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Unlucky Stars

September 24, 2018

Stars wander close to a black hole at their own peril. Any star that gets too close can be ripped apart by the black hole’s powerful gravity.

Astronomers reported a couple of these brilliant star deaths earlier this year. They monitored the events for about a decade, learning details about the black holes, and how they devour stars.

One of the events took place in the heart of a colliding galaxy that’s about 150 million light-years away. Astronomers first detected something odd happening there in 2005. They followed the event at all wavelengths, with telescopes on the ground and in space.

They determined that a star was being ripped apart by a black hole about 20 million times the mass of the Sun. Gas from the star formed a superhot disk around the black hole. As gas spiraled toward the black hole, magnetic fields funneled some of it into powerful jets. The jets raced into space at about a quarter of the speed of light.

The second event took place in a galaxy that’s about 800 million light-years away — not in its heart, but on its outskirts. X-ray telescopes in space detected a brilliant outburst. Over the following decade, the outburst faded and cooled. Astronomers concluded it was the result of a star being swallowed by a black hole about 50,000 times the mass of the Sun. The astronomers say it’s one of the best examples yet of an intermediate-mass black hole — a middle-range monster swallowing an unlucky star.


Script by Damond Benningfield

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