Issue |
A&A
Volume 688, August 2024
|
|
---|---|---|
Article Number | A206 | |
Number of page(s) | 20 | |
Section | Planets and planetary systems | |
DOI | https://doi.org/10.1051/0004-6361/202450064 | |
Published online | 23 August 2024 |
Exploring the ultra-hot Jupiter WASP-178b
Constraints on atmospheric chemistry and dynamics from a joint retrieval of VLT/CRIRES+ and space photometric data
1
Universitäts-Sternwarte, Ludwig-Maximilians-Universität München,
Scheinerstrasse 1,
81679
München,
Germany
e-mail: david.cont@lmu.de
2
Exzellenzcluster Origins,
Boltzmannstrasse 2,
85748
Garching bei München,
Germany
3
Institut für Astrophysik und Geophysik, Georg-August-Universität Göttingen,
Friedrich-Hund-Platz 1,
37077
Göttingen,
Germany
4
Department of Astronomy, University of Science and Technology of China,
Hefei
230026,
PR
China
5
Thüringer Landessternwarte Tautenburg,
Sternwarte 5,
07778
Tautenburg,
Germany
6
Institut de Recherche en Astrophysique et Planétologie, Université de Toulouse, CNRS,
IRAP/UMR 5277, 14 avenue Edouard Belin,
31400
Toulouse,
France
7
Department of Physics and Astronomy, Uppsala University,
Box 516,
75120
Uppsala,
Sweden
8
Max-Planck-Institut für Sonnensystemforschung,
Justus-von-Liebig-Weg 3,
37077
Göttingen,
Germany
9
European Southern Observatory,
Karl-Schwarzschild-Str. 2,
85748
Garching bei München,
Germany
10
Instituto de Astrofísica de Andalucía (IAA-CSIC),
Glorieta de la Astronomía s/n,
18008
Granada,
Spain
Received:
21
March
2024
Accepted:
25
June
2024
Despite recent progress in the spectroscopic characterization of individual exoplanets, the atmospheres of key ultra-hot Jupiters (UHJs) still lack comprehensive investigations. These include WASP-178b, one of the most irradiated UHJs known to date. We observed the dayside emission signal of this planet with CRIRES+ in the spectral K band. By applying the cross-correlation technique and a Bayesian retrieval framework to the high-resolution spectra, we identified the emission signature of 12CO (S/N = 8.9) and H2O (S/N = 4.9), and a strong atmospheric thermal inversion. A joint retrieval with space-based secondary eclipse measurements from TESS and CHEOPS allowed us to refine our results on the thermal profile and thus to constrain the atmospheric chemistry, yielding a solar to super-solar metallicity (1.4 ± 1.6 dex) and a solar C/O ratio (0.6 ± 0.2). We infer a significant excess of spectral line broadening and identify a slight Doppler-shift between the 12CO and H2O signals. These findings provide strong evidence for a super-rotating atmospheric flow pattern and suggest the possible existence of chemical inhomogeneities across the planetary dayside hemisphere. In addition, the inclusion of photometric data in our retrieval allows us to account for stellar light reflected by the planetary atmosphere, resulting in an upper limit on the geometric albedo (0.23). The successful characterization of WASP-178b’s atmosphere through a joint analysis of CRIRES+, TESS, and CHEOPS observations highlights the potential of combined studies with space- and ground-based instruments and represents a promising avenue for advancing our understanding of exoplanet atmospheres.
Key words: techniques: spectroscopic / planets and satellites: atmospheres / planets and satellites: individual: WASP-178b
© The Authors 2024
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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