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

• Published in: Nature (London) Vol. 614; no. 7949; pp. 664 - 669
• Main Authors: Alderson, Lili, Wakeford, Hannah R., Alam, Munazza K., Batalha, Natasha E., Lothringer, Joshua D., Adams Redai, Jea, Barat, Saugata, Brande, Jonathan, Damiano, Mario, Daylan, Tansu, Espinoza, Néstor, Flagg, Laura, Goyal, Jayesh M., Grant, David, Hu, Renyu, Inglis, Julie, Lee, Elspeth K. H., Mikal-Evans, Thomas, Ramos-Rosado, Lakeisha, Roy, Pierre-Alexis, Wallack, Nicole L., Batalha, Natalie M., Bean, Jacob L., Benneke, Björn, Berta-Thompson, Zachory K., Carter, Aarynn L., Changeat, Quentin, Colón, Knicole D., Crossfield, Ian J. M., Désert, Jean-Michel, Foreman-Mackey, Daniel, Gibson, Neale P., Kreidberg, Laura, Line, Michael R., López-Morales, Mercedes, Molaverdikhani, Karan, Moran, Sarah E., Morello, Giuseppe, Moses, Julianne I., Mukherjee, Sagnick, Schlawin, Everett, Sing, David K., Stevenson, Kevin B., Taylor, Jake, Aggarwal, Keshav, Ahrer, Eva-Maria, Allen, Natalie H., Barstow, Joanna K., Bell, Taylor J., Blecic, Jasmina, Casewell, Sarah L., Chubb, Katy L., Crouzet, Nicolas, Cubillos, Patricio E., Decin, Leen, Feinstein, Adina D., Fortney, Joanthan J., Harrington, Joseph, Heng, Kevin, Iro, Nicolas, Kempton, Eliza M.-R., Kirk, James, Knutson, Heather A., Krick, Jessica, Leconte, Jérémy, Lendl, Monika, MacDonald, Ryan J., Mancini, Luigi, Mansfield, Megan, May, Erin M., Mayne, Nathan J., Miguel, Yamila, Nikolov, Nikolay K., Ohno, Kazumasa, Palle, Enric, Parmentier, Vivien, Petit dit de la Roche, Dominique J. M., Piaulet, Caroline, Powell, Diana, Rackham, Benjamin V., Redfield, Seth, Rogers, Laura K., Rustamkulov, Zafar, Tan, Xianyu, Tremblin, P., Tsai, Shang-Min, Turner, Jake D., de Val-Borro, Miguel, Venot, Olivia, Welbanks, Luis, Wheatley, Peter J., Zhang, Xi
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 23.02.2023; Nature Publishing Group
• Subjects: 639/33/34/2810; 639/33/34/862; Absorption; Astrophysics; Atmosphere; Atmospheric and Oceanic Physics; Atmospheric models; Carbon dioxide; Earth and Planetary Astrophysics; Equilibrium; Extrasolar planets; Gas giant planets; Humanities and Social Sciences; Light; Metallicity; multidisciplinary; Near infrared radiation; Oxygen; Physics; Planetary atmospheres; Ratios; Science; Science (multidisciplinary); Sciences of the Universe; Sulfur dioxide; Time series
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/s41586-022-05591-3

Measuring the abundances of carbon and oxygen in exoplanet atmospheres is considered a crucial avenue for unlocking the formation and evolution of exoplanetary systems 1 , 2 . Access to the chemical inventory of an exoplanet requires high-precision observations, often inferred from individual molecular detections with low-resolution space-based 3 – 5 and high-resolution ground-based 6 – 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 CO 2 (28.5 σ ) and H 2 O (21.5 σ ), and identify SO 2 as the source of absorption at 4.1 μm (4.8 σ ). 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 SO 2 , 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 range 10 . The medium-resolution transmission spectrum of the exoplanet WASP-39b, described using observations from the Near Infrared Spectrograph G395H grating aboard JWST, shows significant absorption from CO 2 and H 2 O and detection of SO 2 .