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Astrophotogallery.org June Hard Object Winner

One of the nearest globulars at 7200 light years, M4 (NGC 6121) would be one of the most impressive globulars in the sky if it were not obscured by heavy clouds of dark interstellar matter in the vicinity of Antares. M4 is one of the most open, or loose, globulars and displays a peculiar 'barred' pattern in it's core, as can be seen in this photo. It was the first globular to be resolved to it's core (by Messier himself) as it is one of the most open, or loose, globulars - its classification in concentration being a class IX. It's diameter (half mass) is about 16 light years.

In 1987, the first millisecond pulsar was discovered in this globular cluster. This pulsar, 1821-24, is a neutron star rotating (and pulsating) once every 3.0 milliseconds, or over 300 times per second, which is even 10 times faster than the Crab pulsar in M1.

June 23, 2009