Exoplanet Atmospheres

TL;DR

Since the first detection of exoplanet atmospheres in the early 2000s, the field has advanced significantly, enabling the study of atmospheric composition, temperature gradients, and the search for biosignatures on potentially habitable planets.

Contribution

This paper reviews the historical development, current state, and future prospects of exoplanet atmosphere research, highlighting key observational achievements and goals.

Findings

Detection of molecular spectral features in exoplanet atmospheres

Observation of day-night temperature gradients

Constraints on vertical atmospheric structure

Abstract

At the dawn of the first discovery of exoplanets orbiting sun-like stars in the mid-1990s, few believed that observations of exoplanet atmospheres would ever be possible. After the 2002 Hubble Space Telescope detection of a transiting exoplanet atmosphere, many skeptics discounted it as a one-object, one-method success. Nevertheless, the field is now firmly established, with over two dozen exoplanet atmospheres observed today. Hot Jupiters are the type of exoplanet currently most amenable to study. Highlights include: detection of molecular spectral features; observation of day-night temperature gradients; and constraints on vertical atmospheric structure. Atmospheres of giant planets far from their host stars are also being studied with direct imaging. The ultimate exoplanet goal is to answer the enigmatic and ancient question, "Are we alone?" via detection of atmospheric biosignatures. Two exciting prospects are the immediate focus on transiting super Earths orbiting in the habitable zone of M-dwarfs, and ultimately the spaceborne direct imaging of true Earth analogs.