Early Release Science of the exoplanet WASP-39b with JWST NIRCam
Creators: name: Ahrer, Eva-Maria
name: Stevenson, Kevin B.
name: Mansfield, Megan
name: Moran, Sarah E.
name: Brande, Jonathan
name: Morello, Giuseppe
name: Murray, Catriona A.
name: Nikolov, Nikolay K.
name: de la Roche, Dominique J. M. Petit dit
name: Schlawin, Everett
name: Wheatley, Peter J.
name: Zieba, Sebastian
name: Batalha, Natasha E.
name: Damiano, Mario
name: Goyal, Jayesh M
name: Lendl, Monika
name: Lothringer, Joshua D.
name: Mukherjee, Sagnick
name: Ohno, Kazumasa
name: Batalha, Natalie M.
name: Battley, Matthew P.
name: Bean, Jacob L.
name: Beatty, Thomas G.
name: Benneke, Björn
name: Berta-Thompson, Zachory K.
name: Carter, Aarynn L.
name: Cubillos, Patricio E.
name: Daylan, Tansu
name: Espinoza, Néstor
name: Gao, Peter
name: Gibson, Neale P.
name: Gill, Samuel
name: Harrington, Joseph
name: Hu, Renyu
name: Kreidberg, Laura
name: Lewis, Nikole K.
name: Line, Michael R.
name: López-Morales, Mercedes
name: Parmentier, Vivien
name: Powell, Diana K.
name: Sing, David K.
name: Tsai, Shang-Min
name: Wakeford, Hannah R
name: Welbanks, Luis
name: Alam, Munazza K.
name: Alderson, Lili
name: Allen, Natalie H.
name: Anderson, David R.
name: Barstow, Joanna K.
name: Bayliss, Daniel
name: Bell, Taylor J.
name: Blecic, Jasmina
name: Bryant, Edward M.
name: Burleigh, Matthew R.
name: Carone, Ludmila
name: Casewell, S. L.
name: Changeat, Quentin
name: Chubb, Katy L.
name: Crossfield, Ian J. M.
name: Crouzet, Nicolas
name: Decin, Leen
name: Désert, Jean-Michel
name: Feinstein, Adina D.
name: Flagg, Laura
name: Fortney, Jonathan J.
name: Gizis, John E.
name: Heng, Kevin
name: Iro, Nicolas
name: Kempton, Eliza M. -R.
name: Kendrew, Sarah
name: Kirk, James
name: Knutson, Heather A.
name: Komacek, Thaddeus D.
name: Lagage, Pierre-Olivier
name: Leconte, Jérémy
name: Lustig-Yaeger, Jacob
name: MacDonald, Ryan J.
name: Mancini, Luigi
name: May, E. M.
name: Mayne, N. J.
name: Miguel, Yamila
name: Mikal-Evans, Thomas
name: Molaverdikhani, Karan
name: Palle, Enric
name: Piaulet, Caroline
name: Rackham, Benjamin V.
name: Redfield, Seth
name: Rogers, Laura K.
name: Roy, Pierre-Alexis
name: Rustamkulov, Zafar
name: Shkolnik, Evgenya L.
name: Sotzen, Kristin S.
name: Taylor, Jake
name: Tremblin, P.
name: Tucker, Gregory S.
name: Turner, Jake D.
name: de Val-Borro, Miguel
name: Venot, Olivia
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: Measuring the metallicity and carbon-to-oxygen (C/O) ratio in exoplanet atmospheres is a fundamental step towards constraining the dominant chemical processes at work and, if in equilibrium, revealing planet formation histories. Transmission spectroscopy provides the necessary means by constraining the abundances of oxygen- and carbon-bearing species; however, this requires broad wavelength coverage, moderate spectral resolution, and high precision that, together, are not achievable with previous observatories. Now that JWST has commenced science operations, we are able to observe exoplanets at previously uncharted wavelengths and spectral resolutions. Here we report time-series observations of the transiting exoplanet WASP-39b using JWST's Near InfraRed Camera (NIRCam). The long-wavelength spectroscopic and short-wavelength photometric light curves span 2.0 - 4.0 $μ$m, exhibit minimal systematics, and reveal well-defined molecular absorption features in the planet's spectrum. Specifically, we detect gaseous H$_2$O in the atmosphere and place an upper limit on the abundance of CH$_4$. The otherwise prominent CO$_2$ feature at 2.8 $μ$m is largely masked by H$_2$O. The best-fit chemical equilibrium models favour an atmospheric metallicity of 1-100$\times$ solar (i.e., an enrichment of elements heavier than helium relative to the Sun) and a sub-stellar carbon-to-oxygen (C/O) ratio. The inferred high metallicity and low C/O ratio may indicate significant accretion of solid materials during planet formation or disequilibrium processes in the upper atmosphere.
description: 35 pages, 13 figures, 3 tables, Nature, accepted