Messier 14

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
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	${\displaystyle {\begin{smallmatrix}\left[{\ce {Fe}}/{\ce {H}}\right]\end{smallmatrix}}}$ = –1.28[3] dex
Other designations	NGC 6402[2]
See also: Globular cluster, List of globular clusters

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.