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

2024; Nature Portfolio; Volume: 8; Issue: 7 Linguagem: Inglês

10.1038/s41550-024-02230-x

2397-3366

Taylor J. Bell, Nicolas Crouzet, Patricio E. Cubillos, Laura Kreidberg, Anjali A. A. Piette, Michael T. Roman, J. K. Barstow, Jasmina Blecic, L. Carone, Louis-Philippe Coulombe, 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, K. L. Chubb, Brice-Olivier Demory, Peter Gao, Elspeth K. H. Lee, Mercedes López‐Morales, Giuseppe Morello, Emily Rauscher, David K. Sing, Xianyu Tan, Olivia Vénot, Hannah R. Wakeford, Keshav Aggarwal, Eva-Maria Ahrer, Munazza K. Alam, Robin Baeyens, D. Barrado, C. Cáceres, Aarynn L. Carter, S. L. Casewell, Ryan C. Challener, Ian J. M. Crossfield, L. Decin, Jean-Michel Désert, Ian Dobbs‐Dixon, Achrène Dyrek, Néstor Espinoza, Adina D. Feinstein, Neale P. Gibson, Joseph Harrington, Ch. Helling, Renyu Hu, Nicolas Iro, Eliza M.-R. Kempton, Sarah Kendrew, Thaddeus D. Komacek, Jessica Krick, Pierre-Olivier Lagage, Jérémy Leconte, M. Lendl, Neil T. Lewis, Joshua D. Lothringer, Isaac Malsky, L. Mancini, Megan Mansfield, Nathan J. Mayne, T. M. Evans, Karan Molaverdikhani, Nikolay Nikolov, Matthew C. Nixon, Ε. Πάλλη, Dominique J. M. Petit dit de la Roche, Caroline Piaulet, Diana Powell, Benjamin V. Rackham, Aaron David Schneider, Maria E. Steinrueck, Jake Taylor, Luis Welbanks, S. N. Yurchenko, Xi Zhang, Sebastian Zieba,

Stellar, planetary, and galactic studies

Abstract Hot 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 (2 σ 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.