# The long-term evolution of known resonant trans-Neptunian objects

## TL;DR

This study models the long-term orbital evolution of resonant trans-Neptunian objects beyond 50 au, revealing that most are unaffected by resonance over giga-year timescales, while some exhibit significant oscillations due to resonance effects.

## Contribution

It introduces a secular model to analyze the long-term evolution of resonant trans-Neptunian objects, highlighting the varying impact of resonance on their orbital dynamics.

## Key findings

- Most objects have secular dynamics similar to non-resonant cases.
- Some objects show high-amplitude oscillations due to resonance.
- Resonance explains the high perihelion of 2015 FJ345 and suggests past resonance for 2014 FZ71.

## Abstract

Aims. Numerous trans-Neptunian objects are known to be in mean-motion resonance with Neptune. We aim to describe their long-term orbital evolution (both past and future) by means of a one-degree-of-freedom secular model. In this paper, we focus only on objects with a semi-major axis larger than 50 astronomical units (au). Methods. For each resonant object considered, a 500 000-year numerical integration is performed. The output is digitally filtered to get the parameters of the resonant secular model. Their long-term (Giga-year) orbital evolution is then represented by the level curves of the secular Hamiltonian. Results. For the majority of objects considered, the mean-motion resonance has little impact on the long-term trajectories (the secular dynamics is similar to a non-resonant one). However, a subset of objects is strongly affected by the resonance, producing moderately-high-amplitude oscillations of the perihelion distance and/or libration of the argument of perihelion around a fixed centre. Moreover, the high perihelion distance of the object 2015 FJ345 is plainly explained by long-term resonant dynamics, allowing us to also deduce its orbital elements at the time of capture in resonance (at least 15 million years ago). The same type of past evolution is expected for 2014 FZ71.