TRAPPIST-1 planets’ climates modeled with energy balance approach

Star system: TRAPPIST-1 | Distance from the Sun: 40.7 light years

TRAPPIST-1 is a system of planets orbiting a low-mass star, with several planets considered potentially habitable. This study uses a version of the HEXTOR energy balance model to explore the possible climate states of these planets, focusing on those that are similar to Earth and orbit in a way that keeps the same side facing their star. The model is first tested on rapidly rotating, Earth-like planets and shows expected patterns of climate stability. It is then adapted for tidally locked planets, like TRAPPIST-1 e and f, and calibrated using results from more complex climate models.

The model examines how different amounts of sunlight and carbon dioxide affect the surface temperatures of these planets. Results suggest that TRAPPIST-1 e could have regions with partial ice cover, while TRAPPIST-1 f would be completely ice-covered unless it has a high carbon dioxide pressure, around one bar or more. This approach shows that even simple models can provide useful insights into the climates of planets around low-mass stars and help guide future observations and more detailed studies.

The findings highlight the usefulness of energy balance models for predicting climate states on exoplanets, especially those in synchronous rotation. These models can help identify which planets are most likely to be habitable and worth further investigation.

Key findings
- Energy balance model adapted for tidally locked planets like TRAPPIST-1 e and f.
- TRAPPIST-1 e may have partial ice cover; TRAPPIST-1 f likely fully ice-covered without high carbon dioxide.
- Model calibrated with general circulation model data for accuracy.
- Simple models can guide more complex studies and observations.
- Approach helps identify promising habitable planet candidates.

Scientific study

Exploring TRAPPIST-1 Climate States with an Energy Balance Model (external link)