WASP-193b: An extremely low-density super-Neptune

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

Research output: Contribution to journalArticlepeer-review

Abstract

Gas giants transiting bright nearby stars are stepping stones for our understanding of planetary system formation and evolution mechanisms. This paper presents a particularly interesting new specimen of this kind of exoplanet discovered by the WASP-South transit survey, WASP-193b. This planet completes an orbit around its Vmag = 12.2 F9 main-sequence host star every 6.25 d. Our analyses found that WASP-193b has a mass of Mp = 0.139 ± 0.029 MJup and a radius of Rp = 1.464 ± 0.058 RJup, translating into an extremely low density of ρp = 0.059 ± 0.014 g/cm3. The planet was confirmed photometrically by the 0.6-m TRAPPIST-South, the 1.0-m SPECULOOS-South telescopes, and the TESS mission, and spectroscopically by the ESO-3.6-m/HARPS and Euler-1.2-m/CORALIE spectrographs. The combination of its large transit depth (dF~1.4 %), its extremely-low density, its high-equilibrium temperature (Teq = 1254 ± 31 K), and the infrared brightness of its host star (magnitude Kmag=10.7) makes WASP-193b an exquisite target for characterization by transmission spectroscopy (transmission spectroscopy metric: TSM ~ 600). One single JWST transit observation would yield detailed insights into its atmospheric properties and planetary mass, within ~0.1 dex and ~1% (vs ~20% currently with radial velocity data) respectively.
Original languageEnglish
JournalAstronomy and Astrophysics
Publication statusAccepted/In press - 29 Aug 2023

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Not yet published as of 14/03/2025.

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