Anisotropic tidal dissipation in misaligned planetary systems

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Main Authors: Auclair-Desrotour, Pierre, Boué, Gwenaël, Loire, Baptiste
Format: Preprint
Published: 2024
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author Auclair-Desrotour, Pierre
Boué, Gwenaël
Loire, Baptiste
author_facet Auclair-Desrotour, Pierre
Boué, Gwenaël
Loire, Baptiste
contents Tides are the main driving force behind the long-term evolution of planetary systems. The associated energy dissipation and momentum exchanges are commonly described by Love numbers, which relate the exciting potential to the tidally perturbed potential. These transfer functions are generally assumed to depend solely on tidal frequency and body rheology, following the isotropic assumption, which presumes invariance of properties by rotation about the centre of mass. We examine the limitations of the isotropic assumption for fluid bodies, where Coriolis acceleration breaks spherical symmetry, resulting in rotational scattering and complex tidal responses. Using angular momentum theory, we derive a new formalism to calculate the tidal rates of energy and momentum transfers in non-isotropic cases. We apply this formalism to the Earth-Moon system to assess the effects of anisotropy in planet-satellite systems with misaligned spin and orbital angular momenta. Our findings indicate that the isotropic assumption can introduce significant errors in planetary evolution models, particularly in the dynamical tide regime. These errors stem from forced wave resonances, with inaccuracies in energy dissipation scaling in proportion to resonance amplification factors.
format Preprint
id arxiv_https___arxiv_org_abs_2412_13149
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Anisotropic tidal dissipation in misaligned planetary systems
Auclair-Desrotour, Pierre
Boué, Gwenaël
Loire, Baptiste
Earth and Planetary Astrophysics
Atmospheric and Oceanic Physics
Geophysics
85-02
Tides are the main driving force behind the long-term evolution of planetary systems. The associated energy dissipation and momentum exchanges are commonly described by Love numbers, which relate the exciting potential to the tidally perturbed potential. These transfer functions are generally assumed to depend solely on tidal frequency and body rheology, following the isotropic assumption, which presumes invariance of properties by rotation about the centre of mass. We examine the limitations of the isotropic assumption for fluid bodies, where Coriolis acceleration breaks spherical symmetry, resulting in rotational scattering and complex tidal responses. Using angular momentum theory, we derive a new formalism to calculate the tidal rates of energy and momentum transfers in non-isotropic cases. We apply this formalism to the Earth-Moon system to assess the effects of anisotropy in planet-satellite systems with misaligned spin and orbital angular momenta. Our findings indicate that the isotropic assumption can introduce significant errors in planetary evolution models, particularly in the dynamical tide regime. These errors stem from forced wave resonances, with inaccuracies in energy dissipation scaling in proportion to resonance amplification factors.
title Anisotropic tidal dissipation in misaligned planetary systems
topic Earth and Planetary Astrophysics
Atmospheric and Oceanic Physics
Geophysics
85-02
url https://arxiv.org/abs/2412.13149