A team of astronomers from the University of Montreal discovered that exoplanet LHS 1140 b is a potentially habitable icy or water world that is similar to a super-Earth. This is reported in an article published in The Astrophysical Journal Letters.
The observations were made using the James Webb Space Telescope (JWST), as well as the Spitzer, Hubble and TESS telescopes. Detecting the atmospheres of rocky planets is a primary goal of JWST, but these signals are much more difficult to detect than those of giant planets.
The exoplanet LHS 1140 b, located in the habitable zone of its host star and located about 48 light-years from Earth in the direction of the constellation Cetus, is most likely not a mini-Neptune, but a super-Earth with a potential atmosphere and ocean of liquid water.
Analysis of JWST data showed that the exoplanet likely has a nitrogen-rich atmosphere similar to Earth's. In this case, 10 to 20 percent of LHS 1140 b's mass could be water, making it a candidate for a water world, resembling a snowball or ice planet with a potential liquid ocean. This ocean is most likely located at the substellar point of the planet, that is, on the side that always faces the parent star due to tidal locking. In the center of the ocean, the temperature can be quite comfortable - about 20 degrees Celsius.
More observations are needed to confirm the nitrogen gas signature, but LHS 1140 b is already less dense than expected for a rocky planet, indicating a strong likelihood of water.
Compared to other known exoplanets in the habitable zone, such as the TRAPPIST-1 planets, LHS 1140 appears quieter and less active, making it much easier to spot signs of a planetary atmosphere against starlight.< /p>