List of stars in Perseus
|Pronunciation||// or //;
|Right ascension||3 h|
|Area||615 sq. deg. (24th)|
|Main stars||6, 22|
|Stars with planets||7|
|Stars brighter than 3.00m||5|
|Stars within 10.00 pc (32.62 ly)||0|
|Brightest star||α Per (Mirfak) (1.79m)|
|Nearest star||GJ 3182
(33.62 ly, 10.31 pc)
Perseus is a constellation in the northern sky, named after the Greek hero Perseus. It was one of the 48 constellations listed by the 2nd century astronomer Ptolemy, and remains one of the 88 modern constellations defined by the International Astronomical Union. Located in the northern celestial hemisphere, it lies nearby several other constellations from the legend of Perseus, including Andromeda (the maiden he rescued), Cetus (the sea monster he slew) and Cepheus and Cassiopeia (Andromeda's royal parents).
Its brightest star is the yellow-white supergiant Alpha Persei, or Mirfak, which shines with a magnitude of 1.79. The most notable star, however, is the famous variable star Algol (Beta Persei), linked with ominous legends on account of its apparent variability. GK Persei was a nova which brightened to magnitude 0.2 in 1901, making it briefly one of the brightest stars in the sky. The constellation also gives its name to the Perseus Cluster (Abell 426), a massive galaxy cluster located 250 million light-years from Earth. The constellation also hosts the annual Perseids meteor shower, one of the most prominent.
History and mythology 
The Greek constellation may be an adaptation of the Babylonian constellation known as the Old Man (MUL.SHU.GI) which is associated with East (as a cardinal direction) in the MUL.APIN, an astronomical compilation dating to around 1000 BCE.
In non-Western astronomy 
Four Chinese constellations existed in the area of the sky now assigned to Perseus. T'ien-tchouen, translated as the "Celestial Boat", was the third paranatellon of the third house of the White Tiger of the West. It represented the boats that Chinese people were reminded to build in case of a catastrophic flood season. Tsi-choui, translated as the "Swollen Waters", was the fourth paranatellon of the third house of the White Tiger of the West. It represented the potential of unusually high floods during the beginning of the flood season, which commenced at the end of August and beginning of September. Ta-ling, translated as the "Great Trench", was the fifth paranatellon of the third house of the White Tiger of the West. It represented the trenches where criminals executed en masse in August were interred. The pile of corpses prior to their interment was represented by Tsi-chi (Algol), the sixth paranatellon of the third house of the White Tiger.
The Double Cluster, h and χ Persei, had special significance in Chinese astronomy. Known as Hsi and Ho, the two clusters represented two astronomers who failed to predict a total solar eclipse and were beheaded thereafter.
In Polynesia, Perseus was not commonly recognized as a separate constellation; the only people that named it were the people of the Society Islands, who called it Faa-iti, meaning "Little Valley". Algol may have been named Matohi by the Maori people, but the evidence for this identification is disputed. Matohi ("Split") occasionally came into conflict with Tangaroa-whakapau over which of them should appear in the sky, the outcome affecting the tides. It matches the Maori description of a blue-white star near Aldebaran but does not disappear as the myth would indicate.
Perseus is bordered by Aries and Taurus to the south, Auriga to the east, Camelopardalis and Cassiopea to the north, and Andromeda and Triangulum to the west. Covering 615 square degrees, it ranks twenty-fourth of the 88 constellations in size. It appears prominently in the northern sky during the Northern Hemisphere's spring. The constellation boundaries, as set by Eugène Delporte in 1930, are defined by a polygon of 26 sides. In the equatorial coordinate system, the right ascension coordinates of these borders lie between 01h 29.1m and 04h 51.2m, while the declination coordinates are between 30.92° and 59.11°. The constellation's three-letter abbreviation, as adopted by the International Astronomical Union in 1922, is "Per".
Notable features 
Algol (from the Arabic Ra's al-Ghul, which means The Demon's Head), also known by its Bayer designation Beta Persei, is the best-known star in Perseus. Representing the eye of the gorgon Medusa, it was also called Rosh ha Satan ("Satan's Head") by the Hebrew people, who saw Algol as representing Lilith. It is 92.8 light-years from Earth and varies in magnitude from a minimum of 3.5 to a maximum of 2.3 with a period of 2.867 days. It is a triple star with the brightest component being of spectral type B8V, the secondary component being K0IV, and the tertiary component being A7. The star system is the prototype of a whole group of eclipsing binary stars named Algol variables. Another Algol variable in Perseus is AG Persei, whose primary component is a B-type main sequence star with an apparent magnitude of 6.69.
Alpha Persei, also known as Mirfak (Arabic for elbow) or Algenib, is the brightest star of this constellation with an apparent brightness of 1.79. A supergiant of spectral type F5Ib located around 590 light-years away from our solar system, Mirfak has a luminosity of 5,000 times the sun and diameter of 42 times that of our sun. It is the brightest member of the Alpha Persei Cluster (also known as Melotte 20 and Collinder 39), which is an open cluster containing many luminous stars. Neighbouring bright stars which are also members include the Be stars Delta (magnitude 3.0), Psi (4.3), and 48 Persei (4.0); the Beta Cephei variable Epsilon Persei (2.9); and the stars 29 (5.2), 30 (5.5), and 34 Persei (4.7).
