paper

The Tale of a Hungry Subgiant and Its Brown Dwarf: Interior Radiative Damping Dominates the Tidal Evolution of TOI-5882

arXiv:2605.04141 · doi:10.3847/2041-8213/ae7e89

Abstract

We present a self-consistent tidal evolution framework that couples binary evolution from MESA to the full linear tidal response from GYRE-tides. Applying this framework to TOI-5882, a subgiant hosting a short-period brown dwarf, we show that interior radiative damping dominates the system's tidal evolution, with the classical equilibrium tidal model significantly underestimating the star's angular momentum evolution by several orders of magnitude. Consequently, our combined framework predicts a 2-6 fold reduction in the engulfment timescale, accelerating the companion's inspiral by roughly 25-110 Myr. By modeling angular momentum transport through the star as it evolves, we demonstrate that the early inspiral is driven by the non-resonant dissipation of internal gravity waves, before transitioning into a regime dominated by resonance crossings as the system approaches Roche-lobe overflow. We highlight the necessity of reframing the historical dichotomy between equilibrium and dynamical tides and instead propose categorizing tidal interactions around their dissipation mechanisms: radiatively damped tides, driven by radiative diffusion, and viscously damped tides, driven by turbulent viscosity. Our framework is broadly applicable to the tidal modeling of a wide class of star-companion systems, from binary stars to hot Jupiters, in a self-consistent and computationally feasible manner.

14 pages, 5 figures, accepted for publication in the Astrophysical Journal Letters. All inlists and the coupled framework are available at https://doi.org/10.5281/zenodo.18855025

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