Dynamical tides in exoplanetary systems containing Hot Jupiters: confronting theory and observations
Authors:
Chernov et al
Abstract:
We study the effect of dynamical tides associated with the excitation of gravity waves in an interior radiative region of the central star on orbital evolution in observed systems containing Hot Jupiters. We consider WASP-43, Ogle-tr-113, WASP-12, and WASP-18 which contain stars on the main sequence (MS). For these systems there are observational estimates regarding the rate of change of the orbital period. We also investigate Kepler-91 which contains an evolved giant star. We adopt the formalism of Ivanov et al. for calculating the orbital evolution. For the MS stars we determine expected rates of orbital evolution under different assumptions about the amount of dissipation acting on the tides, estimate the effect of stellar rotation for the two most rapidly rotating stars and compare results with observations. All cases apart from possibly WASP-43 are consistent with a regime in which gravity waves are damped during their propagation over the star. However, at present this is not definitive as observational errors are large. We find that although it is expected to apply to Kepler-91, linear radiative damping cannot explain this dis- sipation regime applying to MS stars. Thus, a nonlinear mechanism may be needed. Kepler-91 is found to be such that the time scale for evolution of the star is comparable to that for the orbit. This implies that significant orbital circularisation may have occurred through tides acting on the star. Quasi-static tides, stellar winds, hydrodynamic drag and tides acting on the planet have likely played a minor role.
TraMoS IV: Discarding the Quick Orbital Decay Hypothesis for OGLE-TR-113b
Authors:
Hoyer et al
Abstract:
In the context of the TraMoS project we present nine new transit observations of the exoplanet OGLE-TR-113b observed with the Gemini South, Magellan Baade, Danish-1.54m and SOAR telescopes. We perform a homogeneous analysis of these new transits together with ten literature transits to probe into the potential detection of an orbital decay for this planet reported by \citet{adams2010}. Our new observations extend the transit monitoring baseline for this system by 6 years, to a total of more than 13 years. With our timing analysis we obtained a P˙=−1.0±6.0 ms~yr−1, which rejects previous hints of a larger orbital decay for OGLE-TR-113b. With our updated value of P˙ we can discard tidal quality factors of Q less than 10^5 for its host star. Additionally, we calculate a 1σ dispersion of the Transit Timing Variations (TTVs) of 42 seconds over the 13 years baseline, which discards additional planets in the system more massive than 0.5−3.0 M⊕ in 1:2, 5:3, 2:1 and 3:1 Mean Motion Resonances with OGLE-TR-113b. Finally, with the joint analysis of the 19 light curves we update transit parameters, such as the relative semi-major axis a/Rs=6.44+0.04−0.05, the planet-to-star radius ratio Rp/Rs=0.14436+0.00096−0.00088, and constrains its orbital inclination to i=89.27+0.51−0.68~degrees.
