Editing Monoceros

{{Short description|Faint constellation on the celestial equator}}
{{About|a faint constellation|other uses}}
{{More citations needed|date=May 2020}}
{{Infobox constellation
| name = Monoceros 
| abbreviation = Mon
| genitive = Monocerotis
| pronounce = {{IPAc-en|m|ə|ˈ|n|ɒ|s|ᵻ|r|ə|s}},<br/>genitive {{IPAc-en|m|ə|ˌ|n|ɒ|s|ᵻ|ˈ|r|oʊ|t|ᵻ|s}}
| symbolism = the [[Unicorn]]
| RA = {{RA|7.15}}
| dec= {{DEC|−5.74}}
| family = [[Orion Family|Orion]]
| quadrant = NQ2
| areatotal = 482
| arearank = 35th
| numbermainstars = 4
| numberbfstars = 32
| numberstarsplanets = 16
| numberbrightstars = 0
| numbernearbystars = 4
| brighteststarname = [[Beta Monocerotis|β Mon]]
| starmagnitude = 3.76
| neareststarname = [[Ross 614]]
| stardistancely = 13.3
| stardistancepc = 4.09
| numbermessierobjects = 1
| meteorshowers = {{Plain list|
* [[December Monocerids]]
* [[Alpha Monocerids]]
}}
| bordering = {{Plain list|
* [[Canis Major]]
* [[Canis Minor]]
* [[Gemini (constellation)|Gemini]]
* [[Hydra (constellation)|Hydra]]
* [[Lepus (constellation)|Lepus]]
* [[Orion (constellation)|Orion]]
* [[Puppis]]
}}
| latmax = [[75th parallel north|75]]
| latmin = [[90th parallel south|90]]
| month = February
| notes=
}}

'''Monoceros''' ([[Greek language|Greek]]: {{Lang|grc|Μονόκερως|italic=no}}, "[[unicorn]]") is a faint [[constellation]] on the [[celestial equator]]. Its definition is attributed to the 17th-century cartographer [[Petrus Plancius]]. It is bordered by [[Orion (constellation)|Orion]] to the west, [[Gemini (constellation)|Gemini]] to the north, [[Canis Major]] to the south, and [[Hydra (constellation)|Hydra]] to the east. Other bordering constellations include [[Canis Minor]], [[Lepus (constellation)|Lepus]], and [[Puppis]].

== Features ==
[[Image:MonocerosCC.jpg|thumb|left|200px|The constellation Monoceros as it can be seen by the naked eye.]]

===Stars===
{{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 Monocerotis]] has a [[visual magnitude]] of 3.93, while for [[Gamma Monocerotis]] it is 3.98.

[[Beta Monocerotis]] is a [[triple star system]]; the three stars form a fixed triangle. The visual magnitudes of the stars are 4.7, 5.2, and 6.1. [[William Herschel]] discovered it in 1781 and called it "one of the most beautiful sights in the heavens".{{Citation needed|date=April 2023}}

[[Epsilon Monocerotis]] is a fixed [[binary star|binary]], with visual magnitudes of 4.5 and 6.5.

[[S Monocerotis]], or 15 Monocerotis, is a bluish white [[variable star]] and is located at the center of [[NGC 2264]]. The variation in its magnitude is slight (4.2–4.6). It has a companion star of visual magnitude 8.

[[V838 Monocerotis]], a variable [[red supergiant]] star, 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, the [[Hubble Space Telescope]] was able to observe a [[light echo]], which illuminated the dust surrounding the star.<ref name="objects">{{cite book |last1=Wilkins |first1=Jamie |url=https://archive.org/details/300astronomicalo0000wilk |title=300 Astronomical Objects: A Visual Reference to the Universe |last2=Dunn |first2=Robert |date=2006 |publisher=Firefly Books |isbn=978-1-55407-175-3 |edition=1st |location=Buffalo, New York |url-access=registration}}</ref>

Monoceros also contains [[Plaskett's Star]], a massive binary system whose combined mass is estimated, per 2008 calculations, to be almost 100 solar masses.<ref name=aaa489_2_713>{{citation | display-authors=1 | last1=Linder | first1=N. | last2=Rauw | first2=G. | last3=Martins | first3=F. | last4=Sana | first4=H. | last5=De Becker | first5=M. | last6=Gosset | first6=E. | title=High-resolution optical spectroscopy of Plaskett's star | journal=Astronomy and Astrophysics | volume=489 | issue=2 | pages=713–723 |date=October 2008 | doi=10.1051/0004-6361:200810003 | bibcode=2008A&A...489..713L |arxiv = 0807.4823 | s2cid=118431215 }}</ref>

