Helium Discovered in Atmosphere of an Exoplanet for the First Time

For the first time, astronomers have detected the element helium in the atmosphere of a planet outside our Solar System, according to a new study published in the journal Nature.

Helium is the second most abundant element in the universe after hydrogen and is one of the main constituents of the gas giants Jupiter and Saturn.

Due to its ubiquity, scientists have long-thought that helium should be easily detectable in larger exoplanets—planets which orbit stars outside the Solar System—however, more than a decade of searching for the gas in the atmospheres of these distant worlds has proven unsuccessful, until now.

Using the Hubble Space Telescope, an international team of astronomers unexpectedly detected the element on WASP-107b—a strange, Jupiter-sized exoplanet located around 200 light-years from Earth with one of the lowest known densities (it only has 12% of Jupiter's mass).

The team were actually looking for methane but analysis of infrared light coming from the atmosphere of WASP-107b showed that the planet's atmosphere was filled with helium. Furthermore, the scientists found that the planet's upper atmosphere extends tens of thousands of miles into space as a result of its weak gravitational pull. It is also slowly eroding due to significant amounts of gas being lost.

The latest findings demonstrate the effectiveness of using infrared detection methods to study the atmosphere of exoplanets. Previously, scientists have relied on techniques that use ultraviolet and optical wavelengths, which have their limitations.

Artist's impression of the exoplanet WASP-107b, a gas giant orbiting a highly active K-type main sequence star. Using spectroscopy, scientists were able to find helium in the escaping atmosphere of the planet—the first detection of this element in the atmosphere of an exoplanet. ESA/Hubble, NASA, M. Kornmesser

"The strong signal from helium we measured demonstrates a new technique to study upper layers of exoplanet atmospheres in a wider range of planets," Jessica Spake, lead author of the study from the University of Exeter in the U.K, said in a statement.

"Current methods, which use ultraviolet light, are limited to the closest exoplanets. We know there is helium in the Earth's upper atmosphere and this new technique may help us to detect atmospheres around Earth-sized exoplanets—which is very difficult with current technology."

The team's new method of detection—alongside upcoming observation missions such as the James Webb Space Telescope—will enable researchers to examine the atmosphere of exoplanets in far greater detail than ever before, a factor which could have important implications in the search for life beyond our planet.