J/A+A/688/A211 TOI-178 light curves (Leleu+, 2024)
Photo-dynamical characterisation of the TOI-178 resonant chain.
Leleu A., Delisle J.-B., Delrez L., Bryant E.M., Brandeker A., Osborn H.P.,
Hara N., Wilson T.G., Billot N., Lendl M., Ehrenreich D., Chakraborty H.,
Guenther M.N., Hooton M.J., Alibert Y., Alonso R., Alves D.R.,
Anderson D.R., Apergis I., Armstrong D., Barczy T., Barrado Navascues D.,
Barros S.C., Battley M.P., Baumjohann W., Bayliss D., Beck T., Benz W.,
Borsato L., Broeg C., Burleigh M.R., Casewell S.L., Collier Cameron A.,
Correia A.C.M., Csizmadia Sz., Cubillos P.E., Davies M.B., Deleuil M.,
Deline A., Demangeon O.D.S., Demory B.-O., Derekas A., Edwards B.,
Erikson A., Fortier A., Fossati L., Fridlund M., Gandolfi D., Gazeas K.,
Gillen E., Gillon M., Goad M.R., Guedel M., Hawthorn F., Heitzmann A.,
Helling Ch., Isaak K.G., Jenkins J.S., Jenkins J.M., Kendall A., Kiss L.,
Korth J., Lam K.W.F., Laskar J., Latham D.W., Lecavelier des Etangs A.,
Magrin D., Maxted P.F.L., McCormac J., Mordasini C., Moyano M.,
Nascimbeni V., Olofsson G., Osborn A., Ottensamer R., Pagano I., Palle E.,
Peter G., Piotto G., Pollacco D., Queloz D., Ragazzoni R., Rando N.,
Rauer H., Ribas I., Ricker G., Saha S., Santos N.C., Scandariato G.,
Seager S., Segransan D., Simon A.E., Smith A.M.S., Sousa S.G., Stalport M.,
Sulis S., Szabo M.Gy., Udry S., Ulmer-Moll S., Van Grootel V.,
Vanderspek R., Venturini J., Villaver E., Vines J.I., Walton N.A.,
West R.G., Wheatley P.J., Winn J., Zivave T.
<Astron. Astrophys. 688, A211 (2024)>
=2024A&A...688A.211L 2024A&A...688A.211L (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Exoplanets ; Binaries, orbits ;
Photometry ; Optical
Keywords: methods: data analysis - techniques: photometric -
techniques: radial velocity - planets and satellites: detection -
planets and satellites: gaseous planets
Abstract:
The TOI-178 system consists of a nearby, late-K-dwarf with six
transiting planets in the super-Earth to mini-Neptune regime,with
radii ranging from ∼1.1 to 2.9R⊕ and orbital periods between
1.9 and 20.7 days. All the planets, but the innermost one, form a
chain of Laplace resonances. Mass estimates derived from a preliminary
radial velocity (RV) dataset suggest that the planetary densities do
not decrease in a monotonic way with the orbital distance to the
star,contrary to what one would expect based on simple formation and
evolution models. The fine-tuning and fragility of such orbital
configurations ensure that no significant scattering or collision
event has taken place since the {formation and migration} of the
planets in the protoplanetary disc, thereby providing important
anchors for planet formation models.
We aim to improve the characterisation of the architecture of this key
system and, in particular, the masses and radii of its planets. In
addition, since this system is one of the few resonant chains that can
be characterised by both photometry and radial velocities, we propose
to use it as a test bench for the robustness of the planetary mass
determination with each technique.
We performed a global analysis of all the available photometry from
CHEOPS, TESS and NGTS, and radial velocity from ESPRESSO, using a
photo-dynamical modelling of the light curve. We also tried different
sets of priors on the masses and eccentricity, as well as different
stellar activity models, to study their effects on the masses
estimated by transit-timing variations (TTVs) and radial velocities
(RVs).
We demonstrate how stellar activity prevents a robust mass estimation
for the three outer planets using radial velocity data alone.We also
show that our joint photo-dynamical and radial velocity analysis has
resulted in a robust mass determination for planets c to g, with
precision of ∼12% for the mass of planet c, and better than 10% for
planets $d$ to g. The new precisions on the radii range from 2 to 3%.
The understanding of this synergy between photometric and radial
velocity measurements will be valuable for the PLATO mission. We also
show that TOI-178 is indeed currently locked in the resonant
configuration, librating around an equilibrium of the chain.
Description:
In this study, we used the TESS, CHEOPS, ESPRESSO, and NGTS data
presented in L21 and D23. In addition, we used 27 new CHEOPS visits, 8
new NGTS observations, and 4 Euler- Cam observations that were taken
in order to monitor the TTVs of the five outer planets of TOI-178.
Objects:
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RA (2000) DE Designation(s)
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00 29 12.30 -30 27 13.4 TOI-178 = TIC 251848941
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
eulerd.dat 43 1708 Detrended Euler data
samples.dat 895 300 *Planetary and stellar parameters samples the
joint photo-dynamical+RV fit
timings.dat 65 1277 Transit timings and errors from the final
posterior of the joint photo-dynamical+RV fit
cheopspr.dat 154 29131 Raw CHEOPS data extracted by PIPE
cheopsd.dat 59 130305 Detrended CHEOPS data
ngtsd.dat 59 51521 Detrended NGTS data
tessd.dat 59 281742 Detrended TESS data
ngtsr.dat 83 51521 Raw NGTS data
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Note on samples.dat: The orbital elements of planets c, d, e, f and g are given
at the date 2458352.55018382 BJD.
