Monoceros (
Greek
Greek may refer to:
Greece
Anything of, from, or related to Greece, a country in Southern Europe:
*Greeks, an ethnic group.
*Greek language, a branch of the Indo-European language family.
**Proto-Greek language, the assumed last common ancestor ...
: Μονόκερως, "
unicorn
The unicorn is a legendary creature that has been described since antiquity as a beast with a single large, pointed, spiraling horn projecting from its forehead.
In European literature and art, the unicorn has for the last thousand years o ...
") is a faint
constellation
A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object.
The origins of the e ...
on the
celestial equator
The celestial equator is the great circle of the imaginary celestial sphere on the same plane as the equator of Earth. This plane of reference bases the equatorial coordinate system. In other words, the celestial equator is an abstract proj ...
. Its definition is attributed to the 17th-century Dutch cartographer
Petrus Plancius
Petrus Plancius (; 1552 – 15 May 1622) was a Dutch-Flemish astronomer, cartographer and clergyman. He was born as Pieter Platevoet in Dranouter, now in Heuvelland, West Flanders. He studied theology in Germany and England. At the age of 24 he ...
. It is bordered by
Orion to the west,
Gemini
Gemini may refer to:
Space
* Gemini (constellation), one of the constellations of the zodiac
** Gemini in Chinese astronomy
* Project Gemini, the second U.S. crewed spaceflight program
* Gemini Observatory, consisting of telescopes in the Norther ...
to the north,
Canis Major
Canis Major is a constellation in the Southern Celestial Hemisphere, southern celestial hemisphere. In the second century, it was included in Ptolemy's 48 constellations, and is counted among the 88 modern constellations. Its name is Latin fo ...
to the south, and
Hydra to the east. Other bordering constellations include
Canis Minor,
Lepus
Hares and jackrabbits are mammals belonging to the genus ''Lepus''. They are herbivores, and live solitarily or in pairs. They nest in slight depressions called forms, and their young are able to fend for themselves shortly after birth. The gen ...
, and
Puppis
Puppis is a constellation in the southern sky. Puppis, the Latin translation of "poop deck", was originally part of an over-large constellation Argo Navis (the ship of Jason and the Argonauts), which centuries after its initial description, was ...
.
Features
Stars
Monoceros contains only a few fourth magnitude stars, making it difficult to see with the naked eye.
Alpha Monocerotis
Alpha Monocerotis, Latinised from α Monocerotis, is the Bayer designation for the brightest star in the equatorial constellation of Monoceros. It can be viewed with the naked eye, having an apparent visual magnitude of 3.94. Based upo ...
has a
visual magnitude
Apparent magnitude () is a measure of the brightness of a star or other astronomical object observed from Earth. An object's apparent magnitude depends on its intrinsic luminosity, its distance from Earth, and any extinction of the object's ...
of 3.93, while for
Gamma Monocerotis
γ Monocerotis, Latinised as Gamma Monocerotis, is a binary star system in the equatorial constellation of Monoceros. Based upon an annual parallax shift of 6.55 mas, it is located roughly 500 light years from the Sun. It ca ...
it is 3.98.
Beta Monocerotis
Beta Monocerotis (Beta Mon, β Monocerotis, β Mon) is a triple star system in the constellation of Monoceros. To the naked eye, it appears as a single star with an apparent visual magnitude of approximately 3.74 ...
is a
triple star
A star system or stellar system is a small number of stars that orbit each other, bound by gravitational attraction. A large group of stars bound by gravitation is generally called a '' star cluster'' or '' galaxy'', although, broadly speak ...
system; the three stars form a fixed triangle. The visual magnitudes of the stars are 4.7, 5.2, and 6.1.
William Herschel
Frederick William Herschel (; german: Friedrich Wilhelm Herschel; 15 November 1738 – 25 August 1822) was a German-born British astronomer and composer. He frequently collaborated with his younger sister and fellow astronomer Caroline H ...
discovered it in 1781 and called it "one of the most beautiful sights in the heavens".
Epsilon Monocerotis
ε Monocerotis, Latinised as Epsilon Monocerotis, is the Bayer designation of a binary star system in the equatorial constellation Monoceros. Its location is a guide for sky navigation toward the Rosette Nebula.
