Planet-star interactions with precise transit timing. IV. Probing the regime of dynamical tides for GK host stars

TL;DR

This study investigates the presence of orbital decay in hot Jupiter systems around GK stars to understand the regime of dynamical tides and their dissipation mechanisms, using transit timing data and theoretical models.

Contribution

It provides observational constraints on dynamical tide dissipation rates in GK star systems by analyzing transit timing data and comparing with theoretical predictions.

Findings

Transit times follow linear ephemerides, indicating no detectable orbital decay.

Lower bounds on tidal dissipation rates were established for the studied systems.

Certain dynamical tide dissipation scenarios, like IGW wave breaking, are rejected in some systems.

Abstract

Statistical studies show that stars of GK spectral types, with masses below 1.1 Sun mass, are depleted in hot Jupiters. This finding is evidence of tidal orbital decay during the main-sequence lifetime. Theoretical considerations show that in some configurations, the tidal energy dissipation can be boosted by non-linear effects in dynamical tides, which are wave-like responses to tidal forcing. To probe the regime of these dynamical tides in GK stars, we searched for orbital period shortening for 6 selected hot Jupiters in systems with 0.8-1 Sun mass host stars: HATS-18, HIP 65A, TrES-3, WASP-19, WASP-43, and WASP-173A. For the hot Jupiters of our sample, we analysed transit timing data sets based on mid-transit points homogeneously determined from observations performed with the Transiting Exoplanet Survey Satellite and high-quality data available in the literature. For the TrES-3 system, we also used new transit light curves we acquired with ground-based telescopes. The mid-transit times were searched for shortening of orbital periods through statistical testing of quadratic transit ephemerides. Theoretical predictions on the dissipation rate for dynamical tides were calculated under the regimes of internal gravity waves (IGWs) undergoing wave breaking (WB) in stellar centres and weak non-linear (WNL) wave-wave interactions in radiative layers. Stellar parameters of the host stars, such as mass and age, which were used in those computations, were homogeneously redetermined using evolutionary models with the Bayesian inference. We found that transit times follow the refined linear ephemerides for all ultra-hot Jupiters of our sample. Non-detection of orbital decay allowed us to place lower constraints on the tidal dissipation rates in those planet-star systems. In three systems, HATS-18, WASP-19, and WASP-43, we reject a scenario with total dissipation of IGWs. We conclude that...