J/A+A/653/A173 CHEOPS 55 Cnc light curve (Morris+, 2021)
CHEOPS Precision Phase Curve of the Super-Earth 55 Cnc e.
Morris B.M., Delrez L., Brandeker A., Cameron A.C., Simon A.E., Futyan D.,
Olofsson G., Hoyer S., Fortier A., Demory B.-O., Lendl M., Wilson T.G.,
Oshagh M., Heng K., Ehrenreich D., Sulis S., Alibert Y., Alonso R.,
Anglada Escude G., Barrado D., Barros S.C.C., Baumjohann W., Beck M.,
Beck T., Bekkelien A., Benz W., Bergomi M., Billot N., Bonfils X.,
Bourrier V., Broeg C., Barczy T., Cabrera J., Charnoz S., Davies M.B.,
De Miguel Ferreras D., Deleuil M., Deline A., Demangeon O.D.S., Erikson A.,
Floren H.G., Fossati L., Fridlund M., Gandolfi D., Garcia Munoz A.,
Gillon M., Guedel M., Guterman P., Isaak K., Kiss L., Laskar J.,
Lecavelier des Etangs A., Lieder M., Lovis C., Magrin D., Maxted P.F.L.,
Nascimbeni V., Ottensamer R., Pagano I., Palle E., Peter G., Piotto G.,
Pizarro Rubio A., Pollacco D., Pozuelos F.J., Queloz D., Ragazzoni R.,
Rando N., Rauer H., Ribas I., Santos N.C., Scandariato G., Smith A.M.S.,
Sousa S.G., Steller M., Szabo Gy.M., Segransan D., Thomas N., Udry S.,
Ulmer B., Van Grootel V., Walton N.A.
<Astron. Astrophys. 653, A173 (2021)>
=2021A&A...653A.173M 2021A&A...653A.173M (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Exoplanets ; Photometry
Keywords: techniques: photometric - methods: observational -
planets and satellites: atmospheres - stars: individual: 55 Cnc -
planets and satellites: individual: 55 Cnc e -
instrumentation: photometers
Abstract:
55 Cnc e is a transiting super-Earth (radius 1.88R⊕ and mass
8M⊕) orbiting a G8V host star on a 17-hour orbit. Spitzer
observations of the planet's phase curve at 4.5um revealed a
time-varying occultation depth, and MOST optical observations are
consistent with a time-varying phase curve amplitude and phase offset
of maximum light. Both broadband and high-resolution spectroscopic
analyses are consistent with either a high mean molecular weight
atmosphere or no atmosphere for planet e. A long term photometric
monitoring campaign on an independent optical telescope is needed to
probe the variability in this system. We seek to measure the phase
variations of 55 Cnc e with a broadband optical filter with the 30 cm
effective aperture space telescope CHEOPS and explore how the
precision photometry narrows down the range of possible scenarios. We
observed 55 Cnc for 1.6 orbital phases in March of 2020. We designed a
phase curve detrending toolkit for CHEOPS photometry which allows us
to study the underlying flux variations of the 55 Cnc system. We
detected a phase variation with a full-amplitude of 72±7ppm but do
not detect a significant secondary eclipse of the planet. The shape of
the phase variation resembles that of a piecewise-Lambertian, however
the non-detection of the planetary secondary eclipse, and the large
amplitude of the variations exclude reflection from the planetary
surface as a possible origin of the observed phase variations. They
are also likely incompatible with magnetospheric interactions between
the star and planet but may imply that circumplanetary or
circumstellar material modulate the flux of the system. Further
precision photometry of 55 Cnc from CHEOPS will measure variations in
the phase curve amplitude and shape over time this year.
Description:
A single primary transit of 55 Cnc e was observed during the CHEOPS
In-Orbit Commissioning (IOC) phase on UT 2020 March 09. Due to the
brightness of the target, an effective exposure time of 30.8 s was
achieved by the stacking of 14 individual readouts of 2.2s.
CHEOPS also observed 1.6 orbital phases of 55 Cnc over 26 hours on UT
2020 March 23-24.
Objects:
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RA (2000) DE Designation(s)
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08 52 35.81 +28 19 51.0 55 Cancri = HR 3522
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
photom.dat 149 1539 Photometric data
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See also:
J/A+A/533/A114 : Transit of super-Earth 55 Cnc e (Demory+, 2011)
J/A+A/539/A28 : super-Earth 55 Cnc e new transit photometry (Gillon+, 2012)
J/A+A/545/A97 : 0.8-6µm calibrated spectrum of 55 Cnc (Crossfield, 2012)
J/ApJ/778/132 : C and O abundances in 55 Cnc (Teske+, 2013)
J/ApJ/792/L31 : HARPS and HARPS-N 55 Cnc radial velocities
(Lopez-Morales+, 2014)
J/A+A/619/A1 : 55 Cnc radial velocities and photometry (Bourrier+, 2018)
J/A+A/615/A117 : 55 CnC geocoronal emission lines template (Bourrier+, 2018)
Byte-by-byte Description of file: photom.dat
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Bytes Format Units Label Explanations
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1- 24 E24.18 d BJD Barycentric Julian Date (TDB)
26- 49 E24.18 --- Flux Normalized flux
51- 74 E24.18 --- e_Flux Normalized flux error
76- 99 E24.18 deg RollAngle Spacecraft roll angle
101-124 E24.18 --- Contam Aperture flux contamination
126-149 E24.18 --- FluxDetrend Detrended normalized flux
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Acknowledgements:
Brett Morris, morrisbrettm(at)gmail.com
(End) Patricia Vannier [CDS] 06-Aug-2021