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{{Short description|Faint constellation on the celestial equator}}
{{Short description|Faint constellation on the celestial equator}}
{{About|a faint constellation|other uses}}
{{About|a faint constellation|other uses}}

{{More citations needed|date=May 2020}}
{{More citations needed|date=May 2020}}
{{Infobox constellation
{{Infobox constellation
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| abbreviation = Mon
| abbreviation = Mon
| genitive = Monocerotis
| genitive = Monocerotis
| pronounce = {{IPAc-en|m|ə|ˈ|n|ɒ|s|ᵻ|r|ə|s}},<br/>genitive {{IPAc-en|ˌ|m|ɒ|n|ə|s|ᵻ|ˈ|r|oʊ|t|ᵻ|s}}
| 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]]
| symbolism = the [[Unicorn]]
| RA = {{RA|7.15}}
| RA = {{RA|7.15}}
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| numberstarsplanets = 16
| numberstarsplanets = 16
| numberbrightstars = 0
| numberbrightstars = 0
| numbernearbystars = 2
| numbernearbystars = 4
| brighteststarname = [[Beta Monocerotis|β Mon]]
| brighteststarname = [[Beta Monocerotis|β Mon]]
| starmagnitude = 3.76
| starmagnitude = 3.76
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| stardistancepc = 4.09
| stardistancepc = 4.09
| numbermessierobjects = 1
| numbermessierobjects = 1
| meteorshowers = [[December Monocerids]]<br />[[Alpha Monocerids]]
| meteorshowers = {{Plain list|
* [[December Monocerids]]
* [[Alpha Monocerids]]
⚫
}}
| bordering = [[Canis Major]]<br />[[Canis Minor]]<br />[[Gemini (constellation)|Gemini]]<br />[[Hydra (constellation)|Hydra]]<br />[[Lepus (constellation)|Lepus]]<br />[[Orion (constellation)|Orion]]<br />[[Puppis]]
| 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]]
| latmax = [[75th parallel north|75]]
| latmin = [[90th parallel south|90]]
| latmin = [[90th parallel south|90]]
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| notes=
| notes=
}}
}}

'''Monoceros''' ([[Greek language|Greek]]: Μονόκερως, "[[unicorn]]") is a faint [[constellation]] on the [[celestial equator]]. Its definition is attributed to the 17th-century Dutch 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]].
'''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 ==
== Features ==
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===Stars===
===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.
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".
[[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.
[[Epsilon Monocerotis]] is a fixed [[binary star|binary]], with visual magnitudes of 4.5 and 6.5.
Line 47: Line 59:
[[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.
[[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 star|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 |title = 300 Astronomical Objects: A Visual Reference to the Universe |last1=Wilkins |first1=Jamie |last2=Dunn |first2 = Robert |publisher = Firefly Books |date = 2006 |edition = 1st |location=Buffalo, New York |isbn = 978-1-55407-175-3}}</ref>
[[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{{By whom|date=December 2020}} to be that of almost 100 solar masses.
Monoceros also contains [[Plaskett's Star]], a massive binary system whose combined mass is estimated{{By whom|date=December 2020}} to be almost 100 solar masses.


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
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>
|last1=Mamajek |first1=Eric E.
|last2=Barenfeld |first2=Scott A.
|last3=Ivanov |first3=Valentin D.
|title=The Closest Known Flyby of a Star to the Solar System
|journal=[[The Astrophysical Journal]]
|volume=800 |issue=1 |pages=L17
|year=2015
|doi=10.1088/2041-8205/800/1/L17
|arxiv=1502.04655|bibcode = 2015ApJ...800L..17M |s2cid=40618530
}}</ref>


One of the nearest known [[black hole]]s to our 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.
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===
===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 [[HARPS]] 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.
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===
===Deep-sky objects===
Part of the galactic plane goes through Monoceros. Monoceros contains many clusters and nebulae, most notable among them are:
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|M50]], an [[open cluster]]
* [[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 [[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}}
* 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}}
* 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}}
* [[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. Though it is named for [[Edwin Hubble]], it was discovered in 1783 by [[William 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}}
* [[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]].
*[[IC 447]], a reflection nebula.


