Ursa Major

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This article is about the constellation. For other uses, see Ursa Major (disambiguation).
Ursa Major
Constellation
Ursa Major
Abbreviation UMa
Genitive Ursae Majoris
Pronunciation /ˈɜrsə ˈmər/,
genitive /ˌɜrs məˈɒrɨs/
Symbolism the Great Bear
Right ascension 10.67
Declination +55.38
Family Ursa Major
Quadrant NQ2
Area 1280 sq. deg. (3rd)
Main stars 7, 20
Bayer/Flamsteed
stars
93
Stars with planets 21
Stars brighter than 3.00m 7
Stars within 10.00 pc (32.62 ly) 8
Brightest star ε UMa (Alioth) (1.76m)
Nearest star Lalande 21185
(8.31 ly, 2.55 pc)
Messier objects 7
Meteor showers Alpha Ursa Majorids
Leonids-Ursids
Bordering
constellations
Draco
Camelopardalis
Lynx
Leo Minor
Leo
Coma Berenices
Canes Venatici
Boötes
Visible at latitudes between +90° and −30°.
Best visible at 21:00 (9 p.m.) during the month of April.
Big dipper.triddle.jpg
The Big Dipper or Plough.

Ursa Major (Latin: "Larger Bear"; also known as the Great Bear and Charles' Wain[1]) is a constellation visible throughout the year in most of the northern hemisphere. It can be seen best in the month of April. It is dominated by the widely recognized asterism known as the Big Dipper or the Plough, which is a useful pointer towards the north, and it has mythological significance in numerous world cultures.

Asterisms[edit]

Main article: Big Dipper

The seven brightest stars of Ursa Major form the asterism known as the Big Dipper in the USA and Canada, the Plough in the United Kingdom, the Großer Wagen in Germany & Austria and the Saptarshi in India.

Six of these seven stars are of 2nd magnitude; just the central star is of 3rd magnitude.

Another asterism known as the "Three Leaps of Gazelle"[2] is recognized in Arab culture, a series of three pairs of stars:

These stars are found along the southwest border of the constellation.

Notable features[edit]

The constellation Ursa Major as it can be seen by the unaided eye.

Stars[edit]

The "Big Dipper" (or "Plough") asterism within Ursa Major is made up of seven bright stars that together comprise one of the best-known patterns in the sky, while also forming the hindquarters and tail of the Great Bear. Starting with the "ladle" portion of the dipper and extending clockwise through the handle, these stars are the following:

  • α Ursae Majoris, known by the Arabic name Dubhe ("the bear"), which at a magnitude of 1.79 is the 35th brightest star in the sky and the second brightest of Ursa Major.
  • β Ursae Majoris, called Merak ("the loins of the bear"), with a magnitude of 2.37.
  • γ Ursae Majoris, or Phecda ("thigh"), with a magnitude of 2.44.
  • δ Ursae Majoris, or Megrez, meaning "root of the tail," an appropriate name given its location as the intersection of the body and tail of the bear (or the ladle and handle of the dipper).
  • ε Ursae Majoris, known as Alioth, a name which refers not to a bear but to a "black horse," the name corrupted from the original and mis-assigned to the similarly named Alcor, the naked-eye binary companion of Mizar.[3] Alioth is the brightest star of Ursa Major and the 33rd brightest in the sky, with a magnitude of 1.76. It is also the brightest of the "peculiar A (Ap) stars," magnetic stars whose chemical elements are either depleted or enhanced, and appear to change as the star rotates.[4]
  • ζ Ursae Majoris, Mizar, the second star in from the end of the handle of the Big Dipper, and the constellation's fourth brightest star. Mizar, which means "girdle," forms a famous double star, with its optical companion Alcor (80 Ursae Majoris), the two of which were termed the "horse and rider" by the Arabs. The ability to resolve the two stars with the naked eye is often quoted as a test of eyesight, although even people with quite poor eyesight can see the two stars.
  • η Ursae Majoris, known as either Alkaid or Benetnash, both meaning the "end of the tail." With a magnitude of 1.85, Alkaid is the third-brightest star of Ursa Major.[5][6]

Except for Dubhe and Alkaid (Eta Ursae Majoris), the stars of the Big Dipper all have proper motions heading toward a common point in Sagittarius. A few other such stars have been identified, and together they are called the Ursa Major Moving Group.

The stars Merak (β Ursae Majoris) and Dubhe (α Ursae Majoris) are known as the "pointer stars" because they are helpful for finding Polaris, also known as the North Star or Pole Star. By visually tracing a line from Merak through Dubhe and continuing, one's eye will land on Polaris, accurately indicating true north.

W Ursae Majoris is the prototype of a class of contact binary variable stars, and ranges between 7.75m and 8.48m.

