Dynamical origin of the Dwarf Planet Ceres

TL;DR

This study models the early Solar System's dynamical evolution to explore how Ceres-sized planetesimals could have been implanted into the asteroid belt from the trans-Saturnian region, explaining Ceres' unique composition.

Contribution

It provides a quantitative analysis of the capture probability and orbital characteristics of Ceres-sized bodies migrating into the asteroid belt from the outer Solar System.

Findings

Capture probability of 2.8e-5 to 1.2e-3 for Ceres-sized bodies.

70% chance of captured bodies having semimajor axes between 2.5 and 3 au.

Estimated 15-51% probability of Ceres being in different regions of the asteroid belt.

Abstract

The Dwarf Planet Ceres revealed the presence of ammonia and other unique properties compared to other asteroids in the main belt which suggests that it was not formed in situ. We model the early dynamical evolution of the outer Solar System to study possible dynamical mechanisms to implant a Ceres-sized planetesimal in the asteroid belt from the trans-Saturnian region. We calculate that the fraction of the population of Ceres-sized planetesimals that are captured in the asteroid belt is in the range of 2.8e-5 to 1.2e-3 depending on the initial location in the outer planetesimal disk. The captured bodies have a 70% probability to have a semimajor axis between 2.5 and 3 au, a 33% probability to have an eccentricity smaller than 0.2 and a 45% probability to have an orbital inclination smaller than 10 degrees. Assuming the existence of 3,600 Ceres-size planetesimals in the inner part of the trans-Saturnian disk, consistent with the estimate of Nesvorny & Vokrouhlicky (2016) for the trans-Neptunian disk, our estimated capture probability and a final 80% depletion of the asteroid belt during the subsequent giant planet instability, lead to capture 1 Ceres in the asteroid belt, with a probability of 15%, 34%, and 51% to be located in the inner, middle and outer belt respectively.