Helium leaking from LHS 1140 b during a September 2024 transit gave astronomers their strongest evidence yet that the rocky super-Earth has an atmosphere.
The finding would be the first confirmed atmosphere on a rocky planet in a star’s habitable zone, a key threshold in assessing whether such worlds could retain water and support life-friendly conditions.
Using the 6.5-meter Magellan Clay Telescope in Chile, the team applied high-resolution transit spectroscopy with WINERED, whose resolving power far exceeds JWST’s top 2,700 for this kind of helium search.
A comparison with nearby LHS 1140 c strengthened the case: the more irradiated inner rocky planet showed no helium, matching models that intense M-dwarf radiation can strip atmospheres away.
At roughly 50 light-years from Earth, LHS 1140 b is now a prime JWST target for follow-up searches for carbon dioxide, water-related clues and possible chemical imbalances linked to habitability.
How did astronomers prove a rocky habitable-zone planet 48 light-years away still has an atmosphere after billions of years?
If LHS 1140 b has escaping helium but no detected water yet, how close are scientists to knowing whether it could host oceans?
LHS 1140 b’s Atmosphere Confirmed: A Breakthrough in the Search for Habitable Worlds Around Red Dwarfs
Overview
LHS 1140 b stands out as a promising super-Earth in the search for habitable worlds. Unlike the TRAPPIST-1 planets, which lose their atmospheres due to intense stellar activity and rapid rotation of their host star, LHS 1140 b orbits a calm, slowly rotating red dwarf. This gentle environment, combined with the planet’s strong gravity, helps it retain a thick, possibly nitrogen-rich atmosphere despite ongoing atmospheric loss from stellar radiation. Scientists believe LHS 1140 b is a water world with a frozen surface and a potential liquid ocean at its sun-facing point, but confirming its true habitability will require years of careful observation with advanced telescopes.