Trifid Nebula

Trifid Nebula
Emission nebula
H II region
reflection nebula and dark nebula
Observation data: J2000 epoch
Right ascension	18h 02m 23s
Declination	−23° 01′ 48″
Distance	4100±200 ly (1,260±70 pc)
Apparent magnitude (V)	+6.3
Apparent dimensions (V)	28 arcmins
Constellation	Sagittarius
Physical characteristics
Radius	21 ly
Notable features	a
Designations	M20, NGC 6514, Sharpless 30, RCW 147, Gum 76
	See also: Lists of nebulae

The Trifid Nebula (catalogued as Messier 20 or M20 and as NGC 6514) is an H II region in the north-west of Sagittarius in a star-forming region in the Milky Way's Scutum–Centaurus Arm.^[3] It was discovered by Charles Messier on June 5, 1764.^[4] Its name means 'three-lobe'. The object is an unusual combination of an open cluster of stars, an emission nebula (the relatively dense, reddish-pink portion), a reflection nebula (the mainly 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.^[5]

The most massive star that has formed in this region is HD 164492A, an O7.5III star with a mass more than 20 times the mass of the Sun.^[6] This star is surrounded by a cluster of approximately 3100 young stars.^[7]

^ ^a ^b ^c ^d "NGC 6514". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2006-11-16.
^ Kuhn, Michael A.; Hillenbrand, Lynne A.; Sills, Alison; Feigelson, Eric D.; Getman, Konstantin V. (2018). "Kinematics in Young Star Clusters and Associations with Gaia DR2". The Astrophysical Journal. 870 (1): 32. arXiv:1807.02115. Bibcode:2019ApJ...870...32K. doi:10.3847/1538-4357/aaef8c. S2CID 119328315.
^ Cambrésy, L.; et al. (2011). "Variation of the extinction law in the Trifid nebula". Astronomy & Astrophysics. 527: A141. arXiv:1101.1089. Bibcode:2011A&A...527A.141C. doi:10.1051/0004-6361/201015863. S2CID 39501333.
^ Messier 20
^ "Trifid Nebula: A Massive Star Factory". Science Daily. August 26, 2009. Retrieved 2010-07-06.
^ Rho, J.; et al. (2004). "Chandra Observation of the Trifid Nebula: X-Ray Emission from the O Star Complex and Actively Forming Pre-Main-Sequence Stars". Astrophysical Journal. 607 (2): 904–912. arXiv:astro-ph/0401377. Bibcode:2004ApJ...607..904R. doi:10.1086/383081. S2CID 119090269.
^ Kuhn, M. A.; et al. (2015). "The Spatial Structure of Young Stellar Clusters. II. Total Young Stellar Populations". Astrophysical Journal. 802 (1): 60. arXiv:1501.05300. Bibcode:2015ApJ...802...60K. doi:10.1088/0004-637X/802/1/60. S2CID 119309858.

[simbad-1] "NGC 6514". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2006-11-16.

[kuhn19-2] Kuhn, Michael A.; Hillenbrand, Lynne A.; Sills, Alison; Feigelson, Eric D.; Getman, Konstantin V. (2018). "Kinematics in Young Star Clusters and Associations with Gaia DR2". The Astrophysical Journal. 870 (1): 32. arXiv:1807.02115. Bibcode:2019ApJ...870...32K. doi:10.3847/1538-4357/aaef8c. S2CID 119328315.

[Cambresy11-3] Cambrésy, L.; et al. (2011). "Variation of the extinction law in the Trifid nebula". Astronomy & Astrophysics. 527: A141. arXiv:1101.1089. Bibcode:2011A&A...527A.141C. doi:10.1051/0004-6361/201015863. S2CID 39501333.

[4] Messier 20

[Science_Daily-5] "Trifid Nebula: A Massive Star Factory". Science Daily. August 26, 2009. Retrieved 2010-07-06.

[Rho04-6] Rho, J.; et al. (2004). "Chandra Observation of the Trifid Nebula: X-Ray Emission from the O Star Complex and Actively Forming Pre-Main-Sequence Stars". Astrophysical Journal. 607 (2): 904–912. arXiv:astro-ph/0401377. Bibcode:2004ApJ...607..904R. doi:10.1086/383081. S2CID 119090269.

[Kuhn15-7] Kuhn, M. A.; et al. (2015). "The Spatial Structure of Young Stellar Clusters. II. Total Young Stellar Populations". Astrophysical Journal. 802 (1): 60. arXiv:1501.05300. Bibcode:2015ApJ...802...60K. doi:10.1088/0004-637X/802/1/60. S2CID 119309858.

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