Scientists using the James Webb space telescope have identified a potentially habitable exoplanet that may host a life-sustaining liquid ocean. The exoplanet, known as LHS 1140 b, sits just 48 light years away from Earth, making it relatively close in the vast reaches of space.

Out of the thousands of planets discovered outside our Solar System, only a handful are located in the "Goldilocks zone" where conditions are neither too hot nor too cold to support liquid water, a crucial ingredient for life. LHS 1140 b is one of these rare exoplanets and has been under close scrutiny since its discovery in 2017.

Initial assessments labeled LHS 1140 b as a small gas giant or "mini-Neptune" with an atmosphere too dense in hydrogen and helium to sustain life. However, recent observations from the Webb telescope have refuted this belief, revealing that the exoplanet is, in fact, a rocky "super-Earth." It is approximately 1.7 times larger than Earth, with a mass 5.6 times greater.

The Webb telescope analyzed the exoplanet's atmosphere as it passed in front of its star, and intriguingly, no traces of hydrogen or helium were detected. This discovery effectively eliminates the possibility of LHS 1140 b being a mini-Neptune. Furthermore, researchers have determined that the planet's density points to the existence of significant quantities of water, potentially accounting for 10 to 20 percent of its mass.

The presence of an atmosphere is still uncertain, but various indications suggest its likelihood. The exoplanet's gentle warming by its red dwarf star, only one-fifth the size of our Sun, leads scientists to speculate that its surface temperature is similar to that of Earth and Mars. The composition of gases, notably carbon dioxide, will play a crucial role in determining whether the exoplanet is covered in ice or hosts a vast liquid ocean.

Simulations based on current modeling suggest the possibility of a liquid ocean around 4,000 kilometers in diameter, roughly half the size of the Atlantic Ocean. Alternatively, the exoplanet may be hiding a liquid water reservoir beneath a thick ice shell, similar to several moons orbiting Jupiter and Saturn.

Notably, the Webb telescope's instruments have detected signs suggesting the presence of nitrogen, which is thought to be another potential component for sustaining life. Researchers anticipate further investigation using the telescope's capabilities to conclusively confirm this finding.

Despite the tantalizing prospects, scientists caution that additional research is needed to gather more data about LHS 1140 b. Confirming the presence of its atmosphere is projected to take at least a year, while detecting the presence of carbon dioxide could require an additional two to three years of observation.

Lead study author Charles Cadieux, a PhD student at the University of Montreal, expresses optimism that LHS 1140 b may eventually serve as conclusive evidence for liquid water on the surface of an alien world, making it a promising candidate among known temperate exoplanets.

The discovery of potentially habitable exoplanets continues to deepen our understanding of the universe. As scientists delve deeper into the mysteries of distant worlds, the quest for identifying signs of life beyond Earth takes on new dimensions, encompassing the search for liquid water and habitable environments.

The research study titled "Transmission Spectroscopy of the Habitable Zone Exoplanet LHS 1140 b with JWST/NIRISS" was published in The Astrophysical Journal Letters.