INTERPRETATION OF (596) SCHEILA'S TRIPLE DUST TAILS

Strange-looking dust cloud around asteroid (596) Scheila was discovered on 2010 December 11.44–11.47. Unlike normal cometary tails, it consisted of three tails and faded within two months. We constructed a model to reproduce the morphology of the dust cloud based on the laboratory measurement of high-velocity impacts and the dust dynamics. As a result, we succeeded in reproducing the peculiar dust cloud by an impact-driven ejecta plume consisting of an impact cone and downrange plume. Assuming an impact angle of 45°, our model suggests that a decameter-sized asteroid collided with (596) Scheila from the direction of (αim, δim) = (60°, −40°) in J2000 coordinates on 2010 December 3. The maximum ejection velocity of the dust particles exceeded 100 m s−1. Our results suggest that the surface of (596) Scheila consists of materials with low tensile strength.

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