Messier 78

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Messier 78
Reflection nebula
Messier 78.jpg
Image of Messier 78 captured using the Wide Field Imager camera on the MPG/ESO 2.2-metre telescope at the La Silla Observatory.
Observation data: J2000.0 epoch
Right ascension05h 46m 46.7s
Declination+00° 00′ 50″
Distance1,350 ly (415 pcly
Apparent magnitude (V)8.3
Apparent dimensions (V)8′ × 6′
ConstellationOrion
Physical characteristics
Radius5 ly
Notable featuresPart of the Orion Complex
DesignationsCed 55u, DG 80, IRAS 05442-0000, [KPS2012] MWSC 0664, NGC 2068
See also: Lists of nebulae

Messier 78 or M78, also known as NGC 2068, is a reflection nebula in the constellation Orion. It was discovered by Pierre Méchain in 1780 and included by Charles Messier in his catalog of comet-like objects that same year.

M78 is the brightest diffuse reflection nebula of a group of nebulae that includes NGC 2064, NGC 2067 and NGC 2071. This group belongs to the Orion B molecular cloud complex and is about 1,350 light-years distant from Earth. M78 is easily found in small telescopes as a hazy patch and involves two stars of 10th and 11th magnitude. These two B-type stars, HD 38563 A and HD 38563 B, are responsible for making the cloud of dust in M78 visible by reflecting their light.

The M78 cloud contains a cluster of stars that is visible in the infrared. Due to gravity, the molecular gas in the nebula has fragmented into a hierarchy of clumps, whose cores have masses ranging from 0.3 M to M. About 45 variable stars of the T Tauri type, young stars still in the process of formation, are members as well. Similarly, 17 Herbig–Haro objects are known in M78.

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Coordinates: Sky map 05h 46.7m 00s, +00° 03′ 00″