The Telltale Heartbeat: Detection and Characterization of Eccentric Orbiting Planets via Tides on their Host Star

TL;DR

This paper develops an analytic model of star tides caused by eccentric orbiting bodies, showing these tides are detectable and useful for identifying and characterizing exoplanets and brown dwarfs.

Contribution

It provides a new analytic framework highlighting the significance of eccentricity in stellar tides for exoplanet detection and characterization.

Findings

Eccentric orbits produce richer tidal signals than circular ones.

Tidal variations are larger and more detectable than other phase variability sources.

Tidal signatures can be observed in photometric and spectroscopic data.

Abstract

We present an analytic description of tides raised on a star by a small orbiting body. In particular, we highlight the disproportionate effect of eccentricity and thus the scope for using these tides to detect and characterise the orbits of exoplanets and brown dwarfs. The tidal distortions of the star produced by an eccentric orbit are, in comparison to a circular orbit, much richer in detail, and potentially visible from any viewing angle. The magnitude of these variations is much larger than that in a circular orbit of the same semi-major axis. These variations are visible in both photometric and spectroscopic data, and dominate other regular sources of phase variability (e.g reflection and Doppler beaming) over a particularly interesting portion of parameter space. These tidal signatures will be a useful tool for planet detection on their own, and used in concert with other methods provide powerful constraints on planetary and stellar properties.