Constructing the secular architecture of the solar system I: The giant planets

TL;DR

This paper uses numerical simulations to analyze how the orbital architecture of the solar system's giant planets could have formed, highlighting the necessity of planetary encounters to match current orbital properties.

Contribution

It demonstrates that smooth migration alone cannot produce the current orbital configuration, emphasizing the role of planetary encounters in shaping the giant planets' secular architecture.

Findings

Smooth migration results in too small eccentricities and inclinations.

Resonance crossing excites eccentricities but not inclinations.

Planetary encounters are necessary to reproduce observed eigenmodes.

Abstract

Using numerical simulations, we show that smooth migration of the giant planets through a planetesimal disk leads to an orbital architecture that is inconsistent with the current one: the resulting eccentricities and inclinations of their orbits are too small. The crossing of mutual mean motion resonances by the planets would excite their orbital eccentricities but not their orbital inclinations. Moreover, the amplitudes of the eigenmodes characterising the current secular evolution of the eccentricities of Jupiter and Saturn would not be reproduced correctly; only one eigenmode is excited by resonance-crossing. We show that, at the very least, encounters between Saturn and one of the ice giants (Uranus or Neptune) need to have occurred, in order to reproduce the current secular properties of the giant planets, in particular the amplitude of the two strongest eigenmodes in the eccentricities of Jupiter and Saturn.