Phase-resolving the Absorption Signatures of Water and Carbon Monoxide in the Atmosphere of the Ultra-hot Jupiter WASP-121b with GEMINI-S/IGRINS

Abstract Ultra-hot Jupiters (UHJs) are among the best targets for atmospheric characterization at high spectral resolution. Resolving their transmission spectra as a function of orbital phase offers a unique window into the 3D nature of these objects. In this work, we present three transits of the UHJ WASP-121b observed with Gemini-S/IGRINS. For the first time, we measure the phase-dependent absorption signals of CO and H 2 O in the atmosphere of an exoplanet, and we find that they are different. While the blueshift of CO increases during the transit, the absorption lines of H 2 O become less blueshifted with phase, and even show a redshift in the second half of the transit. These measurements reveal the distinct spatial distributions of both molecules across the atmospheres of UHJs. Also, we find that the H 2 O signal is absent in the first quarter of the transit, potentially hinting at cloud formation on the evening terminator of WASP-121b. To further interpret the absorption trails of CO and H 2 O, as well as the Doppler shifts of Fe previously measured with VLT/ESPRESSO, we compare the data to simulated transits of WASP-121b. To this end, we post-process the outputs of the global circulation models with a 3D Monte-Carlo radiative transfer code. Our analysis shows that the atmosphere of WASP-121b is subject to atmospheric drag, as previously suggested by small hotspot offsets inferred from phase-curve observations. Our study highlights the importance of phase-resolved spectroscopy in unravelling the complex atmospheric structure of UHJs and sets the stage for further investigations into their chemistry and dynamics.

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Publication Details

Journal
Publications of the Astronomical Society of the Pacific
Published
2024-08-01
DOI
https://doi.org/10.1088/1538-3873/ad5c9f
Citations
21
Primary Topic
Astro and Planetary Science
Type
article
Field-Weighted Citation Impact
6.96

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article

Phase-resolving the Absorption Signatures of Water and Carbon Monoxide in the Atmosphere of the Ultra-hot Jupiter WASP-121b with GEMINI-S/IGRINS

Peter Smith, Lorenzo Pino, Siddharth Gandhi, Elspeth K. H. Lee et al.
21 citations
Publications of the Astronomical Society of the Pacific
Astro and Planetary Science
6.96
article

Phase-resolving the Absorption Signatures of Water and Carbon Monoxide in the Atmosphere of the Ultra-hot Jupiter WASP-121b with GEMINI-S/IGRINS

Peter Smith, Lorenzo Pino, Siddharth Gandhi, Elspeth K. H. Lee, Matteo Brogi, Xianyu Tan, Jean-Michel Désert, Jayne Birkby, Colette I. Levens, Jacob L. Bean, Shang‐Min Tsai, Vivien Parmentier, Megan Mansfield, Joost P. Wardenier, Michael R. Line
article en
21 citations

Abstract

Abstract Ultra-hot Jupiters (UHJs) are among the best targets for atmospheric characterization at high spectral resolution. Resolving their transmission spectra as a function of orbital phase offers a unique window into the 3D nature of these objects. In this work, we present three transits of the UHJ WASP-121b observed with Gemini-S/IGRINS. For the first time, we measure the phase-dependent absorption signals of CO and H 2 O in the atmosphere of an exoplanet, and we find that they are different. While the blueshift of CO increases during the transit, the absorption lines of H 2 O become less blueshifted with phase, and even show a redshift in the second half of the transit. These measurements reveal the distinct spatial distributions of both molecules across the atmospheres of UHJs. Also, we find that the H 2 O signal is absent in the first quarter of the transit, potentially hinting at cloud formation on the evening terminator of WASP-121b. To further interpret the absorption trails of CO and H 2 O, as well as the Doppler shifts of Fe previously measured with VLT/ESPRESSO, we compare the data to simulated transits of WASP-121b. To this end, we post-process the outputs of the global circulation models with a 3D Monte-Carlo radiative transfer code. Our analysis shows that the atmosphere of WASP-121b is subject to atmospheric drag, as previously suggested by small hotspot offsets inferred from phase-curve observations. Our study highlights the importance of phase-resolved spectroscopy in unravelling the complex atmospheric structure of UHJs and sets the stage for further investigations into their chemistry and dynamics.

Publications of the Astronomical Society of the PacificVol. 136(8)
University of California, Riverside (US), University of Bern (CH), Leiden University (NL), Centre National de la Recherche Scientifique (FR), University of Arizona (US), Shanghai Jiao Tong University (CN), Arcetri Astrophysical Observatory (IT), University of Warwick (GB), University of Oxford (GB), University of Chicago (US), Osservatorio Astrofisico di Torino (IT), Observatoire de la Côte d’Azur (FR), Montreal Clinical Research Institute (CA), University of Turin (IT), Arizona State University (US), University of Amsterdam (NL)
National Science Foundation, National Aeronautics and Space Administration, University of Oxford, European Commission, Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung, Nuclear Safety and Security Commission, Fondation familiale Trottier, Science and Technology Facilities Council
Openalex Percentile: Top 3%
Astro and Planetary Science
6.96
DOIOpen Access PDFOpenAlex
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