Assessing the Habitability of the TRAPPIST-1 System Using a 3D Climate Model

By E. Wolf. 2017

169 citations recorded by the source corpus.

The TRAPPIST-1 system provides an extraordinary opportunity to study multiple terrestrial extrasolar planets and their atmospheres. Here, we use the National Center for Atmospheric Research Community Atmosphere Model version 4 to study the possible climate and habitability of the planets in the TRAPPIST-1 system. We assume the worlds are ocean-covered, with atmospheres composed of N2, CO2, and H2O, and with orbital and geophysical properties defined from observation. Model results indicate that the inner three planets (b, c, and d) presently reside interior to the inner edge of the traditional liquid water habitable zone. Thus, if water ever existed on the inner planets, they would have undergone a runaway greenhouse and lost their water to space, leaving them dry today. Conversely, the outer three planets (f, g, and h) fall beyond the maximum CO2 greenhouse outer edge of the habitable zone. Model results indicate that the outer planets cannot be warmed, despite having as much as 30 bar CO2 atmospheres, instead entering a snowball state. The middle planet (e) represents the best chance for a presently habitable ocean-covered world in the TRAPPIST-1 system. Planet e can maintain at least some habitable surface area with 0–2 bar CO2, depending on the background N2 content. Near-present-day Earth surface temperatures can be maintained for an ocean-covered planet e with either 1 bar N2 + 0.4 bar CO2, or a 1.3 bar pure CO2 atmosphere.

Subfields: Astronomy and Astrophysics, Atmospheric Science, Global and Planetary Change

View Paper: https://www.semanticscholar.org/paper/c34ee480de74a73fbf9592aaee76732ee2824539

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In Astronomy and Astrophysics

1. Jon Fortney
2. T. Robinson
3. Laura Kreidberg
4. J. Leconte
5. F. Selsis
6. N. Madhusudhan
7. C. Morley
8. V. Meadows

In Atmospheric Science

1. J. Leconte
2. F. Selsis
3. T. Robinson
4. J. Naar
5. Jon Fortney
6. Francois Forget
7. Giada N. Arney
8. V. Meadows

In Global and Planetary Change

1. J. Leconte
2. F. Selsis
3. T. Robinson
4. J. Naar
5. Jon Fortney
6. Francois Forget
7. Giada N. Arney
8. V. Meadows

Citations in the corpus

• The Transit Light Source Effect: False Spectral Features and Incorrect Densities for M-dwarf Transiting Planets (2017, background): “…radiation from the host star (Wheatley et al. 2017), however, can lead to significant water loss for these planets (Bolmont et al. 2017), and 3D climate modeling suggests TRAPPIST-1e provides the best opportunity for present-day surface water and an Earth-like temperature in the system (Wolf 2017).”
• Modeling climate diversity, tidal dynamics and the fate of volatiles on TRAPPIST-1 planets (2017, methodology): “This would suppress the runaway glaciation positive feedback invoked by Wolf (2017).”
• Observing the Atmospheres of Known Temperate Earth-sized Planets with JWST (2017, methodology): “Wolf (2017) assessed the relative habitability of each of the TRAPPIST-1 planets using a climate model (National Center for Atmospheric Research Community Atmosphere Model), and find that TRAPPIST-1e is the most amenable to liquid water on the surface.”
• Exoplanet Biosignatures: A Review of Remotely Detectable Signs of Life (2017, result): “, 2016b) while also showing perhaps more pessimistic results for the outer edge compared with 1D results (Wolf, 2017).”