Tidal Evolution of the Evection Resonance/Quasi-Resonance and the Angular Momentum of the Earth-Moon System

Abstract

Forming the Moon by a high-angular momentum impact may explain the Earth-Moon isotopic similarities, however, the post-impact angular momentum needs to be reduced by a factor of 2 or more to the current value (1 L_EM) after the Moon forms. Capture into the evection resonance, occurring when the lunar perigee precession period equals one year, could remove the angular momentum excess. However the appropriate angular momentum removal appears sensitive to the tidal model and chosen tidal parameters. In this work, we use a constant-time delay tidal model to explore the Moon's orbital evolution through evection. We find that exit from formal evection occurs early and that subsequently, the Moon enters a quasi-resonance regime, in which evection still regulates the lunar eccentricity even though the resonance angle is no longer librating. Although not in resonance proper, during quasi-resonance angular momentum is continuously removed from the Earth-Moon system and transferred to Earth's heliocentric orbit. The final angular momentum, set by the timing of quasi-resonance escape, is a function of the ratio of tidal strength in the Moon and Earth and the absolute rate of tidal dissipation in the Earth. We consider a physically-motivated model for tidal dissipation in the Earth as the mantle cools from a molten to a partially molten state. We find that as the mantle solidifies, increased terrestrial dissipation drives the Moon out of quasi-resonance. For post-impact systems that contain >2 L_EM, final angular momentum values after quasi-resonance escape remain significantly higher than the current Earth-Moon value.

accepted to JGR-Planets

References in corpus (3)

• Melting and Mixing States of the Earth's Mantle after the Moon-Forming Impact
• Dynamics of Planetary Systems in Star Clusters
• Analytical Model for the Tidal Evolution of the Evection Resonance and the Timing of Resonance Escape

Cited by in corpus (10)

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• Collision Chains among the Terrestrial Planets. III. Formation of the Moon
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• Effect of Equation of State and Cutoff Density in Smoothed Particle Hydrodynamics Simulations of the Moon-Forming Giant Impact
• Can tidal evolution lead to close-in planetary bodies around white dwarfs I: Orbital period distribution
• Can tidal evolution lead to close-in planetary bodies around white dwarfs II: volcanism and transits
• The Limited Role of the Streaming Instability During Moon and Exomoon Formation
• The Moon-forming Impact as a Constraint for the Inner Solar System's Formation
• The possibility of a giant impact on Venus
• The Resonant Tidal Evolution of the Earth-Moon Distance