What caused this huge asteroid to disappear mysteriously?

200,000-ton asteroids don't usually just disappear into space (okay, maybe sometimes do), but when astronomers at NASA trained the Hubble on this asteroid, they were puzzled to see it was falling apart right before their eyes, the first time they'd ever seen such a sight.

Of course, asteroids do sometimes break apart, but that's typically the result of a collision with another object in space, and this asteroid, designated P/2013 R3, hadn't experienced any recent crashes. So what do astronomers think is happening? The have a theory that the apparent breakdown of the asteroid is due to a much more gentle force: the sunlight.

P/2013 R3 first began falling apart as it neared the sun, as it moved closer to the sun, the sunlight slowly increased the asteroid's rate of rotation. This in turn upped the centrifugal force acting on the asteroid, causing it to pull itself apart from within. Scientists have theorized about this possibility for awhile now, but this is the first time that they think they might have actually seen it in action.

You can see stills of the asteroid as it falls apart over the course of several months below:

What caused this huge asteroid to disappear mysteriously?

Images: NASA, ESA, D. Jewitt (UCLA)