Early Release Science of the exoplanet WASP-39b with JWST NIRISS

Abstract The Saturn-mass exoplanet WASP-39b has been the subject of extensive efforts to determine its atmospheric properties using transmission spectroscopy 1–4 . However, these efforts have been hampered by modelling degeneracies between composition and cloud properties that are caused by limited data quality 5–9 . Here we present the transmission spectrum of WASP-39b obtained using the Single-Object Slitless Spectroscopy (SOSS) mode of the Near Infrared Imager and Slitless Spectrograph (NIRISS) instrument on the JWST. This spectrum spans 0.6–2.8 μm in wavelength and shows several water-absorption bands, the potassium resonance doublet and signatures of clouds. The precision and broad wavelength coverage of…

• NS
  National Science Foundation

  Awards: 1746045, DGE-1746045
• NA
  National Aeronautics and Space Administration

  Awards: 5-03127, NAS 5-03127
• ST
  Space Telescope Science Institute

  Awards: 5-03127, NAS 5-03127
• NS
  Natural Sciences and Engineering Research Council of Canada
• SA
  Science and Technology Facilities Council

  Awards: ST/W006960/1, ST/K001612/1, ST/T004479/1, ST/X001121/1, ST/R003726/1, ST/W00089X/1, ST/T001836/1, ST/V000861/1, ST/V000454/1, ST/T000406/1