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Into the storm : Diving into the winds of the ultra-hot Jupiter WASP-76 b with HARPS and ESPRESSO

Seidel, J. V. ; Ehrenreich, D. ; Allart, R. ; Hoeijmakers, H. J. LU ; Lovis, C. ; Bourrier, V. ; Pino, L. ; Wyttenbach, A. ; Adibekyan, V. and Alibert, Y. , et al. (2021) In Astronomy and Astrophysics 653.
Abstract

Context. Despite swift progress in the characterisation of exoplanet atmospheres in composition and structure, the study of atmospheric dynamics has not progressed at the same speed. While theoretical models have been developed to describe the lower layers of the atmosphere, and independently, the exosphere, little is known about the intermediate layers up to the thermosphere. Aims. We aim to provide a clearer picture of atmospheric dynamics for the class of ultra-hot Jupiters, which are highly irradiated gas giants, based on the example of WASP-76 b. Methods. We jointly analysed two datasets that were obtained with the HARPS and ESPRESSO spectrographs to interpret the resolved planetary sodium doublet. We then applied the MERC code,... (More)

Context. Despite swift progress in the characterisation of exoplanet atmospheres in composition and structure, the study of atmospheric dynamics has not progressed at the same speed. While theoretical models have been developed to describe the lower layers of the atmosphere, and independently, the exosphere, little is known about the intermediate layers up to the thermosphere. Aims. We aim to provide a clearer picture of atmospheric dynamics for the class of ultra-hot Jupiters, which are highly irradiated gas giants, based on the example of WASP-76 b. Methods. We jointly analysed two datasets that were obtained with the HARPS and ESPRESSO spectrographs to interpret the resolved planetary sodium doublet. We then applied the MERC code, which retrieves wind patterns, speeds, and temperature profiles on the line shape of the sodium doublet. An updated version of MERC, with added planetary rotation, also provides the possibility of modelling the latitude dependence of the wind patterns. Results. We retrieve the highest Bayesian evidence for an isothermal atmosphere, interpreted as a mean temperature of 3389 ± 227 K, a uniform day- to nightside wind of 5.5-2.0+1.4 km s-1 in the lower atmosphere with a vertical wind in the upper atmosphere of 22.7-4.1+4.9 km s-1, switching atmospheric wind patterns at 10-3 bar above the reference surface pressure (10 bar). Conclusions. Our results for WASP-76 b are compatible with previous studies of the lower atmospheric dynamics of WASP-76 b and other ultra-hot Jupiters. They highlight the need for vertical winds in the intermediate atmosphere above the layers probed by global circulation model studies to explain the line broadening of the sodium doublet in this planet. This work demonstrates the capability of exploiting the resolved spectral line shapes to observationally constrain possible wind patterns in exoplanet atmospheres. This is an invaluable input to more sophisticated 3D atmospheric models in the future.

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organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Line: profiles, Methods: data analysis, Planets and satellites: atmospheres, Planets and satellites: individual: WASP-76 b, Techniques: spectroscopic
in
Astronomy and Astrophysics
volume
653
article number
A73
publisher
EDP Sciences
external identifiers
  • scopus:85114964014
ISSN
0004-6361
DOI
10.1051/0004-6361/202140569
language
English
LU publication?
yes
additional info
Publisher Copyright: © ESO 2021. Copyright: Copyright 2021 Elsevier B.V., All rights reserved.
id
b21434e6-00f4-4f51-b1f6-f72c0445cfc6
date added to LUP
2021-09-29 09:45:16
date last changed
2023-02-21 11:22:02
@article{b21434e6-00f4-4f51-b1f6-f72c0445cfc6,
  abstract     = {{<p>Context. Despite swift progress in the characterisation of exoplanet atmospheres in composition and structure, the study of atmospheric dynamics has not progressed at the same speed. While theoretical models have been developed to describe the lower layers of the atmosphere, and independently, the exosphere, little is known about the intermediate layers up to the thermosphere. Aims. We aim to provide a clearer picture of atmospheric dynamics for the class of ultra-hot Jupiters, which are highly irradiated gas giants, based on the example of WASP-76 b. Methods. We jointly analysed two datasets that were obtained with the HARPS and ESPRESSO spectrographs to interpret the resolved planetary sodium doublet. We then applied the MERC code, which retrieves wind patterns, speeds, and temperature profiles on the line shape of the sodium doublet. An updated version of MERC, with added planetary rotation, also provides the possibility of modelling the latitude dependence of the wind patterns. Results. We retrieve the highest Bayesian evidence for an isothermal atmosphere, interpreted as a mean temperature of 3389 ± 227 K, a uniform day- to nightside wind of 5.5-2.0+1.4 km s-1 in the lower atmosphere with a vertical wind in the upper atmosphere of 22.7-4.1+4.9 km s-1, switching atmospheric wind patterns at 10-3 bar above the reference surface pressure (10 bar). Conclusions. Our results for WASP-76 b are compatible with previous studies of the lower atmospheric dynamics of WASP-76 b and other ultra-hot Jupiters. They highlight the need for vertical winds in the intermediate atmosphere above the layers probed by global circulation model studies to explain the line broadening of the sodium doublet in this planet. This work demonstrates the capability of exploiting the resolved spectral line shapes to observationally constrain possible wind patterns in exoplanet atmospheres. This is an invaluable input to more sophisticated 3D atmospheric models in the future. </p>}},
  author       = {{Seidel, J. V. and Ehrenreich, D. and Allart, R. and Hoeijmakers, H. J. and Lovis, C. and Bourrier, V. and Pino, L. and Wyttenbach, A. and Adibekyan, V. and Alibert, Y. and Borsa, F. and Casasayas-Barris, N. and Cristiani, S. and Demangeon, O. D.S. and Di Marcantonio, P. and Figueira, P. and González Hernández, J. I. and Lillo-Box, J. and Martins, C. J.A.P. and Mehner, A. and Molaro, P. and Nunes, N. J. and Palle, E. and Pepe, F. and Santos, N. C. and Sousa, S. G. and Sozzetti, A. and Tabernero, H. M. and Zapatero Osorio, M. R.}},
  issn         = {{0004-6361}},
  keywords     = {{Line: profiles; Methods: data analysis; Planets and satellites: atmospheres; Planets and satellites: individual: WASP-76 b; Techniques: spectroscopic}},
  language     = {{eng}},
  month        = {{09}},
  publisher    = {{EDP Sciences}},
  series       = {{Astronomy and Astrophysics}},
  title        = {{Into the storm : Diving into the winds of the ultra-hot Jupiter WASP-76 b with HARPS and ESPRESSO}},
  url          = {{http://dx.doi.org/10.1051/0004-6361/202140569}},
  doi          = {{10.1051/0004-6361/202140569}},
  volume       = {{653}},
  year         = {{2021}},
}