A nearby exoplanet could be a water-world with a nitrogen atmosphere similar to Earth’s, according to the latest data from the James Webb Space Telescope (JWST).
Exoplanet LHS 1140 b orbits a red dwarf star 48 lightyears away.
LHS 1140 b is in the star’s habitable zone, meaning the climate of the exoplanet could be temperate enough for liquid water to exist.
Studying LHS 1140 b
Detailed observations reveal the density of the exoplanet is consistent with a rocky world that’s between 10% and 20% water, enough to cover the entire surface in water or ice.
Recent measurements taken by JWST have also hinted that the planet has a nitrogen rich atmosphere, just as our own planet does.
It could even be partially covered in ice, but for a single liquid ocean, making LHS 1140 b appear like an eyeball.
"This is the first time we have ever seen a hint of an atmosphere on a habitable zone rocky or ice-rich exoplanet," says Ryan MacDonald from the University of Michigan, who took part in the analysis.
"Detecting atmospheres on small, rocky world is a major goal from JWST, but these signals are much harder to see than for giant planet atmospheres."
The detection of nitrogen still requires more observations to fully confirm, but the team have investigated what the world might look like with such an atmosphere.
The planet is probably tidally locked meaning one side constantly faces its host star.
If this is the case and the planet has an Earth-like atmosphere then the world could have a single 4,000km wide ocean, with a surface temperature of around 20ºC.
"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," says Charles Cadieux, lead author of the paper from the Université de Montréal.
"This would be a major milestone in the search for potentially habitable exoplanets."
Read the full paper at iopscience.iop.org/article/10.3847/2041-8213/ad5afa