Monoceros is the location of the binary system [[Scholz's Star]], host to a [[red dwarf]] primary and [[brown dwarf]] secondary; 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 the [[Oort cloud]].<ref name="Mamajek2015">{{cite journal |last1=Mamajek |first1=Eric E. |last2=Barenfeld |first2=Scott A. |last3=Ivanov |first3=Valentin D. |year=2015 |title=The Closest Known Flyby of a Star to the Solar System |journal=[[The Astrophysical Journal]] |volume=800 |issue=1 |pages=L17 |arxiv=1502.04655 |bibcode=2015ApJ...800L..17M |doi=10.1088/2041-8205/800/1/L17 |s2cid=40618530 |doi-access=free}}</ref>

One of the nearest known [[black hole]]s to the Solar System is in this constellation. The binary star system [[A0620-00]] in 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===
Monoceros contains two super-Earth [[exoplanet]]s in one [[planetary system]]: [[CoRoT-7b]] was detected by the [[CoRoT]] satellite and [[CoRoT-7c]] was detected by the [[High Accuracy Radial Velocity Planet Searcher]] from ground-based telescopes. Until the announcement of [[Kepler-10b]] in 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===
Part of the [[galactic plane]] goes through Monoceros, so background galaxies are concealed by [[interstellar dust]]. Monoceros contains many clusters and nebulae; most notable among them are:
* [[Messier 50]], an [[open cluster]]
* The [[Rosette Nebula]] (NGC 2237, 2238, 2239, and 2246) is a [[diffuse nebula]] in 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 many [[Bok globule]]s in its dark areas. It was independently discovered in the 1880s by [[Lewis Swift]] (early 1880s) and [[Edward Emerson Barnard]] (1883) as they hunted for [[comets]].{{sfn|Levy|2005|p=104}}
* The [[Christmas Tree Cluster]] (NGC 2264) is another open cluster in Monoceros. Named for its resemblance to a [[Christmas 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 star [[V429 Monocerotis]] represents its top.{{sfn|Levy|2005|pp=82-83}}<ref name="NYT-20231219">{{cite news |last=Miller |first=Katrina |title=It's Christmastime in the Cosmos - Astronomers have a long tradition of finding holiday cheer in outer space. |url=https://www.nytimes.com/2023/12/19/science/christmas-stars-galaxies-webb-nasa.html |date=19 December 2023 |work=[[The New York Times]] |url-status=live |archiveurl=https://archive.today/20231219114751/https://www.nytimes.com/2023/12/19/science/christmas-stars-galaxies-webb-nasa.html |archivedate=19 December 2023 |accessdate=19 December 2023 }}</ref>
* The [[Cone 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 several [[Herbig–Haro object]]s, which are small irregularly variable nebulae. They are associated with [[protostar]]s.{{sfn|Levy|2005|p=83}}
* [[NGC 2254]] is 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.{{sfn|Levy|2005|p=85}}
* [[Hubble's Variable Nebula]] (NGC 2261) is a nebula with an approximate magnitude of 10, 2500 light-years from Earth. It is named for [[Edwin Hubble]], and was discovered in 1783 by Herschel. Hubble's Variable Nebula is illuminated by [[R Monocerotis]], a young variable star embedded in the nebula; the star's unique interaction with the material in the nebula makes it both an [[emission nebula]] and a [[reflection nebula]]. One hypothesis regarding their interaction is that the nebula and its illuminating star are a very early stage planetary system.{{sfn|Levy|2005|pp=105-106}}
*[[IC 447]], a reflection nebula.

== History ==

[[File:Sidney Hall - Urania's Mirror - Monoceros, Canis Minor, and Atelier Typographique.jpg|thumb|400px|The constellation Monoceros, from ''[[Urania's Mirror]]'', a set of star charts from 1825. Includes [[Canis Minor]] and the obsolete constellation [[Officina Typographica|Printer's Workshop]]]]

