Messier 78

Messier 78 is a reflection nebula in the constellation of Orion, located 1.350 light-years away. It was discovered by Pierre Mechain in 1780 and included by Charles Messier in his catalogue at the same time. It has an apparent magnitude on +8,3 and is 10 light-years wide.

M 78 is the brightest reflection nebula in the Orion B molecular cloud that includes, among others, NGC 2064, NGC 2067 and NGC 2071 reflection nebulae. M 78 reflects the light of two blue B-type giant stars, HD 38563A and HD 38563B.

The nebula also has an embedded open cluster, visible only in infrared. Because of gravity, the nebulosity started fragmenting into individual clumps of matter, with masses between 0,3 and 5 Suns. 45 T-Tauri variable stars (very young stars in the pre-main sequence contracting stage) and 17 Herbig-Haro objects (newly formed stars embedded in nebulosity, that emit high-speed powerful jets of partly ionized gas) were detected in M 78.