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Scientists have discovered potential signs of life on an exoplanet which they believe is covered with water and is currently orbiting a dim red star not too far from our solar system. The exoplanet in question is K2-18b which is some 120 light-years away and as scientists have previously predicted as an ocean planet with a hydrogen-rich atmosphere, or Hycean world. 

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About the new finding

The research into K2-18b – the findings for which were accepted into The Astrophysical Journal Letters – reveals the presence of carbon dioxide and methane but it was the presence of a different chemical that drew the scientists' attention. 

The exoplanet, as per the latest research, had hints of dimethyl sulphide, which is a signature of biology that the scientists have predicted may be detected on Hycean worlds. But here on Earth, dimethyl sulphide is only produced by life and a large part of it is attributed to marine phytoplankton.

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“Our findings underscore the importance of considering diverse habitable environments in the search for life elsewhere,” said Nikku Madhusudhanan, an astronomer at the University of Cambridge and lead author of the paper, in a statement. 

He added, “Traditionally, the search for life on exoplanets has focused primarily on smaller rocky planets, but the larger Hycean worlds are significantly more conducive to atmospheric observations.”

The recent findings were obtained after using the James Webb Space Telescope’s (JWST) near-infrared NIRSpec and NIRISS instruments as it orbited between us and its host star, twice. 

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The researchers were trying to study several aspects, including the difference in the star’s light, the result of having travelled through and being changed by the composition of the exoplanet’s atmosphere.

It was after they analysed the data and dissected the changes that they found evidence of carbon molecules, carbon dioxide, and methane while the spectrum of light revealed hints of dimethyl sulphide.

“Upcoming Webb observations should be able to confirm if dimethyl sulphide is indeed present in the atmosphere of K2-18 b at significant levels,” said Madhusudhan. “Our findings are a promising step towards a deeper understanding of Hycean worlds in this quest,” he added. 

What do we know about K2-18b?

It is worth noting that the exoplanet is not very different from Earth but it is significantly heftier, with K2-18b being 2.6 times the radius and 8.6 times the mass of Earth. It also orbits its star within the habitable zone, where temperatures could allow liquid water to exist, the researchers said. 

K2-18b orbits the red cool dwarf star K2-18 in the habitable zone and orbits it once every 33 days. It is also worth noting that it was Madhusudhan and his colleagues who found that habitability is possible on the K2-18b in 2020. 

The year after that they also identified K2-18b as a potential Hycean. The planet was also the subject of significant media coverage in 2019, as two different teams reported the detection of water vapour in its hydrogen-rich atmosphere.

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