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Extra weight can make a big difference in lifespan — whether it’s a person or a star.

Consider Procyon, the Little Dog Star. It’s actually a binary — two stars locked in orbit around each other. They were born together, a couple of billion years ago. But one of the stars was more massive than the other. As a result, it’s been “dead” for more than a billion years, while its companion has lived on.

Procyon is in the east-southeast at nightfall. It’s only 11 and a half light-years away, and it stands not far to the upper left of Sirius, the brightest star in the night sky. The combination makes Procyon easy to spot.

The system’s main star is Procyon A. It’s bigger, brighter, and heavier than the Sun. Procyon B is a dead stellar core — a white dwarf. It’s about 60 percent as massive as the Sun, but only about the size of Earth.

Procyon B was much heavier when it was born. Because of that, its core was much hotter than Procyon A, which revved up its nuclear reactions. That caused Procyon B to age much faster. After only about 700 million years, the reactions ended, the core collapsed, and the star’s outer layers were kicked off into space.

Procyon A was less massive, so it kept going. But today, it, too, is nearing the end. It’s making the transition to the next stage of life, which will end with the formation of a white dwarf as well. So Procyon will end as a pair of dead stars whirling through the darkness.

Script by Damond Benningfield

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