A record of planet migration in the Main Asteroid Belt

TL;DR

This paper investigates the distribution of asteroids in the Main Belt, revealing patterns of depletion linked to historical planetary migrations and resonance sweeping, which shaped the current asteroid distribution.

Contribution

It provides evidence that asteroid depletion patterns are due to ancient planetary migration, not just current planetary perturbations.

Findings

Depletion patterns are associated with specific Jupiter resonances.

Asteroid distribution shows excess depletion outside stable regions.

Migration of Jupiter and Saturn caused resonance sweeping affecting asteroid orbits.

Abstract

The main asteroid belt lies between the orbits of Mars and Jupiter, but the region is not uniformly filled with asteroids. There are gaps, known as the Kirkwood gaps, in the asteroid distribution in distinct locations that are associated with orbital resonances with the giant planets; asteroids placed in these locations follow chaotic orbits and escape from the asteroid belt. Here we show that the observed distribution of main belt asteroids does not fill uniformly even those regions that are dynamically stable over the age of the solar system. We find a pattern of excess depletion of asteroids, particularly just outward of the Kirkwood Gaps associated with the 5:2, the 7:3, and the 2:1 jovian resonances. These features are not accounted for by planetary perturbations in the current structure of the solar system, but are consistent with dynamical ejection of asteroids by the sweeping of gravitational resonances during the migration of Jupiter and Saturn ~4 gigayears ago.