J/A+A/671/L8 TOI-1055 b CHEOPS transits (Bonfanti+, 2023)
TOI-1055 b: A neptunian planet characterised with HARPS, TESS, and CHEOPS.
Bonfanti A., Gandolfi D., Egger J.A., Fossati L., Cabrera J., Krenn A.,
Alibert Y., Benz W., Billot N., Floren H.-G., Lendl M., Adibekyan V.,
Salmon S., Santos N.C., Sousa S.G., Wilson T.G., Barragan O.,
Collier Cameron A., Delrez L., Esposito M., Goffo E., Osborne H.,
Osborn H.P., Serrano L.M., Van Eylen V., Alarcon J., Alonso R., Anglada G.,
Barczy T., Barrado Navascues D., Barros S.C.C., Baumjohann W., Beck M.,
Beck T., Bedell M., Bonfils X., Borsato L., Brandeker A., Broeg C.,
Charnoz S., Corral Van Damme C., Csizmadia Sz., Cubillos P.E., Davies M.B.,
Deleuil M., Demangeon O.D.S., Demory B.-O., Ehrenreich D., Erikson A.,
Fortier A., Fridlund M., Gillon M., Guedel M., Hoyer S., Isaak K.G.,
Kerschbaum F., Kiss L.L., Laskar J., Lecavelier des Etangs A.,
Lorenzo-Oliveira D., Lovis C., Magrin D., Marafatto L., Maxted P.F.L.,
Melendez J., Mordasini C., Nascimbeni V., Olofsson G., Ottensamer R.,
Pagano I., Palle E., Peter G., Piazza D., Piotto G., Pollacco D., Queloz D.,
Ragazzoni R., Rando N., Rauer H., Ribas I., Scandariato G., Segransan 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.
<Astron. Astrophys. 671, L8 (2023)>
=2023A&A...671L...8B 2023A&A...671L...8B (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Exoplanets ; Photometry ; Optical
Keywords: techniques: radial velocities - techniques: photometric -
planets and satellites: fundamental parameters -
stars: fundamental parameters
Abstract:
TOI-1055 is a Sun-like star known to host a transiting Neptune-sized
planet on a 17.5-day orbit (TOI-1055 b). Radial velocity (RV) analyses
carried out by two independent groups using nearly the same set of
HARPS spectra have provided measurements of planetary masses that
differ by ∼2σ.
Our aim in this work is to solve the inconsistency in the published
planetary masses by significantly extending the set of HARPS RV
measurements and employing a new analysis tool that is able to account
and correct for stellar activity. Our further aim was to improve the
precision on measurements of the planetary radius by observing two
transits of the planet with the CHEOPS space telescope.
We fit a skew normal function to each cross correlation function
extracted from the HARPS spectra to obtain RV measurements and
hyperparameters to be used for the detrending. We evaluated the
correlation changes of the hyperparameters along the RV time series
using the breakpoint technique. We performed a joint photometric and
RV analysis using a Markov chain Monte Carlo scheme to simultaneously
detrend the light curves and the RV time series.
We firmly detected the Keplerian signal of TOI-1055 b, deriving a
planetary mass of Mb=20.4-2.5+2.6M⊕ (∼12%). This value is
in agreement with one of the two estimates in the literature, but it
is significantly more precise. Thanks to the TESS transit light curves
combined with exquisite CHEOPS photometry, we also derived a planetary
radius of Rb=3.490-0.064+0.070^R⊕ (∼1.9%). Our mass and
radius measurements imply a mean density of
ρb=2.65-0.35+0.37g/cm-3 (∼14%). We further inferred the
planetary structure and found that TOI-1055 b is very likely to host a
substantial gas envelope with a mass of 0.41-0.20+0.34M⊕
and a thickness of 1.05-0.29+0.30R⊕.
Our RV extraction combined with the breakpoint technique has played a
key role in the optimal removal of stellar activity from the HARPS
time series, enabling us to solve the tension in the planetary mass
values published so far for TOI-1055 b.
Description:
The CHEOPS space telescope carried out two transit observations of
TOI-1055 b, the first on 25 May 2021 (file key:
CHPR100024TG012301_V0200) and the second one on 11 June 2021 (file
key: CHPR100024TG012302_V0200).
Objects:
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RA (2000) DE Designation(s)
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19 33 08.59 -54 31 56.5 TOI-1055 = HIP 96160
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
dtg12301.dat 28 967 Detrended TG12301 light curve
dtg12302.dat 28 1033 Detrended TG12302 light curve
lc12301.dat 181 998 TG012301 light curve
lc12302.dat 181 1052 TG012302 light curve
fits/* . 2 fits files of TG012301 and TG012302 light curves
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Byte-by-byte Description of file: dtg12301.dat dtg12302.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 11 F11.6 d BJD Barycentric Julain date (BJD-2450000)
13- 20 F8.6 --- NFlux Normalised flux
22- 28 E7.3 --- e_NFlux Normalised flux error
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Byte-by-byte Description of file: lc12301.dat lc12302.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 26 A26 "datime" Time UTC time, middle of the measurements
(UTC_TIME)
28- 39 F12.6 d MJD Modified Julian Day, middle of the
measurements (MJD_TIME)
41- 54 F14.6 d BJD Barycentric date, middle of measurements
(BJD_TIME)
56- 67 E12.6 e- Flux Star flux measurement, corresponding to time
measurements (FLUX)
69- 80 E12.6 e- e_Flux Error on the star flux measurement,
corresponding to time measurements (FLUXERR)
82 I1 --- Status [0/1] Flags indicating the status of the
measurements (STATUS)
84- 89 I6 --- Event Flags indicating the possible events that
might be of bad quality (EVENT)
91- 97 F7.2 e- Dark Dark light curve (DARK)
99-110 E12.6 e- Bckg Background light curve (BACKGROUND)
112-123 E12.6 --- ContaLC Contamination of the target, corresponding to
time measurements (CONTA_LC)
125-136 E12.6 --- e_ContaLC Contamination error for the target,
corresponding to time measurements
(CONTALCERR)
138-144 F7.3 e- SmearLC Smearing of the target, corresponding to time
measurements (SMEARING_LC)
146-148 F3.1 e- e_SmearLC [0] Smearing error for the target
150-157 F8.4 deg RollAngle Computed mean roll angle of the CCD
(i.e. of th (ROLL_ANGLE)
159-161 I3 pix LocX [280] intended X position of target on CCD
[SOC coordinates] (LOCATION_X)
163-165 I3 pix LocY [828] intended Y position of target on CCD
[SOC coordinates] (LOCATION_Y)
167-173 F7.3 pix CentX calculated X position of target on CCD
[SOC coo (CENTROID_X)
175-181 F7.3 pix CentY calculated Y position of target on CCD
[SOC coo (CENTROID_Y)
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Acknowledgements:
Andrea Bonfanti, Andrea.Bonfanti(at)oeaw.ac.at
(End) Patricia Vannier [CDS] 21-Feb-2023