Trifid Nebula
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. It was discovered by Charles Messier on June 5, 1764. 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.
| 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 |
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. This star is surrounded by a cluster of approximately 3100 young stars.