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.
Stars: atmospheres
Brown dwarfs
Planetary systems
Stars: individual: KELT-1
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
P. Guterman
CS20330
Laboratoire d'Astrophysique de Marseille
Kevin Heng
The University of Warwick
University of Bern
O. Demangeon
University of Porto
A. Bonfanti
Institut fur Weltraumforschung
S. Salmon
University of Geneva
V. Singh
Istituto nazionale di astrofisica (INAF)
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
G. Anglada
Institute of Space Sciences (ICE) - CSIC
Institute of Space Studies of Catalonia (IEEC)
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
N. Billot
University of Geneva
X. Bonfils
Institut de Planétologie et d’Astrophysique de Grenoble (IPAG)
A. Brandeker
Stockholm University
C. Broeg
University of Bern
J. Cabrera
German Aerospace Center (DLR)
S. Charnoz
Institut de Physique du Globe de Paris
A. Collier Cameron
University of St Andrews
C. Corral Van Damme
European Space Research and Technology Centre (ESA ESTEC)
Szilard Csizmadia
German Aerospace Center (DLR)
M. B. Davies
Lund University
M. Deleuil
Laboratoire d'Astrophysique de Marseille
L. Delrez
University of Liège
B.O. Demory
University of Bern
Anders Erikson
German Aerospace Center (DLR)
J. Farinato
Istituto nazionale di astrofisica (INAF)
A. Fortier
University of Bern
L. Fossati
Institut fur Weltraumforschung
Malcolm Fridlund
Leiden University
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
D. Gandolfi
University of Turin
Michaël Gillon
University of Liège
M. Gudel
University of Vienna
S. Hoyer
Laboratoire d'Astrophysique de Marseille
K. Isaak
European Space Research and Technology Centre (ESA ESTEC)
L. Kiss
Hungarian Academy of Sciences
Eötvös Loránd University (ELTE)
E. Kopp
German Aerospace Center (DLR)
J. Laskar
Paris Observatory
A. L. des Etangs
Institut d 'Astrophysique de Paris
C. Lovis
University of Geneva
D. Magrin
Istituto nazionale di astrofisica (INAF)
P. Maxted
Keele University
M. Mecina
University of Vienna
Valerio Nascimbeni
Istituto nazionale di astrofisica (INAF)
G. Olofsson
Stockholm University
R. Ottensamer
University of Vienna
I. Pagano
Istituto nazionale di astrofisica (INAF)
G. Peter
German Aerospace Center (DLR)
D. Piazza
University of Bern
Giampaolo P. Piotto
Istituto nazionale di astrofisica (INAF)
University of Padua
Don L. Pollacco
The University of Warwick
D. Queloz
Swiss Federal Institute of Technology in Zürich (ETH)
University of Cambridge
Roberto Ragazzoni
Istituto nazionale di astrofisica (INAF)
University of Padua
N. Rando
European Space Research and Technology Centre (ESA ESTEC)
H. Rauer
German Aerospace Center (DLR)
Technische Universität Berlin
Freie Universität Berlin
I. Ribas
Institute of Space Sciences (ICE) - CSIC
Institute of Space Studies of Catalonia (IEEC)
Gaetano Scandariato
Istituto nazionale di astrofisica (INAF)
D. Segransan
University of Geneva
A.E. Simon
University of Bern
Alexis M. S. Smith
German Aerospace Center (DLR)
Manfred B. Steller
Institut fur Weltraumforschung
G.M. Szabó
Eötvös Loránd University (ELTE)
Nicolas Thomas
University of Bern
S. Udry
University of Geneva
V. Van Grootel
University of Liège
N. A. Walton
University of Cambridge
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 668 A93Subject Categories
Meteorology and Atmospheric Sciences
Astronomy, Astrophysics and Cosmology
Geophysics
DOI
10.1051/0004-6361/202244117