M20 - The Trifid Nebula
Credits: NASA, ESA, STScI and A. Sarajedini (University of Florida)
Discovered by Charles Messier on 5th June, 1764, M20 (also catalogued as NGC6514) is a star-forming nebula located 9,000 light-years away from Earth in the constellation Sagittarius.
Also known as the Trifid Nebula, M20 has an apparent magnitude of 6.3 and can be spotted with a small telescope. It is best observed during August.
Its name means 'divided into three lobes'. The object is an unusual combination of an open cluster of stars; an emission nebula (the lower, red portion), a reflection nebula (the upper, blue portion) and a dark nebula (the apparent 'gaps' within the emission nebula that cause the trifurcated appearance; these are 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.
The Trifid Nebula is a star-forming region in the Scutum spiral arm of the Milky Way. 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.
Facts about M20 by Keith Turnecliff
In January 2005, NASA's Spitzer Space Telescope discovered 30 embryonic stars and 120 newborn stars not seen in visible light images.