The tidal deformation and atmosphere of WASP-12 b from its phase curve
Artikel i vetenskaplig tidskrift, 2024
Context. Ultra-hot Jupiters present a unique opportunity to understand the physics and chemistry of planets, their atmospheres, and interiors at extreme conditions. WASP-12 b stands out as an archetype of this class of exoplanets, with a close-in orbit around its star that results in intense stellar irradiation and tidal effects. Aims. The goals are to measure the planet's tidal deformation, atmospheric properties, and also to refine its orbital decay rate. Methods. We performed comprehensive analyses of the transits, occultations, and phase curves of WASP-12b by combining new CHEOPS observations with previous TESS and Spitzer data. The planet was modeled as a triaxial ellipsoid parameterized by the second-order fluid Love number of the planet, h2, which quantifies its radial deformation and provides insight into the interior structure. Results. We measured the tidal deformation of WASP-12b and estimated a Love number of h2 = 1.55- 0.49+0.45 (at 3.2σ) from its phase curve. We measured occultation depths of 333 ± 24 ppm and 493 ± 29 ppm in the CHEOPS and TESS bands, respectively, while the nightside fluxes are consistent with zero, and also marginal eastward phase offsets. Our modeling of the dayside emission spectrum indicates that CHEOPS and TESS probe similar pressure levels in the atmosphere at a temperature of ~2900 K. We also estimated low geometric albedos of Ag = 0.086 ± 0.017 and Ag = 0.01 ± 0.023 in the CHEOPS and TESS passbands, respectively, suggesting the absence of reflective clouds in the high-temperature dayside of the planet. The CHEOPS occultations do not show strong evidence for variability in the dayside atmosphere of the planet at the median occultation depth precision of 120 ppm attained. Finally, combining the new CHEOPS timings with previous measurements refines the precision of the orbital decay rate by 12% to a value of - 30.23 ± 0.82 ms yr- 1, resulting in a modified stellar tidal quality factor of Q′∗ = 1.70 ± 0.14 × 105. Conclusions. WASP-12 b becomes the second exoplanet, after WASP-103b, for which the Love number has been measured from the effect of tidal deformation in the light curve. However, constraining the core mass fraction of the planet requires measuring h2 with a higher precision. This can be achieved with high signal-to-noise observations with JWST since the phase curve amplitude, and consequently the induced tidal deformation effect, is higher in the infrared.
Planets and satellites: individual: WASP-12b
Planets and satellites: interiors
Författare
B. Akinsanmi
Université de Genève
S.C.C. Barros
Universidade do Porto
M. Lendl
Université de Genève
L. Carone
Institut fur Weltraumforschung
P. E. Cubillos
Istituto nazionale di astrofisica (INAF)
Institut fur Weltraumforschung
A. Bekkelien
Université de Genève
A. Fortier
Universität Bern
H.-G. Florén
Stockholms universitet
A. Collier Cameron
University of St Andrews
G. Boue´
Observatoire de Paris
G. Bruno
Istituto nazionale di astrofisica (INAF)
B.O. Demory
Universität Bern
A. Brandeker
Stockholms universitet
S.G. Sousa
Universidade do Porto
T.G. Wilson
The University of Warwick
A. Deline
Université de Genève
A. Bonfanti
Institut fur Weltraumforschung
Gaetano Scandariato
Istituto nazionale di astrofisica (INAF)
M.J. Hooton
University of Cambridge
A. Correia
Centre for Physics of the University of Coimbra
O. Demangeon
Universidade do Porto
