Stellar disk destruction by dynamical interactions in the Orion Trapezium star cluster

TL;DR

This study demonstrates that the observed distribution of circumstellar disk sizes in the Orion Trapezium cluster can be accurately explained by dynamical truncation from stellar encounters, revealing insights into the cluster's past dynamical state.

Contribution

The paper introduces a simulation-based approach that reproduces observed disk size distributions solely through dynamical interactions, linking disk properties to cluster formation conditions.

Findings

Observed disk sizes match simulation results from stellar encounters.

Cluster parameters like star count and density reproduce observed distributions.

Dynamical interactions explain disk truncation within 0.2-0.5 Myr.

Abstract

We compare the observed size distribution of circum stellar disks in the Orion Trapezium cluster with the results of $N$-body simulations in which we incorporated an heuristic prescription for the evolution of these disks. In our simulations, the sizes of stellar disks are affected by close encounters with other stars (with disks). We find that the observed distribution of disk sizes in the Orion Trapezium cluster is excellently reproduced by truncation due to dynamical encounters alone. The observed distribution appears to be a sensitive measure of the past dynamical history of the cluster, and therewith on the conditions of the cluster at birth. The best comparison between the observed disk size distribution and the simulated distribution is realized with a cluster of $N = 2500\pm500$ stars with a half-mass radius of about 0.5\,pc in virial equilibrium (with a virial ratio of $Q = 0.5$, or somewhat colder $Q \simeq 0.3$), and with a density structure according to a fractal dimension of $F \simeq 1.6$. Simulations with these parameters reproduce the observed distribution of circum stellar disks in about 0.2--0.5\,Myr.