The mysterious rock, located in the asteroid belt between Mars and Jupiter, was seen spewing matter from its surface by the telescope on September 10. Then in a second image taken on September 23 the asteroid, dubbed P/2013 P5, appeared to have swung around significantly.
Professor David Jewitt – of the Department of Earth and Space Sciences at the University of California, Los Angeles – told The Register that the appearance of the asteroid is unique, and the team has some ideas of how it came to exhibit such unusual characteristics.
“One idea was that we were seeing ice on the asteroid outgassing, but the object is too hot, around 170 Kelvin, for ice,” he explained. “An impact with the asteroid was discussed but that would leave one large plume, not six.”
The current idea is that the asteroid is being spun around so quickly that it is breaking apart under the strain of its own rotation. The spin is probably the result of hundreds of thousands of years of slight pressure from solar emissions.
Stars like our Sun emit protons and radiation that can push against objects in its heliosphere, and for asteroids of a certain shape these emissions cause rotation. Since the pressure from the Sun is constant, and space is virtually frictionless, then asteroids can spin faster and faster until they disintegrate.
This YORP effect (named after the four scientists who contributed to the theory: Yarkovsky, O’Keefe, Radzievskii, and Paddack) has been suggested as a reason for the relative paucity of small, asymmetrical objects within our Solar System in comparison to rounder rocks, and the search is now on for more observations of the theory in action.
“In astronomy, where you find one, you eventually find a whole bunch more,” Prof Jewitt said. “This is an amazing object and almost certainly the first of many more to come.” ®
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