The Implications of Shock Heating in Giant Impacts and their Remnants*

Planet formation involves collisions of large, similarly sized bodies (i.e. giant impacts) [1]. These events are studied using hydrodynamic simulations [e.g. 2], as well as laboratory measurements extrapolated to larger scales [e.g. 3]. As planets grow, their escape (and thus impact) velocities exceed the sound speed, which generates shocks, exacerbates numerical effects, and causes deviations from scaling laws. For example, there is a notable increase in erosion in supersonic collisions beyond what is expected from scaling laws [4]. We performed SPH giant impact simulations that span the supersonic transition<!-- Can you cite our publication?
-->. We find that as planets grow, their ejected debris is predominantly vapor, helping explain the dearth of mantle debris in the asteroid belt [5]. We also find that reimpacting ejecta induces excess post-impact heating compared to velocity-scaling derived for cratering scenarios [e.g. 2]. Finally, we demonstrate how SPH artificial viscosity and resolution strongly influence thermodynamic fate of impact remnants.

[1] Wetherill, G. W. ARA&A 18.1 (1980)

[2] Okeefe, J. D., and T. J. Ahrens. LPSC. Vol. 8. (1977)

[3] Kraus, Richard G., et al. Nat. Geosci 8.4 (2015)

[4] Gabriel, T.S.J., et al. ApJ 892.1 (2020)

[5] Bell, J. F., Davis., et al. Asteroids II (1989)