Early Release Science of the exoplanet WASP-39b with JWST NIRISS
Creators: name: Feinstein, Adina D.
name: Radica, Michael
name: Welbanks, Luis
name: Murray, Catriona Anne
name: Ohno, Kazumasa
name: Coulombe, Louis-Philippe
name: Espinoza, Néstor
name: Bean, Jacob L.
name: Teske, Johanna K.
name: Benneke, Björn
name: Line, Michael R.
name: Rustamkulov, Zafar
name: Saba, Arianna
name: Tsiaras, Angelos
name: Barstow, Joanna K.
name: Fortney, Jonathan J.
name: Gao, Peter
name: Knutson, Heather A.
name: MacDonald, Ryan J.
name: Mikal-Evans, Thomas
name: Rackham, Benjamin V.
name: Taylor, Jake
name: Parmentier, Vivien
name: Batalha, Natalie M.
name: Berta-Thompson, Zachory K.
name: Carter, Aarynn L.
name: Changeat, Quentin
name: Santos, Leonardo A. Dos
name: Gibson, Neale P.
name: Goyal, Jayesh M
name: Kreidberg, Laura
name: López-Morales, Mercedes
name: Lothringer, Joshua D
name: Miguel, Yamila
name: Molaverdikhani, Karan
name: Moran, Sarah E.
name: Morello, Giuseppe
name: Mukherjee, Sagnick
name: Sing, David K.
name: Stevenson, Kevin B.
name: Wakeford, Hannah R.
name: Ahrer, Eva-Maria
name: Alam, Munazza K.
name: Alderson, Lili
name: Allen, Natalie H.
name: Batalha, Natasha E.
name: Bell, Taylor J.
name: Blecic, Jasmina
name: Brande, Jonathan
name: Caceres, Claudio
name: Casewell, S. L.
name: Chubb, Katy L.
name: Crossfield, Ian J. M.
name: Crouzet, Nicolas
name: Cubillos, Patricio E.
name: Decin, Leen
name: Désert, Jean-Michel
name: Harrington, Joseph
name: Heng, Kevin
name: Henning, Thomas
name: Iro, Nicolas
name: Kempton, Eliza M. -R.
name: Kendrew, Sarah
name: Kirk, James
name: Krick, Jessica
name: Lagage, Pierre-Olivier
name: Lendl, Monika
name: Mancini, Luigi
name: Mansfield, Megan
name: May, E. M.
name: Mayne, N. J.
name: Nikolov, Nikolay K.
name: Palle, Enric
name: de la Roche, Dominique J. M. Petit dit
name: Piaulet, Caroline
name: Powell, Diana
name: Redfield, Seth
name: Rogers, Laura K.
name: Roman, Michael T.
name: Roy, Pierre-Alexis
name: Nixon, Matthew C.
name: Schlawin, Everett
name: Tan, Xianyu
name: Tremblin, P.
name: Turner, Jake D.
name: Venot, Olivia
name: Waalkes, William C.
name: Wheatley, Peter J.
name: Zhang, Xi
Publisher: name: arXiv
Year: 2022
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: Transmission spectroscopy provides insight into the atmospheric properties and consequently the formation history, physics, and chemistry of transiting exoplanets. However, obtaining precise inferences of atmospheric properties from transmission spectra requires simultaneously measuring the strength and shape of multiple spectral absorption features from a wide range of chemical species. This has been challenging given the precision and wavelength coverage of previous observatories. Here, we present the transmission spectrum of the Saturn-mass exoplanet WASP-39b obtained using the SOSS mode of the NIRISS instrument on the JWST. This spectrum spans $0.6 - 2.8 μ$m in wavelength and reveals multiple water absorption bands, the potassium resonance doublet, as well as signatures of clouds. The precision and broad wavelength coverage of NIRISS-SOSS allows us to break model degeneracies between cloud properties and the atmospheric composition of WASP-39b, favoring a heavy element enhancement ("metallicity") of $\sim 10 - 30 \times$ the solar value, a sub-solar carbon-to-oxygen (C/O) ratio, and a solar-to-super-solar potassium-to-oxygen (K/O) ratio. The observations are best explained by wavelength-dependent, non-gray clouds with inhomogeneous coverage of the planet's terminator.
description: 48 pages, 12 figures, 2 tables. Under review at Nature