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Journal Articles Celestial Mechanics and Dynamical Astronomy Year : 2022

Librations of a body composed of a deformable mantle and a fluid core

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Abstract

We present fully three-dimensional equations to describe the rotations of a body made of a deformable mantle and a fluid core. The model in its essence is similar to that used by INPOP19a (Integration Planétaire de l'Observatoire de Paris) Fienga et al. (INPOP19a planetary ephemerides. Notes Scientifiques et Techniques de l'Institut de Mécanique Céleste, vol 109, 2019), and by JPL (Jet Propulsion Laboratory) (Park et al. The JPL Planetary and Lunar Ephemerides DE440 and DE441. Astron J 161(3):105, 2021. doi:10.3847/1538-3881/abd414), to represent the Moon. The intended advantages of our model are: straightforward use of any linear-viscoelastic model for the rheology of the mantle; easy numerical implementation in time-domain (no time lags are necessary); all parameters, including those related to the "permanent deformation", have a physical interpretation. The paper also contains: (1) A physical model to explain the usual lack of hydrostaticity of the mantle (permanent deformation). (2) Formulas for free librations of bodies in and out-of spin-orbit resonance that are valid for any linear viscoelastic rheology of the mantle. (3) Formulas for the offset between the mantle and the idealised rigid-body motion (Peale's Cassini states). (4) Applications to the librations of Moon, Earth, and Mercury that are used for model validation.

Dates and versions

insu-03718986 , version 1 (10-07-2022)

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Clodoaldo Ragazzo, Gwenaël Boué, Yeva Gevorgyan, Lucas S. Ruiz. Librations of a body composed of a deformable mantle and a fluid core. Celestial Mechanics and Dynamical Astronomy, 2022, 134, ⟨10.1007/s10569-021-10055-3⟩. ⟨insu-03718986⟩
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