Products and Models for "A multidimensional map of the dayside of an extrasolar planet"

This archive contains the data products associated with the paper "A multidimensional map of the dayside of an extrasolar planet" by Challener & Weiner Mansfield et al. The tar.gz file contains a short README and three subdirectories: (1) eigenspectra, (2) retrievals, and (3) theresa. The eigenspectra directory contains a README, the eigenspectra data products in the numpy format, and the materials necessary to produce many of the figures in the manuscript. The retrievals directory contains separate subdirectories for the PyratBay and HyDRA retrieval results, each with their own README files describing the contents. The theresa directory includes a README, the ThERESA inputs, outputs, configuration file, and a subdirectory with the scripts used to make the remaining figures.

Abstract:

Highly-irradiated, synchronously-rotating exoplanets are anticipated to exhibit large variations of atmospheric temperature and chemistry as a function of longitude, latitude,and altitude. Previous observations have hinted at these variations but the existing data have been fundamentally restricted to probing hemisphere-integrated spectra, thereby providing only coarse information on atmospheric gradients. Here we present the first spectroscopic eclipse map of a transiting extrasolar planet, resolving the atmosphere in multiple dimensions simultaneously. We applied the Eigenspectra mapping method to a secondary eclipse of the ultra-hot Jupiter WASP-18b observed with the NIRISS instrument on JWST. The mapping reveals weaker longitudinal temperature gradients than were predicted by theoretical models,indicating the importance of hydrogen dissociation and/or nightside clouds in shaping global thermal emission. Additionally, we identify two thermally distinct regions of the planet’s atmosphere: a “hotspot” surrounding the substellar point and a “ring” near the dayside limbs. Our analysis of the hotspot region shows a strongly inverted thermal structure due to the presence of absorbers in the optical. The water abundance in the hotspot is marginally lower than the hemispheric average, in accordance with theoretical predictions. The ring region shows colder temperatures and poorly constrained chemical abundances. Similar analyses of future JWST observations will reveal three-dimensional structures across a broad population of exoplanet atmospheres.