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Life of Procyon

December 28, 2013

A nearby stellar neighbor climbs into good view at this time of year. Procyon is the leading light of Canis Minor, the little dog, so it’s known as the Little Dog Star. It’s only about 11 light-years away, so it shines brightly in our sky. It’s low in the east by about 8 o’clock, and climbs high across the south later on.

Astronomers recently pieced together Procyon’s life story.

It’s a binary — two stars that orbit each other once every 41 years. One of the stars is bright, while the other is faint. The bright star is a bit hotter and more massive than the Sun, so it shines pale yellow.

Over the eons, a star’s size and brightness change. By matching the properties of Procyon’s brighter star to models of how stars age, astronomers deduced that it was born almost two billion years ago. That means the star is only 40 percent as old as the Sun. When our solar system was that age, Earth had primitive life. No one knows, however, whether Procyon has any planets, let alone whether such worlds are home to life.

The fainter star was once much brighter than it is now. Astronomers estimate it was about 2.6 times as massive as the Sun when it was born. In its youth, it shined brilliant blue. In fact, it was brighter than its companion. But the star expelled its outer layers into space, leaving only its small, dead core — a cosmic cinder known as a white dwarf.


Script by Ken Croswell, Copyright 2013

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