The stable climate of KELT-9b
Journal article, 2022

Even among the most irradiated gas giants, so-called ultra-hot Jupiters, KELT-9b stands out as the hottest planet thus far discovered with a dayside temperature of over 4500 K. At these extreme irradiation levels, we expect an increase in heat redistribution efficiency and a low Bond albedo owed to an extended atmosphere with molecular hydrogen dissociation occurring on the planetary dayside. We present new photometric observations of the KELT-9 system throughout 4 full orbits and 9 separate occultations obtained by the 30 cm space telescope CHEOPS. The CHEOPS bandpass, located at optical wavelengths, captures the peak of the thermal emission spectrum of KELT-9b. In this work we simultaneously analyse CHEOPS phase curves along with public phase curves from TESS and Spitzer to infer joint constraints on the phase curve variation, gravity-darkened transits, and occultation depth in three bandpasses, as well as derive 2D temperature maps of the atmosphere at three different depths. We find a day-night heat redistribution efficiency of similar to 0.3 which confirms expectations of enhanced energy transfer to the planetary nightside due to dissociation and recombination of molecular hydrogen. We also calculate a Bond albedo consistent with zero. We find no evidence of variability of the brightness temperature of the planet, excluding variability greater than 1% (1 sigma).

techniques: photometric

planets and satellites: gaseous planets

occultations

eclipses

instrumentation: photometers

planets and satellites: atmospheres

Author

K. Jones

University of Bern

B. M. Morris

University of Bern

B-O Demory

University of Bern

K. Heng

The University of Warwick

University of Bern

M. J. Hooton

University of Bern

University of Cambridge

N. Billot

University of Geneva

D. Ehrenreich

University of Geneva

S. Hoyer

Aix Marseille University

A. E. Simon

University of Bern

M. Lendl

University of Geneva

O. D. S. Demangeon

University of Porto

S. G. Sousa

University of Porto

A. Bonfanti

Austrian Academy of Sciences

T. G. Wilson

University of St Andrews

S. Salmon

University of Geneva

Sz Csizmadia

German Aerospace Center (DLR)

H. Parviainen

Instituto de Astrofísica de Canarias

G. Bruno

Istituto nazionale di astrofisica (INAF)

Y. Alibert

University of Bern

R. Alonso

University of La Laguna

Instituto de Astrofísica de Canarias

G. Anglada

Centre Tecnològic de Telecomunicacions de Catalunya (CTTC)

Spanish National Research Council (CSIC)

T. Barczy

Admatis

D. Barrado

Spanish National Research Council (CSIC)

S. C. C. Barros

University of Porto

W. Baumjohann

Austrian Academy of Sciences

M. Beck

University of Geneva

T. Beck

University of Bern

W. Benz

University of Bern

X. Bonfils

Grenoble Alpes University

A. Brandeker

Stockholm University

C. Broeg

University of Bern

J. Cabrera

German Aerospace Center (DLR)

S. Charnoz

Paris Descartes University

A. Collier Cameron

University of St Andrews

M. B. Davies

Lund University

M. Deleuil

Aix Marseille University

A. Deline

University of Geneva

L. Delrez

University of Liège

A. Erikson

German Aerospace Center (DLR)

A. Fortier

University of Bern

L. Fossati

Austrian Academy of Sciences

Malcolm Fridlund

Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics

D. Gandolfi

University of Turin

M. Gillon

University of Liège

M. Gudel

University of Vienna

K. G. Isaak

European Space Research and Technology Centre (ESA ESTEC)

L. L. Kiss

Eötvös Loránd University (ELTE)

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

V Nascimbeni

Istituto nazionale di astrofisica (INAF)

G. Olofsson

Stockholm University

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

University of Padua

Istituto nazionale di astrofisica (INAF)

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)

F. Ratti

European Space Agency (ESA)

H. Rauer

Freie Universität Berlin

German Aerospace Center (DLR)

Technische Universität Berlin

C. Reimers

University of Vienna

I Ribas

Centre Tecnològic de Telecomunicacions de Catalunya (CTTC)

Spanish National Research Council (CSIC)

N. C. Santos

University of Porto

G. Scandariato

Istituto nazionale di astrofisica (INAF)

D. Segransan

University of Geneva

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

V. Van Grootel

University of Liège

I Walter

German Aerospace Center (DLR)

N. A. Walton

University of Cambridge

W. Wang Jungo

University of Bern

Astronomy and Astrophysics

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

Vol. 666 A118

Subject Categories (SSIF 2011)

Astronomy, Astrophysics and Cosmology

Atom and Molecular Physics and Optics

Condensed Matter Physics

DOI

10.1051/0004-6361/202243823

More information

Latest update

3/9/2025 1