Messier Index/M12

From Wikibooks, open books for an open world
Jump to navigation Jump to search
Messier 12, from 2MASS
Observation data (J2000 epoch)
Class IX
Constellation Ophiuchus
Right ascension 16h 47m 14.52s[1]
Declination -01° 56′ 52.1″[1]
Distance 16.0 kly (4.9 kpc)
Apparent magnitude (V) +7.68[1]
Apparent dimensions (V) 16′.0
Physical characteristics
Mass kg ( M)
Radius 37.2 ly[2]
Other designations NGC 6218[1]

Messier 12 or M 12 (also designated NGC 6218) is a w:globular cluster in the w:constellation of w:Ophiuchus. It was discovered by w:Charles Messier on w:May 30, w:1764.

Located roughly 3° in the sky from the cluster M10, M12 is about 16,000 w:light-years from Earth and has a spatial diameter of about 75 light-years. The brightest stars of M12 are of 12th magnitude. It is rather loosely packed for a globular and was once thought to be a tightly concentrated w:open cluster. Thirteen w:variable stars have been recorded in this cluster.

A study published in w:2006 concluded that this cluster has an unusually low number of low mass stars. The authors surmise that they were stripped from the cluster by the gravitational influence of the w:Milky Way.[1]

External links


  1. a b c d "SIMBAD Astronomical Database". Results for NGC 6218. Retrieved 2006-11-15. 
  2. distance × sin( diameter_angle / 2 ) = 37.2 ly. radius