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Monoceros

Coordinates:Sky map07h09m00s,−05° 44′ 24″
From Wikipedia, the free encyclopedia
This article is about a faint constellation. For other uses, seeMonoceros (disambiguation).
Monoceros
Constellation
Monoceros
List of stars in Monoceros
AbbreviationMon
GenitiveMonocerotis
Pronunciation/məˈnɒsɪrəs/,
genitive/məˌnɒsɪˈroʊtɪs/
SymbolismtheUnicorn
Right ascension7.15h
Declination−5.74°
QuadrantNQ2
Area482 sq. deg. (35th)
Main stars4
Bayer/Flamsteed
stars		32
Stars withplanets16
Stars brighter than 3.00m0
Stars within 10.00 pc (32.62 ly)4
Brightest starβ Mon(3.76m)
Messier objects1
Meteor showers
Bordering
constellations
Visible at latitudes between +75° and −90°.
Best visible at 21:00 (9 p.m.) during the month ofFebruary.

Monoceros(Greek:Μονόκερως,"unicorn") is a faintconstellationon thecelestial equator.Its definition is attributed to the 17th-century cartographerPetrus Plancius.It is bordered byOrionto the west,Geminito the north,Canis Majorto the south, andHydrato the east. Other bordering constellations includeCanis Minor,Lepus,andPuppis.

Features

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The constellation Monoceros as it can be seen by the naked eye.

Stars

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See also:List of stars in Monoceros

Monoceros contains only a few fourth magnitude stars, making it difficult to see with the naked eye.Alpha Monocerotishas avisual magnitudeof 3.93, while forGamma Monocerotisit is 3.98.

Beta Monocerotisis atriple star system;the three stars form a fixed triangle. The visual magnitudes of the stars are 4.7, 5.2, and 6.1.William Herscheldiscovered it in 1781 and called it "one of the most beautiful sights in the heavens".[citation needed]

Epsilon Monocerotisis a fixedbinary,with visual magnitudes of 4.5 and 6.5.

S Monocerotis,or 15 Monocerotis, is a bluish whitevariable starand is located at the center ofNGC 2264.The variation in its magnitude is slight (4.2–4.6). It has a companion star of visual magnitude 8.

V838 Monocerotis,a variablered supergiantstar, had an outburst starting on January 6, 2002; in February of that year, its brightness increased by a factor of 10,000 in one day. After the outburst was over, theHubble Space Telescopewas able to observe alight echo,which illuminated the dust surrounding the star.[1]

Monoceros also containsPlaskett's Star,a massive binary system whose combined mass is estimated[by whom?]to be almost 100 solar masses.

Monoceros is the location of the binary systemScholz's Star,host to ared dwarfprimary andbrown dwarfsecondary; the system performed a close flypast of the Solar System approximately 70,000 years ago, travelling within 120,000 astronomical units of the Sun within theOort cloud.[2]

One of the nearest knownblack holesto the Solar System is in this constellation. The binary star systemA0620-00in the constellation of Monoceros is at a distance of roughly 3,300 light-years (1,000 parsecs) away. The black hole is estimated to be 6.6 solar masses.

Planets

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Monoceros contains two super-Earthexoplanetsin oneplanetary system:CoRoT-7bwas detected by theCoRoTsatellite andCoRoT-7cwas detected by theHigh Accuracy Radial Velocity Planet Searcherfrom ground-based telescopes. Until the announcement ofKepler-10bin January 2011, CoRoT-7b was the smallest exoplanet to have its diameter measured, at 1.58 times that of the Earth (which would give it a volume 3.95 times Earth's). Both planets in this system were discovered in 2009.

Deep-sky objects

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Part of thegalactic planegoes through Monoceros, so background galaxies are concealed byinterstellar dust.Monoceros contains many clusters and nebulae; most notable among them are:

