	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.