Three-dimensional structure of mean motion resonances beyond Neptune

Abstract

We propose a semianalytical method for the calculation of widths, libration centers and small-amplitude libration periods of the mean motion resonances $k_p$:k in the framework of the circular restricted three-body problem valid for arbitrary eccentricities and inclinations. Applying the model to the trans-Neptunian region, we obtain several atlas of resonances between 30 and 100 au, showing their domain in the plane (a, e) for different orbital inclinations. The resonance width may change substantially when varying the argument of the perihelion of the resonant object, and in order to take into account these variations, we introduce the concept of resonance fragility. Resonances 1:k and 2:k are the widest, strongest, most isolated ones and associated with lower fragility for all intervals of inclinations and eccentricities. We discuss the existence of high $k_p$:k resonances. We analyze the distribution of the resonant populations inside resonances 1:1, 2:3, 3:5, 4:7, 1:2 and 2:5. We found that the populations are in general located near the regions of the space (e, i) where the resonances are wider and less fragile with the notable exception of the population inside the resonance 4:7 and in a lesser extent the population inside 3:5 which are shifted to lower eccentricities.