High-resolution reflection spectra for Proxima b and Trappist-1e models for ELT observations

TL;DR

This paper models high-resolution reflection spectra of Proxima b and Trappist-1e to aid upcoming ELT observations, highlighting key biosignatures and climate indicators for these nearby potentially habitable exoplanets.

Contribution

It provides detailed spectral models for two nearby habitable exoplanets across various atmospheric conditions, informing future high-resolution observational strategies.

Findings

Spectral features like O2, CH4, CO2, and H2O are detectable in the models.

High-resolution observations are essential to identify certain biosignatures like oxygen.

Proxima b and Trappist-1e are prime targets for upcoming ELT reflected light studies.

Abstract

The closest stars that harbor potentially habitable planets are cool M-stars. Upcoming ground- and space-based telescopes will be able to search the atmosphere of such planets for a range of chemicals. To facilitate this search and to inform upcoming observations, we model the high-resolution reflection spectra of two of the closest potentially habitable exoplanets for a range of terrestrial atmospheres and surface pressures for active and inactive phases of their host stars for both oxic and anoxic conditions: Proxima b, the closest potentially habitable exoplanet, and Trappist-1e, one of 3 Earth-size planets orbiting in the Habitable Zone of Trappist-1. We find that atmospheric spectral features, including biosignatures like O2 in combination with a reduced gas like CH4 for oxic atmospheres, as well as climate indicators like CO2 and H2O for all atmospheres, show absorption features in the spectra of Proxima b and Trappist-1e models. However for some features like oxygen, high-resolution observations will be critical to identify them in a planet's reflected flux. Thus these two planets will be among the best targets for upcoming observations of potential Earth-like planets in reflected light with planned Extremely Large Telescopes.