Numerical Non-Adiabatic Tidal Calculations with GYRE-tides: The WASP-12 Test Case

TL;DR

This paper uses the GYRE-tides code to perform detailed non-adiabatic tidal calculations for the WASP-12 system, confirming the robustness of the numerical approach and highlighting the need for nonlinear damping to explain observed orbital decay.

Contribution

It introduces GYRE-tides as an open-source tool for detailed tidal dissipation calculations in exoplanet systems, validated against previous estimates and applied to WASP-12.

Findings

Linear tides are insufficient to explain the observed decay rate.

Numerical dissipation rates agree with semi-analytic and adiabatic estimates.

Nonlinear damping may be necessary to match observations.

Abstract

We revisit the tidal evolution of the WASP-12 system using direct numerical calculations with the GYRE-tides code. WASP-12b is a hot Jupiter on a 1.1-day orbit around a slightly evolved F-type star. Its observed orbital decay rate, $|\dot{P}_{\rm orb}/P_{\rm orb}| \approx 3.2\,\mathrm{Myr}^{-1}$, provides a strong constraint on stellar tidal dissipation. We confirm that linear tides with radiative damping and convective damping, as currently implemented, are not sufficient to reproduce the observed inspiral timescale. Nevertheless, our calculations, based on fully non-adiabatic forced oscillations in MESA stellar models with convective envelopes, yield dissipation rates that are consistent with previous semi-analytic and adiabatic estimates, confirming the robustness of our numerical framework. As the only open-source, actively maintained tool capable of computing orbital evolution in exoplanet systems, GYRE-tides provides a benchmark calculation for WASP-12 and future applications. Our results validate GYRE-tides as a tool for analyzing combined radiative and convective damping, and indicate that the observed decay rate requires tidal dissipation operating in or near the fully damped regime, which may be achieved through nonlinear damping. These contributions could also be evaluated by computing the wave luminosity at the radiative-convective boundary using our tool. GYRE-tides offers an open-source framework for computing tidal dissipation in short-period exoplanet systems, including the many systems expected to show orbital decay in upcoming Roman surveys.