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Globular cluster in Ophiuchus From Wikipedia, the free encyclopedia
Messier 14 (also known as M14 or NGC 6402) is a globular cluster of stars in the constellation Ophiuchus. It was discovered by Charles Messier in 1764.
Messier 14 | |
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![]() Globular cluster Messier 14 in Ophiuchus | |
Observation data (J2000 epoch) | |
Class | VIII[1] |
Constellation | Ophiuchus |
Right ascension | 17h 37m 36.15s[2] |
Declination | –03° 14′ 45.3″[2] |
Distance | 30.3 kly (9.3 kpc)[3] |
Apparent magnitude (V) | 7.6[4] |
Apparent dimensions (V) | 11.0′ |
Physical characteristics | |
Mass | 1.04×106[3] M☉ |
Radius | 50 ly[5] |
Metallicity | = –1.28[3] dex |
Other designations | NGC 6402[2] |
At a distance of about 30,000 light-years, M14 contains several hundred thousand stars. At an apparent magnitude of +7.6 it can be easily observed with binoculars. Medium-sized telescopes will show some hint of the individual stars of which the brightest is of magnitude +14.
The total luminosity of M14 is in the order of 400,000 times that of the Sun corresponding to an absolute magnitude of -9.12. The shape of the cluster is decidedly elongated. M14 is about 100 light-years across.[6]
A total of 70 variable stars are known in M14, many of the W Virginis variety common in globular clusters. In 1938, a nova appeared, although this was not discovered until photographic plates from that time were studied in 1964. It is estimated that the nova reached a maximum brightness of magnitude +9.2, over five times brighter than the brightest 'normal' star in the cluster.
Slightly over 3° southwest of M14 lies the faint globular cluster NGC 6366.