Asteroid Breaking Apart Seen by Hubble


An astronomical forensics investigation was led by David Jewitt of the University of California at Los Angeles in order to determine the cause of an asteroid breaking apart. The asteroid observed, P/2013 R3, is located in the asteroid belt between Mars and Jupiter. While asteroids have certainly been breaking apart for countless years, never before has the process been documented by scientists. This particular asteroid, P/2013 R3, has been seen breaking apart by researchers using the Hubble Space Telescope.

An asteroid might fragment when it drifts too near the sun and the ices create vapor out-gassing, which in turn causes the structure to split apart. Recently, this has been seen with Comet ISON in November 2013. However, P/2013 R3 is too far away from the sun for this to have occurred. Additionally, the pieces of the asteroid are moving too slowly for the break up to have happened due to a collision. Scientists were left wondering as to the cause of the disintegration until the data from the Hubble Telescope could be analyzed.

The detailed observations as seen from the Hubble Space Telescope revealed the process responsible for the asteroid breaking apart. The Yarkovsky-O’Keefe-Radzievskii-Paddack (YORP) effect is the currently held theory about the reason behind the fragmentation. The YORP effect happens when the larger side of an asymmetrical rock is heated up by the sun and then rotates away into darkness. As it rotates, the bigger portion can radiate more energy than the smaller areas and increase the spin rate. When the spin rate becomes greater than the ability of the asteroid to hold together, the asteroid succumbs to centrifugal forces and simply falls apart.

The observations from the W. M. Keck Observatory in Hawaii have confirmed rock bodies moving together and enveloped in a field of dust almost the size of Earth. The asteroid may have broken into as many as ten discrete pieces. Discovered on Sept. 15, 2013 by the surveys from Catalina and Pan-STARRS, a closer look was taken by researchers using the superior resolution of the Hubble Space Telescope in October. The examination found that there were a number of pieces, the four largest of which are almost 200 yards in radius, twice the length of a football field.

While the asteroid has been fragmenting since last year, recent images show that new pieces continue to appear. The pieces are slowly drifting away from each other at about one mile per hour. Asteroid P/2013 R3 most likely had a structurally weakened interior, possibly from collisions with other asteroids. The belief is that most smaller asteroids are damaged in this manner, giving them fractured internal configurations.

The debris from this disintegration, which weighs about 200,000 tons, will likely become future meteoroids. The belief is that most of them will fall into the Sun yet the possibility remains that some of them will hit the Earth. The observations of P/2013 R3 through the Hubble Space Telescope will likely continue, as scientists have never before seen an asteroid breaking apart in this manner.

By Dee Mueller


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