Sunday, August 8, 2010

Globular Clusters

Globular clusters are dense groups of stars that orbit large galaxies, such as the Milky Way.  Studies indicate that the stars found in these clusters are very old.  There are over 150 known globular clusters orbiting our galaxy, and there may be as many as 180 to 200 total.

Most globular globular clusters are only 100 to 200 light years across, and may contain anywhere from 10,000 to a million stars. The stars are held within the cluster by their mutual gravity.  The density of stars per cubic area of space is very high, with as many as 100 to 1,000 stars per cubic parsec at the core!

The term "globular" comes from the Latin word, globulus, which describes the spherical shape of the clusters.

Several globular clusters are within the reach of amateur telescopes, and a few are even visible to the naked eye.  Charles Messier cataloged several of them.  I have imaged a few.  Due to various issues with the NJP mount, though, I do not consider all of my attempts successful.  Here, though, are the ones that I've kept:

Messier 3, in Canis Venatici; E-200; 52x15
Messier 13 and galaxy NGC 62 in Hercules; E-200; 7x120
Messier 22 in Sagittarius; E-200; 18x120

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