| Messier 12 | |
|---|---|
M12 core by HST, 3.18′ view |
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| 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 | |
| Radius | 37.2 ly[NB 1] |
| Other designations | NGC 6218[1] |
| See also: Globular cluster, List of globular clusters | |
Messier 12 or M 12 (also designated NGC 6218) is a globular cluster in the constellation of Ophiuchus. It was discovered by Charles Messier on May 30, 1764.
Located roughly 3° in the sky from the cluster M10, M12 is about 16,000 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 open cluster. Thirteen variable stars have been recorded in this cluster.
A study published in 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 Milky Way.[2]
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