Black Holes Grow by Eating Stars

How does a black hole grow larger? By eating stars, of course!

That may sound like a joke told by your five-year-old kid, but that's what astronomers discovered:

A study led by a University of Utah astrophysicist found a new explanation for the growth of supermassive black holes in the center of most galaxies: they repeatedly capture and swallow single stars from pairs of stars that wander too close.

Using new calculations and previous observations of our own Milky Way and other galaxies, “we found black holes grow enormously as a result of sucking in captured binary star partners,” says physics and astronomy Professor Ben Bromley, lead author of the study, which is set for online publication April 2 in Astrophysical Journal Letters.

“I believe this has got to be the dominant method for growing supermassive black holes,” he adds. “There are two ways to grow a supermassive black hole: with gas clouds and with stars. Sometimes there’s gas and sometimes there is not. We know that from observations of other galaxies. But there are always stars.”