New Constraints on DMS and DMDS in the Atmosphere of K2-18 b from JWST MIRI

Abstract The sub-Neptune frontier has opened a new window into the rich diversity of planetary environments beyond the solar system. The possibility of hycean worlds, with planet-wide oceans and H 2 -rich atmospheres, significantly expands and accelerates the search for habitable environments elsewhere. Recent JWST transmission spectroscopy of the candidate hycean world K2-18 b in the near-infrared led to the first detections of the carbon-bearing molecules CH 4 and CO 2 in its atmosphere, with a composition consistent with predictions for hycean conditions. The observations also provided a tentative hint of dimethyl sulfide (DMS), a possible biosignature gas, but the inference was of low statistical…

• NA
  National Aeronautics and Space Administration

  Awards: 5-03127, NAS 5-03127, NAS 5-031
• DE
  Dell EMC
• ST
  Space Telescope Science Institute

  Awards: 5-03127, NAS 5-03127, JWST-GO-02722
• UR
  UK Research and Innovation

  Award: EP/X025179/1
• EA
  Engineering and Physical Sciences Research Council

  Awards: EP/X025179/1, EP/P020259/1, EP/P020259, EP/P020259/
• SA
  Science and Technology Facilities Council

  Award: EP/P020259/1