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Coma Star Cluster

April 18, 2013

A sprinkling of faint stars stands high in the east as night falls this evening, well above brilliant Arcturus, the brightest star in that part of the sky. Those strands of stars are the main feature of Coma Berenices, a constellation that was first drawn just a few centuries ago.

The constellation represents Berenice II, a queen of Egypt. The legend says that when her husband, the king, was about to head into battle, she offered her beautiful golden hair to the gods in exchange for his safety. When he returned home, she cut her hair and placed it in a temple; the gods then placed it in the stars.

In reality, those stars are part of a stellar family - the Coma Star Cluster.

The cluster is just 300 light-years away, which is quite close - only two other clusters are closer. It probably contains about a hundred stars, most of which are smaller and fainter than the Sun. The cluster probably was born with more stars. But it’s close to half-a-billion years old. That’s plenty of time for the incessant gravitational pull of other stars and gas clouds to strip away stars at the cluster’s edges - pulling them out of the stellar nursery that gave them birth.

The stars of the Coma Cluster are quite faint, and there’s a lot of moonlight to compete with them. So they’re best seen with binoculars - the glistening tresses of a queen who sacrificed them to save her husband.

We’ll talk about a much bigger Coma cluster tomorrow.


Script by Damond Benningfield, Copyright 2013

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