You are here


January 23, 2016

Call it “The Revenge of the Scrawny.”

The star system known as Procyon was born with two stars. One was bigger and heavier than the other, so it shined much more brightly. Because of that showiness, though, it burned out much more quickly. Today, all that’s left is the star’s tiny, dead core — while the scrawny companion shines on.

Procyon is in good view tonight, rising to the right of the full Moon.

What we see of Procyon is the scrawny survivor, Procyon A. In this case, though, “scrawny” is relative. The star is roughly twice as big as the Sun, and about 40 percent heavier. That mass puts it near the top 10 percent of all the stars in the galaxy.

When the system was born, though, the other star, Procyon B, was much more impressive. Because of its greater mass, it burned through the nuclear fuel in its core much more quickly. That made the star much brighter than Procyon A.

But it used up its fuel in a hurry. It puffed up, then cast its outer layers into space. All that remains is its core, known as a white dwarf. It’s about 60 percent the mass of the Sun, but only a bit bigger than Earth. It’ll shine feebly for billions of years as it slowly cools.

In the meantime, Procyon A is about to follow in its footsteps. The star is nearing the end of its “normal” lifetime, so it’ll soon puff up to giant proportions. Then it, too, will cast off its outer layers. That will leave Procyon with two “dead” stars shining feebly into the cosmic darkness.

Script by Damond Benningfield, Copyright 2015

Get Premium Audio

Listen to today's episode of StarDate on the web the same day it airs in high-quality streaming audio without any extra ads or announcements. Choose a $8 one-month pass, or listen every day for a year for just $30.