J/A+A/677/A112 CHEOPS observations of 55 Cnc e (Meier Valdes+, 2023)
Investigating the visible phase curve variability of 55 Cnc e.
Meier Valdes E.A., Morris B.M., Demory B.-O., Brandeker A., Kitzmann D.,
Benz W., Deline A., Floren H.-G., Sousa S. G., Bourrier V., Singh V.,
Heng K., Strugarek A., Bower D. J., Jaeggi N., Carone L., Lendl M.,
Jones K., Oza A.V., Demangeon O.D.S., Alibert Y., Alonso R.,
Anglada G., Asquier J., Barczy T., Barrado Navascues D., Barros S.C.C.,
Baumjohann W., Beck M., Beck T., Billot N., Bonfils X., Borsato L.,
Broeg C., Cabrera J., Charnoz S., Collier Cameron A., Csizmadia Sz.,
Cubillos P. E., Davies M. B., Deleuil M., Delrez L., Ehrenreich D.,
Erikson A., Fortier A., Fossati L., Fridlund M., Gandolfi D., Gillon M.,
Guedel M., Guenther M.N., Hoyer S., Isaak K. G., Kiss L. L., Laskar J.,
Lecavelier des Etangs A., Lovis C., Magrin D., Maxted P.F.L.,
Mordasini C., Nascimbeni V., Olofsson G., Ottensamer R., Pagano I.,
Palle E., Peter G., Piotto G., Pollacco D., Queloz D., Ragazzoni R.,
Rando N., Rauer H., Ribas I., Santos N. C., Sarajlic M., Scandariato G.,
Segransan D., Sicilia D., Simon A.E., Smith A.M.S., Steller M.,
Szabo Gy.M., Thomas N., Udry S., Ulmer B., Van Grootel V., Venturini J.,
Walton N.A., Wilson T.G., Wolter D.
<Astron. Astrophys. 677, A112 (2023)>
=2023A&A...677A.112M 2023A&A...677A.112M (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Exoplanets ; Photometry ; Optical
Keywords: stars: individual: 55 Cnc - techniques: photometric -
planets and satellites: individual: 55 Cnc e
Abstract:
55 Cnc e is an ultra-short period super-Earth transiting a Sun-like
star. Past observations in the optical range detected a time-variable
flux modulation phased with the planetary orbital period whose
amplitude is too large to be explained by reflected light and thermal
emission alone.
The goal of the study is to investigate the origin of the variability
and timescale of 55 Cnc e's phase curve modulation. To that end, we
used the CHaracterising ExOPlanet Satellite (CHEOPS) whose exquisite
photometric precision provides an opportunity to characterise minute
changes in the phase curve from orbit to orbit.
CHEOPS observed 29 individual visits of 55 Cnc e between March 2020
and February 2022. Based on these observations, we investigate the
different processes that could be at the origin of the observed
modulation. In particular, we build a toy model to assess whether a
circumstellar torus of dust driven by radiation pressure and gravity
could match the observed flux variability timescale.
We find that 55 Cnc e's phase curve amplitude and peak offset do
vary between visits. The sublimation timescales of selected dust
species reveal that silicates expected in an Earth-like mantle would
not survive long enough to explain the observed phase curve
modulation. We find that silicon carbide, quartz and graphite are
plausible candidates for the circumstellar torus composition due to
their long sublimation timescales.
The extensive CHEOPS observations confirm that the phase curve
amplitude and offset vary in time. We find that dust could provide the
grey opacity source required to match the observations. However, the
data at hand do not provide evidence that circumstellar material with
variable grain mass per unit area is actually causing the observed
variability. Future observations with JWST promise exciting insights
on this iconic super-Earth.
Description:
We present CHEOPS photometry of 55 Cnc containing 29 observations.
raw.dat contains the raw photometric time-series with detrending
variables. detrended.dat contains the detrended photometric
time-series. Raw data can be obtained from the CHEOPS data archive:
https://cheops-archive.astro.unige.ch/archive_browser/
Objects:
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RA (2000) DE Designation(s)
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08 52 35.81 +28 19 50.95 55 Cancri = rho01 Cnc
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
raw.dat 159 37446 CHEOPS raw photometric time-series with
detrending variables
detrend.dat 60 29004 CHEOPS detrended photometric time-series
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See also:
https://cheops-archive.astro.unige.ch/archive_browser/ : CHEOPS archive browser
Byte-by-byte Description of file: raw.dat
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Bytes Format Units Label Explanations
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1- 17 F17.12 d Time Time (BJD-2450000) (TDB)
19- 36 F18.8 --- Flux Normalised raw flux
38- 55 F18.12 --- e_Flux 1-sigma uncertainty in normalised flux
57- 79 F23.19 deg roll Roll angle
81-102 F22.14 e-/s/pix bg Background
104-121 F18.14 pix x X-centroid position
123-140 F18.14 pix y Y-centroid position
142-159 F18.14 K therm Thermistor readout ThermFront2
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Byte-by-byte Description of file: detrend.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 17 F17.12 d Time Time (BJD-2450000) (TDB)
19- 36 F18.16 --- Flux Normalised detrended flux
38- 60 E23.17 --- e_Flux [] 1-sigma uncertainty in normalised
detrended flux
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Acknowledgements:
Erik Meier Valdes, erik.meiervaldes(at)unibe.ch
(End) Patricia Vannier [CDS] 03-Aug-2023