In 2023, researchers using NASA's James Webb Space Telescope (JWST) reported the potential presence of dimethyl sulfide (DMS) on K2-18b, which is nearly nine times more massive than Earth and circles in the "habitable zone" of a star about 120 light-years away from us.
Here on Earth, DMS is produced primarily by life — most prolifically by phytoplankton and other marine microbes — so the 2023 study was met with some enthusiasm. The excitement was tempered, however, by the preliminary nature of the find; JWST's observations were consistent with the presence of DMS but did not confirm it. So the study team looked again, but in a slightly different way this time.
JWST can probe exoplanet atmospheres when these worlds "transit," or cross the face of, their host stars from the observatory's perspective: The telescope detects certain molecules in the air based on the wavelengths of starlight that they absorb.
The team made the original, tentative DMS detection using JWST's NIRISS (Near-Infrared Imager and Slitless Spectrograph) and NIRSpec (Near-Infrared Spectrograph) instruments. For the new study, the researchers employed the $10 billion telescope's Mid-Infrared Instrument (MIRI), which scrutinizes different wavelengths of light.
MIRI also detected the fingerprint of DMS (and/or dimethyl disulfide, or DMDS, a close chemical cousin and also a potential biosignature), the researchers report in the new study, which was published online today (April 17) in The Astrophysical Journal Letters.
Source: www.space.com
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