06/jul/17 – Dinâmica de pequenos satélites de Saturno I: região entre Mimas e Enceladus (Nelson Callegari, UNESP)

The dynamics of Methone, Anthe and Pallene, small bodies located between the orbits of the major Saturnian satellites Mimas and Enceladus, is investigated. In the first part, we give a detailed description of the mean-motion resonances (MMR) involving these small satellites and Mimas and/or Enceladus, where we correctly determine the critical angles associated to the MMRs, namely: 11:10 Mimas-Anthe, 15:14 Mimas-Methone, 19:16 Pallene-Enceladus in the osculating domain. In the second part we show the results of numerical integrations of ensembles of orbits taken around the current position of the small satellites. We determine the domains of the resonances in the frequency domain through Fourier spectra of the integrated orbits, which allow us to estimate the  evolution of fundamental frequencies of the system, i.e, the resonant ones and thoserelated to the long-term precession of the orbits due to the effects of oblateness of Saturn and mutual perturbations. Among our main results we also include our investigations on the detection of short-term, high-perturbation of the orbits of Methone and Anthe due to both Saturn’s oblateness and the very small eccentricity of orbits of Methone and Anthe. The consequences of these perturbation are that, in the osculating domain, the fast circulation of the pericenter of the orbits of Methone and Anthe avoid the libration of determined critical angles associated to the 11:10 Mimas-Anthe and 15:14 Mimas-Methone, so classical approach to study the dynamics of MMRs by isolating critical angles can be applied. We confirm our results with the recent data of the satellites orbits given by ephemeris system “Horizons”.