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Dynamical Tides in Jupiter as Revealed by Juno

Idini, Benjamin and Stevenson, David J. (2021) Dynamical Tides in Jupiter as Revealed by Juno. Planetary Science Journal, 2 (2). Art. No. 69. ISSN 2632-3338. doi:10.3847/PSJ/abe715.

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The Juno orbiter has continued to collect data on Jupiter's gravity field with unprecedented precision since 2016, recently reporting a nonhydrostatic component in the tidal response of the planet. At the mid-mission perijove 17, Juno registered a Love number k₂ = 0.565 ± 0.006 that is −4% ± 1% (1σ) from the theoretical hydrostatic k₂^((hs))=0.590. Here we assess whether the aforementioned departure of tides from hydrostatic equilibrium represents the neglected gravitational contribution of dynamical tides. We employ perturbation theory and simple tidal models to calculate a fractional dynamical correction Δk₂ to the well-known hydrostatic k₂. Exploiting the analytical simplicity of a toy uniform-density model, we show how the Coriolis acceleration motivates the negative sign in the Δk₂ observed by Juno. By simplifying Jupiter's interior into a coreless, fully convective, and chemically homogeneous body, we calculate Δk₂ in a model following an n = 1 polytrope equation of state. Our numerical results for the n = 1 polytrope qualitatively follow the behavior of the uniform-density model, mostly because the main component of the tidal flow is similar in each case. Our results indicate that the gravitational effect of the Io-induced dynamical tide leads to Δk₂ = − 4% ± 1%, in agreement with the nonhydrostatic component reported by Juno. Consequently, our results suggest that Juno obtained the first unambiguous detection of the gravitational effect of dynamical tides in a gas giant planet. These results facilitate a future interpretation of Juno tidal gravity data with the purpose of elucidating the existence of a dilute core in Jupiter.

Item Type:Article
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URLURL TypeDescription Paper
Idini, Benjamin0000-0002-2697-3893
Stevenson, David J.0000-0001-9432-7159
Additional Information:© 2021. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Received 2020 December 4; revised 2021 February 2; accepted 2021 February 15; published 2021 April 6. We acknowledge the support of NASA's Juno mission. B.I. thanks Erin Burkett for her comments. We acknowledge the constructive comments from two anonymous referees. Software: Matplotlib (Hunter 2007).
Funding AgencyGrant Number
Subject Keywords:Tides; Jupiter; Gravitational fields; Galilean satellites; Planetary interior
Issue or Number:2
Classification Code:Unified Astronomy Thesaurus concepts: Tides (1702); Jupiter (873); Gravitational fields (667); Galilean satellites (627); Planetary interior (1248)
Record Number:CaltechAUTHORS:20210422-104346137
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Official Citation:Benjamin Idini and David J. Stevenson 2021 Planet. Sci. J. 2 69
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:108803
Deposited By: Tony Diaz
Deposited On:23 Apr 2021 17:54
Last Modified:16 Nov 2021 19:32

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