# Secular evolution of eccentricity in protoplanetary discs with gap-opening planets

## TL;DR

This paper investigates how a planet's gravitational influence can induce and evolve eccentricity in a protoplanetary disc, combining hydrodynamical simulations with linear theory to understand the growth and saturation of eccentricity.

## Contribution

It provides a detailed analysis of eccentricity growth mechanisms in gap-opening planet-disc systems, validating linear theory predictions with simulations for the first time.

## Key findings

- Eccentricity growth occurs when planet-to-star mass ratio exceeds 0.003.
- Simulation results align with linear theory predictions for precession and growth rates.
- Eccentricity growth saturates into a non-linear regime after reaching a certain amplitude.

## Abstract

We explore the evolution of the eccentricity of an accretion disc perturbed by an embedded planet whose mass is sufficient to open a large gap in the disc. Various methods for representing the orbit-averaged motion of an eccentric disc are discussed. We characterize the linear instability which leads to the growth of eccentricity by means of hydrodynamical simulations. We numerically recover the known result that eccentricity growth in the disc is possible when the planet-to-star mass ratio exceeds 0.003. For mass ratios larger than this threshold, the precession rates and growth rates derived from simulations, as well as the shape of the eccentric mode, compare well with the predictions of a linear theory of eccentric discs. We study mechanisms by which the eccentricity growth eventually saturates into a non-linear regime.