Astronomers detect atmosphere on rocky exoplanet in major breakthrough

Astronomers have detected an atmosphere around a rocky, Earth-like planet in another star’s habitable zone, marking a major advance in the search for potentially life-supporting worlds beyond the Solar System.

The discovery, published July 16 in Science, provides the strongest evidence so far that a rocky planet with potentially Earth-like conditions can retain an atmosphere for billions of years, according to ScienceDaily.

"An atmosphere is essential for a planet to support life as we know it," said lead author Collin Cherubim, who recently earned his Ph.D. in Earth and Planetary Sciences from Harvard University.

"This is the first time anyone has found an atmosphere on a rocky planet in the habitable zone of another star."

The researchers detected helium escaping from LHS 1140 b, a rocky exoplanet located about 48 light-years from Earth. The planet orbits a red dwarf star within its habitable zone, where conditions may allow liquid water to exist on the surface.

Although astronomers have discovered thousands of exoplanets, including rocky worlds in habitable zones, confirming the presence of atmospheres on such planets has remained a major challenge.

"Twenty years ago we wondered whether other terrestrial-type planets even existed," said Robin Wordsworth, a Harvard professor and one of Cherubim's dissertation advisors. "Then we learned they're common, and found some in the habitable zone. The next question was whether any of them had managed to keep an atmosphere. Now we know at least one has."

The researchers developed a model predicting that helium would be present in the upper atmosphere of LHS 1140 b and would gradually escape into space. They then tested the prediction using the WINERED spectrograph at the Magellan Observatory in Chile.

During observations, LHS 1140 b and another planet passed in front of their star on the same night. While no atmospheric signal was detected from the second planet, researchers observed a clear helium signal from LHS 1140 b, indicating that the planet still possesses an atmosphere.

"Collin analyzed the planets we knew about and predicted that this one would have a helium atmosphere," said David Charbonneau, head of Harvard's Department of Astronomy. "Then he organized telescope time, got the data, and the detection was statistically rock solid."

Scientists estimate that the atmosphere may have survived for more than three billion years, making LHS 1140 b a promising target for further study.

Researchers now hope to determine the atmosphere's full chemical composition and investigate whether the planet may have surface oceans or other features associated with habitability.

"This has been a model validation, and hopefully it's just the first of many more observations to come," Cherubim said.

By Sabina Mammadli