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Examining the orbital decay targets KELT-9 b, KELT-16 b, and WASP-4 b, and the transit-timing variations of HD 97658 b,

Harre, J.-V. ; Davies, M.B. LU and Wohler, B. (2023) In Astronomy and Astrophysics 669.
Abstract
Context. Tidal orbital decay is suspected to occur for hot Jupiters in particular, with the only observationally confirmed case of this being WASP-12 b. By examining this effect, information on the properties of the host star can be obtained using the so-called stellar modified tidal quality factor Q′∗, which describes the efficiency with which the kinetic energy of the planet is dissipated within the star. This can provide information about the interior of the star. Aims. In this study, we aim to improve constraints on the tidal decay of the KELT-9, KELT-16, and WASP-4 systems in order to find evidence for or against the presence of tidal orbital decay. With this, we want to constrain the Q′∗ value for each star. In addition, we aim to... (More)
Context. Tidal orbital decay is suspected to occur for hot Jupiters in particular, with the only observationally confirmed case of this being WASP-12 b. By examining this effect, information on the properties of the host star can be obtained using the so-called stellar modified tidal quality factor Q′∗, which describes the efficiency with which the kinetic energy of the planet is dissipated within the star. This can provide information about the interior of the star. Aims. In this study, we aim to improve constraints on the tidal decay of the KELT-9, KELT-16, and WASP-4 systems in order to find evidence for or against the presence of tidal orbital decay. With this, we want to constrain the Q′∗ value for each star. In addition, we aim to test the existence of the transit timing variations (TTVs) in the HD 97658 system, which previously favoured a quadratic trend with increasing orbital period. Methods. Making use of newly acquired photometric observations from CHEOPS (CHaracterising ExOplanet Satellite) and TESS (Transiting Exoplanet Survey Satellite), combined with archival transit and occultation data, we use Markov chain Monte Carlo (MCMC) algorithms to fit three models to the data, namely a constant-period model, an orbital-decay model, and an apsidal-precession model. Results. We find that the KELT-9 system is best described by an apsidal-precession model for now, with an orbital decay trend at over 2 σ being a possible solution as well. A Keplerian orbit model with a constant orbital period provides the best fit to the transit timings of KELT-16 b because of the scatter and scale of their error bars. The WASP-4 system is best represented by an orbital decay model at a 5 σ significance, although apsidal precession cannot be ruled out with the present data. For HD 97658 b, using recently acquired transit observations, we find no conclusive evidence for a previously suspected strong quadratic trend in the data. © The Authors 2023. (Less)
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keywords
planet-star interactions, planets and satellites: dynamical evolution and stability, techniques: photometric, Decay (organic), Extrasolar planets, Kinetic energy, Kinetics, Markov processes, Orbits, Photometry, Stars, Timing circuits, Decay model, Exo-planets, Orbital decay, Orbital periods, Planet-star interactions, Planets and satellites: dynamical evolution and stabilities, Precession model, Techniques: photometric, Timing variations, Transit timing, Satellites
in
Astronomy and Astrophysics
volume
669
article number
A124
publisher
EDP Sciences
external identifiers
  • scopus:85147138880
ISSN
0004-6361
DOI
10.1051/0004-6361/202244529
language
English
LU publication?
yes
id
4911b301-7016-4428-a476-de319bd54c15
date added to LUP
2023-02-16 12:40:38
date last changed
2023-02-16 12:40:38
@article{4911b301-7016-4428-a476-de319bd54c15,
  abstract     = {{Context. Tidal orbital decay is suspected to occur for hot Jupiters in particular, with the only observationally confirmed case of this being WASP-12 b. By examining this effect, information on the properties of the host star can be obtained using the so-called stellar modified tidal quality factor Q′∗, which describes the efficiency with which the kinetic energy of the planet is dissipated within the star. This can provide information about the interior of the star. Aims. In this study, we aim to improve constraints on the tidal decay of the KELT-9, KELT-16, and WASP-4 systems in order to find evidence for or against the presence of tidal orbital decay. With this, we want to constrain the Q′∗ value for each star. In addition, we aim to test the existence of the transit timing variations (TTVs) in the HD 97658 system, which previously favoured a quadratic trend with increasing orbital period. Methods. Making use of newly acquired photometric observations from CHEOPS (CHaracterising ExOplanet Satellite) and TESS (Transiting Exoplanet Survey Satellite), combined with archival transit and occultation data, we use Markov chain Monte Carlo (MCMC) algorithms to fit three models to the data, namely a constant-period model, an orbital-decay model, and an apsidal-precession model. Results. We find that the KELT-9 system is best described by an apsidal-precession model for now, with an orbital decay trend at over 2 σ being a possible solution as well. A Keplerian orbit model with a constant orbital period provides the best fit to the transit timings of KELT-16 b because of the scatter and scale of their error bars. The WASP-4 system is best represented by an orbital decay model at a 5 σ significance, although apsidal precession cannot be ruled out with the present data. For HD 97658 b, using recently acquired transit observations, we find no conclusive evidence for a previously suspected strong quadratic trend in the data. © The Authors 2023.}},
  author       = {{Harre, J.-V. and Davies, M.B. and Wohler, B.}},
  issn         = {{0004-6361}},
  keywords     = {{planet-star interactions; planets and satellites: dynamical evolution and stability; techniques: photometric; Decay (organic); Extrasolar planets; Kinetic energy; Kinetics; Markov processes; Orbits; Photometry; Stars; Timing circuits; Decay model; Exo-planets; Orbital decay; Orbital periods; Planet-star interactions; Planets and satellites: dynamical evolution and stabilities; Precession model; Techniques: photometric; Timing variations; Transit timing; Satellites}},
  language     = {{eng}},
  publisher    = {{EDP Sciences}},
  series       = {{Astronomy and Astrophysics}},
  title        = {{Examining the orbital decay targets KELT-9 b, KELT-16 b, and WASP-4 b, and the transit-timing variations of HD 97658 b,}},
  url          = {{http://dx.doi.org/10.1051/0004-6361/202244529}},
  doi          = {{10.1051/0004-6361/202244529}},
  volume       = {{669}},
  year         = {{2023}},
}