Searching for Rapid Orbital Decay of WASP-18b

Wilkins, Ashlee; Delrez, Laetitia; Barker, Adrian J.; Deming, Drake; Hamilton, D. P.; Gillon, M.; Jehin, Emmanuël

doi:10.3847/2041-8213/aa5d9f

Cited by 69 publications

(76 citation statements)

References 48 publications

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“…Here and elsewhere, this limit was obtained by calculating the 95%-confidence limit on dP/dt and then applying Equation (1) to convert it into a limit on Q . The uncertainty of 0.4 is based on the propagation of the uncertainties in M p /M and a/R from Table 1. Our result for WASP-18 is consistent with the 2-σ limit Q > 10 6 derived by Wilkins et al (2017).…”

Section: Introductionsupporting

confidence: 91%

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The Continuing Search for Evidence of Tidal Orbital Decay of Hot Jupiters

Patra

Winn

Holman

et al. 2020

Self Cite

105

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Many of the known hot Jupiters are formally unstable to tidal orbital decay. The only hot Jupiter for which orbital decay has been directly detected is WASP-12, for which transit timing measurements spanning more than a decade have revealed that the orbital period is decreasing at a rate of dP/dt ≈ 10 −9 , corresponding to a reduced tidal quality factor of about 2 × 10 5 . Here, we present a compilation of transit-timing data for WASP-12 and eleven other systems which are especially favorable for detecting orbital decay: 19, 43, 72, 103, 114, and 122; HAT-P-23; HATS-18; and OGLE-TR-56. For most of these systems we present new data that extend the time baseline over which observations have been performed. None of the systems besides WASP-12 displays convincing evidence for period changes, with typical upper limits on dP/dt on the order of 10 −9 or 10 −10 , and lower limits on the reduced tidal quality factor on the order of 10 5 . One possible exception is WASP-19, which shows a statistically significant trend, although it may be a spurious effect of starspot activity. Further observations are encouraged.

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Section: Introductionsupporting

confidence: 91%

“…planet's mass is large enough that the system is not formally unstable to tidal decay, although the period may be shrinking as the system approaches synchronization. Wilkins et al (2017) (Ricker et al 2015), adding high-precision transit times to the existing ephemeris.…”

Section: Introductionmentioning

confidence: 99%

The Continuing Search for Evidence of Tidal Orbital Decay of Hot Jupiters

Patra

Winn

Holman

et al. 2020

Self Cite

105

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show abstract

“…For hot Jupiters that have been monitored over baselines exceeding 10 years, secular changes in their orbital periods are currently being constrained to a precision of 10 msec yr −1 (Wilkins et al 2017;Maciejewski et al 2018;Baluev et al 2019;Petrucci et al 2020;Patra et al 2020). This is roughly commensurate with the level of signal many outer companions are expected to induce ( Figure 5).…”

Section: 3mentioning

confidence: 99%

WASP-4 Is Accelerating toward the Earth

Bouma

Winn

Howard

et al. 2020

ApJL

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The orbital period of the hot Jupiter WASP-4b appears to be decreasing at a rate of −8.64 ± 1.26 msec yr −1 , based on transit-timing measurements spanning 12 years. Proposed explanations for the period change include tidal orbital decay, apsidal precession, and acceleration of the system along the line of sight. To investigate further, we performed new radial velocity measurements and speckle imaging of WASP-4. The radial-velocity data show that the system is accelerating towards the Sun at a rate of −0.0422 ± 0.0028 m s −1 day −1 . The associated Doppler effect should cause the apparent period to shrink at a rate of −5.94 ± 0.39 msec yr −1 , comparable to the observed rate. Thus, the observed change in the transit period is mostly or entirely produced by the line-of-sight acceleration of the system. This acceleration is probably caused by a wide-orbiting companion of mass 10-300 M Jup and orbital distance 10-100 AU, based on the magnitude of the radial-velocity trend and the non-detection of any companion in the speckle images. We expect that the orbital periods of 1 out of 3 hot Jupiters will change at rates similar to WASP-4b, based on the hot-Jupiter companion statistics of Knutson et al. (2014). Continued radial velocity monitoring of hot Jupiters is therefore essential to distinguish the effects of tidal orbital decay or apsidal precession from line-of-sight acceleration.

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“…Many groups have searched for direct evidence of tidal decay in individual systems as a secularly decreasing period. However, no studies have found unambiguous evidence of tidal inspiral (e.g., Maciejewski et al 2016; Corresponding author: Jacob H. Hamer jhamer3@jhu.edu kschlaufman@jhu.edu Patra et al 2017;Wilkins et al 2017;Maciejewski et al 2018;Bouma et al 2019). In most hot Jupiter systems, no departure from a linear ephemeris has been observed (e.g., HAT-P-23, KELT-1, .…”

Section: Introductionmentioning

confidence: 99%

Hot Jupiters Are Destroyed by Tides While Their Host Stars Are on the Main Sequence

Hamer¹,

Schlaufman²

2019

108

102

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While cooler giant planets are often observed with nonzero eccentricities, the short-period circular orbits of hot Jupiters suggest that they lose orbital energy and angular momentum due to tidal interactions with their host stars. However, orbital decay has never been unambiguously observed. We use data from Gaia Data Release 2 to show that hot Jupiter host stars have a smaller Galactic velocity dispersion than a similar population of stars without hot Jupiters. Since Galactic velocity dispersion is correlated with age, this observation implies that the population of hot Jupiter host stars is on average younger than the field population. The best explanation for this inference is that tidal interactions cause hot Jupiters to inspiral while their host stars are on the main sequence. This observation requires that the typical modified stellar tidal quality factor Q * for solar-type stars is in the range log 10 Q * 7.

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Searching for Rapid Orbital Decay of WASP-18b

Cited by 69 publications

References 48 publications

The Continuing Search for Evidence of Tidal Orbital Decay of Hot Jupiters

The Continuing Search for Evidence of Tidal Orbital Decay of Hot Jupiters

WASP-4 Is Accelerating toward the Earth

Hot Jupiters Are Destroyed by Tides While Their Host Stars Are on the Main Sequence

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