For the first time, astronomers have detected the presence of helium in the atmosphere of an exoplanet. The discovery was possible thanks to infrared observations of the object, which allowed the researchers to spot chemical signatures that they hadn't seen before.
The exoplanet in question is called WASP-107b and is located 200 light-years away in the constellation of Virgo. It is a super-Neptune, roughly the size of Jupiter but one-eighth of its mass. It orbits its star in just six days.
The research was conducted by an international team, led by Jessica Spake from the University of Exeter, and is published in Nature. Helium is found in abundance on Jupiter and Saturn, and it has long been suggested that it should be seen in exoplanets. Astronomers have conducted observations using ultraviolet light, but this time the team used a new near-infrared technique to study the planet.
"We hope to use this technique with the upcoming James Webb Space Telescope, for example, to learn what kind of planets have large envelopes of hydrogen and helium, and how long planets can hold on to their atmospheres," Spake said in a statement. "By measuring infrared light, we can see further out into space than if we were using ultraviolet light."
The star is so close to the planet that its intense activity ionizes the WASP-107b upper atmosphere. This recombines to form excited helium, which was spotted by the team. The signal that they discovered was very strong and spread out beyond the expected confines of the atmosphere.
"The helium we detected extends far out to space as a tenuous cloud surrounding the planet," co-author Tom Evans added. "If smaller, Earth-sized planets have similar helium clouds, this new technique offers an exciting means to study their upper atmospheres in the very near future."
By using the new technique, the team believe that they can investigate exoplanets even further away, and also study smaller objects. Maybe even Earth-sized ones. And infrared might help us detect other exciting features too. Exoplanetary atmospheres have the largest number of spectral features in infrared, so we could detect molecules such as carbon dioxide, water, methane, and carbon monoxide.
The James Webb Space Telescope, which is set to launch in 2020, is expected to play a crucial role in this type of research.
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