The Apparent Tidal Decay of WASP-4 b Can Be Explained by the Rømer Effect

Harre, Jan-Vincent; Smith, Alexis M. S.

doi:10.3390/universe9120506

Cited by 4 publications

(1 citation statement)

References 44 publications

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“…A decreasing orbital period can also be caused by mechanisms other than orbital decay. One of them is the Rømer effect, which is a light-time effect (LTE) induced by a wide-orbit companion [65]. Whether the observed period change is caused by the Rømer effect instead of orbital decay can only be solved through radial velocity measurements over a long time span.…”

Section: Discussionmentioning

confidence: 99%

Update on WASP-19

Korth,

Parviainen

2023

Universe

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Tidal interaction between a star and a close-in massive exoplanet causes the planetary orbit to shrink and eventually leads to tidal disruption. Understanding orbital decay in exoplanetary systems is crucial for advancing our knowledge of planetary formation and evolution. Moreover, it sheds light on the broader question of the long-term stability of planetary orbits and the intricate interplay of gravitational forces within stellar systems. Analyzing Transiting Exoplanet Survey Satellite (TESS) data for the ultra-short period gas giant WASP-19, we aim to measure orbital period variations and constrain the stellar tidal quality parameter. For this, we fitted the TESS observations together with two WASP-19 transits observed using the Las Cumbres Observatory Global Telescope (LCOGT) and searched for orbital decay in combination with previously published transit times. As a result, we find a deviation from the constant orbital period at the 7σ level. The orbital period changes at a rate of P˙=−3.7±0.5msyear−1, which translates into a tidal quality factor of Q★′=(7±1)×105. We additionally modeled WASP-19 b’s phase curve using the new TESS photometry and obtained updated values for the planet’s eclipse depth, dayside temperature, and geometric albedo. We estimate an eclipse depth of 520±60 ppm, which is slightly higher than previous estimates and corresponds to a dayside brightness temperature of 2400±60 K and geometric albedo of 0.20±0.04.

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Section: Discussionmentioning

confidence: 99%

Update on WASP-19

Korth,

Parviainen

2023

Universe

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Evidence of apsidal motion and a possible co-moving companion star detected in the WASP-19 system

Bernabò,

Csizmadia,

Smith

et al. 2024

A&A

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Love numbers measure the reaction of a celestial body to perturbing forces, such as the centrifugal force caused by rotation, or tidal forces resulting from the interaction with a companion body. These parameters are related to the interior density profile. The non-point mass nature of the host star and a planet orbiting around each other contributes to the periastron precession. The rate of this precession is characterized mainly by the second-order Love number, which offers an opportunity to determine its value. When it is known, the planetary interior structure can be studied with one additional constraint beyond the mass, radius, and orbital parameters. We aim to re-determine the orbital period, eccentricity, and argument of the periastron for WASP-19Ab, along with a study of its periastron precession rate. We calculated the planetary Love number from the observed periastron precession rate, based on the assumption of the stellar Love number from stellar evolutionary models. We collected all available radial velocity (RV) data, along with the transit and occultation times from the previous investigations of the system. We supplemented the data set with 19 new RV data points of the host star WASP-19A obtained by HARPS. Here, we summarize the technique for modeling the RV observations and the photometric transit timing variations (TTVs) to determine the rate of periastron precession in this system for the first time. We excluded the presence of a second possible planet up to a period of sim 4200 d and with a radial velocity amplitude bigger than simeq 1 m s$^ $. We show that a constant period is not able to reproduce the observed radial velocities. We also investigated and excluded the possibility of tidal decay and long-term acceleration in the system. However, the inclusion of a small periastron precession term did indeed improve the quality of the fit. We measured the periastron precession rate to be 233 $^ prime d^ $. By assuming synchronous rotation for the planet, it indicates a $k_2$ Love number of 0.20 $^ $ for WASP-19Ab. The derived Lovep value of the planet has the same order of magnitude as the estimated fluid Love number of other Jupiter-sized exoplanets (WASP-18Ab, WASP-103b, and WASP-121b). A low value of Lovep indicates a higher concentration of mass toward the planetary nucleus.

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Hints of a close outer companion to the ultra-hot Jupiter TOI-2109 b

Harre,

Smith,

Barros

et al. 2024

A&A

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Hot Jupiters (HJs) with close-by planetary companions are rare, with only a handful of them having been discovered so far. This could be due to their suggested dynamical histories, which lead to the possible ejection of other planets. TOI-2109\,b is special in this regard because it is the HJ with the closest relative separation from its host star, being separated by less than 2.3 stellar radii. Unexpectedly, transit timing measurements from recently obtained CHEOPS observations show low-amplitude transit-timing variations (TTVs). We aim to search for signs of orbital decay and to characterise the apparent TTVs in an attempt to gain information about a possible companion. We fitted the newly obtained CHEOPS light curves using TLCM and extracted the resulting mid-transit timings. Successively, we used these measurements in combination with TESS and archival photometric data and radial velocity (RV) data to estimate the rate of tidal orbital decay of TOI-2109\,b, and also to characterise the TTVs using the N-body code TRADES and the photo-dynamical approach of PyTTV We find tentative evidence at $3 for orbital decay in the TOI-2109 system when we correct the mid-transit timings using the best-fitting sinusoidal model of the TTVs. We do not detect additional transits in the available photometric data, but find evidence supporting the authenticity of the apparent TTVs indicating a close-by, outer companion with $P_ c > 1.125\,$d. Due to the fast rotation of the star, the new planetary candidate cannot be detected in the available RV measurements, and its parameters can only be loosely constrained by our joint TTV and RV modelling. TOI-2109 could join a small group of rare HJ systems that host close-by planetary companions, only one of which (WASP-47\,b) has an outer companion. More high-precision photometric measurements are necessary to confirm the existence of this planetary companion.

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The Apparent Tidal Decay of WASP-4 b Can Be Explained by the Rømer Effect

Cited by 4 publications

References 44 publications

Update on WASP-19

Update on WASP-19

Evidence of apsidal motion and a possible co-moving companion star detected in the WASP-19 system

Hints of a close outer companion to the ultra-hot Jupiter TOI-2109 b

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