Tides and angular momentum redistribution inside low-mass stars hosting planets: a first dynamical model

TL;DR

This paper presents an analytical framework to model how tides and stellar winds influence angular momentum redistribution inside low-mass stars with close-in planets, enabling simultaneous evolution predictions of stellar rotation and planetary orbits.

Contribution

It introduces a novel analytical model for internal angular momentum transport in stars with planetary companions, incorporating tidal and wind effects in a unified way.

Findings

Model successfully predicts stellar spin and orbital evolution.

Application to an F-type star with hot Jupiter demonstrates model's utility.

Framework can be used to interpret asteroseismic data on stellar rotation profiles.

Abstract

We introduce a general mathematical framework to model the internal transport of angular momentum in a star hosting a close-in planetary/stellar companion. By assuming that the tidal and rotational distortions are small and that the deposit/extraction of angular momentum induced by stellar winds and tidal torques are redistributed solely by an effective eddy-viscosity that depends on the radial coordinate, we can formulate the model in a completely analytic way. It allows us to compute simultaneously the evolution of the orbit of the companion and of the spin and the radial differential rotation of the star. An illustrative application to the case of an F-type main-sequence star hosting a hot Jupiter is presented. The general relevance of our model to test more sophisticated numerical dynamical models and to study the internal rotation profile of exoplanet hosts, submitted to the combined effects of tides and stellar winds, by means of asteroseismology are discussed.