Theoretical models of planetary system formation. II. Post-formation evolution

TL;DR

This paper models the long-term evolution of planetary systems post-formation, revealing minor changes in mass and semi-major axes, and highlighting the need for additional phenomena to explain observed eccentricities.

Contribution

It extends planetary formation models by simulating 100 million-year evolution, analyzing eccentricity changes, and comparing results with observed exoplanet data.

Findings

Mass and semi-major axis distributions change minimally over time.

Planetary eccentricities can increase or decrease depending on initial conditions.

Additional phenomena like stellar fly-bys are needed to explain observed eccentricities.

Abstract

We extend the results of planetary formation synthesis by computing the long-term evolution of synthetic systems from the clearing of the gas disk into the dynamical evolution phase. We use the symplectic integrator SyMBA to numerically integrate the orbits of planets for 100 Ma, using populations from previous studies as initial conditions.We show that within the populations studied, mass and semi-major axis distributions experience only minor changes from post-formation evolution. We also show that, depending upon their initial distribution, planetary eccentricities can statistically increase or decrease as a result of gravitational interactions. We find that planetary masses and orbital spacings provided by planet formation models do not result in eccentricity distributions comparable to observed exoplanet eccentricities, requiring other phenomena such as e.g. stellar fly-bys to account for observed eccentricities.