Interpretation of (596) Scheila's Triple Dust Tails

TL;DR

This study models the unique triple dust tails of asteroid (596) Scheila, attributing their formation to a decameter-sized impact that ejected high-velocity dust, revealing insights into the asteroid's surface composition.

Contribution

It presents a novel impact-driven model that successfully reproduces the triple tail morphology of Scheila, linking it to a specific impact event and material properties.

Findings

Impact from a decameter-sized asteroid caused the dust tails.

Ejection velocities exceeded 100 m/s.

Surface materials likely have low tensile strength.

Abstract

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 the result, we succeeded in the reproduction of peculiar dust cloud by an impact-driven ejecta plume consisting of an impact cone and downrange plume. Assuming an impact angle of 45 deg, our model suggests that a decameter-sized asteroid collided with (596) Scheila from the direction of (alpha, delta) = (60deg, -40deg) in J2000 coordinates on 2010 December 3. The maximum ejection velocity of the dust particles exceeded 100 m/s. Our results suggest that the surface of (596) Scheila consists of materials with low tensile strength.