Asymmetry in the atmosphere of the ultra-hot Jupiter WASP-76 b***
Artikel i vetenskaplig tidskrift, 2024

Context.
WASP-76 b has been a recurrent subject of study since the detection of a signature in high-resolution transit spectroscopy data indicating an asymmetry between the two limbs of the planet. The existence of this asymmetric signature has been confirmed by multiple studies, but its physical origin is still under debate. In addition, it contrasts with the absence of asymmetry reported in the infrared (IR) phase curve.
Aims.
We provide a more comprehensive dataset of WASP-76 b with the goal of drawing a complete view of the physical processes at work in this atmosphere. In particular, we attempt to reconcile visible high-resolution transit spectroscopy data and IR broadband phase curves. Methods. We gathered 3 phase curves, 20 occultations, and 6 transits for WASP-76 b in the visible with the CHEOPS space telescope. We also report the analysis of three unpublished sectors observed by the TESS space telescope (also in the visible), which represents 34 phase curves.
Results.
WASP-76 b displays an occultation of 260 ± 11 and 152 ± 10 ppm in TESS and CHEOPS bandpasses respectively. Depending on the composition assumed for the atmosphere and the data reduction used for the IR data, we derived geometric albedo estimates that range from 0.05 ± 0.023 to 0.146 ± 0.013 and from <0.13 to 0.189 ± 0.017 in the CHEOPS and TESS bandpasses, respectively. As expected from the IR phase curves, a low-order model of the phase curves does not yield any detectable asymmetry in the visible either. However, an empirical model allowing for sharper phase curve variations offers a hint of a flux excess before the occultation, with an amplitude of ∼40 ppm, an orbital offset of ∼−30◦, and a width of ∼20◦. We also constrained the orbital eccentricity of WASP-76 b to a value lower than 0.0067, with a 99.7% confidence level. This result contradicts earlier proposed scenarios aimed at explaining the asymmetry observed in high-resolution transit spectroscopy.
Conclusions.
In light of these findings, we hypothesise that WASP-76 b could have night-side clouds that extend predominantly towards its eastern limb. At this limb, the clouds would be associated with spherical droplets or spherically shaped aerosols of an unknown species, which would be responsible for a glory effect in the visible phase curves.

planets

techniques: photometric

satellites: composition

planets and satellites: atmospheres

Författare

O. Demangeon

Universidade do Porto

P. E. Cubillos

Istituto nazionale di astrofisica (INAF)

Institut fur Weltraumforschung

V. Singh

Istituto nazionale di astrofisica (INAF)

T.G. Wilson

The University of Warwick

L. Carone

Institut fur Weltraumforschung

A. Bekkelien

Université de Genève

A. Deline

Université de Genève

D. Ehrenreich

Université de Genève

P. Maxted

Keele University

B.O. Demory

Universität Bern

Tiziano Zingales

Istituto nazionale di astrofisica (INAF)

Università di Padova

M. Lendl

Université de Genève

A. Bonfanti

Institut fur Weltraumforschung

S. G. Sousa

Universidade do Porto

A. Brandeker

Stockholms universitet

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)

S.C.C. Barros

Universidade do Porto

W. Baumjohann

Institut fur Weltraumforschung

M. Beck

Université de Genève

T. Beck

Universität Bern

W. Benz

Universität Bern

N. Billot

Université de Genève

F. Biondi

Max-Planck-Gesellschaft

Istituto nazionale di astrofisica (INAF)

L. Borsato

Istituto nazionale di astrofisica (INAF)

C. Broeg

Universität Bern

M. Buder

Deutsches Zentrums für Luft- und Raumfahrt (DLR)

A. Collier Cameron

University of St Andrews

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

Anders Erikson

Deutsches Zentrums für Luft- und Raumfahrt (DLR)

A. Fortier

Universität Bern

L. Fossati

Institut fur Weltraumforschung

Malcolm Fridlund

Chalmers, Rymd-, geo- och miljövetenskap, Astronomi och plasmafysik

Universiteit Leiden

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

Magyar Tudomanyos Akademia

Eötvös Loránd University (ELTE)

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)

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)

Giampaolo P. Piotto

Università di Padova

Istituto nazionale di astrofisica (INAF)

D. Pollacco

The University of Warwick

D. Queloz

Eidgenössische Technische Hochschule Zürich (ETH)

University of Cambridge

R. Ragazzoni

Università di Padova

Istituto nazionale di astrofisica (INAF)

N. Rando

European Space Research and Technology Centre (ESA ESTEC)

H. Rauer

Freie Universität Berlin

Technische Universität Berlin

Deutsches Zentrums für Luft- und Raumfahrt (DLR)

I. Ribas

Institut d'Estudis Espacials de Catalunya (IEEC)

Institut de Ciències de l'Espai (ICE) - CSIC

M. Rieder

Universität Bern

S. Salmon

Université de Genève

N. C. Santos

Universidade do Porto

Gaetano Scandariato

Istituto nazionale di astrofisica (INAF)

D. Segransan

Université de Genève

A.E. Simon

Universität Bern

A. M.S. Smith

Deutsches Zentrums für Luft- und Raumfahrt (DLR)

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. 684 A27

Ämneskategorier

Astronomi, astrofysik och kosmologi

Infrastruktur

Onsala rymdobservatorium

DOI

10.1051/0004-6361/202348270

Mer information

Senast uppdaterat

2024-08-08