Nightside clouds and disequilibrium chemistry on the hot Jupiter WASP-43b

• DOI: 10.1038/s41550-024-02230-x
• Publication Date: 2024-04-30T10:01:58Z
• Authors: Taylor J. Bell; Nicolas Crouzet; Patricio E. Cubillos; Laura Kreidberg; Anjali A. A. Piette; Michael T. Roman; Joanna K. Barstow; Jasmina Blecic; Ludmila Carone; Louis-Philippe Co...; Elsa Ducrot; Mark Hammond; João M. Mendonça; Julianne I. Moses; Vivien Parmentier; Kevin B. Stevenson; Lucas Teinturier; Michael Zhang; Natalie M. Batalha; Jacob L. Bean; Björn Benneke; Benjamin Charnay; Katy L. Chubb; Brice-Olivier Demory; Peter Gao; Elspeth K. H. Lee; Mercedes López-Mo...; Giuseppe Morello; Emily Rauscher; David K. Sing; Xianyu Tan; Olivia Venot; Hannah R. Wakeford; Keshav Aggarwal; Eva-Maria Ahrer; Munazza K. Alam; Robin Baeyens; David Barrado; Claudio Caceres; Aarynn L. Carter; Sarah L. Casewell; Ryan C. Challener; Ian J. M. Crossfield; Leen Decin; Jean-Michel Désert; Ian Dobbs-Dixon; Achrène Dyrek; Néstor Espinoza; Adina D. Feinstein; Neale P. Gibson; Joseph Harrington; Christiane Helling; Renyu Hu; Nicolas Iro; Eliza M.-R. Kempton; Sarah Kendrew; Thaddeus D. Komacek; Jessica Krick; Pierre-Olivier La...; Jérémy Leconte; Monika Lendl; Neil T. Lewis; Joshua D. Lothringer; Isaac Malsky; Luigi Mancini; Megan Mansfield; Nathan J. Mayne; Thomas M. Evans-Soma; Karan Molaverdikhani; Nikolay K. Nikolov; Matthew C. Nixon; Enric Palle; Dominique J. M. P...; Caroline Piaulet; Diana Powell; Benjamin V. Rackham; Aaron D. Schneider; Maria E. Steinrueck; Jake Taylor; Luis Welbanks; Sergei N. Yurchenko; Xi Zhang; Sebastian Zieba
• Keywords: atmospheric chemistry; 530 Physics; atmospheric models; Astronomy & Astrophysics; 530; Article; cosmologia e scienza dello spazio; [SDU] Sciences of the Universe [physics]; RADIATIVE-TRANSFER; ROTATION-VIBRATION SPECTRUM; GENERAL-CIRCULATION MODEL; disequilibrium chemistry; MOLECULAR LINE LISTS; Science & Technology; Settore FIS/05; Exoplanets; 520 Astronomy; 500; DAS; COLLISION-INDUCED ABSORPTION; 520; exoplanets; [SDU]Sciences of the Universe [physics]; Physical Sciences; COMPUTER-PROGRAM; RAYLEIGH-SCATTERING; MULTIPLE-SCATTERING; exoplanet atmosphere space mission JWST; Settore PHYS-05/A - Astrofisica; BAYESIAN-INFERENCE; Astrophysics - Instrumentation and Methods for Astrophysics; ATMOSPHERIC CIRCULATION; Astrophysics - Earth and Planetary Astrophysics

AbstractHot Jupiters are among the best-studied exoplanets, but it is still poorly understood how their chemical composition and cloud properties vary with longitude. Theoretical models predict that clouds may condense on the nightside and that molecular abundances can be driven out of equilibrium by zonal winds. Here we report a phase-resolved emission spectrum of the hot Jupiter WASP-43b measured from 5 μm to 12 μm with the JWST’s Mid-Infrared Instrument. The spectra reveal a large day–night temperature contrast (with average brightness temperatures of 1,524 ± 35 K and 863 ± 23 K, respectively) and evidence for water absorption at all orbital phases. Comparisons with three-dimensional atmospheric models show that both the phase-curve shape and emission spectra strongly suggest the presence of nightside clouds that become optically thick to thermal emission at pressures greater than ~100 mbar. The dayside is consistent with a cloudless atmosphere above the mid-infrared photosphere. Contrary to expectations from equilibrium chemistry but consistent with disequilibrium kinetics models, methane is not detected on the nightside (2σ upper limit of 1–6 ppm, depending on model assumptions). Our results provide strong evidence that the atmosphere of WASP-43b is shaped by disequilibrium processes and provide new insights into the properties of the planet’s nightside clouds. However, the remaining discrepancies between our observations and our predictive atmospheric models emphasize the importance of further exploring the effects of clouds and disequilibrium chemistry in numerical models.