Messier 78 or
M78, also known as
NGC 2068, is a
reflection nebula in the
constellationOrion. It was discovered by
Pierre Méchain in 1780 and included by
Charles Messier in his catalog of
comet-like objects that same year.
[4]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.
[2] 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.
[5]The M78 cloud contains a cluster of stars that is visible in the
infrared.
[2] Due to gravity, the molecular gas in the nebula has fragmented into a hierarchy of clumps,
[2] whose cores have masses ranging from 0.3
M☉ to 5
M☉.
[6] About 45
variable stars of the
T Tauri type,
[7] young stars still in the process of formation, are members as well. Similarly, 17
Herbig–Haro objects are known in M78.
[8] 
Comments