Dynamics, Origin, and Activation of Main Belt Comets

TL;DR

This paper investigates the dynamics and activation mechanisms of Main Belt Comets, suggesting they formed in-situ from icy asteroid remnants and that collisions may trigger their activity, with some potentially contributing water to Earth.

Contribution

It provides new numerical simulations showing the stability of MBC orbits, their potential to reach terrestrial planets, and the role of collisions in activating cometary activity.

Findings

Many MBCs have stable orbits with low eccentricity and inclination.

Approximately 20% of scattered MBCs could reach Earth's region.

Collisions can expose sub-surface ice, triggering activity.

Abstract

The discovery of Main Belt Comets (MBCs) has raised many questions regarding the origin and activation mechanism of these objects. Results of a study of the dynamics of these bodies suggest that MBCs were formed in-situ as the remnants of the break-up of large icy asteroids. Simulations show that similar to the asteroids in the main belt, MBCs with orbital eccentricities smaller than 0.2 and inclinations lower than 25 degrees have stable orbits implying that many MBCs with initially larger eccentricities and inclinations might have been scattered to other regions of the asteroid belt. Among scattered MBCs, approximately 20 percent reach the region of terrestrial planets where they might have contributed to the accumulation of water on Earth. Simulations also show that collisions among MBCs and small objects could have played an important role in triggering the cometary activity of these bodies. Such collisions might have exposed sub-surface water ice which sublimated and created thin atmospheres and tails around MBCs. This paper discusses the results of numerical studies of the dynamics of MBCs and their implications for the origin of these objects. The results of a large numerical modeling of the collisions of m-sized bodies with km-sized asteroids in the outer part of the asteroid belt are also presented and the viability of the collision-triggering activation scenario is discussed.