causing it to glow with a blue-white hue. X-ray emission Gamma Cassiopeiae is the prototype of a small group of stellar sources of X-ray radiation that is about 10 times stronger than emitted from other B or Be stars. The character of the X-ray spectrum is Be thermal, possibly emitted from plasmas of temperatures up to least ten million kelvins, and shows very short term and long-term cycles. Historically, it has been held that these X-rays might be excited by matter originating from the star, from a hot wind or a disk around the star, accreting onto the surface of a degenerate companion, such as a white dwarf or neutron star. However, there are difficulties with either of these hypotheses. For example, it is not clear that enough matter can be accreted by a white dwarf, at the distance of the purported secondary star implied by the orbital period, sufficient to power an X-ray emission of nearly 1033 erg/s or 100 YW. A neutron star could easily power this X-ray flux, but X-ray emission from neutron stars is known to be non-thermal, and thus in apparent variance with the spectral properties. Evidence suggests that the X-rays may be associated with the Be star itself or caused by some complex interaction between the star and surrounding decretion disk. One line of evidence is that the X-ray production is known to vary on both short and long time scales with respect to various UV line and continuum changes associated with a B star or with circumstellar matter close to the star. Moreover, the X-ray emissions exhibit long-term cycles that correlate with the light curves in the visible wavelengths. Gamma Cassiopeiae exhibits characteristics consistent with a strong disordered magnetic field. No field can be measured directly from the Zeeman effect because of the star's rotation-broadened spectral lines. Instead, the presence of this field is inferred from a robust periodic signal of 1.21 days that suggests a magnetic field rooted on the rotating star's surface. The star's UV and optical spectral lines show ripples moving from blue to red over several hours, which indicates clouds of matter being held frozen over the star's surface by strong magnetic fields. This evidence suggests that a magnetic field from the star is interacting with the decretion disk, resulting in the X-ray emission. A disk dynamo has been advanced as a mechanism to explain this modulation of the