Early Release Science of the exoplanet WASP-39b with JWST NIRSpec G395H

Lili Alderson, Hannah R. Wakeford, Munazza K. Alam, Natasha E. Batalha, Joshua D. Lothringer, Jea Adams Redai, Saugata Barat, Jonathan Brande, Mario Damiano, Tansu Daylan, Néstor Espinoza, Laura Flagg, Jayesh M. Goyal, David Grant, Renyu Hu, Julie Inglis, Elspeth K.H. Lee, Thomas Mikal-Evans, Lakeisha Ramos-Rosado, Pierre Alexis RoyNicole L. Wallack, Natalie M. Batalha, Jacob L. Bean, Björn Benneke, Zachory K. Berta-Thompson, Aarynn L. Carter, Quentin Changeat, Knicole D. Colón, Ian J.M. Crossfield, Jean Michel Désert, Daniel Foreman-Mackey, Neale P. Gibson, Laura Kreidberg, Michael R. Line, Mercedes López-Morales, Karan Molaverdikhani, Sarah E. Moran, Giuseppe Morello, Julianne I. Moses, Sagnick Mukherjee, Everett Schlawin, David K. Sing, Kevin B. Stevenson, Jake Taylor, Keshav Aggarwal, Eva Maria Ahrer, Natalie H. Allen, Joanna K. Barstow, Taylor J. Bell, Jasmina Blecic, Sarah L. Casewell, Katy L. Chubb, Nicolas Crouzet, Patricio E. Cubillos, Leen Decin, Adina D. Feinstein, Joanthan J. Fortney, Joseph Harrington, Kevin Heng, Nicolas Iro, Eliza M.R. Kempton, James Kirk, Heather A. Knutson, Jessica Krick, Jérémy Leconte, Monika Lendl, Ryan J. MacDonald, Luigi Mancini, Megan Mansfield, Erin M. May, Nathan J. Mayne, Yamila Miguel, Nikolay K. Nikolov, Kazumasa Ohno, Enric Palle, Vivien Parmentier, Dominique J.M. Petit dit de la Roche, Caroline Piaulet, Diana Powell, Benjamin V. Rackham, Seth Redfield, Laura K. Rogers, Zafar Rustamkulov, Xianyu Tan, P. Tremblin, Shang Min Tsai, Jake D. Turner, Miguel de Val-Borro, Olivia Venot, Luis Welbanks, Peter J. Wheatley, Xi Zhang

Research output: Contribution to journalArticlepeer-review

91 Scopus citations


Measuring the abundances of carbon and oxygen in exoplanet atmospheres is considered a crucial avenue for unlocking the formation and evolution of exoplanetary systems1,2. Access to the chemical inventory of an exoplanet requires high-precision observations, often inferred from individual molecular detections with low-resolution space-based3–5 and high-resolution ground-based6–8 facilities. Here we report the medium-resolution (R ≈ 600) transmission spectrum of an exoplanet atmosphere between 3 and 5 μm covering several absorption features for the Saturn-mass exoplanet WASP-39b (ref. 9), obtained with the Near Infrared Spectrograph (NIRSpec) G395H grating of JWST. Our observations achieve 1.46 times photon precision, providing an average transit depth uncertainty of 221 ppm per spectroscopic bin, and present minimal impacts from systematic effects. We detect significant absorption from CO2 (28.5σ) and H2O (21.5σ), and identify SO2 as the source of absorption at 4.1 μm (4.8σ). Best-fit atmospheric models range between 3 and 10 times solar metallicity, with sub-solar to solar C/O ratios. These results, including the detection of SO2, underscore the importance of characterizing the chemistry in exoplanet atmospheres and showcase NIRSpec G395H as an excellent mode for time-series observations over this critical wavelength range10.

Original languageEnglish (US)
Pages (from-to)664-669
Number of pages6
Issue number7949
StatePublished - Feb 23 2023

ASJC Scopus subject areas

  • General

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