Astronomers have discovered an exoplanet whose atmosphere is inflated like a balloon. According to astronomers, the atmosphere is mostly made up of helium gas, which is escaping from the atmosphere and giving it the shape of an inflated balloon.
The discovery was made by an international team of astronomers, led by academics from the University of Geneva (UNIGE) in Switzerland.
Helium is the second most abundant element in the universe, after hydrogen. It is one of the main components of stars and gaseous planets, like Jupiter and Saturn. The inert gas was first noticed by astronomer Norman Lockyer in 1868. He observed a yellow spectral line while studying sunlight and proposed that the line was due to some unknown element. He named the new element helium, after Helios - the Greek Titan of the Sun.
The exoplanet found by UNIGE astronomers is named HAT-P-11b. It is located about 124 light years from Earth and lies in the Cygnus constellation. It is almost the same size as Neptune, and about 20 times closer to its host star than the Earth is from the Sun.
The discovery was made after astronomers observed HAT-P-11b using the Carmenes spectrograph installed on the 4-metre telescope at Calar Alto, Spain. The data obtained from Carmenes enabled scientists to determine the speed of helium atoms present in the atmosphere of the exoplanet. The research team found that the helium is present in an extended cloud and is escaping from the planet.
A computer simulation, which tracked the trajectory of helium atoms, also supported the results from Carmenes spectrograph.
"This is a really exciting discovery, particularly as helium was only detected in exoplanet atmospheres for the first time earlier this year," said Jessica Spake from the University of Exeter, who was involved in the study.
Earlier this year, Hubble Space Telescope had also made some observations of HAT-P-11b, but astronomers could not interpret the data properly. Then, they decided to use Carmenes spectrograph for further investigation.
"Helium is blown away from the day side of the planet to its night side at over 10,000 km an hour. Because it is such a light gas, it escapes easily from the attraction of the planet and forms an extended cloud all around it," said Vincent Bourrier, co-author of the study.
As a result of the phenomenon, HAT-P-11b atmosphere has become inflated, like a balloon.
The findings of the study are published in the journal Science.
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Scientists estimate that the exoplanet has already lost up to 35 per cent of its mass over its lifetime