The air over there: exploring exoplanet atmospheres

TL;DR

This paper reviews how exoplanet atmospheric compositions depend on planetary bulk, orbit, and formation history, highlighting upcoming observational advances and challenges for studying terrestrial planet atmospheres.

Contribution

It consolidates current knowledge from giant planet atmospheres and discusses future observational prospects and challenges for terrestrial exoplanet atmospheres.

Findings

Atmospheric composition depends on planetary bulk and orbit.

Upcoming observatories will enhance atmospheric characterization.

Challenges remain in studying terrestrial exoplanet atmospheres.

Abstract

Atmospheric compositions for rocky exoplanets will depend strongly on the bulk planetary composition and the orbital position of the planet. Non-traditional gases may be present in the atmospheres of exceptionally hot planets. Atmospheres of more clement planets will depend on the abundances of volatiles acquired during planet formation and atmospheric removal processes, including escape, condensation, and reaction with the surface. While the observations of exoplanet atmospheres to date has focused on giant planets, a series of new space and ground-based observatories over the coming decade will revolutionize the precision and spectral resolution with which we are able to probe exoplanet atmospheres. This article consolidates lessons learned from the study of giant planet atmospheres, and points to the observations and challenges on the horizon for terrestrial planets.