Alpha Cygni star

An Alpha Cygni star is a type of supergiant pulsating variable star, of spectral type A or B, that undergoes non-radial pulsations with a period of 5 to 10 days and a visual amplitude of 0.1 magnitude or less, named for the prototype, Alpha Cygni (Deneb). The stellar oscillations may be complex, consisting of multiple pulsation frequencies as well as the fundamental one, so that the brightness changes appear irregular. The changes can only be small, however; otherwise, the star would become unstable and blow apart.