Sulphur dioxide in the mid-infrared transmission spectrum of WASP-39b
Creators: name: Powell, Diana
name: Feinstein, Adina D.
name: Lee, Elspeth K. H.
name: Zhang, Michael
name: Tsai, Shang-Min
name: Taylor, Jake
name: Kirk, James
name: Bell, Taylor
name: Barstow, Joanna K.
name: Gao, Peter
name: Bean, Jacob L.
name: Blecic, Jasmina
name: Chubb, Katy L.
name: Crossfield, Ian J. M.
name: Jordan, Sean
name: Kitzmann, Daniel
name: Moran, Sarah E.
name: Morello, Giuseppe
name: Moses, Julianne I.
name: Welbanks, Luis
name: Yang, Jeehyun
name: Zhang, Xi
name: Ahrer, Eva-Maria
name: Bello-Arufe, Aaron
name: Brande, Jonathan
name: Casewell, S. L.
name: Crouzet, Nicolas
name: Cubillos, Patricio E.
name: Demory, Brice-Olivier
name: Dyrek, Achrène
name: Flagg, Laura
name: Hu, Renyu
name: Inglis, Julie
name: Jones, Kathryn D.
name: Kreidberg, Laura
name: López-Morales, Mercedes
name: Lagage, Pierre-Olivier
name: Valdés, Erik A. Meier
name: Miguel, Yamila
name: Parmentier, Vivien
name: Piette, Anjali A. A.
name: Rackham, Benjamin V.
name: Radica, Michael
name: Redfield, Seth
name: Stevenson, Kevin B.
name: Wakeford, Hannah R.
name: Aggarwal, Keshav
name: Alam, Munazza K.
name: Batalha, Natalie M.
name: Batalha, Natasha E.
name: Benneke, Björn
name: Berta-Thompson, Zach K.
name: Brady, Ryan P.
name: Caceres, Claudio
name: Carter, Aarynn L.
name: Désert, Jean-Michel
name: Harrington, Joseph
name: Iro, Nicolas
name: Line, Michael R.
name: Lothringer, Joshua D.
name: MacDonald, Ryan J.
name: Mancini, Luigi
name: Molaverdikhani, Karan
name: Mukherjee, Sagnick
name: Nixon, Matthew C.
name: Oza, Apurva V.
name: Palle, Enric
name: Rustamkulov, Zafar
name: Sing, David K.
name: Steinrueck, Maria E.
name: Venot, Olivia
name: Wheatley, Peter J.
name: Yurchenko, Sergei N.
Publisher: name: arXiv
Year: 2024
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: The recent inference of sulphur dioxide (SO$_2$) in the atmosphere of the hot ($\sim$1100 K), Saturn-mass exoplanet WASP-39b from near-infrared JWST observations suggests that photochemistry is a key process in high temperature exoplanet atmospheres. This is due to the low ($&lt;$1 ppb) abundance of SO$_2$ under thermochemical equilibrium, compared to that produced from the photochemistry of H$_2$O and H$_2$S (1-10 ppm). However, the SO$_2$ inference was made from a single, small molecular feature in the transmission spectrum of WASP-39b at 4.05 $μ$m, and therefore the detection of other SO$_2$ absorption bands at different wavelengths is needed to better constrain the SO$_2$ abundance. Here we report the detection of SO$_2$ spectral features at 7.7 and 8.5 $μ$m in the 5-12 $μ$m transmission spectrum of WASP-39b measured by the JWST Mid-Infrared Instrument (MIRI) Low Resolution Spectrometer (LRS). Our observations suggest an abundance of SO$_2$ of 0.5-25 ppm (1$σ$ range), consistent with previous findings. In addition to SO$_2$, we find broad water vapour absorption features, as well as an unexplained decrease in the transit depth at wavelengths longer than 10 $μ$m. Fitting the spectrum with a grid of atmospheric forward models, we derive an atmospheric heavy element content (metallicity) for WASP-39b of $\sim$7.1-8.0 $\times$ solar and demonstrate that photochemistry shapes the spectra of WASP-39b across a broad wavelength range.
description: Published in Nature