CHEOPS finds KELT-1b darker than expected in visible light: Discrepancy between the CHEOPS and TESS eclipse depths
Journal article, 2022
Recent studies based on photometry from the Transiting Exoplanet Survey Satellite (TESS) have suggested that the dayside of KELT-1b, a strongly irradiated brown dwarf, is significantly brighter in visible light than what would be expected based on Spitzer observations in the infrared. We observed eight eclipses of KELT-1b with CHaracterising ExOPlanet Satellite (CHEOPS) to measure its dayside brightness temperature in the bluest passband observed so far, and we jointly modelled the CHEOPS photometry with the existing optical and near-infrared photometry from TESS, LBT, CFHT, and Spitzer. Our modelling has led to a self-consistent dayside spectrum for KELT-1b covering the CHEOPS, TESS, H, Ks, and Spitzer IRAC 3.6 and 4.5 μm bands, where our TESS, H, Ks, and Spitzer band estimates largely agree with the previous studies. However, we discovered a strong discrepancy between the CHEOPS and TESS bands. The CHEOPS observations yield a higher photometric precision than the TESS observations, but they do not show a significant eclipse signal, while a deep eclipse is detected in the TESS band. The derived TESS geometric albedo of 0.36-0.13+0.12 is difficult to reconcile with a CHEOPS geometric albedo that is consistent with zero because the two passbands have considerable overlap. Variability in cloud cover caused by the transport of transient nightside clouds to the dayside could provide an explanation for reconciling the TESS and CHEOPS geometric albedos, but this hypothesis needs to be tested by future observations.
Planetary systems
Stars: individual: KELT-1
Brown dwarfs
Stars: atmospheres
Methods: observational
Author
H. Parviainen
Instituto de Astrofísica de Canarias
University of La Laguna
T.G. Wilson
University of St Andrews
M. Lendl
University of Geneva
D. Kitzmann
University of Bern
Enric Palle
Instituto de Astrofísica de Canarias
University of La Laguna
L. M. Serrano
University of Turin
E. Meier Valdes
University of Bern
W. Benz
University of Bern
A. Deline
University of Geneva
D. Ehrenreich
University of Geneva
O. Demangeon
University of Porto
A. Bonfanti
Institut fur Weltraumforschung
P. Guterman
Laboratoire d'Astrophysique de Marseille
Division Technique INSU
S. Salmon
University of Geneva
Kevin Heng
The University of Warwick
University of Bern
N. C. Santos
University of Porto
S.G. Sousa
University of Porto
Y. Alibert
University of Bern
R. Alonso
Instituto de Astrofísica de Canarias
University of La Laguna
Nicolas Thomas
University of Bern
S. Udry
University of Geneva
Manfred B. Steller
Institut fur Weltraumforschung
D. Segransan
University of Geneva
Gaetano Scandariato
Istituto nazionale di astrofisica (INAF)
I. Ribas
Centre Tecnològic de Telecomunicacions de Catalunya (CTTC)
Spanish National Research Council (CSIC)
A.E. Simon
University of Bern
Alexis M. S. Smith
German Aerospace Center (DLR)
G.M. Szabó
Eötvös Loránd University (ELTE)
V. Van Grootel
University of Liège
V. Singh
Istituto nazionale di astrofisica (INAF)
D. Queloz
University of Cambridge
Swiss Federal Institute of Technology in Zürich (ETH)
N. A. Walton
University of Cambridge
Roberto Ragazzoni
University of Padua
Istituto nazionale di astrofisica (INAF)
N. Rando
European Space Agency (ESA)
Giampaolo P. Piotto
Istituto nazionale di astrofisica (INAF)
University of Padua
P. Maxted
Keele University
M. Deleuil
Laboratoire d'Astrophysique de Marseille
G. Anglada
Centre Tecnològic de Telecomunicacions de Catalunya (CTTC)
Spanish National Research Council (CSIC)
D. Barrado
Centro de Astrobiologia (CAB)
T. Bárczy
Admatis
W. Baumjohann
Institut fur Weltraumforschung
S.C.C. Barros
University of Porto
M. Beck
University of Geneva
N. Billot
University of Geneva
T. Beck
University of Bern
C. Broeg
University of Bern
X. Bonfils
Domaine universitaire de Grenoble
A. Brandeker
Stockholm University
J. Cabrera
German Aerospace Center (DLR)
A. Collier Cameron
University of St Andrews
S. Charnoz
Institut de Physique du Globe de Paris
H. Rauer
Technische Universität Berlin
German Aerospace Center (DLR)
Freie Universität Berlin
Szilard Csizmadia
German Aerospace Center (DLR)
C. Corral Van Damme
European Space Agency (ESA)
M. B. Davies
Lund University
B.O. Demory
University of Bern
Anders Erikson
German Aerospace Center (DLR)
L. Delrez
University of Liège
M. Gudel
University of Vienna
J. Farinato
Istituto nazionale di astrofisica (INAF)
A. Fortier
University of Bern
L. Fossati
Institut fur Weltraumforschung
Malcolm Fridlund
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
Leiden University
D. Gandolfi
University of Turin
Michaël Gillon
University of Liège
L. Kiss
Eötvös Loránd University (ELTE)
Hungarian Academy of Sciences
S. Hoyer
Laboratoire d'Astrophysique de Marseille
K. Isaak
European Space Agency (ESA)
E. Kopp
German Aerospace Center (DLR)
J. Laskar
Paris Observatory
A. L. des Etangs
Institut d 'Astrophysique de Paris
C. Lovis
University of Geneva
G. Peter
German Aerospace Center (DLR)
D. Magrin
Istituto nazionale di astrofisica (INAF)
Don L. Pollacco
The University of Warwick
Valerio Nascimbeni
Istituto nazionale di astrofisica (INAF)
M. Mecina
University of Vienna
G. Olofsson
Stockholm University
R. Ottensamer
University of Vienna
I. Pagano
Istituto nazionale di astrofisica (INAF)
D. Piazza
University of Bern
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 668 A93Subject Categories (SSIF 2011)
Meteorology and Atmospheric Sciences
Astronomy, Astrophysics and Cosmology
Geophysics
DOI
10.1051/0004-6361/202244117