Two-dimensional numerical modeling of the Rheasilvia impact formation

Abstract

We numerically modeled the formation of Rheasilvia crater, an enormous impact basin centered on asteroid 4 Vesta's south pole. Using a trial and error method, our models were adjusted to produce the best possible fit to Rheasilvia's size and shape, as observed during the Vesta orbital stage of the Dawn mission. The final model yields estimates of the shock wave decay, escaped material volume, depth of excavation, and other relevant characteristics, to the extent allowed by the two-dimensional (axially symmetric) approximation of the Simplified Arbitrary Lagrangian Eulerian hydrocode. Our model results permit interpretation of the Dawn data on Vesta's shape, topographic crater profiles, and the origin of the Vestoid asteroid family as escaped ejecta from the Rheasilvia crater. Key Points The numerical model is fitted to reproduce Rheasilvia crater size and shape We estimate shock decay, escaped mass, and excavation depth We analyze the Rheasilvia crater formation over the older Veneneia basin ©2013. American Geophysical Union. All Rights Reserved.