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

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posted on 2024-01-24, 19:01 authored by AD Feinstein, M Radica, L Welbanks, CA Murray, K Ohno, LP Coulombe, N Espinoza, JL Bean, JK Teske, B Benneke, MR Line, Z Rustamkulov, A Saba, A Tsiaras, JK Barstow, JJ Fortney, P Gao, HA Knutson, RJ MacDonald, T Mikal-Evans, BV Rackham, J Taylor, V Parmentier, NM Batalha, ZK Berta-Thompson, AL Carter, Q Changeat, LA dos Santos, NP Gibson, JM Goyal, L Kreidberg, M López-Morales, JD Lothringer, Y Miguel, K Molaverdikhani, SE Moran, G Morello, S Mukherjee, DK Sing, KB Stevenson, HR Wakeford, EM Ahrer, MK Alam, L Alderson, NH Allen, NE Batalha, TJ Bell, J Blecic, J Brande, C Caceres, SL Casewell, KL Chubb, IJM Crossfield, N Crouzet, PE Cubillos, L Decin, JM Désert, J Harrington, K Heng, T Henning, N Iro, EMR Kempton, S Kendrew, J Kirk, J Krick, PO Lagage, M Lendl, L Mancini, M Mansfield, EM May, NJ Mayne, NK Nikolov, E Palle, DJM Petit dit de la Roche, C Piaulet, D Powell, S Redfield, LK Rogers, MT Roman, PA Roy, MC Nixon, E Schlawin, X Tan, P Tremblin, JD Turner, O Venot, WC Waalkes, PJ Wheatley, X Zhang

The Saturn-mass exoplanet WASP-39b has been the subject of extensive efforts to determine its atmospheric properties using transmission spectroscopy1–4. However, these efforts have been hampered by modelling degeneracies between composition and cloud properties that are caused by limited data quality5–9. 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.

History

Author affiliation

School of Physics & Astronomy, University of Leicester

Version

  • VoR (Version of Record)

Published in

Nature

Volume

614

Pagination

670-675

Publisher

Springer Science and Business Media LLC

issn

0028-0836

eissn

1476-4687

Copyright date

2023

Available date

2024-01-24

Spatial coverage

England

Language

eng

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