== History ==
== History ==

{{See also|Dutch celestial cartography in the Age of Discovery|Constellations created and listed by Dutch celestial cartographers}}
[[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]]]]
[[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]]]]


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|magazine=Galaxy Science Fiction
|magazine=Galaxy Science Fiction
|pages=90–99
|pages=90–99
}}</ref> Its first certain appearance was on a globe created by the Dutch cartographer [[Petrus Plancius]] in 1612 or 1613<ref>[http://www.atlascoelestis.com/desu%20Plancius.htm Le costellazioni di Petrus Plancius] on [http://www.atlascoelestis.com/ atlascoelestis.com]</ref> and it was later charted by German astronomer [[Jakob Bartsch]] as Unicornu on his star chart of 1624.<ref>
}}</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
{{cite web
| title= Jacob Bartsch and seven new constellations
| title= Jacob Bartsch and seven new constellations
| last= Ridpath
| last= Ridpath
| first= Ian
| first= Ian
| url= http://www.ianridpath.com/startales/bartsch.htm
| url= http://www.ianridpath.com/startales/bartsch.html
}}
}}
</ref>
</ref>


German astronomers [[Heinrich Wilhelm Olbers]] and [[Ludwig Ideler]]<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}}
{{cite book
| last= Ideler
| first= Ludwig
⚫
| title= Untersuchungen über den Ursprung und die Bedeutung der Sternnamen: Ein Beytrag zur Geschichte des gestirnten Himmels
| url= https://books.google.com/books?id=+Xdo3AAAAMAAJ&pg=+PA1
| publisher= Berlin
| year= 1809
| pages= 354..355
⚫
}}
</ref>
</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>
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>
Line 134: Line 128:


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


== Citations ==
==References==
{{Reflist}}
{{Reflist}}


== References ==
===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 }}
* {{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}}
* {{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}}


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


{{Stars of Monoceros}}
{{Stars of Monoceros}}
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{{DEFAULTSORT:Constellation, Monoceros}}
{{DEFAULTSORT:Constellation, Monoceros}}
[[Category:Monoceros (constellation)| ]]
[[Category:Monoceros| ]]
[[Category:Equatorial constellations]]
[[Category:Equatorial constellations]]
[[Category:Constellations listed by Petrus Plancius]]
[[Category:Constellations listed by Petrus Plancius]]
[[Category:Dutch celestial cartography in the Age of Discovery]]
[[Category:Astronomy in the Dutch Republic]]
[[Category:1610s in the Dutch Republic]]
[[Category:Unicorns]]
[[Category:Unicorns]]

Latest revision as of 20:08, 24 August 2024

This article is about a faint constellation. For other uses, see Monoceros (disambiguation).
Monoceros
Constellation
Monoceros
List of stars in Monoceros
AbbreviationMon
GenitiveMonocerotis
Pronunciation/məˈnɒsɪrəs/,
genitive /məˌnɒsɪˈroʊtɪs/
Symbolismthe Unicorn
Right ascension7.15h
Declination−5.74°
QuadrantNQ2
Area482 sq. deg. (35th)
Main stars4
Bayer/Flamsteed
stars		32
Stars with planets16
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 of February.

Monoceros (Greek: Μονόκερως, "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 to the west, Gemini to the north, Canis Major to the south, and Hydra to the east. Other bordering constellations include Canis Minor, Lepus, and Puppis.

Eigenschaften

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

Stars

[edit]
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]

Epsilon Monocerotis is a fixed 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.[1]

Monoceros also contains Plaskett'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 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.[2]

One of the nearest known black holes 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

[edit]

Monoceros contains two super-Earth exoplanets 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

[edit]

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 globules 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.[3]
  • 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.[4][5]
  • 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 objects, which are small irregularly variable nebulae. They are associated with protostars.[6]
  • 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.[7]
  • 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.[8]
  • IC 447, a reflection nebula.

History

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The constellation Monoceros, from Urania's Mirror, a set of star charts from 1825. Includes Canis Minor and the obsolete constellation Printer's Workshop

In Western astronomy, Monoceros is a relatively modern constellation, not one of Ptolemy's 48 in the Almagest.[9] Its first certain appearance was on a globe created by the cartographer Petrus Plancius in 1612 or 1613[10] and it was later charted by German astronomer Jakob Bartsch as Unicornu on his star chart of 1624.[11]

German astronomers Heinrich Wilhelm Olbers and Ludwig Ideler[12] indicate (according to Richard Hinckley Allen's allegations) that the constellation may be older, quoting an astrological work[13] from 1564 that mentioned "the second horse between the Twins and the 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 is reported[14] to have found Monoceros on an ancient Persian sphere. French astronomer Camille Flammarion believed that a former constellation, Neper (the "Auger"), occupied the area of the sky now home to Monoceros and Microscopium, 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. ISBN 978-1-55407-175-3.
  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. S2CID 40618530.
  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. Archived from the original on 19 December 2023. Retrieved 19 December 2023.
  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. Retrieved 2023-04-14.
  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. ^ a b Allen, p. 290.

Sources

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Wikimedia Commons has media related to Monoceros.
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