Sh2-279

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Sh-279
Nebula
NGC1977 Running Man Nebula from the Mount Lemmon SkyCenter Schulman Telescope courtesy Adam Block.jpg
Observation data: J2000.0 epoch
Right ascension 05h 35m 15.45s
Declination -04° 48′ 23′ 06.7″
Distance 1,500 ly
Apparent magnitude (V) 7.0
Apparent dimensions (V) 40′×25′ (1977) arcmins
Constellation Orion
Physical characteristics
Radius ~7.5 ly (1977), 2 ly (1975)
1 ly (1973) ly
Designations Sh-279, NGC 1977-73-75
See also: Lists of nebulae

Sh2-279 (alternatively designated S279 or Sharpless 279) is an HII region and bright nebulae that includes a reflection nebula located in the constellation Orion. It is the northernmost part of the asterism known as Orion's Sword, lying 0.6° north of the Orion Nebula. The reflection nebula embedded in Sh2-279 is popularly known as the Running Man Nebula.[1][2]

Sh2-279[3] comprises three NGC nebulae, NGC 1973, NGC 1975, and NGC 1977[4] that are divided by darker nebulous regions. It also includes the open cluster NGC 1981. The brightest nebulosity, later listed as NGC 1977, was discovered by William Herschel in 1786. He catalogued it as "H V 30" and described "!! 42 Orionis and neb[ula]". The two smaller reflection nebulae were first noted by French astronomer Heinrich Louis d'Arrest, NGC 1973 in 1862 and NGC 1975 in 1864.[5] All three were included in the New General Catalogue in 1888.[6] The designation NGC 1977 is used in various sources for the reflection area around 42 Orionis (the south-east portion of the reflection nebula), for the entire reflection nebula (including NGC 1973 and NGC 1975), or for the whole nebula complex.[5]

This whole region in Orion's Sword was also later catalogued as Orion 1c. In 1966, van den Bergh distinguished the weak clustering of reflection nebula that includes Sh2-279 as Ori R2.[7] Every reflection nebulae appearing within the Sharpless catalogue were first identified on blue plates of the Palomar Sky Survey, and then double checked against the red plates to eliminate possible plate faults. Van den Berg found that there was a strong concentration of new T Tauri stars around the Orion Nebula, tapering off into a tail approaching Sh2-279.[7]

The Running Man Nebula is a popular target for amateur astrophotographers, as it lies close to the Orion Nebula and has many nearby guide stars. The outline of the running man shows up primarily in photographs; it is difficult to perceive visually through telescopes, though the reflection nebula itself is visible in small to medium apertures in dark skies.

Ionization Source[edit]

The whole reflection nebula region is likely excited by the hot young star (YSO) called c Orionis, 42 Orionis or HD 37018[8] in NGC 1977,[9] which appears as a 4.6 magnitude star some 3.8 from the centre of Sh2-279. (See image box.) Other massive stars include the yellow giant 45 Orionis and the variable KX Orionis.[10]

Image gallery[edit]

References[edit]

  1. ^ Normandin, George P. "NGC 1977, NGC 1975, and NGC 1973, Running Man Nebula". www.kopernik.org. Retrieved 5 March 2017. 
  2. ^ "'Running Man' Races in Spectacular Nebula Photo". Space.com. Retrieved 5 March 2017. 
  3. ^ "Sh2-279 – SIMBAD". simbad.u-strasbg.fr. Retrieved 12 March 2017. 
  4. ^ "APOD: 2007 December 20 - Reflections on the 1970s". apod.nasa.gov. Retrieved 5 March 2017. 
  5. ^ a b Peterson, D.E.; Megeath, S.T. (2008). The Orion Molecular Cloud 2/3 and NGC 1977 Regions : Handbook of Star Forming Regions, Volume I: The Northern Sky ASP Monograph Publications, Vol. 4. Edited by Bo Reipurth. ASP. pp. 590–618. arXiv:0809.4006Freely accessible. Bibcode:2008hsf1.book..590P. 
  6. ^ Dreyer, J. L. E. (1888). "A New General Catalogue of Nebulae and Clusters of Stars, being the Catalogue of the late Sir John F.W. Herschel, Bart., revised, corrected, and enlarged" (PDF). Memoirs of the Royal Astronomical Society. 49: 1–237. Bibcode:1888MmRAS..49....1D. 
  7. ^ a b van den Bergh, S. (1966). "A study of reflection nebulae". Astrophysical Journal. 71: 990–998. Bibcode:1966AJ.....71..990V. doi:10.1086/109995. 
  8. ^ "c Ori – SIMBAD". simbad.u-strasbg.fr. Retrieved 12 March 2017. 
  9. ^ Kim, J.S.; Clarke, C.J.; Fang, M.; Facchini, S. (2016). "Proplyds Around a B1 Star: 42 Orionis in NGC 1977". Astrophysical Journal Letters. 82 (1): L15–L20. Bibcode:2016ApJ...826L..15K. doi:10.3847/2041-8205/826/1/L15. 
  10. ^ Johnson, H. M.; Snow, T. P., Jr.; Gehrz, R. D.; Hackwell, J. A. (1977). "Copernicus spectra and infrared photometry of 42 Orionis". Publications of the Astronomical Society of the Pacific. 89: 165. doi:10.1086/130096. ISSN 0004-6280. 

External links[edit]