On the observed clustering of major bodies in solar and extrasolar subsystems

TL;DR

This paper rigorously demonstrates that the secular evolution of (exo)planets and satellites naturally leads to their observed intermediate clustering in subsystems, challenging previous theories based on disk spreading.

Contribution

It provides a rigorous proof that secular evolution causes intermediate accumulation of massive bodies, offering a new perspective on planetary and satellite system formation.

Findings

Massive bodies cluster at intermediate mean-motion values.

Orbital evolution halts near mean-motion resonances due to angular-momentum transfer.

Results challenge existing theories based on disk spreading and accretion models.

Abstract

Major (exo)planetary and satellite bodies seem to concentrate at intermediate areas of the radial distributions of all the objects present in each (sub)system. We prove rigorously that the secular evolution of (exo)planets and satellites necessarily results in the observed intermediate accumulation of the massive objects in all such subsystems. We quantify a "middle" as the mean of mean motions (orbital angular velocities) of three or more massive objects involved. Orbital evolution is expected to be halted or severely diminished when the survivors settle near mean-motion resonances and substantial angular-momentum transfer between bodies ceases to occur (gravitational Landau damping). The dynamics is opposite in direction to what has been theorized for viscous and magnetized accretion disks in which gas spreads out and away from either side of any conceivable intermediate area. The results are bound to change the way we think about planet and moon formation and evolution.