At the center of our Milky Way galaxy is a supermassive black hole. It weighs as much as four million suns. The black hole is hefty, but it's pretty tranquil most of the time.

It does act up on occasion, though. Astrophysicists estimate that the black hole devours a star every 100,000 years or so, producing a major flare as the star is shredded and then ingested.

And smaller flares are observed more or less daily. For a few hours the galaxy's central black hole becomes brighter at x-ray wavelengths by a factor of a few up to 100.

What could produce these frequent flares? A trio of astrophysicists in Europe has an idea. They propose that the black hole could be steadily feeding on a cloud of asteroids in the Milky Way's center. Those asteroids would have been stripped from orbits around nearby stars. The report will appear in the Monthly Notices of the Royal Astronomical Society. [Kastytis Zubovas et al., "Sgr A* flares: tidal disruption of asteroids and planets?"]

The researchers estimate that the destruction of an asteroid 10 or 20 kilometers across would produce an observable flare. That's quite an impressive feat. But for a supermassive black hole, it's all in a day's work.

—John Matson

[The above text is a transcript of this podcast.]