Composition of Solar System Small Bodies

TL;DR

This chapter reviews the compositional diversity of small bodies in the solar system, discusses dynamical models, and proposes a primordial compositional gradient before planetary migrations, providing a synthetic overview of their distribution.

Contribution

It offers a comprehensive synthesis of small bodies' compositions and evaluates their implications for solar system formation models.

Findings

Identification of compositional differences across small body reservoirs

Discussion of dynamical models and their caveats

Proposal of a primordial compositional gradient

Abstract

The aim of the chapter is to summarize our understanding of the compositional distribution across the different reservoirs of small bodies (main belt asteroids, giant planet trojans, irregular satellites of the giant planets, TNOs, comets). We then use this information to i) discuss current dynamical models (Nice and Grand Tack models), ii) mention possible caveats in these models if any, and iii) draw a preliminary version of the primordial compositional gradient across the solar system before planetary migrations occured. Note that the composition of both planetary satellites (the regular ones) and that of the transient populations (NEOs, centaurs) is not discussed here. We strictly focus on the composition of the main reservoirs of small bodies. The manuscript's objective is to provide a global and synthetic view of small bodies' compositions rather than a very detailed one, for specific reviews regarding the composition of small bodies, see papers by Burbine (2014) for asteroids, Emery et al. (2015) for Jupiter trojans, Mumma and Charnley (2011) for comets, and Brown (2012) for KBOs.