M20

M20 - Trifid Nebula

Messier 20 or M20 (also designated NGC 6514) is a nebula and star cluster in the constellation Sagittarius. It has an apparent visual magnitude of 9 and its angular diameter is 28 arc-minutes. M20 lies at an estimated distance of 5200 light years. The Equinox 2000 coordinates are RA= 18h 02.6m, Dec= -23° 02´ which makes M20 best seen during the summer. The Messier Summer Star Chart shows the position of all Messier objects visible during that season. As one of the more famous objects in the Messier Catalog, it is commonly known as the Trifid Nebula.

The image above shows the uncropped view of M20 through the Takahashi E-180 Astrograph (North is to right). A 3x enlargement of this image appears to the right.

This nebula and star cluster were discovered by Messier in 1764 although he failed to detect the nebulosity. The Trifi Nebula is remarkable for the three-lobed appearance of its hydrogen emission nebula as well the nearby blue reflection nebula. According to Kharchenko et al. (2005), the distance of M20 is 2660 light years and its diameter is 15 light years. It contains >120 stars and its estimated age is 0.3-0.4 million years.

For more information, see the Messier Catalog as well as specific entries for M20 in Wikipedia and SEDS.

Messier's Description of M20

June 5, 1764
`Cluster of stars, a little above the Ecliptic, between the bow of Sagittarius and the right foot of Ophiuchus. Reviewed on March 22, 1781.' [see also description of M21]

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