Astronomers find surprising ice world in the habitable zone with JWST data

A workforce of astronomers has recognized a temperate exoplanet as a promising super-Earth ice or water world.

The findings, led by Université de Montréal, present that the habitable zone exoplanet, LHS 1140 b, isn’t seemingly a mini-Neptune, a small so-called gas giant—massive planets composed largely of fuel—with a thick hydrogen-rich atmosphere. The planet, positioned about 48 light-years away within the constellation Cetus, emerges as one of the vital promising liveable zone exoplanet candidates identified, probably harboring an environment and even a liquid water ocean.

Information from the James Webb Area Telescope (JWST) had been collected in December 2023 and added to earlier information from different space telescopes Spitzer, Hubble, and TESS to solidify this outcome, accepted for publication in The Astrophysical Journal Letters this week and presently available on the arXiv preprint server.

“That is the primary time we’ve got ever seen a touch of an environment on a liveable zone rocky or ice-rich exoplanet. Detecting atmospheres on small, rocky worlds is a significant purpose for JWST, however these alerts are a lot tougher to see than for big planet atmospheres,” stated Ryan MacDonald, NASA Sagan Fellow within the U-M Division of Astronomy, who was key within the evaluation of LHS 1140 b’s ambiance.

“LHS 1140 b is among the greatest small exoplanets within the liveable zone able to supporting a thick ambiance, and we would simply have discovered proof of air on this world.”

LHS 1140 b, a possible liveable world

LHS 1140 b, an exoplanet orbiting a low-mass red dwarf star roughly one-fifth the dimensions of the sun, has captivated scientists attributable to it being one of many closest exoplanets to the solar system that lies inside its star’s liveable zone. Exoplanets discovered on this “Goldilocks Zone” have temperatures that might enable water to exist on them in liquid kind, an important aspect for all times as we all know it on Earth.

One of many important questions on LHS 1140 b was whether or not it’s a mini-Neptune sort exoplanet or a super-Earth—a rocky or water-rich planet bigger than Earth.

“Of all presently identified temperate exoplanets, LHS 1140 b may nicely be our greatest guess to 1 day not directly affirm liquid water on the floor of an alien world past our solar system,” stated Charles Cadieux, lead creator of the science paper and doctoral scholar at Université de Montréal. “This could be a significant milestone within the seek for probably liveable exoplanets.”

JWST information results in new insights

Evaluation of the workforce’s observations strongly excluded the mini-Neptune state of affairs, with proof suggesting the exoplanet LHS 1140 b is a super-Earth which will also have a nitrogen-rich ambiance like that of Earth’s. Nevertheless, the workforce cautions that further observations with JWST observations can be mandatory to verify the signature of nitrogen fuel.

Estimates primarily based on all collected information reveal that LHS 1140 b is much less dense than anticipated for a rocky planet with an Earth-like composition, suggesting that 10 to twenty% of its mass could also be composed of water. This discovery factors to LHS 1140 b being a compelling candidate water world, seemingly resembling a snowball or ice planet with a possible liquid ocean on the sub-stellar level, or the realm of the planet’s floor that might at all times be dealing with the system’s host star as a result of planet’s synchronous rotation (very like the Earth’s moon).

Potential presence of an environment and ocean

MacDonald carried out the atmospheric retrieval evaluation that implies LHS 1140 b has a nitrogen-rich ambiance, probably just like the Earth’s ambiance, which is 78% nitrogen. Whereas it’s nonetheless solely a tentative outcome, the presence of a nitrogen-rich ambiance would recommend the planet has retained a considerable ambiance, creating circumstances which may assist liquid water.

This discovery favors the water world/snowball state of affairs as essentially the most believable. Present fashions point out that if LHS 1140 b has an Earth-like ambiance, it will be a snowball planet with a bull’s-eye ocean about 4,000 kilometers in diameter, equal to half the floor space of the Atlantic Ocean. The floor temperature on the heart of this alien ocean may even be a cushty 20 levels Celsius.

LHS 1140 b’s potential ambiance and favorable circumstances for liquid water make it an distinctive candidate for future habitability research. This planet gives a singular alternative to check a world that would assist life, given its place within the liveable zone and the chance of getting an environment that may retain warmth and assist a steady local weather.

“That is our first tantalizing glimpse of an environment on an excellent Earth within the liveable zone. In comparison with different identified liveable zone exoplanets, akin to these within the TRAPPIST-1 system, the star LHS 1140 seems to be calmer and fewer energetic, making it considerably much less difficult to disentangle LHS 1140 b’s ambiance from stellar alerts attributable to starspots,” MacDonald stated.

“Our preliminary reconnaissance of LHS 1140 b with JWST has revealed this to be maybe the most effective liveable zone exoplanet presently identified for atmospheric characterization. Whereas we’d like extra JWST observations to verify the nitrogen-rich ambiance, and to seek for different gases, it is a very promising begin.”