A Short History of (Orbital) Decay: Roman’s Prospects for Detecting Dying Planets

Abstract

The Roman Space Telescope Galactic Bulge Time Domain Survey (GBTDS) is expected to detect ∼10 ^5 transiting planets. Many of these planets will have short orbital periods and are thus susceptible to tidal decay. We use a catalog of simulated transiting planet detections to predict the yield of orbital decay detections in the Roman GBTDS. Assuming a constant stellar tidal dissipation factor, ${Q}_{* }^{{\prime} }$ , of 10 ^6 , we predict ∼5–10 detections. We additionally consider an empirical period-dependent parameterization of ${Q}_{* }^{{\prime} }\propto {P}^{-3}$ and find a substantially suppressed yield. We conclude that Roman will provide constraints on the rate of planet engulfment in the Galaxy and probe the physics of tidal dissipation in stars.

Keywords

• Exoplanets
• Exoplanet tides
• Surveys
• Transits