The white-hued prima ...
is a fixed
binary
Binary may refer to:
Science and technology Mathematics
* Binary number, a representation of numbers using only two digits (0 and 1)
* Binary function, a function that takes two arguments
* Binary operation, a mathematical operation that t ...
, with visual magnitudes of 4.5 and 6.5.
S Monocerotis, or 15 Monocerotis, is a bluish white
variable star
A variable star is a star whose brightness as seen from Earth (its apparent magnitude) changes with time. This variation may be caused by a change in emitted light or by something partly blocking the light, so variable stars are classified as ...
and is located at the center of
NGC 2264
NGC 2264 is the designation number of the New General Catalogue that identifies two astronomical objects as a single object: the Cone Nebula, and the Christmas Tree Cluster. Two other objects are within this designation but not officially incl ...
. The variation in its magnitude is slight (4.2–4.6). It has a companion star of visual magnitude 8.
V838 Monocerotis
V838 Monocerotis (Nova Monocerotis 2002) is a spectroscopic binary star system in the constellation Monoceros (constellation), Monoceros about 19,000 light years (6 parsec, kpc) from the Sun. The previously unremarked star was observed i ...
, a
variable
Variable may refer to:
* Variable (computer science), a symbolic name associated with a value and whose associated value may be changed
* Variable (mathematics), a symbol that represents a quantity in a mathematical expression, as used in many ...
red supergiant
Red supergiants (RSGs) are stars with a supergiant luminosity class ( Yerkes class I) of spectral type K or M. They are the largest stars in the universe in terms of volume, although they are not the most massive or luminous. Betelgeuse and Anta ...
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
The Hubble Space Telescope (often referred to as HST or Hubble) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. It was not the first space telescope, but it is one of the largest and most versa ...
was able to observe a
light echo
309x309px, Reflected light following path B arrives shortly after the direct flash following path A but before light following path C. B and C have the same apparent distance from the star as seen from Earth.">Earth.html" ;"title="apparent distan ...
, which illuminated the dust surrounding the star.
Monoceros also contains
Plaskett's Star, a massive binary system whose combined mass is estimated to be that of almost 100 solar masses.
Monoceros is the location of the binary system
Scholz's Star
Scholz's Star ( WISE designation WISE 0720−0846 or fully WISE J072003.20−084651.2) is a dim binary stellar system from the Sun in the constellation Monoceros near the galactic plane. It was discovered in 2013 by astronomer Ralf- ...
, host to a
red dwarf
''Red Dwarf'' is a British science fiction comedy franchise created by Rob Grant and Doug Naylor, which primarily consists of a television sitcom that aired on BBC Two between 1988 and 1999, and on Dave since 2009, gaining a cult following. T ...
primary and
brown dwarf
Brown dwarfs (also called failed stars) are substellar objects that are not massive enough to sustain nuclear fusion of ordinary hydrogen ( 1H) into helium in their cores, unlike a main-sequence star. Instead, they have a mass between the most ...
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
The Oort cloud (), sometimes called the Öpik–Oort cloud, first described in 1950 by the Dutch astronomer Jan Oort, is a theoretical concept of a cloud of predominantly icy planetesimals proposed to surround the Sun at distances ranging from 2 ...
.
One of the nearest known
black hole
A black hole is a region of spacetime where gravitation, gravity is so strong that nothing, including light or other Electromagnetic radiation, electromagnetic waves, has enough energy to escape it. The theory of general relativity predicts t ...
s to our Solar System is in this constellation. The binary star system
A0620-00
A0620-00 (abbreviated from 1A 0620-00) is a binary star system in the constellation of Monoceros, with an apparent magnitude of 11.2
A0620-00 consists of two objects. The first object is a K-type main-sequence star. The second object ...
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
An exoplanet or extrasolar planet is a planet outside the Solar System. The first possible evidence of an exoplanet was noted in 1917 but was not recognized as such. The first confirmation of detection occurred in 1992. A different planet, init ...
s in one
planetary system
A planetary system is a set of gravitationally
In physics, gravity () is a fundamental interaction which causes mutual attraction between all things with mass or energy. Gravity is, by far, the weakest of the four fundamental interacti ...
