Why is there a Dearth of Close-In Planets around Fast-Rotating stars?

Abstract

We propose that the reported dearth of $Kepler$ Objects of Interest (KOIs) with orbital periods $P_{\rm orb} \lesssim 2-3\;$days around stars with rotation periods $P_{\rm rot} \lesssim 5-10\;$days can be attributed to tidal ingestion of close-in planets by their host stars. We show that the planet distribution in this region of the $\log{P_{\rm orb}}-\log{P_{\rm rot}}$ plane is qualitatively reproduced with a model that incorporates tidal interaction and magnetic braking as well as the dependence on the stellar core--envelope coupling timescale. We demonstrate the consistency of this scenario with the inferred break in the $P_{\rm orb}$ distribution of close-in KOIs and point out a potentially testable prediction of this interpretation.