{"about":{"site":"https://codewithpapers.app","non_affiliation":"Code with Papers and Syntology are not affiliated with, endorsed by, or sponsored by Papers with Code, Meta, or the pwc-archive mirror.","licence":"CC BY-SA 4.0","licence_url":"https://creativecommons.org/licenses/by-sa/4.0/legalcode","attribution":"https://codewithpapers.app/attribution","modified":"archive material modified by Syntology; see the attribution page"},"url":"/paper/sulphur-dioxide-in-the-mid-infrared","title":"Sulphur dioxide in the mid-infrared transmission spectrum of WASP-39b","arxiv_id":"2407.07965","date":"2024-07-10","proceeding":null,"authors":["Diana Powell","Adina D. Feinstein","Elspeth K. H. Lee","Michael Zhang","Shang-Min Tsai","Jake Taylor","James Kirk","Taylor Bell","Joanna K. Barstow","Peter Gao","Jacob L. Bean","Jasmina Blecic","Katy L. Chubb","Ian J. M. Crossfield","Sean Jordan","Daniel Kitzmann","Sarah E. Moran","Giuseppe Morello","Julianne I. Moses","Luis Welbanks","Jeehyun Yang","Xi Zhang","Eva-Maria Ahrer","Aaron Bello-Arufe","Jonathan Brande","S. L. Casewell","Nicolas Crouzet","Patricio E. Cubillos","Brice-Olivier Demory","Achrène Dyrek","Laura Flagg","Renyu Hu","Julie Inglis","Kathryn D. Jones","Laura Kreidberg","Mercedes López-Morales","Pierre-Olivier Lagage","Erik A. Meier Valdés","Yamila Miguel","Vivien Parmentier","Anjali A. A. Piette","Benjamin V. Rackham","Michael Radica","Seth Redfield","Kevin B. Stevenson","Hannah R. Wakeford","Keshav Aggarwal","Munazza K. Alam","Natalie M. Batalha","Natasha E. Batalha","Björn Benneke","Zach K. Berta-Thompson","Ryan P. Brady","Claudio Caceres","Aarynn L. Carter","Jean-Michel Désert","Joseph Harrington","Nicolas Iro","Michael R. Line","Joshua D. Lothringer","Ryan J. MacDonald","Luigi Mancini","Karan Molaverdikhani","Sagnick Mukherjee","Matthew C. Nixon","Apurva V. Oza","Enric Palle","Zafar Rustamkulov","David K. Sing","Maria E. Steinrueck","Olivia Venot","Peter J. Wheatley","Sergei N. Yurchenko"],"abstract":"The recent inference of sulphur dioxide (SO$_2$) in the atmosphere of the hot ($\\sim$1100 K), Saturn-mass exoplanet WASP-39b from near-infrared JWST observations suggests that photochemistry is a key process in high temperature exoplanet atmospheres. This is due to the low ($<$1 ppb) abundance of SO$_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 $\\mu$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 $\\mu$m in the 5-12 $\\mu$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$\\sigma$ 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 $\\mu$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.","url_abs":"https://arxiv.org/abs/2407.07965v1","url_pdf":"https://arxiv.org/pdf/2407.07965v1.pdf","source":{"archive":"pwc-archive (Hugging Face), CC BY-SA 4.0","snapshot":"2025-07-28","licence_url":"https://creativecommons.org/licenses/by-sa/4.0/legalcode","row_kind":"links_only","authors_date_abstract":"arXiv metadata, CC0 1.0 (https://info.arxiv.org/help/license), from the Kaggle arXiv metadata snapshot of 2026-09-12"},"code_links":[{"paper_slug":"sulphur-dioxide-in-the-mid-infrared","repo_url":"https://github.com/exoclime/FastChem","is_official":1,"mentioned_in_paper":0,"mentioned_in_github":0,"framework":"none","reach":{"status":"ok","spdx":"GPL-3.0"}}],"tasks":[],"methods":[],"datasets_introduced":[],"methods_introduced":[],"results":[],"syntology":{"syntology_url":null,"atlas_url":null,"mcp":null,"developers":"https://syntology.ai/developers"},"arxiv_metadata":null,"syntology_extracted_results":null}