Gamma Cygni (γ Cygni,), officially named Sadr is a star in the northern constellation of Cygnus, forming the intersection of an asterism of five stars called the Northern Cross. Based upon parallax measurements obtained during the Hipparcos mission, it is approximately 1,800 light-years (560 parsecs) from the Sun.
Compared to the Sun this is an enormous star, with 12 times the Sun’s mass and about 150 times the Sun’s radius. It is emitting over 33,000 times as much energy as the Sun, at an effective temperature of 6,100 K in its outer envelope. This temperature is what gives the star the characteristic yellow-white hue of an F-type star. Massive stars such as this consume their nuclear fuel much more rapidly than the Sun, so the estimated age of this star is only about 12 million years old.
The Sadr Region (also known as IC 1318 or the Gamma Cygni Nebula) is the diffuse emission nebula surrounding Sadr (γ Cygni) at the center of Cygnus’s cross. The Sadr Region is one of the surrounding nebulous regions; others include the Butterfly Nebula and the Crescent Nebula. It contains many dark nebulae in addition to the emission diffuse nebulae.