Cygnus OB2 (Cyg OB2)
Fr.: Cygnus OB2
The nearest example of a → massive star region of → star formation, containing 65 known → O-type stars and hundreds of → B-type stars. Cygnus OB2 lies at a distance of 1.45 → kpc. It is the central association, the most famous, and one of the youngest of the Cygnus region. Cyg OB2 possibly has two → populations with ages of 3.5-5 Myr, while the → O stars seem to belong to a younger population, aged about 2 Myr.