Chaotic Dynamics of Trans-Neptunian Objects Perturbed by Planet Nine

TL;DR

This study investigates the complex chaotic dynamics of trans-Neptunian objects influenced by a hypothetical Planet Nine, revealing resonance overlap and chaos as key factors in their orbital evolution.

Contribution

The paper introduces a simplified mapping model to analyze resonance overlap and chaos in TNO dynamics perturbed by Planet Nine, enhancing understanding of their orbital behavior.

Findings

Chaos and resonance overlap significantly influence TNO orbital evolution.

Gravitational interactions with Neptune affect TNO dynamics.

The mapping model clarifies the web of mean-motion resonances.

Abstract

Observations of clustering among the orbits of the most distant trans-Neptunian objects (TNOs) has inspired interest in the possibility of an undiscovered ninth planet lurking in the outskirts of the solar system. Numerical simulations by a number of authors have demonstrated that, with appropriate choices of planet mass and orbit, such a planet can maintain clustering in the orbital elements of the population of distant TNOs, similar to the observed sample. However, many aspects of the rich underlying dynamical processes induced by such a distant eccentric perturber have not been fully explored. We report the results of our investigation of the dynamics of coplanar test-particles that interact with a massive body on an circular orbit (Neptune) and a massive body on a more distant, highly eccentric orbit (the putative Planet Nine). We find that a detailed examination of our idealized simulations affords tremendous insight into the rich test-particle dynamics that are possible. In particular, we find that chaos and resonance overlap plays an important role in particles' dynamical evolution. We develop a simple mapping model that allows us to understand, in detail, the web of overlapped mean-motion resonances explored by chaotically evolving particles. We also demonstrate that gravitational interactions with Neptune can have profound effects on the orbital evolution of particles. Our results serve as a starting point for a better understanding of the dynamical behavior observed in more complicated simulations that can be used to constrain the mass and orbit of Planet 9.