Observations of Exoplanet Atmospheres

TL;DR

This paper reviews current knowledge of exoplanet atmospheres, highlighting recent progress, key atmospheric processes, and future prospects with upcoming observational facilities.

Contribution

It provides an observer's perspective on the state of exoplanet atmospheric characterization and discusses the challenges and opportunities ahead.

Findings

Advances in understanding molecular and atomic abundances.

Insights into cloud properties and thermal structures.

Anticipation of rapid discoveries with next-generation telescopes.

Abstract

Detailed characterization of an extrasolar planet's atmosphere provides the best hope for distinguishing the makeup of its outer layers, and the only hope for understanding the interplay between initial composition, chemistry, dynamics & circulation, and disequilibrium processes. In recent years, some areas have seen rapid progress while developments in others have come more slowly and/or have been hotly contested. This article gives an observer's perspective on the current understanding of extrasolar planet atmospheres prior to the considerable advances expected from the next generation of observing facilities. Atmospheric processes of both transiting and directly-imaged planets are discussed, including molecular and atomic abundances, cloud properties, thermal structure, and planetary energy budgets. In the future we can expect a continuing and accelerating stream of new discoveries, which will fuel the ongoing exoplanet revolution for many years to come.