Tidal pull of the Earth strips the proto-Moon of its volatiles
Abstract
Prevailing models for the formation of the Moon invoke a giant impact between a planetary embryo and the proto-Earth \citep{Canup_2004, Cuk_Stewart_2012}. Despite similarities in the isotopic and chemical abundances of refractory elements compared to Earth's mantle, the Moon is depleted in volatiles \citep{Wolf_Anders_1980}. Current models favour devolatilisation via incomplete condensation of the proto-Moon in an Earth-Moon debris-disk \citep{Charnoz_Michaut_2015,Canup_2015,Lock_2018}. However the physics of this protolunar disk is poorly understood and thermal escape of gas is inhibited by the Earth's strong gravitational field \citep{Nakajima_Stevenson_2014}. Here we investigate a simple process, wherein the Earth's tidal pull promotes intense hydrodynamic escape from the liquid surface of a molten proto-Moon assembling at 3-6 Earth radii. Such tidally-driven atmospheric escape persisting for less than 1 Kyr at temperatures K reproduces the measured lunar depletion in K and Na.
Keywords
Cite
@article{arxiv.2105.00917,
title = {Tidal pull of the Earth strips the proto-Moon of its volatiles},
author = {S. Charnoz and P. A. Sossi and Y-N Lee and J. Siebert and R. Hyodo and L. Allibert and F. C. Pignatale and M. Landeau and A. V. Oza and F. Moynier},
journal= {arXiv preprint arXiv:2105.00917},
year = {2021}
}
Comments
Accepted for publication in ICARUS