http://arxiv.org/abs/1804.01209
Observations of Kuiper belt objects (KBOs) in Neptune’s 5:2 resonance present two puzzles: this third order resonance hosts a surprisingly large population, comparable to the prominent populations of Plutinos and Twotinos in the first order 3:2 and 2:1 resonances, respectively; secondly, their eccentricities are concentrated near 0.4. To shed light on these puzzles, we investigate the phase space near this resonance with use of Poincar\’e sections of the circular planar restricted three body model. We find several transitions in the phase space structure with increasing eccentricity, which we explain with the properties of the resonant orbit relative to Neptune’s. The resonance width is narrow for very small eccentricities, but widens dramatically for $e\gtrsim0.2$, reaching a maximum near $e\approx0.4$, where it is similar to the maximum widths of the 2:1 and 3:2 resonances. We confirm these results with N-body numerical simulations, including the effects of all four giant planets and a wide range of orbital inclinations of the KBOs. We find that the long term stability of KBOs in this resonance is not strongly sensitive to inclination and that the boundaries of the stable resonant zone are very similar to those found with the simplified three body model, with the caveat that orbits of eccentricity above $\sim0.55$ are unstable; such orbits are phase-protected from close encounters with Neptune but not from destabilizing encounters with Uranus. We conclude that the 5:2 resonant KBOs can be understood fairly naturally in light of the phase space structure and basic considerations of long term stability in this resonance.
R. Malhotra, L. Lan, K. Volk, et. al.
Thu, 5 Apr 18
37/50
Comments: Submitted to AAS Journals