Implications of second-order resonance for the thermal and orbital evolution of Mimas. Issue 1 (6th December 2019)

• Record Type: Journal Article
• Authors: Tian, ZhenLiang; Nimmo, Francis
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 492:Issue 1(2020)
• Page Start: 369
• Page End: 376
• Publication Date: 2019-12-06
• Subjects: celestial mechanics -- planets and satellites: dynamical evolution and stability -- planets and satellites: formation -- planets and satellites: interiors; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/stz3427
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: Mimas's current eccentricity is not being excited by any present-day resonance. We investigate whether its eccentricity could have been excited by passage through the set of resonances associated with the Mimas:Enceladus 3:2 commensurability, which occurred roughly 0.3 Gyr ago. Both the 3:2 e -Mimas resonance and the 6:4 mixed resonance can explain the present-day eccentricity without violating heat flux constraints imposed by the absence of relaxation of the Herschel impact basin. We favour the 6:4 mixed resonance because it occurs first and often prevents capture into the subsequent 3:2. During passage through the 6:4 the k 2 / Q of Mimas was less than $\rm 2\times 10^{-5}$, while that of Enceladus was $\lt \rm \sim 5\times 10^{-5}$ . Mimas's lack of dissipation can be explained by a cold, rigid ice shell and no subsurface ocean, while Enceladus must have subsequently become more dissipative, probably as a result of its capture into the 2:1 resonance with Dione.