A prominent constellation of the northern sky, representing a swan. It is sometimes known as the Northern Cross because of the shape formed by its main stars, the brightest of which is Deneb (Alpha Cygni). Albireo (Beta Cygni) is a famous double star; another notable double is *61 Cygni. P Cygni is a 5th-magnitude variable blue supergiant. M39 is a 5th-magnitude open cluster, and NGC 6826 is a planetary nebula known as the Blinking Planetary. Cygnus lies in the Milky Way and is replete with fascinating objects: the radio source Cygnus A; the X-ray source Cygnus X-1; the brightest dwarf nova, SS Cygni; the Veil Nebula, part of the Cygnus Loop; the North America Nebula; and the Great Rift.
Subjects: Astronomy and Astrophysics.