Cygnus (constellation)
| Constellation | |
 | |
| Abbreviation | Cyg |
|---|---|
| Genitive | Cygni |
, genitive /ˈsɪɡnaɪ/
| symbolism = the Swan or The Northern Cross
| RA = 20.62
| dec= +42.03
| family = Hercules
| quadrant = NQ4
| areatotal = 804
| arearank = 16th
| numbermainstars = 9
| numberbfstars = 84
| numberstarsplanets = 57
| numberbrightstars = 4
| numbernearbystars = 1
| brighteststarname = Deneb (α Cyg)
| starmagnitude = 1.25
| neareststarname = 61 Cyg
| stardistancely = 11.36
| stardistancepc = 3.48
| numbermessierobjects = 2
| meteorshowers = October Cygnids
Kappa Cygnids
| bordering = Cepheus
Draco
Lyra
Vulpecula
Pegasus
Lacerta
| latmax = 90
| latmin = 40
| month = September
| notes=}}
Cygnus (/[invalid input: 'icon']ˈsɪɡnəs/) is a northern constellation lying on the plane of the Milky Way. Its name is the Latinized Hellenic (Greek) word for swan. 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.
Notable features
Stars
There are several bright stars in Cygnus. Alpha Cygni, called Deneb, is the brightest star in Cygnus. It is a blue-white hued supergiant star of magnitude 1.3, 3200 light-years away. The traditional name of Alpha Cygni 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.[1]
There are several other dimmer double and binary stars in Cygnus. Mu Cygni is a binary star with an optical tertiary component. The binary system has a period of 790 years and is 73 light-years from Earth. The primary and secondary, both white stars, are of magnitude 4.8 and 6.2, respectively. The unrelated tertiary component is of magnitude 6.9. Though the tertiary component is divisible in binoculars, the primary and secondary currently require a medium-sized amateur telescope to split, as they will through the year 2020. The two stars will be closest between 2043 and 2050, when they will require a telescope with larger aperture to split. Omicron Cygni is a contrasting double star similar to the brighter Albireo. The components, 30 Cygni and 31 Cygni, are divisible in binoculars. The primary, 31 Cygni, is an orange-hued star of magnitude 3.8, 1400 light-years from Earth. The secondary, 30 Cygni, is a blue-green hued star of magnitude 4.8, 720 light-years from Earth. 31 Cygni itself is a binary star; the tertiary component is a blue star of magnitude 7.0. Psi Cygni is a binary star divisible in small amateur telescopes, with two white components. The primary is of magnitude 5.0 and the secondary is of magnitude 7.5. 61 Cygni is a binary star divisible in large binoculars or a small amateur telescope. It is 11.4 light-years from Earth and has a period of 650 years. Both components are orange-hued dwarf (main sequence) stars; the primary is of magnitude 5.2 and the secondary is of magnitude 6.1. 61 Cygni is significant because Friedrich Wilhelm Bessel determined its parallax in 1838, the first star to have a known parallax. 16 Cygni is a binary star 70 light-years from Earth. Both components are white and of the 6th magnitude.[1]
Cygnus is also home to several variable stars. Chi Cygni is a red giant and the second-brightest Mira variable star at its maximum. Its maximum magnitude is 3.3 and its minimum magnitude is 14; it has a diameter of 300 solar diameters. Chi Cygni has a period of 400 days and is 350 light-years from Earth. P Cygni is a large, unstable blue supergiant that is evolving into a red supergiant. In 1600, it brightened suddenly to 3rd magnitude, though its normal magnitude is approximately 5. It began to brighten gradually in the 1700s and has continued to brighten to the present day; this is part of the process of stellar evolution. W Cygni is a semi-regular variable red giant star, 618 light-years from Earth. It has a maximum magnitude of 5 and a minimum magnitude 8; its period of 130 days.[1]
There are several asterisms in Cygnus. Patchik 56 is one less prominent, a small asterism that measures 3.3 by 2.2 arcminutes. Named for its discoverer, Dana Patchik, an amateur astronomer, it appears in small amateur telescopes as a group of six stars described as resembling a dolphin.[2]
to be in a teardrop shape. More of the nebula's eastern portion is visible with an O III (doubly ionized oxygen) filter. There is an orange star of magnitude 10 nearby and a star of magnitude 9 near the nebula's northwest edge. Further to the northwest, there is a dark rift and another bright patch. The whole nebula measures 15 arcminutes in diameter. Sharpless 2-115 is another emission nebula with a complex pattern of light and dark patches. Two pairs of stars appear in the nebula; it is larger near the southwestern pair. The open cluster Berkeley 90 is embedded in this large nebula, which measures 30 by 20 arcminutes.[2]
Also of note is the Crescent Nebula (NGC 6888), located between Gamma and Eta Cygni, which was formed by the Wolf-Rayet star HD 192163.
The constellation also contains the X-ray source Cygnus X-1, which is now thought to be caused by a black hole accreting matter in a binary star system. The system is located close to the star Eta Cygni on star charts.
