|Right Ascension||17 : 19.2 (h:m)
|Declination||-18 : 31 (deg:m)
|Visual Brightness||7.7 (mag)
|Apparent Dimension||9.3 (arc min)
Discovered 1764 by Charles Messier.
M9 is one of the nearer globular clusters to the nucleus of our Galaxy, with a computed distance of 5500 light-years from the Galactic Center (Burnham gives 7500, a slightly too high value). Its 9.3 arc minutes angular diameter corresponds to a linear extension of 70 light years at its distance of about 26,700 light years from our Solar system. To the north and west, its light is significantly dimmed by interstellar dust, as it lies at the edge of a patch of dark nebula; its light is probably weakened by at least one magnitude (a factor of about 2.5). Visually it appeared oval to Mallas, and the ellipticity of 9 mentioned by Shapley can be seen in our photograph also.
M9 is receding from us at the very high velocity of 224 km/sec. 13 variables have been found in this cluster.
Last Modification: 9 Dec 1999, 22:58 MET