Inclination damping on Callisto. Issue 1 (14th September 2020)

• Record Type: Journal Article
• Authors: Downey, Brynna G; Nimmo, Francis; Matsuyama, Isamu
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 499:Issue 1(2020)
• Page Start: 40
• Page End: 51
• Publication Date: 2020-09-14
• Subjects: planets and satellites: dynamical evolution and stability -- planets and satellites: interiors -- planets and satellites: oceans; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/staa2802
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: Callisto is thought to possess a subsurface ocean, which will dissipate energy due to obliquity tides. This dissipation should have damped any primordial inclination within 1 Gyr – and yet Callisto retains a present-day inclination. We argue that Callisto's inclination and eccentricity were both excited in the relatively recent past (∼0.3 Gyr). This excitation occurred as Callisto migrated outwards according to the 'resonance-locking' model and passed through a 2:1 mean-motion resonance with Ganymede. Ganymede's orbital elements were likewise excited by the same event. To explain the present-day orbital elements, we deduce a solid-body tidal k 2 / Q ≈ 0.05 for Callisto and a significantly lower value for Ganymede.