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Billy Henry
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Capella
Capella is a big mismatch. It’s a system of four stars, divided into two widely separated pairs. The members of one pair are both about two and a half times the mass of the Sun. But the members of the other pair are only about half the Sun’s mass. As a result, the two pairs face quite different futures. Capella is the brightest star of Auriga, the charioteer, and the sixth-brightest star in the entire night sky. It climbs into good view in the northeast in early evening and soars high overhead during the night. The system appears to be about 600 million years old – four billion years younger than the Sun. Yet the stars in the heavier pair are both at the end of life. They’ve burned through the original hydrogen fuel in their cores. That’s made them puff up to giant proportions. Before long, both stars will shed their outer layers. The stars are close enough together that the expelled gas should act like a brake, causing the stars to spiral close together. But as the gas disperses, the stars will be much lighter. That will loosen their grip on each other, causing them to move farther apart. So no one is quite sure what the system’s final configuration will look like. The smaller stars, on the other hand, will remain in the prime phase of life for tens of billions of years longer. But as the heavier stars trim down, the two pairs are likely to drift apart – splitting up a stellar quartet. Script by Damond Benningfield
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