the primary component and brightest member of this system, designated 59 cyg aa, is a rapidly rotating be star with a stellar classification of b1.5 vnne. this is a well-studied star thanks to pronounced spectral variations that have been observed since 1916, and two short-term shell star phases that were observed in 1973 and 1974–5. it is actually a confirmed spectroscopic binary system with a high temperature subdwarf o-type companion in a 28-day orbital period. the latter is heating the nearest side of the circumstellar gaseous disk that surrounds the primary.