Astronomers have utilized spectral data from the Magellan-Cray telescope at Las Campanas Observatory to identify helium leakage from LHS 1140b, a rocky exoplanet situated in the habitable zone of the nearby low-mass star LHS 1140.
Artist’s concept of the rocky planets LHS 1140b and LHS 1140c. Image credit: Melissa Weiss / Harvard University and Smithsonian Center for Astrophysics.
LHS 1140 is a dormant M-dwarf star aged approximately 3 billion years, located around 39 light-years away in the constellation Cetus.
Cataloged as Gliese 3053 or GJ 3053, it is orbited by three planets: LHS 1140b, 1140c, and 1140d.
Discovered in 2017, LHS 1140b features a mass 5.6 times that of Earth and a radius 1.73 times that of our planet.
With an orbital period of 24.7 days, it receives 42% of the stellar radiation that Earth does, yielding an equilibrium temperature of 226 K (-47 degrees Celsius or -53 degrees Fahrenheit).
“Twenty years ago, we wondered if other terrestrial planets existed,” said Robin Wordsworth, a Harvard University professor.
“We now know they are common, with several residing in the habitable zone. The next challenge was to determine whether any could sustain an atmosphere. Today, we confirm at least one does.”
Astronomers studied LHS 1140b in 2024 with the advanced Warm Infrared Echelle Spectrometer for Extreme Dispersion (WINERED) on the Magellan-Clay Telescope, revealing evidence of helium escaping from its atmosphere.
“After thorough analysis of the spectra, we found helium being released from LHS 1140b’s atmosphere in 2024, attributed to heating from the star’s X-rays and extreme ultraviolet light,” explained Dr. Shreyas Visapragada, an astronomer at Carnegie Scientific Observatory.
“However, observations in 2025 indicated no helium leaks, suggesting that atmospheric leaks are variable.”
“Observing atmospheric changes in exoplanets over such short human timescales is a unique opportunity.”
By combining these findings with prior observations and advanced exoplanet evolution models, researchers suggest the presence of a multi-layered atmosphere on LHS 1140b.
They hypothesize that the planet features an upper atmosphere rich in helium and low in hydrogen, with other components such as water potentially trapped at lower altitudes near the surface.
No atmosphere was detected on planet LHS 1140c, possibly indicating that these two worlds exist on opposite sides of the so-called cosmic coastline.
On one side, planets retain atmospheres for billions of years; on the other side, planets lose them rapidly to space.
“Atmospheres are crucial for supporting life as we know it,” states Dr. Colin Cherubim from Harvard University.
“This marks the first discovery of an atmosphere around a rocky planet situated in the habitable zone of another star.”
“With helium present and escaping, we must ask: Is LHS 1140b merely a barren rock intermittently releasing gas or does it maintain a stable atmosphere similar to Earth?” questions Dr. Jason Dittman, an astronomer at the University of Florida.
“The upcoming four to five years of Webb data will search for water. If water is found in the atmosphere, it likely indicates a stable atmospheric condition.”
The findings were published in a research paper in today’s edition of Science.
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Colin Cherubim et al.. Helium released from the atmosphere of a nearby rocky exoplanet in its habitable zone. Science published online on July 16, 2026. doi: 10.1126/science.aea9708
Source: www.sci.news
