A bizarre spinning object, described by NASA as "weird and freakish"
and shooting jets of matter that causes it to move, has been spotted in
our Solar System.
The mysterious rock, located in the asteroid
belt between Mars and Jupiter, was seen spewing matter from its surface
by the Hubble space 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," said Prof Jewitt, whose study of the rock [
PDF] was
published in the
Astrophysical Journal of Letters. "This is an amazing object and almost certainly the first of many more to come."
