Dissemin is shutting down on January 1st, 2025

Published in

Nature Research, Nature, 7973(620), p. 292-298, 2023

DOI: 10.1038/s41586-023-06230-1

arXiv, 2023

DOI: 10.48550/arxiv.2301.08192

Links

Tools

Export citation

Search in Google Scholar

A broadband thermal emission spectrum of the ultra-hot Jupiter WASP-18b

Journal article published in 2023 by Louis-Philippe Coulombe ORCID, Björn Benneke, Ryan Challener, Anjali A. A. Piette, Lindsey S. Wiser, Megan Mansfield, Ryan J. MacDonald, Hayley Beltz, Adina D. Feinstein, Michael Radica, Arjun B. Savel, Leonardo A. Dos Santos, Leonardo A. Dos Santos, Jacob L. Bean, Vivien Parmentier and other authors.
This paper was not found in any repository, but could be made available legally by the author.
This paper was not found in any repository, but could be made available legally by the author.

Full text: Unavailable

Green circle
Preprint: archiving allowed
Orange circle
Postprint: archiving restricted
Red circle
Published version: archiving forbidden
Data provided by SHERPA/RoMEO

Abstract

AbstractClose-in giant exoplanets with temperatures greater than 2,000 K (‘ultra-hot Jupiters’) have been the subject of extensive efforts to determine their atmospheric properties using thermal emission measurements from the Hubble Space Telescope (HST) and Spitzer Space Telescope1–3. However, previous studies have yielded inconsistent results because the small sizes of the spectral features and the limited information content of the data resulted in high sensitivity to the varying assumptions made in the treatment of instrument systematics and the atmospheric retrieval analysis3–12. Here we present a dayside thermal emission spectrum of the ultra-hot Jupiter WASP-18b obtained with the NIRISS13instrument on the JWST. The data span 0.85 to 2.85 μm in wavelength at an average resolving power of 400 and exhibit minimal systematics. The spectrum shows three water emission features (at >6σconfidence) and evidence for optical opacity, possibly attributable to H, TiO and VO (combined significance of 3.8σ). Models that fit the data require a thermal inversion, molecular dissociation as predicted by chemical equilibrium, a solar heavy-element abundance (‘metallicity’,${\rm{M/H}}=1.0{3}_{-0.51}^{+1.11}$M/H=1.03−0.51+1.11times solar) and a carbon-to-oxygen (C/O) ratio less than unity. The data also yield a dayside brightness temperature map, which shows a peak in temperature near the substellar point that decreases steeply and symmetrically with longitude towards the terminators.