An asteroid disintegrating into at least ten pieces has been observed by the Hubble Space Telescope. This is the first time in history such an event has been recorded.
The object, designated P/2013 R3, was in a stable orbit in the main asteroid belt, revolving around the Sun, between the planets Mars and Jupiter.
In many ways, P/2013 R3 was an oddball from the time it was first discovered on 15 September last year. Astronomers studying the object found the asteroid behaved like a comet in many ways.
The object was first discovered as part of the PanSTARRS and Catalina sky surveys. On 1 October 2013, astronomers aimed the Keck Telescope in Hawaii at the object. They found P/2013 R3 consisted of at least three bodies, moving together through space. The objects were surrounded by a cloud-like veil of dust and gas larger than the Earth.
A further study using the Hubble Space Telescope showed the image as ten different objects. Over time, they were seen moving slowly apart from one another, at a snail's pace of just one mile per hour. The four largest bodies are each 1200 feet in diameter.
"Seeing this rock fall apart before our eyes is pretty amazing," David Jewitt, a UCLA professor who led the study, said.
Astronomers believe the object started falling apart about a year ago. New pieces are being seen as additional images from Hubble are studied.
Why P/2013 R3 is breaking apart is still a question for researchers, and the cause may be one never seen before in astronomy. The leisurely rate of the breakup suggests the object did not collide with another body - such a collision would result in a much faster rate of disintegration. Heat within the interior is not likely to be the cause, either. The heat of the Sun in the asteroid belt is not great enough to cause this effect. Astronomers believe the Sun heated P/2013 R3, increasing the rate at which it rotated. As rotational velocity increased, the object fell apart from centrifugal force. This hypothetical process is called "YORP torque," and it has never before been seen in nature.
If this was the cause of the disintegration, the core of P/2013 R3 must have been fractured, allowing the break up to take place. This may have been caused by minor collisions with small objects before the disintegration started.
Sunlight may be a driving force behind the disintegration of many small asteroids, according to new studies. NASA recently announced the discovery of an asteroid, P/2013 P5, that is sending off gases, creating six distinct tails.
Study of the images was detailed on the Astrophysical Journal Letters on 6 March.