47 Ursae Majoris is a Sun-like star with a three-planet system.[7] 47 Ursae Majoris b, discovered in 1996, orbits every 1078 days and is 2.53 times the mass of Jupiter.[8] 47 Ursae Majoris c, discovered in 2001, orbits every 2391 days and is 0.54 times the mass of Jupiter.[9] 47 Ursae Majoris d, discovered in 2010, has an uncertain period, lying between 8907 and 19097 days; it is 1.64 times the mass of Jupiter.[10] The star is of magnitude 5.0 and is approximately 46 light-years from Earth.[7]

The star TYC 3429-697-1 has been recognized as the state star of Delaware, and is informally known as the Delaware Diamond.[11]

Deep-sky objects[edit]

Several bright galaxies are found in Ursa Major, including the pair Messier 81 (one of the brightest galaxies in the sky) and Messier 82 above the bear's head, and Pinwheel Galaxy (M101), a spiral northeast of η Ursae Majoris. The spiral galaxies Messier 108 and Messier 109 are also found in this constellation. The bright planetary nebula Owl Nebula (M97) can be found along the bottom of the bowl of the Big Dipper.

M81 is a nearly face-on spiral galaxy 11.8 million light-years from Earth. Like most spiral galaxies, it has a core made up of old stars, with arms filled with young stars and nebulae. Along with M82, it is a part of the galaxy cluster closest to the Local Group.

M82 is a galaxy that is interacting gravitationally with M81. It is the brightest infrared galaxy in the sky.[12] SN 2014J, an apparent Type Ia supernova, was observed in M82 on 21 January 2014.[13]

M97, also called the Owl Nebula, is a planetary nebula 1,630 light-years from Earth; it has a magnitude of approximately 10. It was discovered in 1781 by Pierre Méchain.[14]

M101, also called the Pinwheel Galaxy, is a face-on spiral galaxy located 25 million light-years from Earth. It was discovered by Pierre Méchain in 1781. Its spiral arms have regions with extensive star formation and have strong ultraviolet emissions.[12] It has an integrated magnitude of 7.5, making it visible in both binoculars and telescopes, but not to the naked eye.[15]

NGC 2787 is a lenticular galaxy at a distance of 24 million light-years. Unlike most lenticular galaxies, NGC 2787 has a bar at its center. It also has a halo of globular clusters, indicating its age and relative stability.[12]

NGC 3079 is a starburst spiral galaxy located 52 million light-years from Earth. It has a horseshoe-shaped structure at its center that indicates the presence of a supermassive black hole. The structure itself is formed by superwinds from the black hole.[12]

NGC 3310 is another starburst spiral galaxy located 50 million light-years from Earth. Its bright white color is caused by its higher than usual rate of star formation, which began 100 million years ago after a merger. Studies of this and other starburst galaxies have shown that their starburst phase can last for hundreds of millions of years, far longer than was previously assumed.[12]

NGC 4013 is an edge-on spiral galaxy located 55 million light-years from Earth. It has a prominent dust lane and has several visible star forming regions.[12]

I Zwicky 18 is a young dwarf galaxy at a distance of 45 million light-years. The youngest known galaxy in the visible universe, I Zwicky 18 is about 4 million years old, about one-thousandth the age of the Solar System. It is filled with star forming regions which are creating many hot, young, blue stars at a very high rate.[12]

The Hubble Deep Field is located to the northeast of δ Ursae Majoris.

Meteor showers[edit]

The Kappa Ursae Majorids are a newly discovered meteor shower, peaking between November 1 and November 10.[16]

Extrasolar planets[edit]

HD 80606, a sun-like star in a binary system, orbits a common center of gravity with its partner, HD 80607; the two are separated by 1,200 AU on average. Research conducted in 2003 indicates that its sole planet, HD 80606 b is a future hot Jupiter, modeled to have evolved in a perpendicular orbit around 5 AU from its sun. The 4-Jupiter mass planet is projected to eventually move into a circular, more aligned orbit via the Kozai mechanism. However, it is currently on an incredibly eccentric orbit that ranges from approximately one astronomical unit at its apoapsis and six stellar radii at periapsis.[17]

History[edit]

Ursa Major has been reconstructed as an Indo-European constellation.[18] It was one of the 48 constellations listed by the 2nd century AD astronomer Ptolemy. It is mentioned by such poets as Homer, Spenser, Shakespeare and Tennyson. The Finnish epic Kalevala mentions it, Vincent van Gogh painted it, and Federico Garcia Lorca mentions in his poem "Song for the Moon" written August 1920. In 2009, the American rock band Third Eye Blind named their fourth album, Ursa Major, after the constellation.

