Oort Cloud Ecology - IV. Exchanging Asteroids

TL;DR

This study uses numerical simulations to examine how different star cluster environments influence asteroid dynamics, capturing, and the formation of distant objects like the Oort Cloud.

Contribution

It compares the effects of sub-virial fractal and virialised Plummer cluster models on asteroid and planetary system evolution over 30 million years.

Findings

Sub-virial fractal clusters show more dynamic activity and higher capture rates.

Regions occupied by trans-Neptunian objects are more often populated by captured asteroids in fractal clusters.

Neither cluster model effectively forms an Oort Cloud.

Abstract

Aims. Investigate the influence of cluster environments on asteroids, with special attention towards captured material. Methods. Using numerical methods, a sub-virial fractally distributed star-forming region and a virialised Plummer distributed star-forming region are simulated. Both models are initialised with a virial radius of 0.5pc and 150 stars. Stellar populations and their corresponding planetary systems are identical between cluster models. Stars initially host 500 asteroids and those with mass M_* <= 2.0 MSun are also orbited by 1 - 8 planets. Clusters are integrated until 30 Myr. Results. The sub-virial fractal cluster exhibits richer dynamics, with asteroids and planets more frequently acquiring high eccentricities and inclinations, along with a larger fraction of captured and rogue objects. Additionally, this cluster configuration has its extreme trans-Neptunian object and Sednoid analogues occupy regions of phase-space in semi-major axis, eccentricity and inclination commonly frequented by captured asteroids. Although the virialised Plummer model can produce such objects, by being less dynamically active, the vast majority of asteroids occupying these regions are native rather than captured. Lastly, neither model efficiently form an Oort Cloud, indicating that Oort Cloud assembly is strongly suppressed in both dynamically hot and more quiescent cluster