:
COROT-7b
CoRoT-7b (previously named CoRoT-Exo-7b) is an exoplanet orbiting the star CoRoT-7 in the constellation of Monoceros (constellation), Monoceros, from Earth. It was first detected Methods of detecting extrasolar planets#Transit photometry, photome ...
was detected by the
COROT
CoRoT (French: ; English: Convection, Rotation and planetary Transits) was a space telescope mission which operated from 2006 to 2013. The mission's two objectives were to search for extrasolar planets with short orbital periods, particularly th ...
satellite and
COROT-7c
CoRoT-7c is an extrasolar planet which orbits the G-type main sequence star CoRoT-7, located approximately 489 light years away in the constellation Monoceros. It's either a super-Earth or a Neptune-like planet, orbiting at 0.046 AU from th ...
was detected by
HARPS
The High Accuracy Radial Velocity Planet Searcher (HARPS) is a high-precision echelle planet-finding spectrograph installed in 2002 on the ESO's 3.6m telescope at La Silla Observatory in Chile. The first light was achieved in February 2003. H ...
from ground-based telescopes. Until the announcement of
Kepler-10b
Kepler-10b is the first confirmed terrestrial planet to have been discovered outside the Solar System by the Kepler Space Telescope. Discovered after several months of data collection during the course of the NASA-directed Kepler Mission, which ...
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. Monoceros contains many clusters and nebulae, most notable among them are:
*
M50, an
open cluster
An open cluster is a type of star cluster made of up to a few thousand stars that were formed from the same giant molecular cloud and have roughly the same age. More than 1,100 open clusters have been discovered within the Milky Way galaxy, and ...
* The
Rosette Nebula
The Rosette Nebula (also known as Caldwell 49) is an H II region located near one end of a giant molecular cloud in the Monoceros region of the Milky Way Galaxy. The open cluster NGC 2244 (Caldwell 50) is closely associated with the nebulosity, th ...
(NGC 2237, 2238, 2239, and 2246) is a
diffuse nebula
A nebula ('cloud' or 'fog' in Latin; pl. nebulae, nebulæ or nebulas) is a distinct luminescent part of interstellar medium, which can consist of ionized, neutral or molecular hydrogen and also cosmic dust. Nebulae are often star-forming region ...
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
In astronomy, Bok globules are isolated and relatively small dark nebulae, containing dense cosmic dust and gas from which star formation may take place. Bok globules are found within H II regions, and typically have a mass of about 2 to 50 solar ...
s in its dark areas. It was independently discovered in the 1880s by
Lewis Swift
Lewis A. Swift (February 29, 1820 – January 5, 1913) was an American astronomer who discovered 13 comets and 1,248 previously uncatalogued nebulae. Only William Herschel discovered more nebulae visually.
Discoveries
Swift discovered or co-discov ...
(early 1880s) and
Edward Emerson Barnard
Edward Emerson Barnard (December 16, 1857 – February 6, 1923) was an American astronomer. He was commonly known as E. E. Barnard, and was recognized as a gifted observational astronomer. He is best known for his discovery of the high proper mo ...
(1883) as they hunted for
comets
A comet is an icy, small Solar System body that, when passing close to the Sun, warms and begins to release gases, a process that is called outgassing. This produces a visible atmosphere or coma, and sometimes also a tail. These phenomena are ...
.
* The
Christmas Tree Cluster
NGC 2264 is the designation number of the New General Catalogue that identifies two astronomical objects as a single object: the Cone Nebula, and the Christmas Tree Cluster. Two other objects are within this designation but not officially incl ...
(NGC 2264) is another open cluster in Monoceros. Named for its resemblance to a
Christmas tree
A Christmas tree is a decorated tree, usually an evergreen conifer, such as a spruce, pine or fir, or an artificial tree of similar appearance, associated with the celebration of Christmas. The custom was further developed in early modern ...
, it is fairly bright at an overall magnitude of 3.9; it is 2400 light-years from Earth. The
variable star
A variable star is a star whose brightness as seen from Earth (its apparent magnitude) changes with time. This variation may be caused by a change in emitted light or by something partly blocking the light, so variable stars are classified as ...
