The atmosphere and architecture of WASP-189 b probed by its CHEOPS phase curve
Journal article, 2022
Context. Gas giants orbiting close to hot and massive early-type stars can reach dayside temperatures that are comparable to those of the coldest stars. These 'ultra-hot Jupiters' have atmospheres made of ions and atomic species from molecular dissociation and feature strong day-to-night temperature gradients. Photometric observations at different orbital phases provide insights on the planet's atmospheric properties. Aims. We aim to analyse the photometric observations of WASP-189 acquired with the Characterising Exoplanet Satellite (CHEOPS) to derive constraints on the system architecture and the planetary atmosphere. Methods. We implemented a light-curve model suited for an asymmetric transit shape caused by the gravity-darkened photosphere of the fast-rotating host star. We also modelled the reflective and thermal components of the planetary flux, the effect of stellar oblateness and light-travel time on transit-eclipse timings, the stellar activity, and CHEOPS systematics. Results. From the asymmetric transit, we measure the size of the ultra-hot Jupiter WASP-189 b, R-p = 1.600(-0.016)(+0.017)R(J), with a precision of 1%, and the true orbital obliquity of the planetary system, Psi(P) = 89.6 +/- 1.2 deg (polar orbit). We detect no significant hotspot offset from the phase curve and obtain an eclipse depth of delta ecl = 96.5(-5.9)(+4).(5) ppm, from which we derive an upper limit on the geometric albedo: A(g) < 0.48. We also find that the eclipse depth can only be explained by thermal emission alone in the case of extremely inefficient energy redistribution. Finally, we attribute the photometric variability to the stellar rotation, either through superficial inhomogeneities or resonance couplings between the convective core and the radiative envelope. Conclusions. Based on the derived system architecture, we predict the eclipse depth in the upcoming Transiting Exoplanet Survey Satellite (TESS) observations to be up to similar to 165 ppm. High-precision detection of the eclipse in both CHEOPS and TESS passbands might help disentangle reflective and thermal contributions. We also expect the right ascension of the ascending node of the orbit to precess due to the perturbations induced by the stellar quadrupole moment J(2) (oblateness).
planets and satellites: atmospheres
techniques: photometric
planets and satellites: individual: WASP-189 b
Author
A. Deline
University of Geneva
M. J. Hooton
University of Bern
M. Lendl
University of Geneva
B. Morris
University of Bern
S. Salmon
University of Geneva
G. Olofsson
Stockholm University
C. Broeg
University of Bern
D. Ehrenreich
University of Geneva
M. Beck
University of Geneva
A. Brandeker
Stockholm University
S. Hoyer
Aix Marseille University
S. Sulis
Aix Marseille University
V. Van Grootel
University of Liège
V Bourrier
University of Geneva
O. Demangeon
University of Porto
B-O Demory
University of Bern
K. Heng
The University of Warwick
Ludwig Maximilian University of Munich (LMU)
University of Bern
H. Parviainen
Instituto de Astrofísica de Canarias
University of La Laguna
L. M. Serrano
University of Turin
V Singh
Istituto nazionale di astrofisica (INAF)
A. Bonfanti
Austrian Academy of Sciences
L. Fossati
Austrian Academy of Sciences
D. Kitzmann
University of Bern
S. G. Sousa
University of Porto
T. G. Wilson
University of St Andrews
Y. Alibert
University of Bern
R. Alonso
University of La Laguna
Instituto de Astrofísica de Canarias
G. Anglada
Spanish National Research Council (CSIC)
T. Barczy
Admatis
D. Barrado Navascues
Spanish National Research Council (CSIC)
S. C. C. Barros
University of Porto
W. Baumjohann
Austrian Academy of Sciences
T. Beck
University of Bern
A. Bekkelien
University of Geneva
W. Benz
University of Bern
N. Billot
University of Geneva
X. Bonfils
Grenoble Alpes University
J. Cabrera
German Aerospace Center (DLR)
S. Charnoz
Paris Descartes University
A. Collier Cameron
University of St Andrews
C. Corral van Damme
European Space Agency (ESA)
Sz Csizmadia
German Aerospace Center (DLR)
M. B. Davies
Lund University
M. Deleuil
Aix Marseille University
L. Delrez
University of Liège
T. de Roche
University of Bern
A. Erikson
German Aerospace Center (DLR)
A. Fortier
University of Bern
Malcolm Fridlund
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
D. Futyan
University of Geneva
D. Gandolfi
University of Turin
M. Gillon
University of Liège
M. Gudel
University of Vienna
P. Gutermann
Aix Marseille University
Institut National des Sciences de l'Univers
J. Hasiba
Austrian Academy of Sciences
K. G. Isaak
European Space Agency (ESA)
L. Kiss
Hungarian Academy of Sciences
J. Laskar
Sorbonne University
A. Lecavelier des Etangs
Sorbonne University
C. Lovis
University of Geneva
D. Magrin
Istituto nazionale di astrofisica (INAF)
P. F. L. Maxted
Keele University
M. Munari
Istituto nazionale di astrofisica (INAF)
V Nascimbeni
Istituto nazionale di astrofisica (INAF)
R. Ottensamer
University of Vienna
I Pagano
Istituto nazionale di astrofisica (INAF)
E. Palle
Instituto de Astrofísica de Canarias
G. Peter
German Aerospace Center (DLR)
G. Piotto
Istituto nazionale di astrofisica (INAF)
University of Padua
D. Pollacco
The University of Warwick
D. Queloz
Swiss Federal Institute of Technology in Zürich (ETH)
University of Cambridge
R. Ragazzoni
University of Padua
Istituto nazionale di astrofisica (INAF)
N. Rando
European Space Agency (ESA)
H. Rauer
German Aerospace Center (DLR)
Freie Universität Berlin
Technische Universität Berlin
I Ribas
Spanish National Research Council (CSIC)
Centre Tecnològic de Telecomunicacions de Catalunya (CTTC)
N. C. Santos
University of Porto
G. Scandariato
Istituto nazionale di astrofisica (INAF)
D. Segransan
University of Geneva
A. E. Simon
University of Bern
A. M. S. Smith
German Aerospace Center (DLR)
M. Steller
Austrian Academy of Sciences
Gy M. Szabo
Eötvös Loránd University (ELTE)
N. Thomas
University of Bern
S. Udry
University of Geneva
I Walter
German Aerospace Center (DLR)
N. Walton
University of Cambridge
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 659 A74Subject Categories (SSIF 2011)
Astronomy, Astrophysics and Cosmology
Atom and Molecular Physics and Optics
Condensed Matter Physics
DOI
10.1051/0004-6361/202142400