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 spectrum of this star shows some unusual dynamic features, including variations in radial velocity of up to , occurring on a time scale of 100 days or more. Indeed, on the Hertzsprung–Russell diagram, Gamma Cygni lies close to the instability strip and its spectrum is markedly like that of a Cepheid variable. This star is surrounded by a diffuse nebula called IC 1318, or the Gamma Cygni region. References External links Sadr by Jim Kaler. http://www.atlasoftheuniverse.com/nebulae/ic1318.html Astronomy Picture of the Day: Supergiant Star Gamma Cygni, NASA, July 9, 2013 Cygni, Gamma Cygnus (constellation) F-type supergiants Sadr Cygni, 37 7796 194093 100453 Durchmusterung objects Suspected variables