Checking the Compatibility of the Cold Kuiper Belt with a Planetary Instability Migration Model

TL;DR

This paper examines whether a more violent planetary instability can explain the cold Kuiper belt's structure, suggesting in situ formation with specific outer edge constraints fits observations.

Contribution

It demonstrates that a violent instability scenario with a compact resonant configuration can reproduce the cold Kuiper belt's features.

Findings

Cold Kuiper belt's structure can be explained by a violent planetary instability.

In situ formation with an outer edge between 44-45 au is consistent with observations.

A less eccentric Neptune orbit during instability is compatible with the belt's structure.

Abstract

The origin of the orbital structure of the cold component of the Kuiper belt is still a hot subject of investigation. Several features of the solar system suggest that the giant planets underwent a phase of global dynamical instability, but the actual dynamical evolution of the planets during the instability is still debated. To explain the structure of the cold Kuiper belt, Nesvorny (2015, AJ 150,68) argued for a soft instability, during which Neptune never achieved a very eccentric orbit. Here we investigate the possibility of a more violent instability, from an initially more compact fully resonant configuration of 5 giant planets. We show that the orbital structure of the cold Kuiper belt can be reproduced quite well provided that the cold population formed in situ, with an outer edge between 44 and 45 au and never had a large mass.