Giant impacts stochastically change the internal pressures of terrestrial planets

Abstract

Pressure is a key parameter in the physics and chemistry of planet formation and evolution. Previous studies have erroneously assumed that internal pressures monotonically increase with the mass of a body. Using smoothed particle hydrodynamics and potential field method calculations, we demonstrate that the hot, rapidly-rotating bodies produced by giant impacts can have much lower internal pressures than cool, slowly-rotating planets of the same mass. Pressures subsequently increase due to thermal and rotational evolution of the body. Using the Moon-forming impact as an example, we show that the internal pressures after the collision could have been less than half that in present-day Earth. The current pressure profile was not established until Earth cooled and the Moon receded, a process that may take up to 10s Myr after the last giant impact. Our work defines a new paradigm for pressure evolution during accretion of terrestrial planets: stochastic changes driven by impacts.

arXiv commentMain text: 23 pages, 6 figures. Supplementary material: 10 pages, 8 figures. Published in Science Advances

References in corpus (11)

• The cosmological simulation code GADGET-2
• Accretion and differentiation of the terrestrial planets with implications for the compositions of early-formed Solar System bodies and accretion of water
• Collisions Between Gravity-Dominated Bodies: 1. Outcome Regimes and Scaling Laws
• Collisions between Gravity-Dominated Bodies: 2. The Diversity of Impact Outcomes during the End Stage of Planet Formation
• The origin of the Moon within a terrestrial synestia
• Melting and Mixing States of the Earth's Mantle after the Moon-Forming Impact
• Formation of Terrestrial Planets from Protoplanets under a Realistic Accretion Condition
• Multiple Impact Origin for the Moon
• Tidal evolution of the Moon from a high-obliquity, high-angular-momentum Earth
• The structure of terrestrial bodies: Impact heating, corotation limits and synestias
• The Tethered Moon

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• The Role of Giant Impacts in Planet Formation
• Effect of Equation of State and Cutoff Density in Smoothed Particle Hydrodynamics Simulations of the Moon-Forming Giant Impact
• The "Drake equation" of exomoons -- a cascade of formation, stability and detection
• Planets or asteroids? A geochemical method to constrain the masses of White Dwarf pollutants
• The energy budgets of giant impacts