Evolved Climates and Observational Discriminants for the TRAPPIST-1 Planetary System

By A. Lincowski, V. Meadows, David Crisp, T. Robinson, R. Luger, J. Lustig-Yaeger, Giada N. Arney. Astrophysical Journal, 2018

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The TRAPPIST-1 planetary system provides an unprecedented opportunity to study terrestrial exoplanet evolution with the James Webb Space Telescope (JWST) and ground-based observatories. Since M dwarf planets likely experience extreme volatile loss, the TRAPPIST-1 planets may have highly evolved, possibly uninhabitable atmospheres. We used a versatile, 1D terrestrial planet climate model with line-by-line radiative transfer and mixing length convection (VPL Climate) coupled to a terrestrial photochemistry model to simulate environmental states for the TRAPPIST-1 planets. We present equilibrium climates with self-consistent atmospheric compositions and observational discriminants of postrunaway, desiccated, 10–100 bar O2- and CO2-dominated atmospheres, including interior outgassing, as well as for water-rich compositions. Our simulations show a range of surface temperatures, most of which are not habitable, although an aqua planet TRAPPIST-1 e could maintain a temperate surface given Earth-like geological outgassing and CO2. We find that a desiccated TRAPPIST-1 h may produce habitable surface temperatures beyond the maximum greenhouse distance. Potential observational discriminants for these atmospheres in transmission and emission spectra are influenced by photochemical processes and aerosol formation and include collision-induced oxygen absorption (O2–O2), and O3, CO, SO2, H2O, and CH4 absorption features, with transit signals of up to 200 ppm. Our simulated transmission spectra are consistent with K2, Hubble Space Telescope, and Spitzer observations of the TRAPPIST-1 planets. For several terrestrial atmospheric compositions, we find that TRAPPIST-1 b is unlikely to produce aerosols. These results can inform JWST observation planning and data interpretation for the TRAPPIST-1 system and other M dwarf terrestrial planets.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/f07b40346576ced78e35ab95844d69538a77be6c

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Citations in the corpus

The Detectability and Characterization of the TRAPPIST-1 Exoplanet Atmospheres with JWST (2019, methodology): “Distinguishing Specific Molecules We now present the sensitivity of each JWST instrument to each gas in the Lincowski et al. (2018) TRAPPIST-1 model transmission spectra.”
High Tide or Riptide on the Cosmic Shoreline? A Water-rich Atmosphere or Stellar Contamination for the Warm Super-Earth GJ 486b from JWST Observations (2023, background): “Both have strong bands between 3 and 5 μm, which can be probed by JWST. Secondary atmospheric CO2 is also potentially common across a range of terrestrial planetary conditions via outgassing (Lincowski et al. 2018), as seen on Venus, Earth, and Mars.”