View source for Trifid Nebula

{{short description|Emission nebula in the constellation Sagittarius}}
{{Infobox nebula
| name     = Trifid Nebula
| image    = Trifid Nebula (noirlab2521ah).jpg
| caption  = The Trifid Nebula as imaged by the [[Vera C. Rubin Observatory]] in very high-resolution, taken on May 28, 2025<ref>{{cite web | title=Trifid and Lagoon (Image) | year=2025 | publisher=NSF–DOE Vera C. Rubin Observatory | url=https://rubinobservatory.org/gallery/collections/first-look-gallery/n4kvj0cemd5pbdqgtjdgp2jg2t| access-date=2025-06-26 }}</ref>
| credit   = [[National_Science_Foundation]]/[[Office_of_Science]]
| type     = H II region
| type2    = [[reflection nebula]] and [[dark nebula]]
| epoch    = [[J2000]]
| ra       = {{RA|18|02|23}}<ref name=simbad>{{cite simbad |title=NGC 6514 |access-date=2006-11-16}}</ref>
| dec      = {{DEC|-23|01|48}}<ref name=simbad/>
| dist_ly  = 4100±200<ref name="kuhn19">
{{cite journal
 |title=Kinematics in Young Star Clusters and Associations with Gaia DR2
 |journal=The Astrophysical Journal
 |volume=870 |issue=1 |pages=32 |year=2018
 |arxiv=1807.02115 |bibcode=2019ApJ...870...32K
 |last1=Kuhn |first1=Michael A.
 |last2=Hillenbrand |first2=Lynne A.
 |last3=Sills |first3=Alison
 |last4=Feigelson |first4=Eric D.
 |last5=Getman |first5=Konstantin V.
 |s2cid=119328315
 |doi=10.3847/1538-4357/aaef8c |doi-access=free
 }}</ref>
| dist_pc = 1,260±70
| appmag_v = +6.3<ref name=simbad/>
| size_v   = 28 [[minute of arc|arcmins]]
| constellation  = [[Sagittarius (constellation)|Sagittarius]]
| radius_ly = 21
| absmag_v =
| notes    =a
| names    = [[Messier object|M]]20, [[New General Catalogue|NGC]] 6514,<ref name=simbad/> [[Sharpless catalog|Sharpless]] 30, [[RCW Catalogue|RCW]] 147, Gum 76
}}

The '''Trifid Nebula''' (catalogued as '''Messier 20''' or '''M20''' and as '''NGC 6514''') is an [[H II region]] in the north-west of [[Sagittarius constellation|Sagittarius]] in a [[star formation|star-forming region]] in the [[Milky Way|Milky Way's]] [[Scutum–Centaurus Arm]].<ref name=Cambresy11>
{{cite journal
 |display-authors=1 |last1=Cambrésy |first1=L.
 |last2=Rho |first2=J.
 |last3=Marshall |first3=D. J.
 |date=2011
 |title=Variation of the extinction law in the Trifid nebula
 |journal=[[Astronomy & Astrophysics]]
 |volume=527 |pages=A141
 |bibcode=2011A&A...527A.141C
 |arxiv=1101.1089 |s2cid=39501333
 |doi=10.1051/0004-6361/201015863}}</ref> It was discovered by [[Charles Messier]] on June 5, 1764.<ref>[http://www.messier.seds.org/m/m020.html Messier 20]</ref> Its name means 'three-lobe'. The object is an unusual combination of an [[open cluster]] of [[star]]s, an [[emission nebula]] (the relatively dense, reddish-pink portion), a [[reflection nebula]] (the mainly [[boxing the compass|NNE]] blue portion), and a [[dark nebula]] (the apparent 'gaps' in the former that cause the trifurcated appearance, also designated '''Barnard 85'''). Viewed through a small [[telescope]], the Trifid Nebula is a bright and peculiar object, and is thus a perennial favorite of amateur astronomers.<ref name="Science Daily">{{cite web
 |title=Trifid Nebula: A Massive Star Factory
 |date=August 26, 2009
 |work=Science Daily
 |url=https://www.sciencedaily.com/releases/2009/08/090826073442.htm
 |access-date=2010-07-06
}}</ref>

The most massive star that has formed in this region is HD 164492A, an [[O-type star|O7.5III star]] with a mass more than 20 times the [[mass of the Sun]].<ref name=Rho04>
{{cite journal
 |display-authors=1 |last1=Rho |first1=J.
 |last2=Ramírez |first2=S. V.
 |last3=Corcoran |first3=M. F.
 |date=2004
 |title=Chandra Observation of the Trifid Nebula: X-Ray Emission from the O Star Complex and Actively Forming Pre-Main-Sequence Stars
 |journal=[[Astrophysical Journal]]
 |volume=607 |issue=2 |pages=904–912
 |bibcode=2004ApJ...607..904R
 |arxiv=astro-ph/0401377 |s2cid=119090269
 |doi=10.1086/383081}}</ref>
This star is surrounded by a cluster of approximately 3100 young stars.<ref name=Kuhn15>
{{cite journal
 |display-authors=1 |last1=Kuhn |first1=M. A.
 |last2=Getman |first2=K. V.
 |last3=Feigelson |first3=E. D.
 |date=2015
 |title=The Spatial Structure of Young Stellar Clusters. II. Total Young Stellar Populations
 |journal=[[Astrophysical Journal]]
 |volume=802 |issue=1 |pages=60
 |bibcode=2015ApJ...802...60K
 |arxiv=1501.05300 |s2cid=119309858
 |doi=10.1088/0004-637X/802/1/60}}</ref>