S Monocerotis represents the tree's trunk, while the variable star
V429 Monocerotis represents its top.
* The
Cone Nebula
The Cone Nebula is an H II region in the constellation of Monoceros. It was discovered by William Herschel on December 26, 1785, at which time he designated it H V.27. The nebula is located about 830 parsecs or 2,700 light-years away from Earth. ...
(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
Herbig–Haro (HH) objects are bright patches of nebula, nebulosity associated with newborn stars. They are formed when narrow jets of partially plasma (physics), ionised gas ejected by stars collide with nearby clouds of gas and dust at several ...
s, which are small irregularly variable nebulae. They are associated with
protostar
A protostar is a very young star that is still gathering mass from its parent molecular cloud. The protostellar phase is the earliest one in the process of stellar evolution. For a low-mass star (i.e. that of the Sun or lower), it lasts about 5 ...
s.
*
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.
*
Hubble's Variable Nebula
NGC 2261 (also known as Hubble's Variable Nebula or Caldwell 46) is a variable nebula located in the constellation Monoceros. The nebula is illuminated by the star R Monocerotis (R Mon), which is not directly visible itself.
Observing history
N ...
(NGC 2261) is a nebula with an approximate magnitude of 10, 2500 light-years from Earth. Though it is named for
Edwin Hubble
Edwin Powell Hubble (November 20, 1889 – September 28, 1953) was an Americans, American astronomer. He played a crucial role in establishing the fields of extragalactic astronomy and observational cosmology.
Hubble proved that many objects ...
, it was discovered in 1783 by
William Herschel
Frederick William Herschel (; german: Friedrich Wilhelm Herschel; 15 November 1738 – 25 August 1822) was a German-born British astronomer and composer. He frequently collaborated with his younger sister and fellow astronomer Caroline H ...
. 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
An emission nebula is a nebula formed of ionized gases that emit light of various wavelengths. The most common source of ionization is high-energy ultraviolet photons emitted from a nearby hot star. Among the several different types of emissio ...
and a
reflection nebula Reflection or reflexion may refer to:
Science and technology
* Reflection (physics), a common wave phenomenon
** Specular reflection, reflection from a smooth surface
*** Mirror image, a reflection in a mirror or in water
** Signal reflection, in s ...
. One hypothesis regarding their interaction is that the nebula and its illuminating star are a very early stage
planetary system
A planetary system is a set of gravitationally
In physics, gravity () is a fundamental interaction which causes mutual attraction between all things with mass or energy. Gravity is, by far, the weakest of the four fundamental interacti ...
.
*
IC 447, a
reflection nebula Reflection or reflexion may refer to:
Science and technology
* Reflection (physics), a common wave phenomenon
** Specular reflection, reflection from a smooth surface
*** Mirror image, a reflection in a mirror or in water
** Signal reflection, in s ...
.
History
In Western astronomy, Monoceros is a relatively modern constellation, not one of
Ptolemy
Claudius Ptolemy (; grc-gre, Πτολεμαῖος, ; la, Claudius Ptolemaeus; AD) was a mathematician, astronomer, astrologer, geographer, and music theorist, who wrote about a dozen scientific treatises, three of which were of importanc ...
's 48 in the ''
Almagest
The ''Almagest'' is a 2nd-century Greek-language mathematical and astronomical treatise on the apparent motions of the stars and planetary paths, written by Claudius Ptolemy ( ). One of the most influential scientific texts in history, it canoni ...
''.
Its first certain appearance was on a globe created by the Dutch cartographer
Petrus Plancius
Petrus Plancius (; 1552 – 15 May 1622) was a Dutch-Flemish astronomer, cartographer and clergyman. He was born as Pieter Platevoet in Dranouter, now in Heuvelland, West Flanders. He studied theology in Germany and England. At the age of 24 he ...
in 1612 or 1613 and it was later charted by German astronomer
Jakob Bartsch
Jakob Bartsch or Jacobus Bartschius (c. 1600 – 26 December 1633) was a German astronomer.
