The hot dayside and asymmetric transit of WASP-189 b seen by CHEOPS
Journal article, 2020

The CHEOPS space mission dedicated to exoplanet follow-up was launched in December 2019, equipped with the capacity to perform photometric measurements at the 20 ppm level. As CHEOPS carries out its observations in a broad optical passband, it can provide insights into the reflected light from exoplanets and constrain the short-wavelength thermal emission for the hottest of planets by observing occultations and phase curves. Here, we report the first CHEOPS observation of an occultation, namely, that of the hot Jupiter WASP-189 b, a MP ≈ 2MJ planet orbiting an A-type star. We detected the occultation of WASP-189 b at high significance in individual measurements and derived an occultation depth of dF = 87.9 ± 4.3 ppm based on four occultations. We compared these measurements to model predictions and we find that they are consistent with an unreflective atmosphere heated to a temperature of 3435 ± 27 K, when assuming inefficient heat redistribution. Furthermore, we present two transits of WASP-189 b observed by CHEOPS. These transits have an asymmetric shape that we attribute to gravity darkening of the host star caused by its high rotation rate. We used these measurements to refine the planetary parameters, finding a ~25% deeper transit compared to the discovery paper and updating the radius of WASP-189 b to 1.619 ± 0.021RJ. We further measured the projected orbital obliquity to be λ = 86.4-4.4+2.9°, a value that is in good agreement with a previous measurement from spectroscopic observations, and derived a true obliquity of ψ = 85.4 ± 4.3°. Finally, we provide reference values for the photometric precision attained by the CHEOPS satellite: for the V = 6.6 mag star, and using a 1-h binning, we obtain a residual RMS between 10 and 17 ppm on the individual light curves, and 5.7 ppm when combining the four visits.

Techniques: photometric

Planets and satellites: individual: WASP-189 b

Planets and satellites: atmospheres

Author

M. Lendl

University of Geneva

Szilard Csizmadia

German Aerospace Center (DLR)

A. Deline

University of Geneva

L. Fossati

Institut fur Weltraumforschung

D. Kitzmann

University of Bern

Kevin Heng

University of Bern

S. Hoyer

Laboratoire d'Astrophysique de Marseille

S. Salmon

University of Geneva

W. Benz

University of Bern

C. Broeg

University of Bern

D. Ehrenreich

University of Geneva

A. Fortier

University of Bern

D. Queloz

University of Geneva

A. Bonfanti

Institut fur Weltraumforschung

A. Brandeker

Stockholm University

A. Collier Cameron

University of St Andrews

L. Delrez

University of Geneva

A. Garcia Munoz

Technische Universität Berlin

M.J. Hooton

University of Bern

P. Maxted

Keele University

Brett M. Morris

University of Bern

V. Van Grootel

University of Liège

T.G. Wilson

University of St Andrews

Y. Alibert

University of Bern

R. Alonso

Instituto Astrofisico de Canarias

J. Asquier

European Space Research and Technology Centre (ESA ESTEC)

T. Bandy

University of Bern

T. Bárczy

Admatis

D. Barrado

Centro de Astrobiologia (CAB)

S.C.C. Barros

University of Porto

W. Baumjohann

Institut fur Weltraumforschung

M. Beck

University of Geneva

T. Beck

University of Bern

A. Bekkelien

University of Geneva

M. Bergomi

Osservatorio Astronomico di Padova

N. Billot

University of Geneva

F. Biondi

Osservatorio Astronomico di Padova

X. Bonfils

Université Grenoble Alpes

V. Bourrier

University of Geneva

M.-D. Busch

University of Bern

J. Cabrera

German Aerospace Center (DLR)

V. Cessa

University of Bern

S. Charnoz

Institut de Physique du Globe de Paris

B. Chazelas

University of Geneva

C. Corral Van Damme

European Space Research and Technology Centre (ESA ESTEC)

Melvyn B. Davies

Lund University

M. Deleuil

Laboratoire d'Astrophysique de Marseille

O. Demangeon

Laboratoire d'Astrophysique de Marseille

B.O. Demory

University of Bern

Anders Erikson

German Aerospace Center (DLR)

J. Farinato

Osservatorio Astronomico di Padova

Malcolm Fridlund

Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics, Galactic Astrophysics

Leiden University

D. Futyan

University of Geneva

D. Gandolfi

Istituto nazionale di astrofisica (INAF)

Michaël Gillon

University of Liège

P. Guterman

Laboratoire d'Astrophysique de Marseille

J. Hasiba

Institut fur Weltraumforschung

E. Hernandez

University of Bern

K. Isaak

European Space Research and Technology Centre (ESA ESTEC)

L.L. Kiss

Hungarian Academy of Sciences

T. Kuntzer

University of Geneva

A. L. des Etangs

Institut d 'Astrophysique de Paris

T. Lüftinger

University of Vienna

J. Laskar

Paris Observatory

C. Lovis

University of Geneva

D. Magrin

Osservatorio Astronomico di Padova

L. Malvasio

University of Bern

L. Marafatto

Osservatorio Astronomico di Padova

H. Michaelis

German Aerospace Center (DLR)

M. Munari

Osservatorio Astrofisico di Catania

Valerio Nascimbeni

Osservatorio Astronomico di Padova

G. Olofsson

Stockholm University

H. Ottacher

Institut fur Weltraumforschung

R. Ottensamer

University of Vienna

I. Pagano

Osservatorio Astrofisico di Catania

E. Palle

Instituto Astrofisico de Canarias

G. Peter

German Aerospace Center (DLR)

D. Piazza

University of Bern

Giampaolo P. Piotto

Osservatorio Astronomico di Padova

Don L. Pollacco

The University of Warwick

F. Ratti

European Space Research and Technology Centre (ESA ESTEC)

H. Rauer

German Aerospace Center (DLR)

Roberto Ragazzoni

Osservatorio Astronomico di Padova

N. Rando

European Space Research and Technology Centre (ESA ESTEC)

I. Ribas

Institute of Space Sciences (ICE) - CSIC

M. Rieder

University of Bern

R. Rohlfs

University of Geneva

F. Safa

European Space Research and Technology Centre (ESA ESTEC)

N. C. Santos

University of Porto

Gaetano Scandariato

Osservatorio Astrofisico di Catania

D. Segransan

University of Geneva

A.E. Simon

University of Bern

V. Singh

Osservatorio Astrofisico di Catania

Alexis M. S. Smith

German Aerospace Center (DLR)

M. Sordet

University of Geneva

S.G. Sousa

University of Porto

Manfred B. Steller

Institut fur Weltraumforschung

G.M. Szabó

Eötvös Loránd University (ELTE)

Nicolas Thomas

University of Bern

M. Tschentscher

German Aerospace Center (DLR)

S. Udry

University of Geneva

V. Viotto

Osservatorio Astronomico di Padova

I. Walter

German Aerospace Center (DLR)

N. A. Walton

University of Cambridge

F. Wildi

University of Geneva

D. Wolter

German Aerospace Center (DLR)

Astronomy and Astrophysics

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

Vol. 643 202038677

Subject Categories

Astronomy, Astrophysics and Cosmology

Atom and Molecular Physics and Optics

Other Physics Topics

Roots

Basic sciences

DOI

10.1051/0004-6361/202038677

More information

Latest update

12/2/2020