Cygnus

Cygnus /ˈsɪɡnəs/ is a northern constellation lying on the plane of the Milky Way, deriving its name from the Latinized Greek word for swan. The swan is one of the most recognizable constellations of the northern summer and autumn, it features a prominent asterism known as the Northern Cross (in contrast to the Southern Cross). Cygnus was among the 48 constellations listed by the 2nd century astronomer Ptolemy, and it remains one of the 88 modern constellations. Cygnus contains Deneb, one of the brightest stars in the night sky and one corner of the Summer Triangle, as well as some notable X-ray sources and the giant stellar association of Cygnus OB2. One of the stars of this association, NML Cygni, is one of the largest stars currently known. The constellation is also home to Cygnus X-1, an distant X-ray binary containing a supergiant and unseen massive companion that was the first object widely held to be a black hole. Many star systems in Cygnus have known planets as a result of the Kepler Mission observing one patch of the sky, the patch is the area around Cygnus. ... A very large constellation, Cygnus is bordered by Cepheus to the north and east, Draco to the north and west, Lyra to the west, Vulpecula to the south, Pegasus to the southeast and Lacerta to the east. The three-letter abbreviation for the constellation, as adopted by the IAU in 1922, is 'Cyg'. ... Stars. ... There are several bright stars in Cygnus. Alpha Cygni, called Deneb, is the brightest star in Cygnus. It is a white supergiant star of spectral type A2Iae that varies between magnitudes 1.21 and 1.29, one of the largest and most luminous A-class stars known. It is located about 3200 light-years away. Its traditional name means "tail" and refers to its position in the constellation. Albireo, designated Beta Cygni, is a celebrated binary star among amateur astronomers for its contrasting hues. The primary is an orange-hued giant star of magnitude 3.1 and the secondary is a blue-green hued star of magnitude 5.1. The system is 380 light-years away and is divisible in large binoculars and all amateur telescopes. Gamma Cygni, traditionally named Sadr, is a yellow-tinged supergiant star of magnitude 2.2, 1500 light-years away. Its traditional name means "breast" and refers to its position in the constellation. Delta Cygni is another bright binary star in Cygnus, 171 light-years with a period of 800 years. The primary is a blue-white hued giant star of magnitude 2.9, and the secondary is a star of magnitude 6.6. The two components are divisible in a medium-sized amateur telescope. The fifth star in Cygnus above magnitude 3 is Gienah, designated Epsilon Cygni. It is an orange-hued giant star of magnitude 2.5, 72 light-years from Earth. ... Deep-sky objects. There is an abundance of deep-sky objects, with many open clusters, nebulae of various types and supernova remnants found in Cygnus due to its position on the Milky Way. Some open clusters can be difficult to make out from a rich background of stars. M39 (NGC 7092) is an open cluster 950 light-years from Earth that is visible to the unaided eye under dark skies. It is loose, with about 30 stars arranged over a wide area; their conformation appears triangular. ... Other open clusters in Cygnus include Dolidze 9, Collinder 421, Dolidze 11, and Berkeley 90. ... NGC 6826, the Blinking Planetary Nebula, is a planetary nebula with a magnitude of 8.5, 3200 light-years from Earth. ... The North America Nebula (NGC 7000) is one of the most well-known nebulae in Cygnus, because it is visible to the unaided eye under dark skies, as a bright patch in the Milky Way. ... To the south of Epsilon Cygni is the Veil Nebula (NGC 6960, 6962, 6979, 6992, and 6995), a 5,000-year-old supernova remnant covering approximately 3 degrees of the sky - it is over 50 light-years long. Because of its appearance, it is also called the Cygnus Loop. ... The Northern Coalsack Nebula, also called the Cygnus Rift, is a dark nebula located in the Cygnus Milky Way. ... The Gamma Cygni Nebula (IC 1318) includes both bright and dark nebulae in an area of over 4 degrees. ... Cygnus X is the largest star-forming region in the Solar neighborhood and includes not only some of the brightest and most massive stars known (such as Cygnus OB2-12), but also Cygnus OB2, a massive stellar association classified by some authors as a young globular cluster. More supernovae have been seen in the Fireworks Galaxy (NGC 6946) than in any other galaxy. Cygnus A is the first radio galaxy discovered; at a distance of 730 million light-years from Earth, it is the closest powerful radio galaxy. [Cygnus (constellation). Wikipedia]