Biography
Bartsch was born in Lauban (Lubań) in Lusatia. He was taught how to use the astrolabe by Sarcephalus (Christopher Hauptfleisch), a librar ...
as Unicornu on his star chart of 1624.
German astronomers
Heinrich Wilhelm Olbers
Heinrich Wilhelm Matthias Olbers (; ; 11 October 1758 – 2 March 1840) was a German physician and astronomer.
Life and career
Olbers was born in Arbergen, Germany, today part of Bremen, and studied to be a physician at Göttingen (1777–80 ...
and
Ludwig Ideler
Ludwig may refer to:
People and fictional characters
* Ludwig (given name), including a list of people and fictional characters
* Ludwig (surname), including a list of people
* Ludwig Ahgren, or simply Ludwig, American YouTube live streamer and ...
indicate (according to
Richard Hinckley Allen In astronomy, stars have a variety of different stellar designations and names, including catalogue designations, current and historical proper names, and foreign language names.
Only a tiny minority of known stars have proper names; all others ha ...
's allegations) that the constellation may be older, quoting an astrological work
from 1564 that mentioned "the second horse between the
Twins
Twins are two offspring produced by the same pregnancy.MedicineNet > Definition of TwinLast Editorial Review: 19 June 2000 Twins can be either ''monozygotic'' ('identical'), meaning that they develop from one zygote, which splits and forms two em ...
and the
Crab
Crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" (abdomen) ( el, βραχύς , translit=brachys = short, / = tail), usually hidden entirely under the thorax. They live in all the ...
has many stars, but not very bright"; these references may ultimately be due to the 13th century Scotsman
Michael Scot
Michael Scot (Latin: Michael Scotus; 1175 – ) was a Scottish mathematician and scholar in the Middle Ages. He was educated at Oxford and Paris, and worked in Bologna and Toledo, where he learned Arabic. His patron was Frederick II of the H ...
, but refer to a horse and not a unicorn, and its position does not quite match.
Joseph Scaliger
Joseph Justus Scaliger (; 5 August 1540 – 21 January 1609) was a French Calvinist religious leader and scholar, known for expanding the notion of classical history from Greek and Ancient Roman history to include Persian, Babylonian, Jewis ...
is reported
[
]
to have found Monoceros on an ancient
Persian
Persian may refer to:
* People and things from Iran, historically called ''Persia'' in the English language
** Persians, the majority ethnic group in Iran, not to be conflated with the Iranic peoples
** Persian language, an Iranian language of the ...
sphere. French astronomer
Camille Flammarion
Nicolas Camille Flammarion FRAS (; 26 February 1842 – 3 June 1925) was a French astronomer and author. He was a prolific author of more than fifty titles, including popular science works about astronomy, several notable early science fiction ...
believed that a former constellation, Neper (the "Auger"), occupied the area of the sky now home to Monoceros and
Microscopium
Microscopium ("the Microscope") is a minor constellation in the southern celestial hemisphere, one of twelve created in the 18th century by French astronomer Nicolas-Louis de Lacaille and one of several depicting scientific instruments. The n ...
, but this is disputed.
[Allen, p. 290.]
Chinese asterisms Sze Fūh, the Four Great Canals; Kwan Kew; and Wae Choo, the Outer Kitchen, all lay within the boundaries of Monoceros.
See also
*
Monoceros (Chinese astronomy) According to traditional Chinese uranography, the modern constellation Monoceros is located within the southern quadrant of the sky, which is symbolized as the Vermillion Bird of the South (南方朱雀, ''Nán Fāng Zhū Què'').
The name of the ...
Citations
References
*
*
External links
VISTA Reveals the Secret of the Unicorn—
ESO
The European Organisation for Astronomical Research in the Southern Hemisphere, commonly referred to as the European Southern Observatory (ESO), is an intergovernmental research organisation made up of 16 member states for ground-based ast ...
Photo Release
The Deep Photographic Guide to the Constellations: Monoceros
{{DEFAULTSORT:Constellation, Monoceros
Equatorial constellations
Constellations listed by Petrus Plancius
Dutch celestial cartography in the Age of Discovery
Astronomy in the Dutch Republic
1610s in the Dutch Republic
Unicorns