EPSC Abstracts Vol. 13, EPSC-DPS2019-1303-1, 2019 EPSC-DPS Joint Meeting 2019 c Author(s) 2019. CC Attribution 4.0 license. Chaos in the inert Oort cloud Melaine Saillenfest (1), Marc Fouchard (1), and Arika Higuchi (2) (1) IMCCE, Observatoire de Paris, France, (2) RISE Project Office/NAOJ, Mitaka, Tokyo, Japan e-mail:
[email protected] µ 16 Abstract 2 εP − εG ÝÖ 14 2 We investigate the orbital dynamics of small bodies in aÙ 9 12 the intermediate regime between the Kuiper belt and − 10 the Oort cloud, i.e. where the planetary perturbations ´ 10 and the galactic tides have the same order of magni- 8 tude. We show that this region is far less inert than it could appear at first sight, despite very weak orbital 6 perturbations. Ô eÖØÙÖbaØiÓÒ 4 Øhe Óf 2 1. Introduction ×iÞe 0 0 500 1000 1500 2000 2500 3000 aÜi× ´aÙµ The orbits of distant trans-Neptunian objects are sub- ×eÑi¹Ña jÓÖ a ject to internal perturbations from the planets, and ex- ternal perturbations from the galactic tides. A distinc- Figure 1: Size of the small parameters appearing in tion is generally made between the Kuiper belt and the the Hamiltonian function (Eq. 1) with respect to the Oort cloud, which are thought to have been initially semi-major axis of the small body. The red curve rep- populated through distinct mechanisms (see e.g. the resents the planetary perturbations, and the blue curve recent review by [4]). However, there is no dynamical represents the galactic tides. boundary between the two populations, and numerical simulations show a continuous transfer of objects in 2.