Locating directions[edit]

It is said that we can find our directions by ursa major we can find pole star and then go following it to go to north

Mythology[edit]

The constellation of Ursa Major has been seen as a bear by many distinct civilizations.[19] This may stem from a common oral tradition stretching back more than 13,000 years.[20] Using statistical and phylogenetic tools, Julien d'Huy reconstructs the following Palaeolithic state of the story: "There is an animal that is a horned herbivore, especially an elk. One human pursues this ungulate. The hunt locates or get to the sky. The animal is alive when it is transformed into a constellation. It forms the Big Dipper".[21]

In Burmese, Pucwan Tārā (pronounced "bazun taja") is the name of a constellation comprising stars from the head and forelegs of Ursa Major; pucwan is a general term for a crustacean, such as prawn, shrimp, crab, lobster, etc.

In Roman mythology, Jupiter (the king of the gods) lusts after a young woman named Callisto, a nymph of Diana. Juno, Jupiter' jealous wife, transforms the beautiful Callisto into a bear. Callisto, while in bear form, later encounters her son Arcas. Arcas almost shoots the bear, but to avert the tragedy, Zeus turns them into bears and puts them in the sky, forming Ursa Major and Ursa Minor. Callisto is Ursa Major and her son, Arcas, is Ursa Minor. In ancient times the name of the constellation was Helike, ("turning"), because it turns around the Pole. In Book Two of Lucan it is called Parrhasian Helice, since Callisto came from Parrhasia in Arcadia, where the story is set.[22] The Odyssey notes that it is the sole constellation that never sinks below the horizon and "bathes in the Ocean's waves", so it is used as a celestial reference point for navigation.[23] It is also referred to as the "Wain".[24]

One of the few star groups mentioned in the Bible (Job 9:9; 38:32; — Orion and the Pleiades being others), Ursa Major was also pictured as a bear by the Jewish peoples. ("The Bear" was translated as "Arcturus" in the Vulgate and it persisted in the KJV.)

In Finnish language, the asterism is sometimes called with its old Finnish name, Otava. The meaning of the name has been almost forgotten in Modern Finnish; it means a salmon weir.

The Iroquois Native Americans interpreted Alioth, Mizar, and Alkaid as three hunters pursuing the Great Bear. According to one version of their myth, the first hunter (Alioth) is carrying a bow and arrow to strike down the bear. The second hunter (Mizar) carries a large pot — the star Alcor — on his shoulder in which to cook the bear while the third hunter (Alkaid) hauls a pile of firewood to light a fire beneath the pot.

The Wampanoag people(Algonquian) Native Americans referred to Ursa Major as "maske", meaning "bear" according to Thomas Morton in The New England Canaan.[25]

In Hinduism, Ursa Major is known as Saptarshi, each of the stars representing one of the Saptarshis or Seven Sages viz. Bhrigu, Atri, Angirasa, Vasishta, Pulastya, Pulalaha and Kratu. The fact that the two front stars of the constellations point to the pole star is explained as the boon given to the boy sage Dhruva by Lord Vishnu.

In Javanese, as known as "Bintang Kartika". This name comes from Sanskrit which refers "krttikã" the same star cluster. In ancient Javanese this brightest seven stars are known as Lintang Wuluh, literally means "seven stars". This star clusters so popular because its emergence into the start time marker for planting.

In South Korea, the constellation is referred to as "the seven stars of the north". In the related myth, a widow with seven sons found comfort with a widower, but to get to his house required crossing a stream. The seven sons, sympathetic to their mother, placed stepping stones in the river. Their mother, not knowing who put the stones in place, blessed them and, when they died, they became the constellation.

In Shinto, the 7 largest stars of Ursa Major belong to Amenominakanushi, the oldest and most powerful of all kami.

In Theosophy, it is believed the Seven Stars of the Pleiades focus the spiritual energy of the Seven Rays from the Galactic Logos to the Seven Stars of the Great Bear, then to Sirius, then to the Sun, then to the god of Earth (Sanat Kumara), and finally through the seven Masters of the Seven Rays to the human race.[26]

The Lakota people call the constellation Wičhákhiyuhapi, or "Great Bear"."[27]

Graphic visualisation[edit]

In European star charts, the constellation was visualized with the 'square' of the Big Dipper forming the bear's body and the chain of stars forming the Dipper's "handle" as a long tail. However, bears do not have long tails, and Jewish astronomers considered Alioth, Mizar, and Alkaid instead to be either three cubs following their mother, and the Native Americans as three hunters.

Noted children's book author H. A. Rey, in his 1952 book The Stars: A New Way to See Them, (ISBN 0-395-24830-2) instead had the "bear" image of the constellation, much as Johannes Hevelius had done (as far as the figure of the bear facing "left"), oriented with Alkaid as the tip of the bear's nose, and the "handle" of the Big Dipper part of the constellation forming the outline of the top of the bear's head and neck, rearwards to the shoulder. Because of Rey's book, many amateur astronomers[who?] have come to accept Rey's star chart interpretation of Ursa Major,[citation needed] dropping the idea of the Big Dipper's "handle" as being the hind end of the bear, with a non-natural "tail" extending rearwards.