Zeta Persei, or Atik, at magnitude 2.86 is the third brightest star in the constellation. Lying around 750 light years distant, it is a blue-white supergiant with around 26–27 times the radius of the sun and 47,000 times its luminosity. It is the brightest star from Earth of another moving group of bright blue-white giant and supergiant stars, the Perseus OB2 Association or Zeta Persei Association. An interesting member is X Persei, a double star with one component being in between an O-type giant and a B-type main sequence star, and the other component being a neutron star. With an apparent magnitude of 6.72, it is too dim to seen even on the best nights. The system is an X-ray source and the primary star appears to be suffering from substantial mass loss. Once thought to be a member, Omicron Persei is a multiple star system with a combined visual magnitude of 3.85. It is composed of two blue-white stars – a giant of spectral class B1.5 and main sequence star of B3 which orbit around each other every 4.5 days. They are so close to each other that they are distorted into egg-shapes. The system has a third star about which little is known. At an estimated distance of 1475 light years, the system is thought to lie too far to belong to the Zeta Persei group.
Another X-ray binary in Perseus is GRO J0422+32. In this system, one component is likely a black hole, while the other component is a red dwarf star. If the system does indeed contain a black hole, it would be the smallest black hole ever recorded as of 2003. The system is an X-ray nova, meaning that it it experiences periodic outbursts in the X-ray band of the spectrum.
Xi Persei, traditionally known as Menkhib, is one of the hottest bright stars in the sky, a blue giant of spectral type O7III. It is also one of the more massive stars, with a mass between 26 and 32 solar masses.
The Double Cluster contains three very large stars: S, RS, and SU Persei. All three are semiregular pulsating M-type supergiants with radii of above 700 solar radii. The stars are not visible to the naked eye, with the brightest (SU Persei) only being of magnitude 7.9, visible through binoculars. The primary component of the binary star system AX Persei is another star in an advanced phase of stellar evolution, in this case a red giant. The red giant is transferring material onto an accretion disc around a smaller star. The star system is a symbiotic binary, but is unusual in the fact that the secondary star is not a white dwarf, but rather an A-type star. The system is also one of the few eclipsing binary symbiotic binaries.
DY Persei is a variable star that is the prototype of DY Persei variables, which are carbon-rich R Coronae Borealis variables that also exhibit the variability of asymptotic giant branch stars. DY Persei itself is a carbon star that is too dim to see even through binoculars, with an apparent magnitude of 10.6.
GK Persei, also known as Nova Persei 1901, is a bright nova which appeared halfway between Algol and Delta Persei. Discovered on February 21, 1901 by Scottish amateur astronomer Thomas David Anderson, it peaked at magnitude 0.2, almost as bright as Capella and Vega. It faded to second magnitude a week later, and then fourth magnitude in two weeks, before oscillating between fourth and sixth magnitudes every four days for several weeks. It faded to 13th magnitude around 30 years after its peak brightness.
Seven stars have been found to have planetary systems. V718 Persei is a young star in the young open cluster IC 348 that appears to be periodically eclipsed by a giant planet every 4.7 years.. This has been inferred to be an object with a maximum mass of 6 times that of Jupiter and an orbital separation of 3.3 Astronomical Units.
Deep-sky objects 
The Double Cluster is two open clusters (NGC 869 and NGC 884), visible in binoculars and small telescopes. They are sometimes known as h and Chi (χ) Persei, respectively. Both lie at distances of more than 7,000 ly and are separated by several hundred light-years. The cluster was first recorded during the reign of the Chinese king Tsung-K'ang, who reigned during the Hsia Dynasty (2858–2146 BCE). Both clusters are of approximately 4th magnitude and 0.5 degrees in diameter. Both are Trumpler class I 3 r clusters, though NGC 869 is a Shapley class f and NGC 884 is a Shapley class e cluster. These classifications indicate that they are both quite rich; NGC 869 is the richer of the pair. Both clusters are distinct from their star field and are clearly concentrated at their centers. The constituent stars, numbering over 100 in each cluster, range widely in brightness. M34 is an open cluster with an apparent brightness of magnitude 5.5, lying at a distance of approximately 1,500 ly (470 pc) and consisting of about 100 stars that are scattered over an area larger than that of the full moon. M34 can be resolved even with good eyesight but is best viewed using a telescope at low magnifications. IC 348 is a somewhat young open cluster that still contains its nebulosity. It is located at approximately 1,027 ly (315 pc) away, is about 2 million years old, and contains many stars with circumstellar disks. Many brown dwarfs have been discovered in this cluster due to its age.
