As telescopes have turn out to be extra highly effective, we’ve been discovering tons of “exoplanets”—planets orbiting faraway stars.
One such planet, referred to as exoplanet TRAPPIST-1 d, has intrigued astronomers in search of probably liveable worlds past our photo voltaic system; it’s comparable in measurement to Earth, rocky, and resides in an space round its star the place liquid water on its floor is theoretically potential.
But in keeping with a new study utilizing information from NASA’s James Webb Space Telescope, it doesn’t have an Earth-like environment.
“Ultimately, we want to know if something like the environment we enjoy on Earth can exist elsewhere, and under what conditions,” stated Caroline Piaulet-Ghorayeb of the University of Chicago and Trottier Institute for Research on Exoplanets (IREx) at Université de Montréal, lead writer of the examine revealed Aug. 13 in The Astrophysical Journal. “While NASA’s James Webb Space Telescope is giving us the ability to explore this question in Earth-sized planets for the first time, at this point we can rule out TRAPPIST-1 d from a list of potential Earth twins or cousins.”
Planet TRAPPIST-1 d
The TRAPPIST-1 system is situated 40 light-years away and was revealed because the record-holder for many Earth-sized rocky planets round a single star in 2017, because of information from NASA’s retired Spitzer Space Telescope and different observatories.
TRAPPIST-1 d, the third planet, is way nearer to its star than Earth is to the solar—it completes a complete orbit round its star in solely 4 Earth days—but it surely’s nonetheless the proper temperature for liquid water, as a result of its star is way dimmer and cooler than our solar.
The Webb Telescope was capable of take an in depth have a look at TRAPPIST-1 d’s environment utilizing its near-infrared spectrograph instrument. It didn’t detect molecules which can be widespread in Earth’s environment, like water, methane or carbon dioxide.
However, Piaulet-Ghorayeb outlined a number of prospects for the exoplanet that stay open for follow-up examine.
“There are a few potential reasons why we don’t detect an atmosphere around TRAPPIST-1 d,” she defined. “It could have an extremely thin atmosphere that is difficult to detect, somewhat like Mars. Alternatively, it could have very thick, high-altitude clouds that are blocking our detection of specific atmospheric signatures—something more like Venus. Or, it could be a barren rock, with no atmosphere at all.”
The star
No matter what the case could also be for TRAPPIST-1 d, it’s powerful being a planet in orbit round a purple dwarf star.
TRAPPIST-1, the host star of the system, is understood to be risky, typically releasing flares of high-energy radiation with the potential to strip off the atmospheres of its small planets, particularly these orbiting most intently.
Nevertheless, scientists are motivated to hunt indicators of atmospheres on the TRAPPIST-1 planets as a result of purple dwarf stars are the most typical stars in our galaxy. If planets can maintain on to an environment right here, underneath waves of harsh stellar radiation, they might, because the saying goes, make it wherever.
“Webb’s sensitive infrared instruments are allowing us to delve into the atmospheres of these smaller, colder planets for the first time,” stated Björn Benneke of IREx at Université de Montréal, a co-author of the examine. “We’re really just getting started using Webb to look for atmospheres on Earth-sized planets, and to define the line between planets that can hold onto an atmosphere, and those that cannot.”
Sibling planets
TRAPPIST-1 has a minimum of six different planets orbiting it. The two closest to the star have already been dominated out as liveable, however scientists are utilizing Webb to watch the 4 which can be additional past.
These maintain each potential and peril. On the one hand, Benneke stated, planets e, f, g and h could have higher probabilities of having atmospheres as a result of they’re additional away from the energetic eruptions of their host star. However, their distance and colder atmosphere will make atmospheric signatures harder to detect, even with Webb’s infrared devices.
“All hope is not lost for atmospheres around the TRAPPIST-1 planets,” Piaulet-Ghorayeb stated. “While we didn’t find a big, bold atmospheric signature for planet d, there is still potential for the outer planets to be holding onto a lot of water and other atmospheric components.”
The James Webb Space Telescope is a global program led by NASA with its companions, ESA (European Space Agency) and CSA (Canadian Space Agency).
Citation: “Strict Limits on Potential Secondary Atmospheres on the Temperate Rocky Exo-Earth TRAPPIST-1 d.” Piaulet-Ghorayeb et al, The Astrophysical Journal, Aug. 13, 2025.
Funding: Canadian Space Agency, Natural Sciences and Engineering Research Council, Trottier Family Foundation, Brinson Foundation, Fonds de recherche du Québec—Nature et applied sciences, iREx, SNSF, Sorbonne University, BELSPO BRAIN, InitiaSciences, TESS Guest Investigator Program, Swiss National Science Foundation, NRC Canada.