Diversity of Exoplanets

TL;DR

This review discusses the diversity, formation, and composition of low-mass exoplanets, highlighting observational advances, compositional variability, and insights from white dwarf studies during stellar evolution.

Contribution

It provides a comprehensive overview of low-mass exoplanet diversity, formation processes, and recent observational developments, especially with JWST's contributions.

Findings

Diverse compositions observed among low-mass exoplanets

JWST is advancing small planet characterization

White dwarf studies offer insights into exoplanet composition during stellar evolution

Abstract

This review article delves into the study of low-mass exoplanets: super-Earths, mini-Neptunes and the new categories within and between that we are starting to discover. We provide an overview of current exoplanet observational capabilities, their limitations, and what they are allowing us to learn about low-mass planets. We briefly summarize the most important aspects of planet formation, with an emphasis on processes that may be testable with small exoplanets, in particular those that affect their composition. We also describe the observed compositional diversity of low-mass exoplanets and what it teaches us about planet formation pathways. We finish this review summarizing the study of the composition of small exoplanets during the very last stage of stellar evolution, by studying white dwarfs. This review is written as the JWST is making its first contributions to small planet characterization, rapidly opening new lines of inquiry.