New observations from Telescópio Espacial James Webb (JWST) indicate that the exoplanet TRAPPIST-1e, considered one of the most similar worlds to Terra, may not have an atmosphere. Initial Sinais of methane detected in 2023 was reinterpreted as contamination of the host star. The study, published November 3 in the journal The Astrophysical Journal Letters, highlights the need for more data to confirm the presence of any gaseous envelope.
The planet orbits in the habitable zone of the red dwarf TRAPPIST-1, 40 light years from Terra. Sua position allows temperatures compatible with liquid water on the surface, but only if there is an atmosphere to retain heat and protect against radiation.
- TRAPPIST-1e has a size and mass close to that of Terra.
- It receives intense ultraviolet radiation from the star, which accelerates the destruction of molecules.
- Observations took place during four transits in 2023 with the NIRSpec instrument.
JWST Initial Remarks
JWST captured variations in starlight during transits of TRAPPIST-1e. Inicialmente, the data suggested a nitrogen-rich atmosphere with traces of methane, similar to that of Titã, moon of Saturno.
Signals varied between transits. Isso indicated interference from the star TRAPPIST-1, a cool red dwarf where molecules like methane form naturally.
Researchers have ruled out thick hydrogen or carbon dioxide-dominated atmospheres, such as in Vênus or Marte.
Stellar Contamination in the Spotlight
Sukrit Ranjan, of Universidade of Arizona, led the analysis that questions the methane evidence. Ele explains that the star can produce the same signals observed.
Ultraviolet radiation destroys methane in TRAPPIST-1e thousands of times faster than in Titã. On the moon of Saturno, the gas persists for millions of years; on the exoplanet, it would only last 200 thousand years.
Geological processes such as volcanism or ice release would not be able to replace methane in the necessary amount.
Imagine this: Just 40 light-years away, orbiting a dim red dwarf star called TRAPPIST-1, there’s a rocky world the size of Earth — TRAPPIST-1e. For years, it’s teased astronomers as the ultimate “Goldilocks” planet: perfectly positioned in the habitable zone where liquid water…pic.twitter.com/V2Zb813FEB
—Black Hole (@konstructivizm)November 21, 2025
Models simulate unlikely scenarios
Simulations tested the feasibility of an Titã type atmosphere in TRAPPIST-1e.
Even under favorable conditions, methane would dissipate quickly without continued replenishment.
Maintaining detected levels would require extreme global volcanic activity or constant planetary resurfacing, scenarios considered implausible.
The results reinforce that the methane signal probably originates from the star, not the planet.
Limited lifespan of methane
In Titã, methane survives for 10 to 100 million years thanks to low radiation.
TRAPPIST-1e receives much larger doses of ultraviolet due to its proximity to the active star.
Any atmospheric methane would disappear in about 200,000 years.
Next steps in observations
Scientists plan observations of double transits, when TRAPPIST-1e and TRAPPIST-1b (without atmosphere) cross the star together.
The comparison will separate stellar signals from planetary ones.
NASA’s Pandora mission, launched in 2026, will observe stars and planets simultaneously to reduce contamination.
An additional 15 transits of TRAPPIST-1e are scheduled at JWST.
Challenges with red dwarfs
Stars like TRAPPIST-1 are cool enough to form molecules in their own atmosphere. Isso complicates the detection of planetary atmospheres.
JWST operates at the sensitivity limit for planets the size of Terra.
TRAPPIST-1e remains among the best candidates for habitable worlds, but the overriding question now is confirming any atmosphere.
Ranjan emphasizes that, if there is a gaseous envelope, the planet would be habitable, but current data does not allow this to be confirmed.
Future perspectives for the system
The TRAPPIST-1 system has seven compact rocky planets. TRAPPIST-1e is fourth from the star.
Previous observations have ruled out atmospheres on the innermost planets.
Techniques like double transits promise to clarify confusing signals.
Despite the uncertainties, the exoplanet remains a priority in searches for worlds similar to Terra.
Implications for the search for life
The presence of an atmosphere is essential for liquid water and radiation protection.
Methane signals in Terra are linked to biological processes.
In the case of TRAPPIST-1e, the stellar origin reduces initial optimism.
New missions and observations will refine understanding of exoplanets in habitable zones.
TRAPPIST-1e exemplifies the challenges in characterizing distant worlds with current technology.
