J/A+A/686/A301 TOI-421 light and velocity curves (Krenn+, 2024)
Characterisation of the TOI-421 planetary system using CHEOPS, TESS, and
archival radial velocity data.
Krenn A.F., Kubyshkina D., Fossati L., Egger J.A., Bonfanti A., Deline A.,
Ehrenreich D., Beck M., Benz W., Cabrera J., Wilson T.G., Leleu A.,
Sousa S.G., Adibekyan V., Correia A.C.M., Alibert Y., Delrez L., Lendl M.,
Patel J.A., Venturini J., Alonso R., Anglada G., Asquier J., Barczy T.,
Barrado Navascues D., Barros S.C.C., Baumjohann W., Beck T., Billot N.,
Bonfils X., Borsato L., Brandeker A., Broeg C., Charnoz S.,
Collier Cameron A., Csizmadia Sz., Cubillos P.E., Davies M.B., Deleuil M.,
Demangeon O.D.S., Demory B.-O., Erikson A., Fortier A., Fridlund M.,
Gandolfi D., Gillon M., Guedel M., Guenther M.N., Hasiba J., Heitzmann A.,
Helling C., Hoyer S., Isaak K.G., Kiss L.L., Lam K.W.F., 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., Rieder M., Santos N.C., Scandariato G., Segransan D., Simon A.E.,
Smith A.M.S., Stalport M., Steller M., Szabo Gy.M., Thomas N., Udry S.,
Ulmer B., Van Grootel V., Villaver E., Viotto V., Walton N.A., Zingales T.
<Astron. Astrophys. 686, A301 (2024)>
=2024A&A...686A.301K 2024A&A...686A.301K (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Exoplanets ; Photometry ; Optical ;
Radial velocities
Keywords: planets and satellites: composition -
planets and satellites: fundamental parameters -
planets and satellites: individual: TOI-421
Abstract:
The TOI-421 planetary system contains two sub-Neptune-type planets
(Pb∼5.2-days, Teq,b∼900K, and Pc∼16.1-days, Teq,c∼650K) and
is a prime target to study the formation and evolution of planets and
their atmospheres. The inner planet is especially interesting as the
existence of a hydrogen-dominated atmosphere at its orbital separation
cannot be explained by current formation models without previous
orbital migration.
We aim to improve the system parameters to further use them to model
the interior structure and simulate the atmospheric evolution of both
planets, to finally gain insights into their formation and evolution.
We also investigate the possibility of detecting transit timing
variations (TTVs).
We jointly analysed photometric data of three TESS sectors and six
CHEOPS visits as well as 156 radial velocity data points to retrieve
improved planetary parameters. We also searched for TTVs and modelled
the interior structure of the planets. Finally, we simulated the
evolution of the primordial H-He atmospheres of the planets using two
different modelling frameworks.
We determine the planetary radii and masses of TOI-421 b and c to be
Rb=2.64±0.08R⊕, Mb=6.7±0.6M⊕,
Rc=5.09±0.07R⊕, and Mc=14.1±1.4M⊕. Using these
results we retrieved average planetary densities of
rhob=0.37±0.05rho⊕ and rhoc=0.107±0.012rho⊕. We
do not detect any statistically significant TTV signals. Assuming the
presence of a hydrogen-dominated atmosphere, the interior structure
modelling results in both planets having extensive envelopes. While
the modelling of the atmospheric evolution predicts for TOI-421 b to
have lost any primordial atmosphere that it could have accreted at its
current orbital position, TOI-421 c could have started out with an
initial atmospheric mass fraction somewhere between 10 and 35%.
We conclude that the low observed mean density of TOI-421b can only be
explained by either a bias in the measured planetary parameters (e.g.
driven by high-altitude clouds) and/or in the context of orbital
migration. We also find that the results of atmospheric evolution
models are strongly dependent on the employed planetary structure
model.
Description:
We present CHEOPS photometry extracted using PIPE (raw and detrended) of
TOI-421 containing four transits of planet b and 2 transits of planet c.
Further we present detrended TESS photometry of TOI-421.
We also present raw and detrended HARPS radial velocities of TOI-421
reduced by fitting a skew normal fit to the CCFs.
Finally, we also include raw and detrended radial velocities of TOI-421
observed by FIES, PFS and HIRES. The raw data was originally published
by Carleo et al. (2020AJ....160..114C 2020AJ....160..114C, Cat. J/AJ/160/114).
ch1.dat contains the raw CHEOPS photometric time series with
auxiliary detrending vectors.
ch2.dat contains the detrended CHEOPS light curve.
te1.dat contains the detrended TESS light curve.
harps.dat, hires.dat, fies.dat and pfs.dat contain the HARPS, HIRES,
FIES and PFS raw and detrended (including offset-corrected) radial
velocities.
Objects:
----------------------------------------------------
RA (2000) DE Designation(s)
----------------------------------------------------
05 27 24.82 -14 16 37.0 TOI-421 = BD-14 1137
----------------------------------------------------
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
cheops1.dat 71 2615 Raw CHEOPS photometric time series with
auxiliary detrending vectors
cheops2.dat 34 2539 Detrended CHEOPS light curve
tess.dat 34 3072 Detrended TESS light curve
harps.dat 56 105 Raw and detrended HARPS radial velocities
hires.dat 56 33 Raw and detrended HIRES radial velocities
fies.dat 56 9 Raw and detrended FIES radial velocities
pfs.dat 56 9 Raw and detrended PFS radial velocities
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See also:
J/AJ/160/114 : Radial velocity monitoring of TOI-421 (Carleo+, 2020)
Byte-by-byte Description of file: cheops1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 16 F16.6 d Time Time of mid-exposure (BJD)
18- 25 F8.6 --- NFlux Normalised raw flux
27- 34 F8.6 --- e_NFlux 1-sigma uncertainty in NFlux
36- 43 F8.4 deg Roll Spacecraft roll angle
45- 52 F8.4 pix CenX X-centroid position
54- 61 F8.4 pix CenY Y-centroid position
63- 71 F9.7 --- Bg Fraction of flux in aperture from background
--------------------------------------------------------------------------------
Byte-by-byte Description of file: cheops2.dat tess.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 16 F16.6 d Time Time of mid-exposure (BJD)
18- 25 F8.6 --- NFluxdet Normalised detrended flux
27- 34 F8.6 --- e_NFluxdet 1-sigma uncertainty in NFluxdet
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Byte-by-byte Description of file: harps.dat hires.dat fies.dat pfs.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 16 F16.6 d Time Time of mid-exposure (BJD)
18- 26 F9.6 km/s RV Radial Velocity
28- 36 F9.6 km/s e_RV 1-sigma uncertainty in RV
38- 46 F9.6 km/s RVdet Detrended Radial Velocity
48- 56 F9.6 km/s e_RVdet 1-sigma uncertainty in RVdet
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Acknowledgements:
Andreas F. Krenn, andreas.krenn(at)oeaw.ac.at
(End) Andreas Krenn [OEAW], Patricia Vannier [CDS] 15-Apr-2024