Doomed Companions

The stars of the binary system SSN 7 are doomed, doomed, and doomed. Each of the two monster stars will collapse to form a black hole. And in the far-distant future, the black holes will merge to form a bigger one.

The system is about 200,000 light-years from Earth. It’s in a massive stellar nursery in the Small Magellanic Cloud, a companion galaxy to the Milky Way.

A recent study found that one star in the system is about 32 time the mass of the Sun, while the other is 55 times the Sun’s mass. That makes them some of the hottest, brightest, and heaviest stars in the universe. They’re only about four million years old — about one percent the age of the Sun. But because they’re so massive, they’re nearing the ends of their lives.

The study concluded that the stars are so close together that they’re touching each other. Not only that, but the heavier star is “stealing” hot gas from its companion. In as little as 700,000 years, the less-massive star will collapse to form a black hole. After a brief quiet period, it will begin pulling in gas from the surviving star, which will collapse as well. The entire scenario should play out in just a few million years.

After that, the black holes will spiral ever closer as they emit gravitational waves — “ripples” in space-time. The study forecasts that they’ll merge in about 18 billion years — several billion years longer than the current age of the universe.
 

Script by Damond Benningfield