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See also:
J/A+A/649/A26 : TOI-178 six transiting planets (Leleu+, 2021)
J/A+A/678/A200 : TOI-178 raw and detrended photometry (Delrez+, 2023)
Byte-by-byte Description of file: eulerd.dat
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Bytes Format Units Label Explanations
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1- 16 F16.8 d Time Date of the observation (BJD)
18- 25 F8.6 --- Flux Normalised raw flux
27- 34 F8.6 --- e_Flux Normalised flux error
36- 43 F8.6 --- FluxDet Normalised detrended flux
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Byte-by-byte Description of file: samples.dat
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Bytes Format Units Label Explanations
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1- 18 F18.15 deg lambda0 Mean longitude planet c
20- 37 F18.16 d P0 Orbital period planet c
39- 62 E24.17 --- k0 ecc * cos (long of pericenter) planet c
64- 87 E24.17 --- h0 ecc * sin (long of pericenter) planet c
89-110 E22.17 Msun m0 Mass planet c
112-129 F18.15 deg lambda1 Mean longitude planet d
131-148 F18.16 d P1 orbital period planet d
150-173 E24.17 --- k1 ecc * cos (long of pericenter) planet d
175-198 E24.17 --- h1 ecc * sin (long of pericenter) planet d
200-221 E22.17 Msun m1 Mass planet d
223-239 F17.14 deg lambda2 Mean longitude planet e
241-257 F17.15 d P2 Orbital period planet e
259-282 E24.17 --- k2 ecc * cos (long of pericenter) planet e
284-307 E24.17 --- h2 ecc * sin (long of pericenter) planet e
309-330 E22.17 Msun m2 Mass planet e
332-349 F18.14 deg lambda3 Mean longitude planet f
351-368 F18.15 d P3 Orbital period planet f
370-393 E24.17 --- k3 ecc * cos (long of pericenter) planet f
395-418 E24.17 --- h3 ecc * sin (long of pericenter) planet f
420-441 E22.17 Msun m3 mass planet f
443-460 F18.15 deg lambda4 Mean longitude planet g
462-479 F18.15 d P4 Orbital period planet g
481-504 E24.17 --- k4 ecc * cos (long of pericenter) planet g
506-529 E24.17 --- h4 ecc * sin (long of pericenter) planet g
531-552 E22.17 Msun m4 Mass planet g
554-573 F20.18 --- R0 Radius planet c, in star radius
575-594 F20.18 --- R1 Radius planet d, in star radius
596-615 F20.18 --- R2 Radius planet e, in star radius
617-636 F20.18 --- R3 Radius planet f, in star radius
638-657 F20.18 --- R4 Radius planet g, in star radius
659-677 F19.17 --- b0 Impact parameter planet c
679-697 F19.17 --- b1 Impact parameter planet d
699-716 F18.16 --- b2 Impact parameter planet e
718-735 F18.16 --- b3 Impact parameter planet f
737-754 F18.16 --- b4 Impact parameter planet g
756-773 F18.16 Sun rho Density of the star
775-792 F18.16 Rsun Rstar Radius of the star
794-811 F18.13 d t0circ0 Date of transit of planet b (BJD-2457000)
813-830 F18.16 d Pcirc0 Orbital period of planet b
832-851 F20.18 --- Rcirc0 Radius of planet b, in star radius
853-872 F20.18 --- bcirc0 Impact parameter of planet b
874-895 E22.17 Msun mcirc0 Mass of planet b
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Byte-by-byte Description of file: timings.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- Name Name of the transiting planet
10- 27 F18.13 d Date Median transit date, BJD-2457000.0
29- 46 F18.13 d e_Date Date 0.15865 quantile, BJD-2457000.0
48- 65 F18.13 d E_Date Date 0.84135 quantile, BJD-2457000.0
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Byte-by-byte Description of file: cheopspr.dat
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Bytes Format Units Label Explanations
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1- 18 F18.13 d Date Date of the observation (BJD-2457000)
20- 37 F18.16 --- Flux Raw flux normalized by dividing by the median
of the raw flux over the visit
39- 59 F21.19 --- e_Flux Raw flux error normalized by dividing by the
median of the raw flux over the visit
61- 82 F22.20 rad RollAngle CHEOPS roll angle
84-107 E24.17 --- YC Position of the centroid along the Y
direction, normalised by deducing its mean
value and dividing it by its standard
deviation over the visit
109-130 F22.19 --- Temp2 Telescope tube temperature, normalised by
deducing its mean value and dividing it by
its standard deviation over the visit
132-154 E23.16 --- BG Background contamination, normalised by
deducing its mean value and dividing it by
its standard deviation over the visit
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Byte-by-byte Description of file: cheopsd.dat ngtsd.dat tessd.dat
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Bytes Format Units Label Explanations
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1- 18 F18.13 d Date Date of the observation (BJD-2457000)
20- 37 F18.16 --- Flux Detrended normalised flux
39- 59 F21.19 --- e_Flux Detrended normalised flux error
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Byte-by-byte Description of file: ngtsr.dat
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Bytes Format Units Label Explanations
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1- 18 F18.13 d Date Date of the observation (BJD-2457000)
20- 37 F18.16 --- Flux Raw flux normalized by dividing by the median
of the raw flux over the visit
39- 59 F21.19 --- e_Flux Raw flux error normalized by dividing by the
median of the raw flux over the visit
61- 83 E23.17 --- Airmass Airmass, normalised by deducing its mean value
and dividing it by its standard deviation
over the visit
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Acknowledgements:
Adrien Leleu, Adrien.Leleu(at)unige.ch
(End) Patricia Vannier [CDS] 12-Jul-2024