# Transient Sulfate Aerosols as a Signature of Exoplanet Volcanism

**Authors:** Amit Misra, Joshua Krissansen-Totton, Matthew C. Koehler, Steven Sholes  
**arXiv:** [1504.04629](https://arxiv.org/abs/1504.04629)  
**Date:** 2015-04-17  
**Summary page:** https://www.summarizepaper.com/en/paper/1504.04629v1/

## Key points

- The search for habitable exoplanets is a major focus in astronomy
- Geological activity is important for the origin of life and maintaining planetary habitability
- Transient sulfate aerosols could be a signature of exoplanet volcanism, indicating a geologically active world
- Detection of these aerosols linked to volcanism could aid in evaluating the habitability of an exoplanet
- Rapid increase and gradual decrease in sulfate aerosol loading associated with eruptions may be detectable with future large-aperture telescopes such as JWST and E-ELT for a planetary system at 10 pc distance
- A signal-to-noise ratio (S/N) of 12.1 and 7.1 could be achieved with E-ELT (assuming photon-limited noise) for an Earth-analog orbiting a Sun-like star and M5V star respectively, even without multiple transits binned together
- Detection of this transient signal would strongly suggest an exoplanet volcanic eruption if potential false positives such as dust storms or bolide impacts can be ruled out
- Detecting transient aerosols linked to volcanism along with O2 would provide more robust biosignatures than O2 alone
- Detecting transient sulfate aerosols could provide valuable insights into exoplanetary geology and habitability evaluations using future telescopes' capabilities

## Summary

The search for habitable exoplanets has been a major focus in astronomy and geological activity is thought to be important for the origin of life and maintaining planetary habitability. In a recent study by Amit Misra et al., it was proposed that transient sulfate aerosols could be a signature of exoplanet volcanism, indicating a geologically active world. The detection of these aerosols linked to volcanism could aid in evaluating the habitability of an exoplanet. On Earth, subduction-induced explosive eruptions inject SO2 directly into the stratosphere leading to the formation of sulfate aerosols with lifetimes of months to years. The authors demonstrated that the rapid increase and gradual decrease in sulfate aerosol loading associated with these eruptions may be detectable in transit transmission spectra with future large-aperture telescopes such as the James Webb Space Telescope (JWST) and European Extremely-Large Telescope (E-ELT) for a planetary system at a distance of 10 pc. They found that even without multiple transits binned together, a signal-to-noise ratio (S/N) of 12.1 and 7.1 could be achieved with E-ELT (assuming photon-limited noise) for an Earth-analog orbiting a Sun-like star and M5V star respectively. The detection of this transient signal would strongly suggest an exoplanet volcanic eruption if potential false positives such as dust storms or bolide impacts can be ruled out. Furthermore, because scenarios exist where O2 can form abiotically in the absence of volcanic activity, detecting transient aerosols linked to volcanism along with O2 would provide more robust biosignatures than O2 alone. This study highlights how detecting transient sulfate aerosols could provide valuable insights into exoplanetary geology and habitability evaluations using future telescopes' capabilities.