GYRE is an open-source stellar oscillation code that calculates wave frequencies and functions for the (unforced) natural modes of an input stellar model. Recently, the code's capabilities have been extended to encompass forced oscillations, allowing it to calculate the interior perturbations of a star caused by the gravitational field of a companion. The standard approach to simulating tides involves using parameterized equations to approximate how tides modify a binary orbit. However, this approach often underestimates the circularization rate and overestimates the orbital shrinking rate.
Our extended code, GYRE-tides, overcomes these limitations by undertaking a full numerical solution of the tidal equations without approximations. As a result, it provides a more accurate analysis and interpretation of observations of binary systems. When applied to selected problems, we find general agreement with results in the published literature, but we also uncover some differences between our direct solution method and the modal decomposition approach adopted by others.
Currently, gyre_tides can model equilibrium and dynamical tides of binaries where radiative diffusion dominates the tidal dissipation (typically, intermediate and high-mass stars on the main sequence). Since the code became publicly available in this January, it has been widely used to study various types of systems, such as the possible Wolf-Rayet star spinning-up mechanism and the orbital migration of exoplanets with their host pulsating stars.