Early Dynamical Evolution of the Solar System: Pinning Down the Initial Condition of the Nice Model

TL;DR

This paper investigates the initial conditions of the Solar System compatible with the Nice model, identifying eight resonant configurations that lead to the current orbital architecture through dynamical evolution involving eccentric phases and planetary scattering.

Contribution

It identifies and characterizes eight fully-resonant initial conditions for the Solar System that support the Nice model's evolution to current planetary orbits.

Findings

Eight initial conditions compatible with the Nice model identified.

Four initial states align with the canonical Nice model.

Other states suggest alternative evolutionary pathways.

Abstract

In the recent years, the "Nice" model of solar system formation has attained an unprecedented level of success in reproducing much of the observed orbital architecture of the solar system by evolving the planets to their current locations from a more compact configuration. Within the context of this model, the formation of the classical Kuiper belt requires a phase during which the ice giants have a high eccentricity. An outstanding question of this model is the initial configuration from which the Solar System started out. Recent work has shown that multi-resonant initial conditions can serve as good candidates, as they naturally prevent vigorous type-II migration. In this paper, we use analytical arguments, as well as self-consistent numerical N-body simulations to identify fully-resonant initial conditions, whose dynamical evolution is characterized by an eccentric phase of the ice-giants, as well as planetary scattering. We find a total of eight such initial conditions. Four of these primordial states are compatible with the canonical "Nice" model, while the others imply slightly different evolutions. The results presented here should prove useful in further development of a comprehensive model for solar system formation.