Gamma Cassiopeiae variable

γ Cassiopeiae variables show irregular changes in brightness on a timescale of decades.

At other times the shell is not detectable in the spectrum, and even the emission lines may disappear.

It distinguishes them from those Be stars that only show smaller amplitude brightness variations.

The GCVS uses the code GCAS to denote γ Cassiopeiae variables.

[2] γ Cassiopeiae variables are understood to be hot stars which have equatorial decretion disks which periodically disappear and reform, or possibly just change dramatically in scale.