Eddie Gonzales Jr. – MessageToEagle.com – Astronomers have discovered a potential super-Earth ice or water world exoplanet with moderate temperatures.
Research from Université de Montréal suggests LHS 1140 b, a habitable zone exoplanet 48 light-years away in Cetus, is likely not a mini-Neptune. Instead, it’s a promising candidate for habitability, potentially having an atmosphere and liquid water ocean.
Temperate exoplanet LHS 1140 b may be a world completely covered in ice (left) similar to Jupiter’s moon Europa or be an ice world with a liquid substellar ocean and a cloudy atmosphere (center). LHS 1140 b is 1.7 times the size of our planet Earth (right) and is the most promising habitable zone exoplanet yet in our search for liquid water beyond the Solar System. Credit: B. Gougeon/Université de Montréal
Data from the James Webb Space Telescope, collected in December 2023, complemented previous findings from Spitzer, Hubble, and TESS telescopes.
This combined result, accepted for publication in The Astrophysical Journal Letters, is currently available on the arXiv preprint server.
“This is the first time we have ever seen a hint of an atmosphere on a habitable zone rocky or ice-rich exoplanet. Detecting atmospheres on small, rocky worlds is a major goal for JWST, but these signals are much harder to see than for giant planet atmospheres,” said Ryan MacDonald, NASA Sagan Fellow in the U-M Department of Astronomy, who was key in the analysis of LHS 1140 b’s atmosphere.
“LHS 1140 b is one of the best small exoplanets in the habitable zone capable of supporting a thick atmosphere, and we might just have found evidence of air on this world.”
LHS 1140 b, a potential habitable world
LHS 1140 b, an exoplanet orbiting a small red dwarf star, interests scientists as one of the nearest planets in its star’s habitable zone.
Planets in this “Goldilocks Zone” could potentially support liquid water, essential for life as we know it.
A key question about LHS 1140 b was whether it’s a mini-Neptune or a super-Earth—a rocky or water-rich planet larger than Earth.
“Of all currently known temperate exoplanets, LHS 1140 b could well be our best bet to one day indirectly confirm liquid water on the surface of an alien world beyond our solar system,” said Charles Cadieux, lead author of the science paper and doctoral student at Université de Montréal. “This would be a major milestone in the search for potentially habitable exoplanets.”
JWST data leads to new insights
The team’s analysis ruled out the mini-Neptune scenario for exoplanet LHS 1140 b, suggesting it’s a super-Earth possibly with a nitrogen-rich atmosphere similar to Earth’s. However, they emphasize that further JWST observations are needed to confirm the nitrogen signature.
Data suggests LHS 1140 b is less dense than expected for a rocky planet, with 10-20% of its mass possibly being water. This makes it a potential water world, resembling a snowball or ice planet with a possible liquid ocean at the sub-stellar point, which always faces the host star due to synchronous rotation.
Possible presence of an atmosphere and ocean
MacDonald’s analysis suggests LHS 1140 b may have a nitrogen-rich atmosphere, similar to Earth’s. This tentative result implies the planet has retained a substantial atmosphere, potentially creating conditions for liquid water.
This finding supports the water world/snowball scenario as most likely. Models suggest that with an Earth-like atmosphere, LHS 1140 b would be a snowball planet with a central ocean 4, 000 km wide, half the Atlantic Ocean’s area. The ocean’s center could have a comfortable 20°C surface temperature.
LHS 1140 b is an exceptional candidate for habitability studies due to its potential atmosphere and conditions for liquid water. Its position in the habitable zone and likely heat-retaining atmosphere make it a unique opportunity to study a potentially life-supporting world.
“This is our first tantalizing glimpse of an atmosphere on a super Earth in the habitable zone. Compared to other known habitable zone exoplanets, such as those in the TRAPPIST-1 system, the star LHS 1140 appears to be calmer and less active, making it significantly less challenging to disentangle LHS 1140 b’s atmosphere from stellar signals caused by starspots,” MacDonald said.
“Our initial reconnaissance of LHS 1140 b with JWST has revealed this to be perhaps the best habitable zone exoplanet currently known for atmospheric characterization. While we need more JWST observations to confirm the nitrogen-rich atmosphere, and to search for other gases, this is a very promising start.”
Written by Eddie Gonzales Jr. – MessageToEagle.com Staff