Phase-dependent chemistry of WASP-43 b revealed with a suite of one-, two-, and three-dimensional models
Abstract
Context. Spectroscopic phase curves of tidally locked giant exoplanets provide us with a unique global picture of their atmospheric chemistry, as different regions of the planet rotate in and out of view. However, the spatially changing composition of tidally locked exoplanets – governed by stellar irradiation and atmospheric circulation – make phase-resolved observations exceptionally hard to interpret. Aims. Our goal is to investigate the chemistry of the hot Jupiter WASP-43 b in detail using theoretical models, considering the constraints of the James Webb Space Telescope’s MIRI phase curve. Methods. With a suite of pseudo-two-dimensional and three-dimensional photochemical models, we simulate the composition of WASP-43 b in various configurations (different metallicities and wind speeds), and compare them with atmospheric retrieval models. Additionally, we probe the robustness of photochemical predictions by comparing the results of four one-dimensional models that have equivalent setups. Results. We confirm that disequilibrium chemistry in our theoretical models reduces the methane concentration on the planet’s night side for wind jet speeds ≳ 500 m s−1. Varying the metallicity in the models induces large changes in the CO2 and SO2 concentrations, with SO2 producing mid-infrared absorption features in synthetic emission spectra of the night side at atmospheric metallicities ≳ 10× solar. Our models provide evidence for pole-to-equator circulation enhancing the CH4, NH3, and HCN abundances, which is nonetheless insufficient for detectable spectral features. Finally, we show that H2O, CO, and CO2 are robustly modeled, but species affected by photochemistry (CH4, NH3, SO2, HCN) are more sensitive to model-specific assumptions and pathways. Conclusions. We conclude that horizontal quenching is the prime mechanism that explains the non-detection of methane in the MIRI phase-curve of WASP-43 b. This mechanism requires only moderate wind speeds and is operative at various thermal structures and atmospheric metallicities. Furthermore, coupled carbon-sulfur chemistry leads to an additional decrease in methane compared to previous models in the literature that did not contain sulfur chemistry. We do not favor a high metallicity as it would have led to observable SO2 features in the MIRI spectra. Our study shows that phase-dependent photochemistry models are essential tools in the interpretation of hot-Jupiter phase curves, but benchmarking is needed to improve the accuracy of photochemical models in the future.
Related
- Mass-dependent multiplicity fraction in low-mass stars revealed by astrometry Gaia
- Mass-dependent multiplicity fraction in low mass stars revealed by Gaia astrometry
- Origin of the ice of the Latitude Dependent Mantle (LDM) revealed by ice-exposing scarps on Mars
- Wind-confined jet collimation revealed by the acceleration-phase photosphere of GRB 220426A
- Dynamically Coupled Three-dimensional Cloud-Chemistry in Rapidly Rotating Irradiated Atmospheres: an Application to the Compact White Dwarf-Brown Dwarf system ZTFJ0038+2030
BibTeX
@misc{baeyens2026phasedependent,
title = {{Phase-dependent chemistry of WASP-43 b revealed with a suite of one-, two-, and three-dimensional models}},
author = {Robin Baeyens and Julianne I. Moses and Jasmina Blecic and Elspeth K. H. Lee and Lucas Teinturier and Shang-Min Tsai and Jeehyun Yang and Jingxuan Yang and Ludmila Carone and Renyu Hu and Sven Kiefer and Anjali A. A. Piette and Taylor J. Bell and Nicolas Crouzet and Ian Dobbs-Dixon and Christiane Helling and Nicolas Iro and Dominic Samra and Olivia Venot and Jean-Michel Désert},
howpublished = {HAL},
year = {2026},
month = jul,
eprint = {2607.08486},
archivePrefix = {arXiv},
url = {https://hal.science/hal-05784985v1},
note = {CC BY-NC-SA 4.0},
}
RIS
TY - UNPB
TI - Phase-dependent chemistry of WASP-43 b revealed with a suite of one-, two-, and three-dimensional models
AU - Robin Baeyens
AU - Julianne I. Moses
AU - Jasmina Blecic
AU - Elspeth K. H. Lee
AU - Lucas Teinturier
AU - Shang-Min Tsai
AU - Jeehyun Yang
AU - Jingxuan Yang
AU - Ludmila Carone
AU - Renyu Hu
AU - Sven Kiefer
AU - Anjali A. A. Piette
AU - Taylor J. Bell
AU - Nicolas Crouzet
AU - Ian Dobbs-Dixon
AU - Christiane Helling
AU - Nicolas Iro
AU - Dominic Samra
AU - Olivia Venot
AU - Jean-Michel Désert
PY - 2026
DA - 2026/07/09
PB - HAL
UR - https://hal.science/hal-05784985v1
AB - Context. Spectroscopic phase curves of tidally locked giant exoplanets provide us with a unique global picture of their atmospheric chemistry, as different regions of the planet rotate in and out of view. However, the spatially changing composition of tidally locked exoplanets – governed by stellar irradiation and atmospheric circulation – make phase-resolved observations exceptionally hard to interpret. Aims. Our goal is to investigate the chemistry of the hot Jupiter WASP-43 b in detail using theoretical models, considering the constraints of the James Webb Space Telescope’s MIRI phase curve. Methods. With a suite of pseudo-two-dimensional and three-dimensional photochemical models, we simulate the composition of WASP-43 b in various configurations (different metallicities and wind speeds), and compare them with atmospheric retrieval models. Additionally, we probe the robustness of photochemical predictions by comparing the results of four one-dimensional models that have equivalent setups. Results. We confirm that disequilibrium chemistry in our theoretical models reduces the methane concentration on the planet’s night side for wind jet speeds ≳ 500 m s−1. Varying the metallicity in the models induces large changes in the CO2 and SO2 concentrations, with SO2 producing mid-infrared absorption features in synthetic emission spectra of the night side at atmospheric metallicities ≳ 10× solar. Our models provide evidence for pole-to-equator circulation enhancing the CH4, NH3, and HCN abundances, which is nonetheless insufficient for detectable spectral features. Finally, we show that H2O, CO, and CO2 are robustly modeled, but species affected by photochemistry (CH4, NH3, SO2, HCN) are more sensitive to model-specific assumptions and pathways. Conclusions. We conclude that horizontal quenching is the prime mechanism that explains the non-detection of methane in the MIRI phase-curve of WASP-43 b. This mechanism requires only moderate wind speeds and is operative at various thermal structures and atmospheric metallicities. Furthermore, coupled carbon-sulfur chemistry leads to an additional decrease in methane compared to previous models in the literature that did not contain sulfur chemistry. We do not favor a high metallicity as it would have led to observable SO2 features in the MIRI spectra. Our study shows that phase-dependent photochemistry models are essential tools in the interpretation of hot-Jupiter phase curves, but benchmarking is needed to improve the accuracy of photochemical models in the future.
ER -