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Double Heart

May 30, 2012

A billion years ago, the galaxy NGC 3393 grew a little bit bigger. It collided with a much smaller galaxy and quickly gobbled it up. The merger gave NGC 3393 a double heart — two supermassive black holes that are just a few hundred light-years apart.

NGC 3393 is a bright spiral galaxy about 160 million light-years away. It’s in Hydra, the water snake, which serpentines its way across the southwestern sky this evening. NGC 3393 is too faint to see without a good-sized telescope, though.

Astronomers already knew that the galaxy contained a supermassive black hole. The galaxy produces large amounts of radio energy, which comes from material around the black hole. And measurements of that material revealed a small, dark, dense object at the middle — a black hole.

Then last year, a team of astronomers reported that observations by an X-ray telescope in space showed that there are two black holes, not one. They’re about 500 light-years apart — closer than Earth is to some of the bright stars visible in the night sky.

Over the ages, the two black holes will move closer together, whipping around each other faster and faster as they do so. Their gravity will stir up the space around them like a high-speed blender, scattering everything around them. Eventually, they may merge, perhaps producing a brief display. That will leave NGC 3393 with just one supermassive black hole — a single dark heart for a bright galaxy.


Script by Damond Benningfield, Copyright 2012


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