Astronomers using the NASA/ESA Hubble Space Telescope have detected helium in the atmosphere of the exoplanet WASP-107b. This is the first time this element has been detected in the atmosphere of a planet outside the Solar System. The discovery demonstrates the ability to use infrared spectra to study exoplanet extended atmospheres.
The international team of astronomers, led by Jessica Spake, a research student at the University of Exeter in the UK, used Hubble’s Wide Field Camera 3 to discover helium in the atmosphere of the exoplanet WASP-107b making it the first detection of its kind.
The international team of astronomers used Hubble’s Wide Field Camera 3 to discover helium in the atmosphere of the exoplanet WASP-107b. Above - the Hubble Space Telescope which is widely viewed as one of the most important scientific and technological achievements of modern times.
Image credit: NASA
“Helium is the second-most common element in the Universe after hydrogen. It is also one of the main constituents of the planets Jupiter and Saturn in our Solar System," Spake said while highlighting the importance of the discovery. "However, up until now, helium had not been detected on exoplanets - despite searches for it.”
The team made the detection by analyzing the infrared spectrum of the atmosphere of WASP-107b compared to previous detections of extended exoplanet atmospheres made by studying the spectrum at ultraviolet and optical wavelengths. “The strong signal from helium we measured demonstrates a new technique to study upper layers of exoplanet atmospheres in a wider range of planets,” Spike noted.
WASP-107b is one of the lowest density planets known. While the planet is about the same size as Jupiter, it has only 12 percent of Jupiter’s mass. The exoplanet is about 200 light-years from Earth and takes less than six days to orbit its host star.
The amount of helium detected in the atmosphere of WASP-107b is so large that its upper atmosphere must extend tens of thousands of kilometers out into space. This also makes it the first time that an extended atmosphere has been discovered at infrared wavelengths.
Since its atmosphere is so extended, the planet is losing a significant amount of its atmospheric gases into space — between ~0.1-4% of its atmosphere’s total mass every billion years, NASA's press advisory reads. As far back as the year 2000, it was predicted that helium would be one of the most readily-detectable gases on giant exoplanets, but until now, searches were unsuccessful.
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