View source for Sh 2-279

{{Short description|Emission nebula in the constellation Orion}}
{{Infobox nebula
| name = Sh-279
| image = NGC1977 Running Man Nebula from the Mount Lemmon SkyCenter Schulman Telescope courtesy Adam Block.jpg
| caption = Sh-279 as taken from the [[Mount Lemmon Observatory]]<ref name=kopernik/>
| type = HII Region / Reflection
| epoch = J2000.0
| ra = {{RA|05|35|16.2}}<ref name="simbad"/>
| dec = {{DEC|-04|47|07}}<ref name="simbad"/>
| dist_ly = 1,500
| appmag_v = 7.0
| size_v = 40{{prime}}×25{{prime}} (1977) [[Minute of arc|arcmins]]
| constellation  = [[Orion (constellation)|Orion]]
| radius_ly = ~7.5 ly (1977), 2 ly (1975)<br>1 ly (1973)
| absmag_v =
<!--| references = <ref name=kopernik/>-->
| names = Sh-279, NGC 1977-73-75
}} 
'''Sh 2-279''' (alternatively designated '''S279''' or '''Sharpless 279''') is an [[HII region]] and bright nebulae that includes a [[reflection nebula]] located in the constellation [[Orion (constellation)|Orion]]. It is the northernmost part of the [[Asterism (astronomy)|asterism]] known as [[Orion's Sword]], lying 0.6° north of the [[Orion Nebula]]. The reflection nebula embedded in 
Sh 2-279 is popularly known as the '''Running Man Nebula'''.<ref name="kopernik">{{cite web
|last1=Normandin|first1=George P.
|title=NGC 1977, NGC 1975, and NGC 1973, Running Man Nebula
|url=http://www.kopernik.org/images/archive/n1977.htm
|website=www.kopernik.org|access-date=5 March 2017}}</ref><ref>{{cite web
|title='Running Man' Races in Spectacular Nebula Photo
|url=http://www.space.com/21520-running-man-nebula-photo.html
|website=Space.com
|date=12 June 2013
|access-date=5 March 2017}}</ref>

[[Sharpless Catalog|Sh 2-]]279<ref name="simbad">{{cite simbad
|title=SH 2-279
|access-date=12 March 2017}}</ref> comprises three [[New General Catalogue|NGC]] nebulae, '''NGC 1973''', '''NGC 1975''', and '''NGC 1977'''<ref>{{cite web
|title=APOD: 2007 December 20 - Reflections on the 1970s
|url=https://apod.nasa.gov/apod/ap071220.html
|website=apod.nasa.gov
|access-date=5 March 2017}}</ref> 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 German astronomer [[Heinrich Louis d'Arrest]], NGC 1973 in 1862 and NGC 1975 in 1864.<ref name="Peterson2008">{{Cite book
|last1=Peterson
|first1= D.E.
|last2=Megeath
|first2=S.T.
|year=2008
|title=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
|publisher=ASP
|pages=590–618
|arxiv=0809.4006
|bibcode=2008hsf1.book..590P}}</ref> All three were included in the [[New General Catalogue]] in 1888.<ref name="Dreyer1888">{{cite journal |last=Dreyer |first=J. L. E. |date=1888 |title=A New General Catalogue of Nebulae and Clusters of Stars, being the Catalogue of the late Sir John F.W. Herschel |journal=Memoirs of the Royal Astronomical Society |series=Memoirs of the Royal Astronomical Society, Vol. 49, p.1 |volume=49 |page=1 |oclc=1049897326 |bibcode=1888MmRAS..49....1D |bibcode-access=free |hdl=2027/uc2.ark:/13960/t6b27rj62 |hdl-access=free }}{{pn|date=January 2025}}</ref> 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.<ref name="Peterson2008" />

This whole region in Orion's Sword was also later catalogued as [[Orion OB1 association|Orion 1c]].  In 1966, van den Bergh distinguished the weak clustering of reflection nebulae that includes Sh 2-279 as '''Ori R2'''.<ref name="Bergh1966">{{Cite journal
|last1=van den Bergh
|first1=S.
|year=1966
|title=A study of reflection nebulae
|journal=Astrophysical Journal
|volume=71
|pages=990–998
|doi=10.1086/109995
|bibcode=1966AJ.....71..990V}}</ref> Every reflection nebula appearing within the [[Sharpless catalog|Sharpless catalogue]] was first identified on blue plates of the [[National Geographic Society – Palomar Observatory Sky Survey|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 Sh 2-279.<ref name="Bergh1966" />

