A Spatial Map of the Atmospheric Limb of a Hot Jupiter

Abstract

Planets are inherently three-dimensional objects shaped by their thermal structure and dynamics. Observations of transiting exoplanets have begun to uncover this three-dimensional nature, with JWST measuring their dayside atmosphere structure with eclipse mapping, and exploring spectroscopic asymmetries in the limbs of planets during transit. We apply the novel mapping method of transmission strings to the hot Jupiter WASP-17b. With this method, we are not only able to extract hemispheric limb asymmetries from east-to-west, but can map equator-to-pole variations around the transmitting atmosphere as a function of angle, spanning 0.6-12μm. We find a clear transition in the thermal scale height around the limb of the atmosphere, with a ∼650K temperature difference between the morning (T=858⁺⁴³⁴₋₂₃₃K) and evening (T=1522⁺¹¹⁶₋₁₁₄K). These results are consistent with both nightside emission and dayside eclipse mapping measurements, and represent a fully comprehensive set of observations for a transiting exoplanet. We are also able to constrain the abundances of H₂O and CO₂ to constant values around the limb, providing observational constraints to results from global circulation models. The transmission string technique combined with the outstanding observability of WASP-17b pushes the study of exoplanet atmospheres further into a three-dimensional understanding of hot Jupiter dynamics and chemistry

Versions

10.1038/s41550-026-02986-4Published version10.1038/s41550-026-02986-4

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BibTeX RIS

BibTeX

@misc{alderson2026spatial,
  title = {{A Spatial Map of the Atmospheric Limb of a Hot Jupiter}},
  author = {Lili Alderson and Hannah R. Wakeford and David Grant and Nikole K. Lewis and Avinash Verma and Jayesh Goyal and Mark Hammond and Daniel Valentine and Natalie H. Allen and Ana Glidden and Amélie Gressier and Jingcheng Huang and Maura Lally and Dana R. Louie and Jacob Lustig-Yaeger and Cathal Maguire and Elijah Mullens and Kristen S. Sotzen and Jeff A. Valenti and Roeland P. van der Marel and Tiffany Kataria},
  howpublished = {arXiv},
  year = {2026},
  month = oct,
  doi = {10.48550/arxiv.2610.18806},
  eprint = {2610.18806},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2610.18806},
  note = {CC BY 4.0},
}

RIS

TY  - UNPB
TI  - A Spatial Map of the Atmospheric Limb of a Hot Jupiter
AU  - Lili Alderson
AU  - Hannah R. Wakeford
AU  - David Grant
AU  - Nikole K. Lewis
AU  - Avinash Verma
AU  - Jayesh Goyal
AU  - Mark Hammond
AU  - Daniel Valentine
AU  - Natalie H. Allen
AU  - Ana Glidden
AU  - Amélie Gressier
AU  - Jingcheng Huang
AU  - Maura Lally
AU  - Dana R. Louie
AU  - Jacob Lustig-Yaeger
AU  - Cathal Maguire
AU  - Elijah Mullens
AU  - Kristen S. Sotzen
AU  - Jeff A. Valenti
AU  - Roeland P. van der Marel
AU  - Tiffany Kataria
PY  - 2026
DA  - 2026/10/13
PB  - arXiv
DO  - 10.48550/arxiv.2610.18806
UR  - https://arxiv.org/abs/2610.18806
AB  - Planets are inherently three-dimensional objects shaped by their thermal structure and dynamics. Observations of transiting exoplanets have begun to uncover this three-dimensional nature, with JWST measuring their dayside atmosphere structure with eclipse mapping, and exploring spectroscopic asymmetries in the limbs of planets during transit. We apply the novel mapping method of transmission strings to the hot Jupiter WASP-17b. With this method, we are not only able to extract hemispheric limb asymmetries from east-to-west, but can map equator-to-pole variations around the transmitting atmosphere as a function of angle, spanning 0.6-12μm. We find a clear transition in the thermal scale height around the limb of the atmosphere, with a ∼650K temperature difference between the morning (T=858^+434_−233K) and evening (T=1522^+116_−114K). These results are consistent with both nightside emission and dayside eclipse mapping measurements, and represent a fully comprehensive set of observations for a transiting exoplanet. We are also able to constrain the abundances of H_2O and CO_2 to constant values around the limb, providing observational constraints to results from global circulation models. The transmission string technique combined with the outstanding observability of WASP-17b pushes the study of exoplanet atmospheres further into a three-dimensional understanding of hot Jupiter dynamics and chemistry
ER  -

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