Unicorn (constellation)

See also: Unicorn (homonymy)

The Unicorn is a modern constellation relatively not very luminous; located a few degrees below the celestial equator, it is visible since most of the terrestrial sphere , except for the pole S.

History

The constellation of the Unicorn probably was named by the Astronome Dutch Petrus Plancius in 1613 and was charted by Jakob Bartsch in 1624. Heinrich Wilhelm Olbers and Ludwig Ideler states however that it appears on work going back to 1564 and Joseph Scaliger brings back to have seen it on an old celestial sphere Perse.

As it is about a modern constellation, the Unicorn is not associated with any Mythologie: it is here about the animal marvellous resembling a Cheval and having a horn on the face.

Principal stars

See also: List of stars of the Unicorn

β  Monocerotis

β  Monocerotis is in itself the most brilliant star of the constellation of the Unicorn, with a magnitude of 3,76. It is however about a triple, distant system of almost 650 light-years. βB  My (magnitude 5,4) and βC  My (magnitude 5,6) Orbit NT one around the other in 4.200 years and are separated from approximately 590 UA. βA  My (most brilliant of the three with a magnitude of 4,6) is far away from the couple of 1.570 ua and orbits in 14.000 years. All three are stars white-blue whose spectrum presents strong emission lines: they turn very quickly on they-even (at least to more than 150 km/s to the equator and are surrounded by a disc of ejected matter.

Other stars

The stars of the Unicorn are not very brilliant and none has a proper name. Most brilliant is α  My, of Magnitude connect 3,94. γ  My little with a magnitude of 3,99 follows it.

V838  My, a variable star distant of approximately 20.000 years light, saw its luminosity suddenly increasing in January 2002 while becoming a Nova, the first which could be followed by the Space telescope Hubble.

Several stars of the constellation have a Exoplanète: HD  46375, HD  52265 and HD  72659.

Celestial objects

The constellation contains on the other hand several celestial objects: M50, NGC 2244 and NGC 2506 are open Amas S. the Nébuleuse of the Rivet washer (NGC 2237) and IC 2177 are diffuse nebulas. NGC 2170, NGC 2182, NGC 2185 and NGC 2261 are nebulas by reflection.

See too

  • List of stars of the Unicorn

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