In Western astronomy, Monoceros is a relatively modern constellation, not one of [[Ptolemy]]'s 48 in the ''[[Almagest]]''.<ref name="ley196312">{{Cite magazine
 |last=Ley
 |first=Willy
 |date=December 1963
 |title=The Names of the Constellations
 |department=For Your Information
 |url=https://archive.org/stream/Galaxy_v22n02_1963-12#page/n46/mode/1up
 |magazine=Galaxy Science Fiction
 |pages=90–99
}}</ref> Its first certain appearance was on a globe created by the cartographer [[Petrus Plancius]] in 1612 or 1613<ref>{{Cite web |title=Le costellazioni di Petrus Plancius |url=http://www.atlascoelestis.com/desu%20Plancius.htm |access-date=2023-04-14 |website=Atlas Coelestis}}</ref> and it was later charted by German astronomer [[Jakob Bartsch]] as Unicornu on his star chart of 1624.<ref>
{{cite web
 | title= Jacob Bartsch and seven new constellations
 | last= Ridpath
 | first= Ian
 | url= http://www.ianridpath.com/startales/bartsch.html
}}
</ref>

German astronomers [[Heinrich Wilhelm Olbers]] and [[Ludwig Ideler]]<ref>
{{cite book |last=Ideler |first=Ludwig |url=https://books.google.com/books?id=gxLA4xSXWy8C |title=Untersuchungen über den Ursprung und die Bedeutung der Sternnamen: Ein Beytrag zur Geschichte des gestirnten Himmels |publisher=Berlin |year=1809 |pages=354..355}}
</ref>
indicate (according to [[Star Names: Their Lore and Meaning|Richard Hinckley Allen]]'s allegations) that the constellation may be older, quoting an astrological work<ref>
{{cite book
 | title= Himmels Lauffs Wirkung und natürliche Influenz der Planeten Gestirne und Zeichen aufs Grund der Astronomie
 | publisher= Frankfurt
 | year= 1564
}}
</ref>
from 1564 that mentioned "the second horse between the [[Gemini (constellation)|Twins]] and the [[Cancer (constellation)|Crab]] has many stars, but not very bright"; these references may ultimately be due to the 13th century Scotsman [[Michael Scot]], but refer to a horse and not a unicorn, and its position does not quite match. [[Joseph Scaliger]] (died 1609) is reported{{sfn|Allen|1899|page= 290}} to have found Monoceros on an ancient [[Persian Empire|Persian]] sphere. Astronomer [[Camille Flammarion]] (died 1925) believed that a former constellation, Neper (the "Auger"), occupied the part of that sky now deemed Monoceros and [[Microscopium]], but this is disputed.{{sfn|Allen|1899|page= 290}}

Chinese asterisms Sze Fūh, the Four Great Canals; Kwan Kew; and Wae Choo, the Outer Kitchen, all lay within the boundaries of Monoceros.{{sfn|Allen|1899|page= 290}}

==See also==
* [[Monoceros in Chinese astronomy]]

==References==
{{Reflist}}

===Sources===
* {{citation |title = Deep Sky Objects |last = Levy |first = David H. |publisher = Prometheus Books |year = 2005 |isbn = 1-59102-361-0 |url-access = registration |url = https://archive.org/details/deepskyobjects00davi }}
* {{cite book |last= Ridpath |first= Ian |author2= Wil Tirion |title= Stars and Planets Guide |year= 2007 |publisher= Collins/Princeton University Press |location= London/Princeton |isbn= 978-0-00-725120-9|url=https://archive.org/details/collinsstarsplan0000ridp|url-access=registration}}
*{{cite book
 | last= Allen
 | first= Richard Hinckley
 | title= Star Names – Their lore and meaning / 1899 title: Star Names and Their Meanings
 | url = https://penelope.uchicago.edu/Thayer/E/Gazetteer/Topics/astronomy/_Texts/secondary/ALLSTA/Monoceros*.html
 | publisher= Dover, New York (1963 reprint), originally D.E. Stechert publications
 | year= 1899
 | isbn=((978-0-48-621079-7))
}}

== External links ==
{{Commons}}
* [http://www.eso.org/public/news/eso1039/ "VISTA Reveals the Secret of the Unicorn"] — [[European Southern Observatory]]
* [http://www.allthesky.com/constellations/monoceros/ "The Deep Photographic Guide to the Constellations: Monoceros"], allthesky.com
* "[http://www.dibonsmith.com/mon_con.htm Monoceros"], Dibon-Smith
* "[http://www.ianridpath.com/startales/monoceros.html Monoceros"], Ian Ridpath's Star Tales

{{Stars of Monoceros}}
{{Constellations}}
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{{DEFAULTSORT:Constellation, Monoceros}}
[[Category:Monoceros| ]]
[[Category:Equatorial constellations]]
[[Category:Constellations listed by Petrus Plancius]]
[[Category:Unicorns]]