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

February 2023 • 2023Natur.614..670F

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

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 NIRISS/SOSS allows us to break model degeneracies between cloud properties and the atmospheric composition of WASP-39b, favouring a heavy-element enhancement (`metallicity') of about 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 also best explained by wavelength-dependent, non-grey clouds with inhomogeneous coverageof the planet's terminator.

Links

• SIMBAD http://simbad.u-strasbg.fr/simbo.pl?bibcode=2023Natur.614..670F
• PREPRINT http://arxiv.org/abs/2211.10493
• DATA https://archive.stsci.edu/mastbibref.php?bibcode=2023Natur.614..670F
• DATA https://hst.esac.esa.int/ehst/#/pages/search;bibcode=2023Natur.614..670F
• ELECTR https://doi.org/10.1038%2Fs41586-022-05674-1