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]
On May 23, 2024, the European Space Agency released an initial set of images from their Euclid mission. This included an unprecedented image of the region including M78.[9]
It showed hundreds of thousands of new objects including sub-stellar sized ones for the first time.
^ abcdWalker-Smith, S. L.; Richer, J. S.; Buckle, J. V.; Smith, R. J.; Greaves, J. S.; Bonnell, I. A. (March 2013), "The structure and kinematics of dense gas in NGC 2068", Monthly Notices of the Royal Astronomical Society, 429 (4): 3252–3265, arXiv:1212.2018, Bibcode:2013MNRAS.429.3252W, doi:10.1093/mnras/sts582.
^ ab"Messier 78". SEDS Messier Catalog. Retrieved 30 April 2022.
^Frommert, Hartmut; Kronberg, Christine (9 October 2018), "Messier 78", SEDS Messier pages, Students for the Exploration and Development of Space (SEDS), retrieved 5 December 2018.
^Strom, S. E.; et al. (July 1974), "Infrared and optical observations of Herbig-Haro objects.", The Astrophysical Journal, 191: 111–142, Bibcode:1974ApJ...191..111S, doi:10.1086/152948.
^Herbig, G. H.; Kuhi, L. V. (February 1963), "Emission-Line Stars in the Region of NGC 2068", The Astrophysical Journal, 137: 398, Bibcode:1963ApJ...137..398H, doi:10.1086/147519.
^Zhao, Bing; et al. (September 1999), "Newly Discovered Herbig-Haro Objects in the NGC 2068 and NGC 2071 Regions", The Astronomical Journal, 118 (3): 1347–1353, Bibcode:1999AJ....118.1347Z, doi:10.1086/301002.