Here are the two images hot off the press. The observations of a strange asteroid were taken about 58 hr apart. It was reported that Steve Larson of the Lunar and Planetary Laboratory, University of Arizona, had imaged the asteroid (596) Scheila on December 11.44-11.47 UT with the 0.68-m Schmidt telescope at Catalina and found it to be in apparent outburst with a comet-like appearance. This is the first well-documented occasion that a main-belt asteroid has been seen to be surrounded by a fuzzy coma.
It is likely that a much smaller object orbiting in the asteroid belt has collided with (596) Scheila excavating a crater of the order of 50-100 metres across and expelling thousands of tons of dust and rock to form a cloud of material in space. This cloud has an appearance similar to that of an outbursting comet. UK amateur astronomer Peter Birtwhistle has captured a nice image of the cloud of material which is spread out in two arcs - see: http://www.birtwhistle.org/Gallery(596)Scheila.htm
Richard Miles (BAA) has been using data taken with Faulkes Telescope North to analyse the phenomenon. The original image by Peter Birtwhistle shows that the surrounding cloud is reflecting around 70+-5% of the light which the asteroid reflects. The observations by Richard Miles (using FTN) indicates around 75 +/-4% is reflected by the debris but it has expanded slightly and faded a little compared with the earlier appearance. With more data and further analysis more details about the initial impact should be able to be determined.
Update - 17 December 2010
On today's image only the strongest 'jet' remains visible. There has been virtually no change in the coma in the sunward's direction for the past 5.5 days showing that radiation pressure is acting on what must be sub-micron sized dust preventing it expanding in that direction. As time goes on the dust close in to the asteroid will be diluted becoming coarser in size in the process.
The image below blinks between the images taken at Great Shefford Observatory and FTN (Provided courtesy of Peter Birtwhistle), showing that the coma is expanding.
We will keep you updated on the progress.
