TRAPPIST-1d is back in the news: the latest observations of the james webb space telescope indicate that this rocky world shows no signs of a gaseous envelope similar to that of the EarthThe discovery, published in The Astrophysical Journal, reduces the chances of this candidate in the temperate zone conserving liquid water in area.
Far from a silent oasis, the data points to a planet exposed to intense radiation already marked thermal changes, a consequence of orbiting very close to a red dwarf particularly active. With this, astronomers recalibrate the search for stable atmospheres in similar systems.
What did the James Webb find on TRAPPIST-1?
With its near-infrared spectrograph NIRSpec, the James Webb analyzed the light during the planet's transits and did not detect clues to key molecules such as water (H₂O), methane (CH₄) or carbon dioxide (CO₂). The absence of these signatures indicates that, if an atmosphere exists, it would be too thin or difficult to detect with current techniques.
The team led by Caroline Piaulet-Ghorayeb (University of Chicago and IREx, University of Montreal) raises several scenarios: an atmosphere Very fine similar to that of Mars, a cover of high clouds and opaque like Venus, which would hide the signs, or simply a world without air exposed to space. In any case, the planet is not on the list of possible Earthly “twins.”
According to co-authors such as Bjorn Benneke, the work represents an advance in precision when studying atmospheres of small and cold worlds with an unprecedented level of detail. The methodology and quality of the data open the door to a more in-depth analysis of other planets in the system with greater precision.
A compact system under an active star
The system TRAPPIST-1 it is about 40 light years, in the constellation of Aquarius, and houses seven rocky planets of similar size to the Earth's. They all revolve around a ultracool red dwarf which, despite its smaller size, is very active.
TRAPPIST-1d is the third planet from the star and is located near the edge of the habitable zoneIts orbit is so close that it is located just one 2% of the Earth-Sun distance and completes a “year” in approximately four days terrestrial, which exposes it to continuous energy bombardment.
Previous observations have already ruled out dense atmospheres on the nearest worlds, such as TRAPPIST-1b. Since its discovery in 2017, this compact system has become an ideal laboratory to explore how well it can withstand the planetary atmospheres in extreme environments.
Why is it so difficult to retain an atmosphere?
The red dwarfs they emit frequently flames and high energy radiation capable of erode slowly eroding the atmospheres of nearby planets. In compact, highly irradiated worlds, gas loss can outstrip replenishment, leaving bare surfaces.
When there isn't one gaseous envelope that cushions the temperature and filters the radiation, the terrain suffers from extreme temperatures and very hostile conditions. This makes the existence of liquid water stable in TRAPPIST-1 d is extremely difficult.
It is important to highlight that “not detecting” signals does not imply that the planet is completely devoid of atmosphere: an atmosphere ultrafine or very high clouds could be hidden below the detection threshold. However, with current measurements, the presence of a earth's atmosphere It is very unlikely.
The gaze shifts to the outer planets
Researchers are now focusing their efforts on TRAPPIST-1 e, f, g and h, which are further away from their star's eruptions and offer better opportunities for retain atmospheresThe main challenge is technical: its most cold and the smallest signal makes detection difficult, even with the James Webb.
As indicated Ryan MacDonald (University of St Andrews), the case of TRAPPIST-1 d highlights the singularity from Earth, but the outer planets of the system could still to surprise with traces of gases or water. Our upcoming observation campaigns will help refine models and prioritize targets.
Since red dwarfs are the most common stars In the galaxy, confirming the existence of stable atmospheres on any of these worlds would have enormous implications for the habitability in our cosmic environment. If they can maintain atmospheres here, they could do so in many other places.
The conclusions on TRAPPIST-1d redefine the search map: although it indicates a planet probably inhospitable, provides crucial information on how lose or the atmospheres are hidden and where to focus future research to detect signs of life.
