The Prospect of Detecting Volcanic Signatures on an ExoEarth Using Direct Imaging

TL;DR

This study explores the potential of using direct imaging to detect volcanic activity on Earth-like exoplanets by analyzing simulated spectra influenced by volcanic eruptions, focusing on ozone and spectral slope changes as key indicators.

Contribution

It introduces a climate model-based simulation of volcanic signatures on exoEarth spectra, identifying observable spectral features indicative of volcanism for future telescope observations.

Findings

Ozone absorption features are significantly affected by volcanism.

Spectral slope changes serve as reliable indicators of volcanic activity.

Detection of volcanic signatures requires specific observation times and spectral analysis.

Abstract

The James Webb Space Telescope (JWST) has provided the first opportunity to study the atmospheres of terrestrial exoplanets and estimate their surface conditions. Earth-sized planets around Sun-like stars are currently inaccessible with JWST however, and will have to be observed using the next generation of telescopes with direct imaging capabilities. Detecting active volcanism on an Earth-like planet would be particularly valuable as it would provide insight into its interior, and provide context for the commonality of the interior states of Earth and Venus. In this work we used a climate model to simulate four exoEarths over eight years with ongoing large igneous province eruptions with outputs ranging from 1.8-60 Gt of sulfur dioxide. The atmospheric data from the simulations were used to model direct imaging observations between 0.2-2.0 $\mu$m, producing reflectance spectra for every month of each exoEarth simulation. We calculated the amount of observation time required to detect each of the major absorption features in the spectra, and identified the most prominent effects that volcanism had on the reflectance spectra. These effects include changes in the size of the O$_3$, O$_2$, and H$_2$O absorption features, and changes in the slope of the spectrum. Of these changes, we conclude that the most detectable and least ambiguous evidence of volcanism are changes in both O$_3$ absorption and the slope of the spectrum.