No random transits in CHEOPS observations of HD 139139*,**
Journal article, 2023
Context. The star HD 139139 (a.k.a. ‘the Random Transiter’) is a star that exhibited enigmatic transit-like features with no apparent periodicity in K2 data. The shallow depth of the events (-200 ppm - equivalent to transiting objects with radii of -1.5 R⊕ in front of a Sun-like star) and their non-periodicity constitute a challenge for the photometric follow-up of this star. Aims. The goal of this study is to confirm with independent measurements the presence of shallow, non-periodic transit-like features on this object.
Methods. We performed observations with CHEOPS for a total accumulated time of 12.75 days, distributed in visits of roughly 20 h in two observing campaigns in years 2021 and 2022. The precision of the data is sufficient to detect 150 ppm features with durations longer than 1.5 h. We used the duration and times of the events seen in the K2 curve to estimate how many events should have been detected in our campaigns, under the assumption that their behaviour during the CHEOPS observations would be the same as in the K2 data of 2017.
Results. We do not detect events with depths larger than 150 ppm in our data set. If the frequency, depth, and duration of the events were the same as in the K2 campaign, we estimate the probability of having missed all events due to our limited observing window would be 4.8%.
Conclusions. We suggest three different scenarios to explain our results: 1) Our observing window was not long enough, and the events were missed with the estimated 4.8% probability. 2) The events recorded in the K2 observations were time critical, and the mechanism producing them was either not active in the 2021 and 2022 campaigns or created shallower events under our detectability level. 3) The enigmatic events in the K2 data are the result of an unidentified and infrequent instrumental noise in the original data set or its data treatment.
Methods. We performed observations with CHEOPS for a total accumulated time of 12.75 days, distributed in visits of roughly 20 h in two observing campaigns in years 2021 and 2022. The precision of the data is sufficient to detect 150 ppm features with durations longer than 1.5 h. We used the duration and times of the events seen in the K2 curve to estimate how many events should have been detected in our campaigns, under the assumption that their behaviour during the CHEOPS observations would be the same as in the K2 data of 2017.
Results. We do not detect events with depths larger than 150 ppm in our data set. If the frequency, depth, and duration of the events were the same as in the K2 campaign, we estimate the probability of having missed all events due to our limited observing window would be 4.8%.
Conclusions. We suggest three different scenarios to explain our results: 1) Our observing window was not long enough, and the events were missed with the estimated 4.8% probability. 2) The events recorded in the K2 observations were time critical, and the mechanism producing them was either not active in the 2021 and 2022 campaigns or created shallower events under our detectability level. 3) The enigmatic events in the K2 data are the result of an unidentified and infrequent instrumental noise in the original data set or its data treatment.
stars
peculiar - planets and satellites
photometric
detection - techniques
Author
R. Alonso
University of La Laguna
Instituto de Astrofísica de Canarias
S. Hoyer
Laboratoire d'Astrophysique de Marseille
M. Deleuil
Laboratoire d'Astrophysique de Marseille
A.E. Simon
University of Bern
M. Beck
University of Geneva
W. Benz
University of Bern
H.-G. Florén
Stockholm University
P. Guterman
CS20330
Laboratoire d'Astrophysique de Marseille
L. Borsato
Istituto nazionale di astrofisica (INAF)
A. Brandeker
Stockholm University
D. Gandolfi
University of Turin
T.G. Wilson
University of St Andrews
Tiziano Zingales
University of Padua
Istituto nazionale di astrofisica (INAF)
Y. Alibert
University of Bern
G. Anglada
Institute of Space Sciences (ICE) - CSIC
Institute of Space Studies of Catalonia (IEEC)
T. Bárczy
Admatis
D. Barrado Navascues
European Space Astronomy Centre (ESAC)
S.C.C. Barros
University of Porto
W. Baumjohann
Institut fur Weltraumforschung
T. Beck
University of Bern
N. Billot
University of Geneva
X. Bonfils
Institut de Planétologie et d’Astrophysique de Grenoble (IPAG)
C. Broeg
University of Bern
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)
P. E. Cubillos
Institut fur Weltraumforschung
Istituto nazionale di astrofisica (INAF)
M.B. Davies
Lund University
A. Deline
University of Geneva
L. Delrez
University of Liège
O. Demangeon
University of Porto
B.O. Demory
University of Bern
D. Ehrenreich
University of Geneva
Anders Erikson
German Aerospace Center (DLR)
A. Fortier
University of Bern
L. Fossati
Institut fur Weltraumforschung
Malcolm Fridlund
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
Leiden University
Michaël Gillon
University of Liège
M. Gudel
University of Vienna
Maximilian N. Günther
European Space Research and Technology Centre (ESA ESTEC)
A. Heitzmann
University of Geneva
Ch. Helling
Institut fur Weltraumforschung
Technische Universität Graz
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)
K. W.F. Lam
German Aerospace Center (DLR)
J. Laskar
Paris Observatory
A. L. des Etangs
Institut d 'Astrophysique de Paris
M. Lendl
University of Geneva
D. Magrin
Istituto nazionale di astrofisica (INAF)
P. Maxted
Keele University
C. Mordasini
University of Bern
Valerio Nascimbeni
Istituto nazionale di astrofisica (INAF)
G. Olofsson
Stockholm University
R. Ottensamer
University of Vienna
I. Pagano
Istituto nazionale di astrofisica (INAF)
Enric Palle
Instituto de Astrofísica de Canarias
University of La Laguna
G. Peter
German Aerospace Center (DLR)
Giampaolo P. Piotto
Istituto nazionale di astrofisica (INAF)
University of Padua
Don L. Pollacco
The University of Warwick
D. Queloz
University of Cambridge
Swiss Federal Institute of Technology in Zürich (ETH)
R. 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 Studies of Catalonia (IEEC)
Institute of Space Sciences (ICE) - CSIC
N. C. Santos
University of Porto
Gaetano Scandariato
Istituto nazionale di astrofisica (INAF)
D. Segransan
University of Geneva
A. M.S. Smith
German Aerospace Center (DLR)
S.G. Sousa
University of Porto
M. Stalport
University of Liège
G.M. Szabó
HUN-REN-ELTE Exoplanet Research Group
Eötvös Loránd University (ELTE)
Nicolas Thomas
University of Bern
S. Udry
University of Geneva
B. Ulmer
German Aerospace Center (DLR)
V. Van Grootel
University of Liège
J. Venturini
University of Geneva
F. Verrecchia
Osservatorio Astronomico di Roma
Agenzia Spaziale Italiana
N. A. Walton
University of Cambridge
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 680 A78Subject Categories
Astronomy, Astrophysics and Cosmology
Probability Theory and Statistics
DOI
10.1051/0004-6361/202347779