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

Creators: Bell, Taylor J.; Crouzet, Nicolas; Cubillos, Patricio E.; Kreidberg, Laura; Piette, Anjali A. A.; Roman, Michael T.; Barstow, Joanna K.; Blecic, Jasmina; Carone, Ludmila; Coulombe, Louis-Philippe; Ducrot, Elsa; Hammond, Mark; Mendonça, João M.; Moses, Julianne I.; Parmentier, Vivien; Stevenson, Kevin B.; Teinturier, Lucas; Zhang, Michael; Batalha, Natalie M.; Bean, Jacob L.; Benneke, Björn; Charnay, Benjamin; Chubb, Katy L.; Demory, Brice-Olivier; Gao, Peter; Lee, Elspeth K. H.; López-Morales, Mercedes; Morello, Giuseppe; Rauscher, Emily; Sing, David K.; Tan, Xianyu; Venot, Olivia; Wakeford, Hannah R.; Aggarwal, Keshav; Ahrer, Eva-Maria; Alam, Munazza K.; Baeyens, Robin; Barrado, David; Caceres, Claudio; Carter, Aarynn L.; Casewell, Sarah L.; Challener, Ryan C.; Crossfield, Ian J. M.; Decin, Leen; Désert, Jean-Michel; Dobbs-Dixon, Ian; Dyrek, Achrène; Espinoza, Néstor; Feinstein, Adina D.; Gibson, Neale P.; Harrington, Joseph; Helling, Christiane; Hu, Renyu; Iro, Nicolas; Kempton, Eliza M.-R.; Kendrew, Sarah; Komacek, Thaddeus D.; Krick, Jessica; Lagage, Pierre-Olivier; Leconte, Jérémy; Lendl, Monika; Lewis, Neil T.; Lothringer, Joshua D.; Malsky, Isaac; Mancini, Luigi; Mansfield, Megan; Mayne, Nathan J.; Evans-Soma, Thomas M.; Molaverdikhani, Karan; Nikolov, Nikolay K.; Nixon, Matthew C.; Palle, Enric; Petit dit de la Roche, Dominique J. M.; Piaulet, Caroline; Powell, Diana; Rackham, Benjamin V.; Schneider, Aaron D.; Steinrueck, Maria E.; Taylor, Jake; Welbanks, Luis; Yurchenko, Sergei N.; Zhang, Xi; Zieba, Sebastian

Abstract

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.

Copyright and License

© The Author(s), under exclusive licence to Springer Nature Limited 2024. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.

Acknowledgement

T.J.B. acknowledges funding support from the NASA Next Generation Space Telescope Flight Investigations program (now JWST) via WBS 411672.07.05.05.03.02. J.K.B. is supported by a UKRI/STFC Ernest Rutherford Fellowship (grant ST/T004479/1). J.B. acknowledges the support received in part from the NYUAD IT High Performance Computing resources, services, and staff expertise. E.D. acknowledges funding as a Paris Region Fellow through the Marie Sklodowska-Curie Action. M.Z. and B.V.R. acknowledge funding from the 51 Pegasi b Fellowship. A.D.F. acknowledges support from the NSF Graduate Research Fellowship Program. M.M., D.P. and L.W. acknowledge funding from the NHFP Sagan Fellowship Program. P.E.C. is funded by the Austrian Science Fund (FWF) Erwin Schroedinger Fellowship program J4595-N. K.L.C. acknowledges funding from STFC, under project number ST/V000861/1. L.D. acknowledges funding from the KU Leuven Interdisciplinary Grant (IDN/19/028), the European Union H2020-MSCA-ITN-2019 under grant no. 860470 (CHAMELEON) and the FWO research grant G086217N. O.V. acknowledges funding from the ANR project ‘EXACT’ (ANR-21-CE49-0008-01) and from the Centre National d’Études Spatiales (CNES). L.T. and B.C. acknowledge access to the HPC resources of MesoPSL financed by the Region Ile de France and the project Equip@Meso (reference ANR-10-EQPX-29-01) of the programme Investissements d’Avenir supervised by the Agence Nationale pour la Recherche.

Contributions

All authors played an appreciable role in one or more of the following: development of the original proposal, management of the project, definition of the target list and observation plan, analysis of the data, theoretical modelling, and preparation of this paper. Some specific contributions are listed as follows. N.M.B., J.L.B. and K.B.S. provided overall programme leadership and management. L.K. and N.C. coordinated the MIRI working group. L.K., V.P., K.B.S., D.K.S., E.M.-R.K., O.V. and P.E.C. made substantial contributions to the design of the programme and the observing proposal. K.B.S. generated the observing plan with input from the team. A.D., P.-O.L., R.C.C., A.L.C., G.M. and M.M. led or co-led working groups and/or contributed to important strategic planning efforts like the design and implementation of the pre-launch data challenges. P.E.C., D.K.S., R.C.C., P.-O.L. and J.B. generated simulated data for pre-launch testing of methods. L.K., T.J.B., M.T.R., N.C., V.P., A.A.A.P. and J.I.M. contributed substantially to the writing of this paper. T.J.B., N.C., M.Z. and E.D. contributed to the development of data analysis pipelines and/or provided the data analysis products used in this analysis that is, reduced the data, modelled the light curves, and/or produced the planetary spectrum. A.A.A.P. coordinated the atmospheric retrieval analysis with contributions from J.K.B., J.B., L.-P.C., M.Z., and K.L.C. M.T.R. coordinated the GCM results and interpretation with contributions from X.T., L.T., L.C., J.M.M. and I.M. T.J.B., N.C., P.E.C., J.B., L.-P.C. and M.H. generated figures for this paper. M.C.N., X.Z., B.V.R., J.K., M.L.-M., B.C., S.L.C. and R.H. provided substantial feedback to the paper, and G.M. and K.L.C. coordinated comments from all authors.

Data Availability

The data used in this paper are associated with JWST DD-ERS programme 1366 (principal investigators N.M.B., J.L.B. and K.B.S.; observation 11) and are publicly available from the Mikulski Archive for Space Telescopes (https://mast.stsci.edu). Additional intermediate and final results from this work are archived on Zenodo at https://doi.org/10.5281/zenodo.10525170 (ref. ¹⁹²).

Code Availability

We used the following codes to process, extract, reduce and analyse the data: STScI’s JWST Calibration pipeline⁴⁶, Eureka!⁴⁵, TEATRO, SPARTA⁴⁸, Generic PCM^{64,65,66,67,68}, SPARC/MITgcm^9,33,81,82, expeRT/GCM^16,72,89, RM-GCM^{8,35,106,107,108}, THOR^{4,116,117,124,126,193}, HyDRA¹³⁴, PyratBay¹⁵⁰, NEMESIS^165,166, SCARLET^160,171, PLATON¹⁷⁹, starry⁵⁴, exoplanet⁶¹, PyMC3⁵⁷, emcee⁶⁰, dynesty⁴⁹, numpy¹⁹⁴, astropy^195,196 and matplotlib¹⁹⁷.

Conflict of Interest

The authors declare no competing interests.

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