Anisotropic Ejection from Active Asteroid P/2010 A2: An Implication of Impact Shattering on an Asteroid

Abstract

We revisited a mass ejection phenomenon that occurred in asteroid P/2010 A2 in terms of the dynamical properties of the dust particles and large fragments. We constructed a model assuming anisotropic ejection within a solid cone-shaped jet and succeeded in reproducing the time-variant features in archival observational images over ~3 years from 2010 January to 2012 October. When we assumed that the dust particles and fragments were ejected in the same direction from a point where no object had been detected in any observations, the anisotropic model can explain all of the observations including (i) the unique dust cloud morphology, (ii) the trail surface brightness and (iii) the motions of the fragments. Our results suggest that the original body was shattered by an impact with the specific energy of Q* <~ 350 J/kg, and remnants of slow antipodal ejecta (i.e., anisotropic ejection in our model) were observed as P/2010 A2. The observed quantities are consistent with those obtained through laboratory impact experiments, supporting the idea that the P/2010 A2 event is the first evidence of the impact shattering occurred in the present main asteroid belt.

accepted for publication in The Astronomical Journal

References in corpus (3)

• A collision in 2009 as the origin of the debris trail of asteroid P/2010 A2
• Cometary Dust Trail Associated with Rosetta Mission Target: 67P/Churyumov-Gerasimenko
• 2014-2015 Multiple Outbursts of 15P/Finlay

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• Activity of main-belt comet 324P/La Sagra
• Nucleus of active asteroid 358P/Pan-STARRS (P/2012 T1)
• The appearance of a 'fresh' surface on 596 Scheila as a consequence of the 2010 impact event