There are many nebulae in Perseus. M76 is a planetary nebula, also called the Little Dumbbell Nebula. It appears two arc-seconds by one arc-second across and has an apparent brightness of magnitude 10.1. NGC 1499, also known as the California Nebula, is an emission nebula, discovered in 1884–85 by the American astronomer Edward E. Barnard. It is a great target for astrophotographers. Due to its low surface brightness, it is a very difficult object when observed visually. NGC 1333 is a reflection nebula and the location of star formation. Perseus also contains a giant molecular cloud, named Perseus molecular cloud; it belongs to the Orion Spur and is well known for its low-star formation.
Perseus contains a few notable galaxies. NGC 1260 is either a lenticular or tightly-wound spiral galaxy about 76.7 megaparsecs distant from Earth that contained the second brightest known object in the universe, SN 2006gy. NGC 1023 is a barred spiral galaxy of magnitude 10.35 around 11.6 megaparsecs distant, and is the principle member of the NGC 1023 group of galaxies, and is possibly interacting with another galaxy. The constellation also contains an interesting galaxy cluster; the Perseus Cluster (Abell 426) is a massive galaxy cluster located 250 million light-years from Earth; at a redshift of 0.0179, it is the closest major cluster to Earth. NGC 1275, a component of the cluster, is a Seyfert galaxy containing an active nucleus that produces massive bubbles which surround the galaxy with its jets of material. The Perseus Cluster also has sound waves traveling through it, caused by these bubbles, with notes of approximately B flat 57 octaves below middle C. NGC 1275, another member of the Perseus Cluster, is a cD galaxy that has undergone many mergers throughout its existence, as evidenced by the "high velocity system" surrounding it (the remnants of a smaller galaxy). Its active nucleus is a strong source of radio waves.
Meteor showers 
The Perseids are a prominent annual meteor shower that radiate from Perseus in late summer, visible from mid-July and peaking in activity being between August 9 and 14 each year. Associated with the comet Swift-Tuttle, they have been observed for about 2000 years.
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- "NAME ALGOL B – Star in double system". SIMBAD. Retrieved 18 February 2013.
- "NAME ALGOL C – Star in double system". SIMBAD. Retrieved 18 February 2013.
- "* AG Per – Eclipsing binary of Algol type (detached)". SIMBAD. Retrieved 15 February 2013.
- "V* alf Per – Variable Star". SIMBAD. Retrieved 31 January 2013.
- "* del Per – Be star". SIMBAD. Retrieved 31 January 2013.
- "* psi Per – Be star". SIMBAD. Retrieved 31 January 2013.
- "* c Per – Be star". SIMBAD. Retrieved 31 January 2013.
- "V* eps Per – Variable Star of beta Cep type". SIMBAD. Retrieved 31 January 2013.
- "* 29 Per – Star". SIMBAD. Retrieved 31 January 2013.
- "* 30 Per – Star". SIMBAD. Retrieved 31 January 2013.
- "* 34 Per – Star". SIMBAD. Retrieved 31 January 2013.
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- "NAME Menkhib – Star". SIMBAD. Retrieved 16 February 2013.
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- "V* S Per – Semi-regular pulsating star". SIMBAD. Retrieved 13 February 2013.
- "V* RS Per – Semi-regular pulsating star". SIMBAD. Retrieved 13 February 2013.
- "V* SU Per – Semi-regular pulsating star". SIMBAD. Retrieved 13 February 2013.
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- "V* AX Per – Symbiotic star". SIMBAD. Retrieved 15 February 2013.
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- "Little Dumbbell Nebula (M76, NGC 650?51)". The Encyclopedia of Astronomy and Astrophysics. 2001. doi:10.1888/0333750888/5314. ISBN 0333750888.
- "NGC 1499 – HII (ionized) region". SIMBAD. Retrieved 19 May 2013.
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- "NGC 1333 – Reflection Nebula". SIMBAD. Retrieved 19 May 2013.
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- "NASA/IPAC Extragalactic Database". Results for NGC 1260. Retrieved 30 March 2013.
- "NASA/IPAC Extragalactic Database". Results for NGC 1023. Retrieved 30 March 2013.
- "NGC 1023 – Interacting galaxies". SIMBAD. Retrieved 30 March 2013.
- "NASA/IPAC Extragalactic Database". Results for Perseus+CLUSTER. Retrieved 19 May 2013.
- Wilkins, Jamie; Dunn, Robert (2006). 300 Astronomical Objects: A Visual Reference to the Universe (1st ed.). Buffalo, New York: Firefly Books. ISBN 978-1-55407-175-3.
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Cited texts 
- Levy, David H. (2005), Deep Sky Objects, Prometheus Books, ISBN 1-59102-361-0
- Makemson, Maud Worcester (1941), The Morning Star Rises: An Account of Polynesian Astronomy, Yale University Press
- Motz, Lloyd; Nathanson, Carol (1991), The Constellations: An Enthusiast's Guide to the Night Sky, London, United Kingdom: Aurum Press, ISBN 978-1-85410-088-7
- Staal, Julius D.W. (1988), The New Patterns in the Sky: Myths and Legends of the Stars, McDonald and Woodward, ISBN 9780939923045
Further reading 
- 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.
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