I looked up Cassiopeia in my book. Gamma Cassiopeiae was the main attraction and the book calls it a "shell star". However, the star gets its own Wikipedia page which does list some features of a shell star, such as very rapid spinning, but calls it an "eruptive variable". It is also the first Be star discovered. I am familiar with the idea of rapid spin producing broader spectral lines because of Doppler Shift but there is a lot more in here to digest!
