Gamma Cygni nebula, also known as the Sadr Region, or IC 1318, is a diffuse emission nebula that can be seen around Sadr (Gamma Cygni). Sadr is the bright star at the centre of the Northern Cross, which marks the heart of Cygnus, the Swan. Despite the name, the star and the nebula are unrelated. Even though it looks embedded in the nebulosity, Sadr is approximately 1, 800 light years distant, while the nebula is much further away, at 4, 900 light years. The Gamma Cygni nebula is considered an emission nebula because it is ionized by the radiation of the nearby stars and it emits visible light as a result. |