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. In the visible spectrum, it appears as an elliptical galaxy in a small cluster. It is classified as an active galaxy because the supermassive black hole at its nucleus is accreting matter, which produces two jets of matter from the poles. The jets' interaction with the interstellar medium creates radio lobes, one source of radio emissions.[3]
Extrasolar planets
Several extrasolar planets including HAT-P-7b, HAT-P-11b, HD 185269 b, HD 187123 b and c, Gliese 777 b and c, and 16 Cygni Bb, have been discovered in Cygnus, but the most notable is Kepler 22b, which is believed to be the first "Earth-twin" planet ever discovered, with an estimated average surface temperature of 73 degrees Fahrenheit. In January 2010 the Kepler Mission announced the discovery of the additional planets Kepler-5b and Kepler-6b, which are expected to be the first of many discovered by the mission, which has a significant part of its field of view in Cygnus. Now with numerous planets discovered by Kepler, Cygnus contains more identified planet-hosting stars than any other constellation, it currently stands at 57.
History and mythology
In Greek mythology, Cygnus has been identified with several different legendary swans. Zeus disguised himself as a swan to seduce Leda, Spartan king Tyndareus's wife, who gave birth to the Gemini, Helen of Troy and Clytemnestra;[1] Orpheus was transformed into a swan after his murder, and was said to have been placed in the sky next to his lyre (Lyra); and the King Cycnus was transformed into a swan.
In Ovid's Metamorphoses, there are three people named Cygnus, all of whom are transformed into swans. Alongside Cycnus, noted above, he mentions a boy from Tempe who commits suicide when Phyllius refuses to give him a tamed bull that he demands, but is transformed into a swan and flies away. He also mentions a son of Neptune who is an invulnerable warrior in the Trojan War who is eventually defeated by Achilles, but Neptune saves him by transforming him into a swan.
Cygnus, together with other avian constellations near the summer solstice, Vultur cadens and Aquila, may be a significant part of the origin of the myth of the Stymphalian Birds, one of The Twelve Labours of Hercules.[4]
Normally, Cygnus is depicted with Delta and Epsilon Cygni as its wings, Deneb as its tail, and Albireo as the tip of its beak.[1]
Equivalents
In Polynesia, Cygnus was often recognized as a separate constellation. In the Society Islands it was called Pirae-tea, in Tonga it was called Tuula-lupe, and in the Tuamotus it was called Fanui-tai. Deneb was also often given a name. In New Zealand it was called Mara-tea, in the Society Islands it was called Pirae-tea or Taurua-i-te-haapa-raa-manu, and in the Tuamotus it was called Fanui-raro. Beta Cygni was named in New Zealand; it was likely called Whetu-kaupo. Gamma Cygni was called Fanui-runga in the Tuamotus.[5]
Musical references
Biosphere's song Cygnus-A, The Mars Volta's song Cygnus....Vismund Cygnus, the Cygnus X-1 duology by Rush, and throughout The Lonely Forest's concept album Nuclear Winter, all include references to Cygnus.
Namesakes
- USS Cygnus (AF-23), a former cargo ship of the United States Navy, is named after the constellation.
See also
- Cygnus Loop
- John Birmingham (astronomer)
- Cygnus Bubble
- Cygnus (Chinese astronomy)
- Kronberger 61
- Orion can be confused with Cygnus by novice observers.
Notes
- ^ a b c d e Ridpath & Tirion 2001, pp. 134–137.
- ^ a b Cite error: The named reference
S&Twas invoked but never defined (see the help page). - ^ Wilkins, Jamie; Dunn, Robert (2006). 300 Astronomical Objects: A Visual Reference to the Universe. Buffalo, New York: Firefly Books. ISBN 978-1-55407-175-3.
- ^ Allen (1963) p. 56.
- ^ Makemson 1941, p. 282.
References
- Allen, R. H., (1963). Star Names: Their Lore and Meaning (Reprint ed.). New York, NY: Dover Publications Inc. ISBN 0-486-21079-0.
{{cite book}}: CS1 maint: extra punctuation (link) CS1 maint: multiple names: authors list (link) - Levy, David H. (2005). Deep Sky Objects. Prometheus Books. ISBN 1-59102-361-0.
{{cite book}}: Invalid|ref=harv(help) - Makemson, Maud Worcester (1941). The Morning Star Rises: an account of Polynesian astronomy. Yale University Press.
{{cite book}}: Invalid|ref=harv(help) - Ridpath, Ian; Tirion, Wil (2001), Stars and Planets Guide, Princeton University Press, ISBN 0-691-08913-2
- Ian Ridpath and Wil Tirion (2007). Stars and Planets Guide, Collins, London. ISBN 978-0-00-725120-9. Princeton University Press, Princeton. ISBN 978-0-691-13556-4.
External links
- The Deep Photographic Guide to the Constellations: Cygnus
- Northern Cygnus Mosaic Pan and Zoom In on deep sky objects in Cygnus.
- The clickable Cygnus
- Star Tales – Cygnus
