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Eta Carinae

October 20, 2015

In a galaxy that contains hundreds of billions of stars, you’d have a tough time finding any that are more impressive than those of Eta Carina. The system consists of two supergiants — stars that are far bigger, heavier, and brighter than the Sun. They’re surrounded by a massive cocoon of gas and dust. And both stars are probably destined to end their lives with titanic explosions.

Eta Carina is about 7500 light-years away, in the constellation Carina, the keel. Its primary star is probably about 90 times as massive as the Sun — one of the heaviest stars in the entire galaxy. And it’s probably about five million times brighter than the Sun. The secondary star is smaller and fainter, but still among the top one percent of the top one percent of all the stars in the Milky Way.

Today, the system is just visible to the unaided eye. But in 1843, it became the second-brightest star in all the night sky. That’s because the bigger star staged a massive eruption. Over a decade or so, it expelled enough gas into space to make 10 Suns. That material formed a cocoon around the stars, causing them to fade; more about that tomorrow.

The primary star is likely to expire in the next million years or so. Its core probably will collapse to form a black hole. But some or all of its outer layers will explode as a supernova. And a few million years later, the second star should explode as well — an impressive end for an impressive star system.


Script by Damond Benningfield, Copyright 2015

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