Dynamical formation of detached trans-Neptunian objects close to the 2:5 and 1:3 mean motion resonances with Neptune

¹ Instituto Nacional de Pesquisas Espaciais (INPE), ETE/DMC, Av. dos Astronautas, 1758 São José dos Campos, Brazil
e-mail: pedro_brasil87@hotmail.com
² Observatório Nacional (ON), GPA, Rua General José Cristino, 77, 20921-400 Rio de Janeiro, Brazil
e-mail: rodney@on.br

Received: 7 June 2013
Accepted: 29 January 2014

Abstract

Aims. It is widely accepted that the past dynamical history of the solar system included a scattering of planetesimals from a primordial disk by the major planets. The primordial scattered population is likely the origin of the current scaterring disk and possibly the detached objects. In particular, an important argument has been presented for the case of 2004XR₁₉₀ as having an origin in the primordial scattered disk through a mechanism including the 3:8 mean motion resonance (MMR) with Neptune. Here we aim at developing a similar study for the cases of the 1:3 and 2:5 resonances that are stronger than the 3:8 resonance.

Methods. Through a semi-analytic approach of the Kozai resonance inside an MMR, we show phase diagrams (e,ω) that suggest the possibility of a scattered particle, after being captured in an MMR with Neptune, to become a detached object. We ran several numerical integrations with thousands of particles perturbed by the four major planets, and there are cases with and without Neptune’s residual migration. These were developed to check the semi-analytic approach and to better understand the dynamical mechanisms that produce the detached objects close to an MMR.

Results. The numerical simulations with and without a residual migration for Neptune stress the importance of a particular resonance mode, which we name the hibernating mode, on the formation of fossilized detached objects close to MMRs. When considering Neptune’s residual migration we are able to show the formation of detached orbits. These objects are fossilized and cannot be trapped in the MMRs again. We find a ratio of the number of fossilized objects with moderate perihelion distance (35 < q < 40 au) to the number of objects with high perihelion distance (q > 40 au) as 3.0/1 for objects close to the 2:5, and 1.7/1 for objects close to the 1:3 resonance. We estimate that the two fossilized population have a total mass between 0.1 and 0.3 Pluto’s mass.