An extended low-density atmosphere around the Jupiter-sized planet WASP-193 b

Barkaoui, Khalid; Pozuelos, Francisco J.; Hellier, Coel; Smalley, Barry; Nielsen, Louise D.; Niraula, Prajwal; Gillon, Michaël; de Wit, Julien; Müller, Simon; Dorn, Caroline; Helled, Ravit; Jehin, Emmanuel; Demory, Brice-Olivier; Van Grootel, Valerie; Soubkiou, Abderahmane; Ghachoui, Mourad; Anderson, David. R.; Benkhaldoun, Zouhair; Bouchy, Francois; Burdanov, Artem; Delrez, Laetitia; Ducrot, Elsa; Garcia, Lionel; Jabiri, Abdelhadi; Lendl, Monika; Maxted, Pierre F. L.; Murray, Catriona A.; Pedersen, Peter Pihlmann; Queloz, Didier; Sebastian, Daniel; Turner, Oliver; Udry, Stephane; Timmermans, Mathilde; Triaud, Amaury H. M. J.; West, Richard G.

Abstract

Gas giants transiting bright nearby stars provide crucial insights into planetary system formation and evolution mechanisms. Most of these planets show certain average characteristics, serving as benchmarks for our understanding of planetary systems. However, outliers like the planet we present in this study, WASP-193 b, offer unique opportunities to explore unconventional formation and evolution processes. This planet completes an orbit around its V-band-magnitude 12.2 F9 main-sequence host star every 6.25 days. Our analyses found that WASP-193 b has a mass of 0.139 +/- 0.029 M-J and a radius of 1.464 +/- 0.058 R-J, translating into an extremely low density of 0.059 +/- 0.014g cm(-3), at least one order of magnitude less than standard gas giants like Jupiter. Typical gas giants such as Jupiter have densities that range between 0.2 g cm(-3) and 2 g cm(-3). The combination of its large transit depth (1.4%), extremely low density, high-equilibrium temperature (1,254 +/- 31 K) and the infrared brightness of its host star (K-band magnitude 10.7) makes WASP-193 b an exquisite target for characterization by transmission spectroscopy (transmission spectroscopy metric similar to 600). One single JWST transit observation would yield detailed insights into its atmospheric properties and planetary mass, providing a unique window to explore the mechanisms behind its exceptionally low density and shed light on giant planets' diverse nature.

Citation

Barkaoui, K., Pozuelos, F. J., Hellier, C., Smalley, B., Nielsen, L. D., Niraula, P., …West, R. G. (in press). An extended low-density atmosphere around the Jupiter-sized planet WASP-193 b. Nature Astronomy, https://doi.org/10.1038/s41550-024-02259-y

• Journal Article Type: Article
• Acceptance Date: Mar 27, 2024
• Online Publication Date: May 14, 2024
• Deposit Date: Jul 9, 2024
• Publicly Available Date: Jul 15, 2024
• Journal: Nature Astronomy
• Print ISSN: 2397-3366
• Electronic ISSN: 2397-3366
• Publisher: Nature Research
• Peer Reviewed: Peer Reviewed
• DOI: https://doi.org/10.1038/s41550-024-02259-y
• Public URL: https://keele-repository.worktribe.com/output/874122
• Publisher URL: https://www.nature.com/articles/s41550-024-02259-y
• Additional Information: Received: 2 March 2022; Accepted: 27 March 2024; First Online: 14 May 2024; : The authors declare no competing interests.