On the potentially dramatic history of the super-Earth rho 55 Cancri e

TL;DR

This paper explores how tidal evolution and secular resonances could have significantly altered the orbit and structure of the super-Earth rho 55 Cancri e, with implications for other multi-planet systems.

Contribution

It demonstrates the potential for secular resonances to cause large orbital and structural changes in inner super-Earths due to tidal evolution.

Findings

Secular resonances can excite eccentricity and inclination of planet e.

Tidal heating may have modified planet e's structure and reduced its mass.

Inner secular resonances could be common in multi-planet systems.

Abstract

We demonstrate that tidal evolution of the inner planet (`e') of the system orbiting the star rho 55 Cancri could have led to passage through two secular resonances with other planets in the system. The consequence of this evolution is excitation of both the planetary eccentricity and inclination relative to the original orbital plane. The large mass ratio between the innermost planet and the others means that these excitations can be of substantial amplitude and can have dramatic consequences for the system organisation. Such evolution can potentially explain the large observed mutual inclination between the innermost and outermost planets in the system, and implies that tidal heating could have substantially modified the structure of planet e, and possibly reduced its mass by Roche lobe overflow. Similar inner secular resonances may be found in many multiple planet systems and suggest that many of the innermost planets in these systems could have suffered similar evolutions.