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4mo ago

Potential Biosignatures Detected on Exoplanet K2-18b Challenge Understanding of Life Beyond Earth

Cambridge-led team identifies sulphur-based gases in the atmosphere of a distant hycean world, though findings remain provisional at 3σ significance.

The gas signatures Madhusudhan and his team at Cambridge have detected are the surest signs of life outside Earth that humanity has ever encountered. How we interpret and build on this data, from 124 light years away, will be crucial, he says.
(Credit: Arndt Stelter/CC 4.0)

Overview

  • The James Webb Space Telescope (JWST) detected dimethyl sulfide (DMS) and dimethyl disulfide (DMDS) in the atmosphere of K2-18b, a sub-Neptune exoplanet 124 light-years away.
  • On Earth, these gases are exclusively produced by life, primarily marine organisms, but their detection on K2-18b remains at a 3σ confidence level, requiring further validation.
  • K2-18b, identified in 2015, is hypothesized to be a 'hycean' planet with a hydrogen-rich atmosphere and potential global ocean, though alternative models suggest a hostile magma surface.
  • The findings, published in *The Astrophysical Journal Letters*, have sparked calls for additional JWST observations to confirm the biosignature claims and rule out abiotic sources.
  • This discovery marks a significant step in exoplanet research, reshaping strategies for identifying extraterrestrial life and advancing the study of distant planetary atmospheres.