Astronomers Identify Helium in Atmosphere of Rocky Exoplanet 48 Light-Years Away

Astronomers report that LHS 1140b, located 48 light-years from Earth, is emitting helium, indicating the presence of an atmosphere. The planet was discovered in 2017 and is described by NASA as a rocky world with a radius 1.73 times Earth's and a mass 5.6 times Earth's.

The study found that the planet's upper atmosphere is dominated by helium. Researchers used a computer model of atmospheric evolution to track how lighter elements such as hydrogen and helium would be affected by the host star's activity.

1140b orbits a red dwarf star named LHS 1140 at a distance about 10 times closer than Earth's distance from the Sun. Despite the proximity, the planet receives roughly half the sunlight Earth receives because the star is smaller and cooler. The planet is positioned in a region where temperatures could allow liquid water to exist, which estimates suggest could account for 20 percent of the planet's mass.

An atmosphere helps retain water, regulate climate, and shield the surface from radiation.

The lead author stated there is currently no evidence for life on the planet. For a planet to be considered habitable, it must be rocky, have an atmosphere, and maintain conditions suitable for liquid water. The findings suggest red dwarfs may pose less risk to nearby planets than previously thought, as the star is dim and no longer emits high levels of radiation.

If confirmed, LHS 1140b would be the first planet observed with conditions that could support life. Exoplanets with atmospheres remain rare. Humans have identified 6,316 exoplanets, and only a small number show evidence of an atmosphere.