A. M.S. Smith
Deutsches Zentrums für Luft- und Raumfahrt (DLR)
V. Singh
Istituto nazionale di astrofisica (INAF)
Y. Alibert
Universität Bern
R. Alonso
Universidad de la Laguna
Instituto de Astrofísica de Canarias
J. Asquier
European Space Research and Technology Centre (ESA ESTEC)
T. Bárczy
Admatis
D. Barrado Navascues
Centro de Astrobiologia (CAB)
W. Baumjohann
Institut fur Weltraumforschung
M. Beck
Université de Genève
T. Beck
Universität Bern
W. Benz
Universität Bern
N. Billot
Université de Genève
X. Bonfils
Institut de Planétologie et d’Astrophysique de Grenoble (IPAG)
L. Borsato
Istituto nazionale di astrofisica (INAF)
C. Broeg
Universität Bern
M. Buder
Deutsches Zentrums für Luft- und Raumfahrt (DLR)
S. Charnoz
Institut de Physique du Globe de Paris
Szilard Csizmadia
Deutsches Zentrums für Luft- und Raumfahrt (DLR)
M. B. Davies
Lunds universitet
M. Deleuil
Laboratoire d'Astrophysique de Marseille
L. Delrez
Universite de Liège
D. Ehrenreich
Université de Genève
Anders Erikson
Deutsches Zentrums für Luft- und Raumfahrt (DLR)
J. Farinato
Istituto nazionale di astrofisica (INAF)
L. Fossati
Institut fur Weltraumforschung
Malcolm Fridlund
Universiteit Leiden
Chalmers, Rymd-, geo- och miljövetenskap, Astronomi och plasmafysik
D. Gandolfi
Universita degli Studi di Torino
Michaël Gillon
Universite de Liège
M. Gudel
Universität Wien
Maximilian N. Günther
European Space Research and Technology Centre (ESA ESTEC)
A. Heitzmann
Université de Genève
Ch. Helling
Institut fur Weltraumforschung
Technische Universität Graz
S. Hoyer
Laboratoire d'Astrophysique de Marseille
K. Isaak
European Space Research and Technology Centre (ESA ESTEC)
L. L. Kiss
Eötvös Loránd University (ELTE)
Magyar Tudomanyos Akademia
K. W.F. Lam
Deutsches Zentrums für Luft- und Raumfahrt (DLR)
J. Laskar
Observatoire de Paris
A. L. des Etangs
Institut d 'Astrophysique de Paris
D. Magrin
Istituto nazionale di astrofisica (INAF)
P. Maxted
Keele University
M. Mecina
Universität Wien
C. Mordasini
Universität Bern
Valerio Nascimbeni
Istituto nazionale di astrofisica (INAF)
G. Olofsson
Stockholms universitet
R. Ottensamer
Universität Wien
I. Pagano
Istituto nazionale di astrofisica (INAF)
Enric Palle
Universidad de la Laguna
Instituto de Astrofísica de Canarias
G. Peter
Deutsches Zentrums für Luft- und Raumfahrt (DLR)
D. Piazza
Universität Bern
Giampaolo P. Piotto
Università di Padova
Istituto nazionale di astrofisica (INAF)
Don L. Pollacco
The University of Warwick
D. Queloz
University of Cambridge
Eidgenössische Technische Hochschule Zürich (ETH)
Roberto Ragazzoni
Istituto nazionale di astrofisica (INAF)
Università di Padova
N. Rando
European Space Research and Technology Centre (ESA ESTEC)
H. Rauer
Freie Universität Berlin
Deutsches Zentrums für Luft- und Raumfahrt (DLR)
Technische Universität Berlin
I. Ribas
Institut de Ciències de l'Espai (ICE) - CSIC
Institut d'Estudis Espacials de Catalunya (IEEC)
N. C. Santos
Universidade do Porto
D. Segransan
Université de Genève
A.E. Simon
Universität Bern
M. Stalport
Universite de Liège
G.M. Szabó
HUN-REN-ELTE Exoplanet Research Group
Eötvös Loránd University (ELTE)
Nicolas Thomas
Universität Bern
S. Udry
Université de Genève
V. Van Grootel
Universite de Liège
J. Venturini
Université de Genève
E. Villaver
Instituto de Astrofísica de Canarias
Universidad de la Laguna
N. A. Walton
University of Cambridge
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 685 A63Ämneskategorier
Astronomi, astrofysik och kosmologi
DOI
10.1051/0004-6361/202348502