==Characteristics==
The Trifid Nebula was the subject of an investigation by astronomers using the [[Hubble Space Telescope]] in 1997, using filters that isolate emission from [[hydrogen]] [[atom]]s, [[ion]]ized [[sulfur]] atoms, and doubly ionized [[oxygen]] atoms. The images were combined into a false-color composite picture to suggest how the nebula might look to the eye.

The close-up images show a dense cloud of dust and gas, which is a [[stellar nursery]] full of embryonic stars. This cloud is about
{{val|8|ul=ly}} away from the nebula's central star. A [[stellar jet]] protrudes from the head of the cloud and is about {{val|0.75|u=ly}} long. The jet's source is a young stellar object deep within the cloud. Jets are the exhaust gasses of star formation and radiation from the nebula's central star makes the jet glow.

The images also showed a finger-like stalk to the right of the jet. It points from the head of the dense cloud directly toward the star that powers the Trifid Nebula. This stalk is a prominent example of [[evaporating gaseous globule]]s, or 'EGGs'. The stalk has survived because its tip is a knot of gas that is dense enough to resist being eaten away by the powerful radiation from the star.

In January 2005, [[NASA]]'s [[Spitzer Space Telescope]] discovered 30 embryonic stars and 120 newborn stars not seen in [[visible light]] images.

It is centered about {{val|4100|u=ly}} from [[Earth]]. Its [[apparent magnitude]] is 6.3.

==Details and features==
<gallery>
File:Trifid.nebula.arp.750pix.jpg|The Trifid Nebula. The outlined area is enlarged right.
File:Trifid.nebula.jet.arp.750pix.jpg|Hubble image of a stellar jet in the Trifid Nebula
File:Cross-fade video comparing views of the Trifid Nebula in visible and infrared light.ogg|This video sequence compares a new view of the Trifid Nebula in infrared light, from the VVV VISTA survey with a more familiar visible-light view from a small telescope.
File:Triffid Nebula.jpg|The Trifid Nebula
File:Trifid Nebula Upclose.jpg|Trifid Nebula close-up
File:Trifid Widefield.jpg|Widefield image of the Trifid Nebula next to [[Lagoon Nebula]]
File:Ssc2005-02a.jpg|Trifid Nebula seen at different [[wavelength]]s
</gallery>

==See also==
* [[List of Messier objects]]
* [[List of nebulae]]
* [[Messier object]]
* [[New General Catalogue]]
* [[Islands (King Crimson album)]], which uses an image of the nebula as its cover
* [[Sh 2-82]], also known as the 'Little Trifid Nebula'
* [[NGC 1579]], also known as the 'Northern Trifid Nebula'

==References==
{{Reflist}}

==External links==
{{Commons category|Trifid Nebula}}
* [https://www.spitzer.caltech.edu/image/ssc2005-02a-new-views-of-a-familiar-beauty New Views of a Familiar Beauty], Spitzer IR Trifid discoveries
* [http://www.messier.seds.org/m/m020.html Messier 20], SEDS Messier pages
* [https://esahubble.org/images/?search=Trifid+Nebula Search results for 'Trifid Nebula'] at ESA/Hubble
* {{cite web |last=Merrifield |first=Michael |title=M20 – Trifid Nebula |work=Deep Sky Videos |publisher=[[Brady Haran]] |url=http://www.deepskyvideos.com/videos/messier/M20_trifid_nebula.html}}
* {{Sky-Map.org|name=The Trifid Nebula}}
* [https://www.constellation-guide.com/trifid-nebula-messier-20/ Trifid Nebula – Messier 20] at Constellation Guide

{{Messier objects}}
{{Sh2 objects}}
{{RCW}}
{{Gum catalogue}}
{{NGC objects:6500-6999}}
{{Portal bar|Astronomy|Stars|Outer space}}
{{Sky|18|02|23|-|23|01|48|9000}}

[[Category:Articles containing video clips]]
[[Category:Carina–Sagittarius Arm]]
[[Category:Discoveries by Charles Messier]]
[[Category:H II regions]]
[[Category:Messier objects]]
[[Category:NGC objects]]
[[Category:Sagittarius (constellation)]]
[[Category:Star-forming regions]]
[[Category:Astronomical objects discovered in 1764|17640605]]