Exoplanet Atmosphere Forecast: Observers Should Expect Spectroscopic Transmission Features to be Muted to 33%

TL;DR

This paper highlights that most exoplanet transmission spectra lack clear molecular features, emphasizing the need for high SNR observations to detect muted atmospheric signals, which are often less than 33% of expected amplitudes.

Contribution

It provides an analysis of 37 exoplanet spectra showing that clear molecular features are rare, informing future observational strategies.

Findings

Clear molecular features in <7% of spectra

Most spectra show muted features around 33% of expected amplitude

High SNR is essential for detecting atmospheric signatures

Abstract

To ensure robust constraints are placed on exoplanet atmospheric transmission spectra, future observations need to obtain high signal-to-noise ratio (SNR) measurements assuming smaller amplitude molecular signatures than those of clear solar metallicity atmospheres. Analyzing 37 exoplanet transmission spectra we find clear solar molecular features are measured in <7% of cases.