The Running Man Nebula is a popular target for [[amateur astronomy|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==
The whole reflection nebula region is likely excited by the hot young star (YSO) called c Orionis, [[42 Orionis]] or HD 37018<ref name="c Ori">{{cite simbad
|title=* c Ori
|access-date=12 March 2017}}</ref> in NGC 1977,<ref name="kim2016">{{cite journal |last1=Kim |first1=Jinyoung Serena |last2=Clarke |first2=Cathie J. |last3=Fang |first3=Min |last4=Facchini |first4=Stefano |title=Proplyds Around a B1 Star: 42 Orionis in NGC 1977 |journal=The Astrophysical Journal Letters |date=20 July 2016 |volume=826 |issue=1 |pages=L15 |doi=10.3847/2041-8205/826/1/L15 |bibcode=2016ApJ...826L..15K |arxiv=1606.08271 |doi-access=free }}</ref> which appears as a 4.6 magnitude star some 3.8[[arc minutes|{{prime}}]] from the centre of Sh 2-279.<!--See http://simbad.u-strasbg.fr/simbad/sim-coo?Coord=05+35.3-04+47&CooFrame=ICRS&CooEqui=2000.0&CooEpoch=J2000&Radius.unit=arcmin&submit=query+around&Radius=4--> (See image box.) Other massive stars include the yellow giant 45 Orionis and the variable KX Orionis.<ref name="JohnsonSnow1977">{{cite journal |last1=Johnson |first1=H. M. |last2=Snow |first2=T. P., Jr. |last3=Gehrz |first3=R. D. |last4=Hackwell |first4=J. A. |title=Copernicus spectra and infrared photometry of 42 Orionis |journal=Publications of the Astronomical Society of the Pacific |date=April 1977 |volume=89 |pages=165 |doi=10.1086/130096 |bibcode=1977PASP...89..165J |doi-access=free }}</ref>

== Proplyds in NGC 1977 ==

One candidate [[proplyd]] was discovered in NGC 1977 with the [[Hubble Space Telescope]] in 2012. The object showed a bent [[Herbig–Haro object|protostellar jet]] and a possible ionization front facing [[42 Orionis]], suggesting it is a proplyd.<ref>{{cite journal |last1=Bally |first1=John |last2=Youngblood |first2=Allison |last3=Ginsburg |first3=Adam |title=The Spindle: An Irradiated Disk and Bent Protostellar Jet in Orion |journal=The Astrophysical Journal |date=10 September 2012 |volume=756 |issue=2 |pages=137 |doi=10.1088/0004-637X/756/2/137 |bibcode=2012ApJ...756..137B |doi-access=free }}</ref> In 2016 a group of astronomers discovered six proplyds with the Hubble Space Telescope and one proplyd with the [[Spitzer Space Telescope]]. The proplyds are pointing to the [[B star|B-star]] 42 Orionis, which is the main source of [[ultraviolet]] radiation in this region. This ultraviolet light is [[Photoevaporation|photoevaporating]] the [[Protoplanetary disk|proto-planetary disks]] and the stellar wind of 42 Orionis is shaping the gas into cometary tails. Proplyds were first discovered in large numbers in the [[Orion Nebula]], but there the ultraviolet source responsible for the photoevaporation is the [[O-type star|O-type]] star [[Theta1 Orionis C|Theta<sup>1</sup> Orionis C]]. 42 Orionis is the first instance of a B-type star being responsible for the photoevaporation.<ref name="kim2016" />

All proplyds in NGC 1977 lie within 0.3 parsec of 42 Orionis and two have resolved central sources in the Hubble images, which might be the disks with radii of about 70 and 48 [[Astronomical unit|astronomical units]].<ref name="kim2016" />

NGC 1977 also includes the young star Parengo 2042 (P&nbsp;2042).<ref>{{Cite web |last=Gianopoulos |first=Andrea |date=2021-11-19 |title=Hubble Spots a Swift Stellar Jet in Running Man Nebula |url=http://www.nasa.gov/feature/goddard/2021/hubble-spots-a-swift-stellar-jet-in-running-man-nebula |access-date=2022-09-27 |website=NASA}}</ref>

==Image gallery==
<gallery>
File:Orion Nebula LRGB 2.jpg|Image of the Running Man nebula and its proximity to the Orion nebula.
File:NGC1977 CDK Large03.jpg|NGC 1977, Running Man Nebula, by W4SM using 17" PlaneWave CDK, Louisa, VA
File:NGC 1977 proplyds zoom.png|Largest [[proplyd]] in NGC 1977 seen by [[Hubble Space Telescope|Hubble]]
File:Proplyd NGC 1977.png|Proplyd imaged by the Spitzer Space Telescope is the elongated object on the upper left. 42 Orionis is in the middle and it is surrounded by glowing dust.
</gallery>

==References==
{{reflist}}

==External links==
{{commonscat}}
*{{APOD |date=2 October 2003 |title=Reflections on the 1970s}}
*[https://galaxymap.org/cat/view/sharpless/279 Sharpless 279 at Galaxymap] {{Webarchive|url=https://web.archive.org/web/20200218033029/https://galaxymap.org/cat/view/sharpless/279 |date=2020-02-18 }}
*[http://www.perseus.gr/Astro-DSO-NGC-1977.htm HaLRGB image based on 190 minutes total exposure]


{{sh2 objects}}
{{NGC20}}

[[Category:Orion (constellation)]]
[[Category:NGC objects]]
[[Category:Orion molecular cloud complex]]
[[Category:Reflection nebulae]]
[[Category:Star-forming regions]]
[[Category:Sharpless objects]]