Harvard astronomers have detected a helium-rich atmosphere around the rocky exoplanet LHS 1140b [1].
This discovery is significant because it represents the first time an atmosphere has been identified on a rocky planet located within its star's habitable zone [2]. Such a finding provides a critical piece of the puzzle in the search for environments capable of supporting alien life [2].
LHS 1140b orbits a red-dwarf star known as LHS 1140 [1]. The planet is situated in the habitable zone, the region around a star where temperatures could allow liquid water to exist on a planetary surface [2]. While many rocky planets are stripped of their gases by stellar radiation, the detection of helium escaping from LHS 1140b indicates that the planet has managed to retain a gaseous envelope [1].
The presence of an atmosphere is a primary requirement for habitability. It can regulate surface temperatures and protect the surface from harmful radiation, factors that are essential for the development of biological organisms [3].
Researchers identified the atmosphere by observing the planet's interaction with its host star [1]. The specific detection of helium suggests a composition that differs from the nitrogen-oxygen mix of Earth, yet the existence of any atmosphere on a rocky world in this zone is a milestone for the field [3].
Astronomers believe that the ability of LHS 1140b to hold onto its atmosphere despite the volatility of its red-dwarf star makes it a high-priority target for future study [1]. Further observations will be required to determine if other gases, such as water vapor, or carbon dioxide, are present in the mix [2].
“The first atmosphere found on a habitable-zone world outside our solar system.”
The detection of an atmosphere on LHS 1140b shifts the focus of exoplanet research from merely finding rocky planets to analyzing their chemical viability. Because red-dwarf stars are often violent, the fact that this planet retained its atmosphere suggests it may be more resilient than previously thought, increasing the statistical likelihood that other rocky worlds in the galaxy could host life-sustaining conditions.
