New evidence from the James Webb space telescope suggests that astronomers may have found the strongest hint of life outside our solar system.
Scientists using Webb’s Mid-Infrared Instrument (MIRI) have detected the chemical characteristics of dimethyl sulfide (DMS) and dimethyl disulfide (DMD) in the K2-18B atmosphere, a potentially habitable exoplanet located at 124 light-years. On Earth, these sulfur compounds are produced almost entirely by living organisms, mainly marine microorganisms.
“This is independent evidence, using different tools and different wavelength ranges of light, where there is no overlap with previous observations.” “The signal passes strongly and clearly.”
This discovery is based on previous Weber observations that carbon-based molecules find methane and carbon dioxide in the K2-18b atmosphere, consistent with predictions for the “Hycean” world, a planet covered by an easily habitable ocean with a rich atmosphere of hydrogen. These earlier measurements also provided a tentative prompt for DMS, but the evidence was weak.
This time, the detection reached a statistically significant “three-embedded” level – which means that the probability of a signal happening by chance is only 0.3%. While impressive, the claim to determine the gold standard for discovery is five sigmas, which will require Weber’s additional observation time.
This finding is particularly interesting in the concentration of these potential biosignature gases in the K2-18b atmosphere. The researchers estimate the level at least 10 parts per million, thousands of times higher than the level on Earth.
“It’s an incredible recognition to see the results appear and be consistent throughout a wide range of independent analyses and robustness tests,” said Måns Holmberg, a researcher at Space Telescope Sciences.
However, the research team urged caution. Although the findings are consistent with predictions of the ocean world of life, theoretically unknown chemical processes can produce these compounds without biology.
“Earlier theoretical work predicted that there might be a high level of DM and DMD-based sulfur gases on Hycean Worlds,” Madhusudhan said. “Now, we have observed it as predicted. Given our knowledge of the planet, it is a sea world with life, and it is the scenario that best suits the data we have.”
K2-18B itself is greater than the Earth, about 8.6 times larger and about 2.6 times wider, bypassing within the habitable areas of its stars, the temperature can allow liquid water to exist on its surface.
The team plans to conduct a follow-up observation of Webb, which could reach a threshold of five sigmas for scientific discovery, while the telescope’s telescope time is only 16-24 hours.
“Our work is the starting point for all investigations that now require confirmation and understanding of the implications of these exciting findings,” said Savvas Constantinou, co-author of the Cambridge Institute of Astronomy.
While stopping without evidence of claiming to have clear alien life, Madhusudhan believes that we are entering a new era in search of alien biology.
“Decades from now on, we might look back at this point in time and realize that this is the time when the universe of life arrives,” Madhusudhan said. “It could be a turning point, and suddenly, whether we are alone in the universe is the basic question we can answer.”
The study was published on April 17 in the Journal of Astrophysics.
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