Constructing the secular architecture of the solar system

I. The giant planets

¹ Dep. Cassiopee, University of Nice - Sophia Antipolis, CNRS, Observatoire de la Côte d'Azur, 06304 Nice, France e-mail: brasser_astro@yahoo.com
² Department of Physics, Aristotle University of Thessaloniki, Thessaloniki, Greece
³ Observatório Nacional, Rio de Janeiro, RJ, Brazil
⁴ Southwest Research Institute, Boulder, CO, USA

Received: 13 July 2009
Accepted: 31 August 2009

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 low. 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, and 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 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.