enigmatic group of Be stars with unusually hard X-rays and an X-ray luminosity of 1031–1033erg s−1, which is higher than a typical value for classical Be stars. The evolutionary status of these mysterious objects and the nature of their X-ray emission remains disputable. I suppose that our understanding of this mystery is in the detailed studies of their optical and X-ray variability on the various time scales from very short to very long. In the present paper the optical and X-ray spectral and photometric observations of these stars are reviewed. The contemporary assumptions on the mechanisms of X-ray radiation generation of γ Cas analogs are discussed. It is concluded that the analysis of the binarity of γ Cas analog helps to understand their inexplicable nature.