A giant companion to a giant star faces an uncertain fate. The star is dying. As it expires, it will blast the companion, drag it inward, zap it with radiation, then loosen its grip on whatever remains.

Mirach is the second-brightest star of Andromeda. It’s passed through the prime phase of life, and now is in the red-giant phase. It’s puffed up to about 85 times the diameter of the Sun, making it shine about 1700 times brighter than the Sun.

Two years ago, astronomers discovered that Mirach has a companion. It’s probably a “failed star” known as a brown dwarf. It’s twice as far from Mirach as Earth is from the Sun.

Before long – astronomically speaking – the star’s outer layers will flow into space at tens of thousands of miles per hour. That will “sandblast” the companion, stripping away some of its bulk. And friction from that material will drag the companion toward the star.

After that, only the star’s hot but dead core will remain – a white dwarf. It’ll pelt the companion with ultraviolet radiation, vaporizing more of it. But the white dwarf will be much less massive than the present star, so it will loosen its gravitational grip on the companion.

No one knows for sure how all of this will play out, so we can’t predict the fate of Mirach’s giant companion.

Mirach is a third of the way up in the east-northeast at nightfall. It’s easy to see, even from most light-polluted cities.

Script by Damond Benningfield