  • Messier 50,anopen cluster
  • TheRosette Nebula(NGC 2237, 2238, 2239, and 2246) is adiffuse nebulain Monoceros. It has an overall magnitude of 6.0 and is 4900 light-years from Earth. The Rosette Nebula, over 100 light-years in diameter, has an associated star cluster and possesses manyBok globulesin its dark areas. It was independently discovered in the 1880s byLewis Swift(early 1880s) andEdward Emerson Barnard(1883) as they hunted forcomets.[3]
  • TheChristmas Tree Cluster(NGC 2264) is another open cluster in Monoceros. Named for its resemblance to aChristmas tree,it is fairly bright at an overall magnitude of 3.9; it is 2400 light-years from Earth. The variable star S Monocerotis represents the tree's trunk, while the variable starV429 Monocerotisrepresents its top.[4][5]
  • TheCone Nebula(NGC 2264), associated with the Christmas Tree Cluster, is a very dim nebula that contains a dark conic structure. It appears clearly in photographs, but is very elusive in a telescope. The nebula contains severalHerbig–Haro objects,which are small irregularly variable nebulae. They are associated withprotostars.[6]
  • NGC 2254is an open cluster with an overall magnitude of 9.7, 7100 light-years from Earth. It is a Shapley class f and Trumpler class I 2 p cluster, meaning that it appears to be a fairly rich cluster overall, though it has fewer than 50 stars. It appears distinct from the background star field and is very concentrated at its center; its stars range moderately in brightness.[7]
  • Hubble's Variable Nebula(NGC 2261) is a nebula with an approximate magnitude of 10, 2500 light-years from Earth. It is named forEdwin Hubble,and was discovered in 1783 by Herschel. Hubble's Variable Nebula is illuminated byR Monocerotis,a young variable star embedded in the nebula; the star's unique interaction with the material in the nebula makes it both anemission nebulaand areflection nebula.One hypothesis regarding their interaction is that the nebula and its illuminating star are a very early stage planetary system.[8]
  • IC 447,a reflection nebula.

History

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The constellation Monoceros, fromUrania's Mirror,a set of star charts from 1825. IncludesCanis Minorand the obsolete constellationPrinter's Workshop

In Western astronomy, Monoceros is a relatively modern constellation, not one ofPtolemy's 48 in theAlmagest.[9]Its first certain appearance was on a globe created by the cartographerPetrus Planciusin 1612 or 1613[10]and it was later charted by German astronomerJakob Bartschas Unicornu on his star chart of 1624.[11]

German astronomersHeinrich Wilhelm OlbersandLudwig Ideler[12] indicate (according toRichard Hinckley Allen's allegations) that the constellation may be older, quoting an astrological work[13] from 1564 that mentioned "the second horse between theTwinsand theCrabhas many stars, but not very bright "; these references may ultimately be due to the 13th century ScotsmanMichael Scot,but refer to a horse and not a unicorn, and its position does not quite match.Joseph Scaligeris reported[14] to have found Monoceros on an ancientPersiansphere. French astronomerCamille Flammarionbelieved that a former constellation, Neper (the "Auger" ), occupied the area of the sky now home to Monoceros andMicroscopium,but this is disputed.[15]

Chinese asterisms Sze Fūh, the Four Great Canals; Kwan Kew; and Wae Choo, the Outer Kitchen, all lay within the boundaries of Monoceros.[15]

See also

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References

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  1. ^Wilkins, Jamie; Dunn, Robert (2006).300 Astronomical Objects: A Visual Reference to the Universe(1st ed.). Buffalo, New York: Firefly Books.ISBN978-1-55407-175-3.
  2. ^Mamajek, Eric E.; Barenfeld, Scott A.; Ivanov, Valentin D. (2015)."The Closest Known Flyby of a Star to the Solar System".The Astrophysical Journal.800(1): L17.arXiv:1502.04655.Bibcode:2015ApJ...800L..17M.doi:10.1088/2041-8205/800/1/L17.S2CID40618530.
  3. ^Levy 2005,p. 104.
  4. ^Levy 2005,pp. 82–83.
  5. ^Miller, Katrina (19 December 2023)."It's Christmastime in the Cosmos - Astronomers have a long tradition of finding holiday cheer in outer space".The New York Times.Archivedfrom the original on 19 December 2023.Retrieved19 December2023.
  6. ^Levy 2005,p. 83.
  7. ^Levy 2005,p. 85.
  8. ^Levy 2005,pp. 105–106.
  9. ^Ley, Willy (December 1963)."The Names of the Constellations".For Your Information.Galaxy Science Fiction.pp. 90–99.
  10. ^"Le costellazioni di Petrus Plancius".Atlas Coelestis.Retrieved2023-04-14.
  11. ^ Ridpath, Ian."Jacob Bartsch and seven new constellations".
  12. ^ Ideler, Ludwig (1809).Untersuchungen über den Ursprung und die Bedeutung der Sternnamen: Ein Beytrag zur Geschichte des gestirnten Himmels.Berlin. pp. 354..355.
  13. ^ Himmels Lauffs Wirkung und natürliche Influenz der Planeten Gestirne und Zeichen aufs Grund der Astronomie.Frankfurt. 1564.
  14. ^ Allen, Richard Hinckley (1899).Star Names – Their lore and meaning.Dover. p. 290.
  15. ^abAllen, p. 290.

Sources

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