|Observation data: J2000.0 epoch|
|Right ascension||05h 46m 46.7s|
|Declination||+00° 00′ 50″|
|Distance||1,350 ly (415 pc) ly|
|Apparent magnitude (V)||8.3|
|Apparent dimensions (V)||8′ × 6′|
|Notable features||Part of the Orion Complex|
|Designations||Ced 55u, DG 80, IRAS 05442-0000, [KPS2012] MWSC 0664, NGC 2068|
Messier 78 or M 78, 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, the denser cores of which about to form stars with masses of up to M☉. 5  About 45 variable stars of the T Tauri type, young stars still in the process of formation as well as some 17 Herbig–Haro objects are known in M78.
- "M 78". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 14 February 2016.
- Walker-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.
- 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.", Astrophysical Journal, 191: 111–142, Bibcode:1974ApJ...191..111S, doi:10.1086/152948.
- Motte, F.; et al. (June 2001), "A SCUBA survey of the NGC 2068/2071 protoclusters", Astronomy and Astrophysics, 372 (3): L41–L44, arXiv:astro-ph/0105019, Bibcode:2001A&A...372L..41M, doi:10.1051/0004-6361:20010543.
- Herbig, G. H.; Kuhi, L. V. (February 1963), "Emission-Line Stars in the Region of NGC 2068", 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.
|Wikimedia Commons has media related to Messier 78.|
- Messier 78 on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images
- SEDS: Starforming Nebula M78
- NASA Astronomy Picture of the Day: M78: Stardust and Starlight (4 November 2005)
- NightSkyInfo.com – M78
- Astronomy Picture of the Day
- Haese, Paul. "M78 – Reflection Nebula". Deep Space Videos. Brady Haran. Missing or empty