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Coma Berenices

March 29, 2016

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 Queen Berenice II of Egypt. The legend says that when her husband 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.

The brightest of those stars looks a lot like the Sun. Beta Coma is about the same size, mass, and brightness as the Sun. It’s also about the same color — fittingly enough, bright gold, which shows up in binoculars or a telescope.

Long-term observations reveal that Beta Coma goes through a 16-and-a-half-year magnetic cycle — half again the length of the solar cycle. During that cycle, the star probably goes through periods of high and low magnetic activity. During active times, more of the dark storms known as “starspots” probably speckle its surface — the result of lines of magnetic force getting twisted and stretched. When they snap, they produce powerful outbursts known as flares — eruptions that are the equivalent of millions or billions of nuclear bombs.

Coma’s real claim to fame isn’t stars, though — it’s a cluster of galaxies. More about that tomorrow.

Script by Damond Benningfield

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