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

Instituto de Astrofísica de Canarias

Universidad de la Laguna

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

Istituto nazionale di astrofisica (INAF)

Università di Padova

Don L. Pollacco

The University of Warwick

D. Queloz

Eidgenössische Technische Hochschule Zürich (ETH)

University of Cambridge

Roberto Ragazzoni

Università di Padova

Istituto nazionale di astrofisica (INAF)

N. Rando

European Space Research and Technology Centre (ESA ESTEC)

H. Rauer

Deutsches Zentrums für Luft- und Raumfahrt (DLR)

Freie Universität Berlin

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

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

Universidad de la Laguna

Instituto de Astrofísica de Canarias

N. A. Walton

University of Cambridge

Astronomy and Astrophysics

0004-6361 (ISSN) 1432-0746 (eISSN)

Vol. 685 A63

Ämneskategorier

Astronomi, astrofysik och kosmologi

DOI

10.1051/0004-6361/202348502

Mer information

Senast uppdaterat

2024-08-08