Ursa Major is also pictured as the Starry Plough, the Irish Flag of Labour, adopted by James Connolly's Irish Citizen Army in 1916, which shows the constellation on a blue background, and on the state flag of Alaska.

See also[edit]

References[edit]

Citations
  1. ^ Wikisource-logo.svg "Charles's Wain". The American Cyclopædia. 1879. 
  2. ^ "Ursa Major & Ursa Minor". Winter Sky Tour. 
  3. ^ Prof. Jim Kaler, Stars: "Alioth" (9/16/2009), http://stars.astro.illinois.edu/sow/alioth.html.
  4. ^ See Kaler.
  5. ^ See generally Mark R. Chartrand III (1983) Skyguide: A Field Guide for Amateur Astronomers, p. 195 (ISBN 0-307-13667-1).
  6. ^ Ridpath, at p. 136.
  7. ^ a b Levy 2005, p. 67.
  8. ^ "Planet 47 Uma b". The Extrasolar Planet Encyclopaedia. Paris Observatory. 11 July 2012. Retrieved 15 July 2012. 
  9. ^ "Planet 47 Uma c". The Extrasolar Planet Encyclopaedia. Paris Observatory. 11 July 2012. Retrieved 15 July 2012. 
  10. ^ "Planet 47 Uma d". The Extrasolar Planet Encyclopaedia. Paris Observatory. 11 July 2012. Retrieved 15 July 2012. 
  11. ^ Delaware Facts and Symbols - State Miscellaneous Symbols, delaware.gov. Accessed on line June 17, 2008.
  12. ^ a b c d e f g 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. 
  13. ^ http://www.astronomerstelegram.org/?read=5786
  14. ^ Levy 2005, pp. 129–130.
  15. ^ Seronik, Gary (July 2012). "M101: A Bear of a Galaxy". Sky & Telescope 124 (1). 
  16. ^ Jenniskens, Peter (September 2012). "Mapping Meteoroid Orbits: New Meteor Showers Discovered". Sky & Telescope: 23. 
  17. ^ Laughlin, Greg (May 2013). "How Worlds Get Out of Whack". Sky and Telescope: 29. 
  18. ^ Mallory, J.P.; Adams, D.Q. (August 2006). "Chapter 8.5: The Physical Landscape of the Proto-Indo-Europeans". Oxford Introduction to Proto-Indo-European and the Proto-Indo-European World. Oxford, GBR: Oxford University Press. p. 131. ISBN 9780199287918. OCLC 139999117. "The most solidly ‘reconstructed’ Indo-European constellation is Ursa Major, which is designated as ‘The Bear’ (Chapter 9) in Greek and Sanskrit (Latin may be a borrowing here), although even the latter identification has been challenged." 
  19. ^ Gibbon, William B. (1964). "Asiatic parallels in North American star lore: Ursa Major". Journal of American Folklore 77 (305): 236–250. doi:10.2307/537746. 
  20. ^ Bradley E Schaefer, The Origin of the Greek Constellations: Was the Great Bear constellation named before hunter nomads first reached the Americas more than 13,000 years ago?, Scientific American, November 2006, reviewed at The Origin of the Greek Constellations; Yuri Berezkin, The cosmic hunt: variants of a Siberian – North-American myth. Folklore, 31, 2005: 79-100.
  21. ^ d'Huy Julien, Un ours dans les étoiles: recherche phylogénétique sur un mythe préhistorique, Préhistoire du sud-ouest, 20 (1), 2012: 91-106; A Cosmic Hunt in the Berber sky : a phylogenetic reconstruction of Palaeolithic mythology, Les Cahiers de l'AARS, 15, 2012.
  22. ^ Hamilton, Edith Mythology New American Library, New York, 1942, chapter 21 (Callisto).
  23. ^ Homer, Odyssey, book 5, 273
  24. ^ Mandelbaum, Allen; translator (1990). The Odyssey of Homer. New York City: Bantam Dell. ISBN 0-553-21399-7. 
  25. ^ https://openlibrary.org/books/OL7142058M/The_new_English_Canaan_of_Thomas_Morton
  26. ^ Baker, Dr. Douglas The Seven Rays:Key to the Mysteries 1952
  27. ^ Ullrich, Jan, ed. (2011). New Lakota Dictionary (2nd ed.). Bloomington, IN: Lakota Language Consortium. p. 956. ISBN 978-0-9761082-9-0. LCCN 2008922508. 
Bibliography

Further reading[edit]

External links[edit]

Coordinates: Sky map 10.67h 00m 00s, +55.38° 00′ 00″