|Right Ascension||13 : 12.9 (h:m)
|Declination||+18 : 10 (deg:m)
|Visual Brightness||7.6 (mag)
|Apparent Dimension||12.6 (arc min)
Discovered 1775 by Johan Elert Bode.
Globular star cluster M53 is one of the more outlying globulars, being about 60,000 light years away from the Galactic center, and almost the same distance (about 59,700 light years) from out Solar system. At this distance, its apparent angular diameter of 14' corresponds to a linear diameter of over 250 light years. It is rapidly approaching us at 112 km/s. M53 has a bright nucleus about 2' in diameter and a gradually decreasing density profile. Messier found it resembles M79, while William Herschel found it similar to M10.
As in all globular clusters, the stars of M53 are apparently "metal-poor", which means that they contain only little quantities of elements heavier than Helium (actually mainly elements like carbon and oxygene); those of M53 are even below the average globular cluster members in "metallicity". It contains the considerably respectable number of 47 known RR Lyrae variables, some of them were reported to have changed their periods irreversibly with time (Kenneth Glyn-Jones).
At only about 1 degree separation to the east, the faint and quite loose globular cluster NGC 5053 comes into the field of view, which is at nearly the same distance as M53 (53,500 light years), and contains significantly less stars so that its classification as globular was doubted in the past (now it was confirmed by spectroscopy).
Last Modification: 9 Dec 1999, 22:58 MET