TRAPPIST-1E Atmosphere and Habitability: Could an Earth-like World Exist Around a Dim Red Dwarf?

The video investigates James Webb Space Telescope observations of TRAPPIST-1E, assessing whether this Earth-sized rocky planet could sustain an atmosphere and possibly harbor life. It explains transmission spectroscopy, what the data imply about atmospheric compositions, and compares Earth-like, methane-dominated, and other scenarios within the unique environment of a tidally locked planet orbiting a red dwarf.

Introduction to TRAPPIST-1E and the System

The host star TRAPPIST-1 is an M8 red dwarf, far dimmer than the Sun, with seven rocky planets all tightly packed in close orbits. TRAPPIST-1E sits in the habitable zone, receiving about two thirds the energy of Earth and is about 0.9 Earth radii. Its proximity makes it an excellent testbed for atmospheric studies with the James Webb Space Telescope (JWST).

Observational Approach

JWST uses transmission spectroscopy to detect an atmosphere by measuring light blocked during transits and how the spectrum changes with wavelength. The Dreams team has already observed four transits of TRAPPIST-1E, using JWST’s near infrared capabilities to search for spectral signatures of gases such as nitrogen, methane, and carbon dioxide. Signatures indicate whether an atmosphere is primordial, CO2 rich, or dominated by heavier molecules typical of a secondary atmosphere.

Atmospheric Scenarios and Implications

Early results rule out a primordial hydrogen-helium atmosphere and a thick CO2 Venus-like atmosphere. An Earth-like, nitrogen-dominated atmosphere with greenhouse gases remains plausible and could support surface habitability with heat transfer that prevents a total dark-side freeze. An alternative is a methane-rich atmosphere that could cool the planet through a reverse greenhouse effect, potentially creating stable conditions near the terminator where life might arise. The study also considers the planet as a possible icy world with subsurface oceans. The star’s activity, especially flares, could strip atmospheres over time, but a magnetic field and tidal heating may help sustain one.

Future Prospects

With additional transit observations planned, researchers aim to confirm or rule out CO2 and determine if a secondary atmosphere exists. The Habitable Worlds Observatory, planned for 2041, could provide more definitive answers about the atmospheres of TRAPPIST-1E and its siblings and whether life could exist in this nearby system.