Hubble clicks pic of mysteriously disintegrating asteroid

The NASA/ESA Hubble Space Telescope has clicked the never-before-seen break-up of an asteroid, which has fragmented into as many as ten smaller pieces.

Although fragile comet nuclei have been seen to fall apart as they approach the Sun, nothing like the breakup of this asteroid, P/2013 R3, has ever been observed before in the asteroid belt.

The crumbling asteroid was first noticed as an unusual, fuzzy-looking object on 15 September 2013 by the Catalina. Follow-up observations on 1 October with the Keck Telescope on Mauna Kea, Hawaii, revealed three co-moving bodies embedded in a dusty envelope that is nearly the diameter of Earth.

David Jewitt of UCLA, USA, who led the astronomical forensics investigation said that Keck showed us that this thing was worth looking at with Hubble.

The Hubble data showed that the fragments are drifting away from each other at a leisurely 1.5 kilometers per hour-slower than the speed of a strolling human. The asteroid began coming apart early last year, but the latest images show that pieces continue to emerge.

The ongoing discovery of more fragments makes it unlikely that the asteroid is disintegrating due to a collision with another asteroid, which would be instantaneous and violent in comparison to what has been observed. Some of the debris from such a high-velocity smash-up would also be expected to travel much faster than has been observed.

It is also unlikely that the asteroid is breaking apart due to the pressure of interior ices warming and vaporizing. The object is too cold for ices to significantly sublimate, and it has presumably maintained its nearly 480-million-kilometer distance from the Sun for much of the age of the solar system.

This leaves a scenario in which the asteroid is disintegrating due to a subtle effect of sunlight that causes the rotation rate to slowly increase over time. Eventually, its component pieces gently pull apart due to centrifugal force.