Alpha Cygni variables are variable stars which exhibit non-radial pulsations. They are supergiant stars of spectral types B or A. Variations in brightness on the order of 0.1 magnitudes are associated with the radial pulsations, which often seem irregular, due to beating of multiple pulsation periods. The pulsations typically have periods of several days to several weeks. Most stars are of nearly constant luminosity. ... Supergiants are the most massive stars. ... In astronomy, stellar classification is a classification of stars based initially on photospheric temperature and its associated spectral characteristics, and subsequenly refined in terms of other characteristics. ... // Headline text HEY!! HOW ARE YOU ALL?? Its nice of you to come read this page. ... An irregular variable is a type of variable star in which variations in brightness show no regular periodicity. ... In acoustics, a beat is an interference between two sounds of slightly different frequencies, perceived as periodic variations in volume whose rate is the difference between the two frequencies. ...

The prototype of these stars, Deneb (α Cygni), exhibits fluctuations in brightness between magnitudes +1.21 and +1.29. Deneb (α Cyg / α Cygni / Alpha Cygni) is the brightest star in the constellation Cygnus and one of the brightest stars in the night sky, with apparent magnitude 1. ...

References

Samus N.N., Durlevich O.V., et al. Combined General Catalog of Variable Stars (GCVS4.2, 2004 Ed.)