SPH calculations of Mars-scale collisions: the role of the Equation of State, material rheologies, and numerical effects

TL;DR

This study uses SPH simulations to analyze large-scale impacts on a Mars-like planet, focusing on how material properties and numerical factors influence the post-impact distribution of material, temperature, and ejected mass.

Contribution

It investigates the effects of material strength, equations of state, and numerical artifacts on impact outcomes in Mars-scale collisions.

Findings

Material strength significantly affects temperature and material distribution after impact.

Equation of State has a subtle influence, noticeable only at very high temperatures.

Numerical effects related to density discontinuities and rotation are also examined.

Abstract

We model large-scale ($\approx$2000km) impacts on a Mars-like planet using a Smoothed Particle Hydrodynamics code. The effects of material strength and of using different Equations of State on the post-impact material and temperature distributions are investigated. The properties of the ejected material in terms of escaping and disc mass are analysed as well. We also study potential numerical effects in the context of density discontinuities and rigid body rotation. We find that in the large-scale collision regime considered here (with impact velocities of 4km/s), the effect of material strength is substantial for the post-impact distribution of the temperature and the impactor material, while the influence of the Equation of State is more subtle and present only at very high temperatures.