Tuesday, July 12, 2011

Globular Cluster Photo Series (Part 7): M69

Today's globular cluster is Messier 69 in Sagittarius. It's a fairly small cluster only 84 light years in diameter and a mere 9.8 arcminutes in apparent size. This is because it is fairly far away from us, about 29,700 light years away.

Messier 69 in Sagittarius.
Charles Messier discovered M69 on the same night he discovered M70, on August 31, 1780 while looking for an object described by Nicolas Lacaille in 1751-2. The two globular clusters are fairly close to each other, only about 1,800 light years apart. I'll have to put M70 on my list of objects to observe when I can, so I can properly document this pair. Both of them are fairly close to the galactic core, only about 6,200 light years distant. Like many of the globular clusters I'll be showing from now on, there isn't that much else to write about it, except that it is one of the most metal-rich globular clusters known (i.e., its stars contain a higher percentage of elements more massive than helium than most other globular clusters, though still much less than the fraction of such elements in the Sun).

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