New constraints on Saturn’s interior from Cassini astrometric data

By V. Lainey, R. Jacobson, R. Tajeddine, N. Cooper, C. Murray, V. Robert, Gabriel Tobie, T. Guillot, S. Mathis, F. Remus and 8 more. 2015

166 citations recorded by the source corpus.

Using astrometric observations spanning more than a century and including a large set of Cassini data, we determine Saturn's tidal parameters through their current effects on the orbits of the eight main and four coorbital Moons. We have used the latter to make the first determination of Saturn's Love number from observations, k2=0.390 ± 0.024, a value larger than the commonly used theoretical value of 0.341 (Gavrilov & Zharkov, 1977), but compatible with more recent models (Helled & Guillot, 2013) for which the static k2 ranges from 0.355 to 0.382. Depending on the assumed spin for Saturn's interior, the new constraint can lead to a significant reduction in the number of potential models, offering great opportunities to probe the planet's interior. In addition, significant tidal dissipation within Saturn is confirmed (Lainey et al., 2012) corresponding to a high present-day tidal ratio k2/Q=(1.59 ± 0.74) × 10−4 and implying fast orbital expansions of the Moons. This high dissipation, with no obvious variations for tidal frequencies corresponding to those of Enceladus and Dione, may be explained by viscous friction in a solid core, implying a core viscosity typically ranging between 1014 and 1016 Pa.s (Remus et al., 2012). However, a dissipation increase by one order of magnitude at Rhea's frequency could suggest the existence of an additional, frequency-dependent, dissipation process, possibly from turbulent friction acting on tidal waves in the fluid envelope of Saturn (Ogilvie & Lin, 2004; Fuller et al. 2016).

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/19606c82e407369e056ec8f2d57b2bbd706ddcbc

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In Astronomy and Astrophysics

1. J. Leconte
2. F. Selsis
3. Francois Forget
4. É. Bolmont
5. M. Turbet
6. J. Naar
7. M. Gillon
8. Gabriel Tobie

Citations in the corpus

• Modeling climate diversity, tidal dynamics and the fate of volatiles on TRAPPIST-1 planets (2017, result): “The lowest value we consider here, which is comparable to the dissipation estimated in Saturn (Lainey et al. 2017), would be representative of planets dominated by tidal response of a massive fluid envelop.”