Transient chaos and fractal structures in planetary feeding zones

TL;DR

This paper explores the complex, fractal nature of planetary feeding zones in the three-body problem, revealing how initial conditions influence accretion and escape processes with implications for planetary growth.

Contribution

It introduces a dynamical systems approach to analyze fractal basin structures and provides new insights into planetary accretion rates and maximum mass limits.

Findings

Fractal structures characterize accretion and escape regions.

Planetary accretion rate transitions from exponential to power-law.

Derived a new expression for the maximum planetary mass.

Abstract

The circular restricted three body problem is investigated in the context of accretion and scattering processes. In our model a large number of identical non-interacting mass-less planetesimals are considered in planar case orbiting a star-planet system. This description allows us to investigate in dynamical systems approach the gravitational scattering and possible captures of the particles by the forming planetary embryo. Although the problem serves a large variety of complex motion, the results can be easily interpreted because of the low dimensionality of the phase space. We show that initial conditions define isolated regions of the disk, where accretion or escape of the planetesimals occur, these have, in fact, a fractal structure. The fractal geometry of these "basins" implies that the dynamics is very complex. Based on the calculated escape rates and escape times, it is also demonstrated that the planetary accretion rate is exponential for short times and follows a power-law for longer integration. A new numerical calculation of the maximum mass that a planet can reach (described by the expression of the isolation mass) is also derived.