# The Hierarchical Distribution of the Young Stellar Clusters in Six Local Star Forming Galaxies

## TL;DR

This study analyzes the hierarchical clustering of young stellar clusters in six nearby star-forming galaxies, revealing how their spatial distribution evolves over time and supports a unified model of star formation.

## Contribution

It provides a detailed analysis of the spatial hierarchy and evolution of stellar clusters using Hubble data, highlighting differences between clusters and associations.

## Key findings

- Clusters become more homogeneously distributed after 40-60 Myr.
- Associations are more strongly correlated and disperse quickly after formation.
- Clustering patterns resemble turbulent interstellar medium structures.

## Abstract

We present a study of the hierarchical clustering of the young stellar clusters in six local (3--15 Mpc) star-forming galaxies using Hubble Space Telescope broad band WFC3/UVIS UV and optical images from the Treasury Program LEGUS (Legacy ExtraGalactic UV Survey). We have identified 3685 likely clusters and associations, each visually classified by their morphology, and we use the angular two-point correlation function to study the clustering of these stellar systems. We find that the spatial distribution of the young clusters and associations are clustered with respect to each other, forming large, unbound hierarchical star-forming complexes that are in general very young. The strength of the clustering decreases with increasing age of the star clusters and stellar associations, becoming more homogeneously distributed after ~40--60 Myr and on scales larger than a few hundred parsecs. In all galaxies, the associations exhibit a global behavior that is distinct and more strongly correlated from compact clusters. Thus, populations of clusters are more evolved than associations in terms of their spatial distribution, traveling significantly from their birth site within a few tens of Myr whereas associations show evidence of disruption occurring very quickly after their formation. The clustering of the stellar systems resembles that of a turbulent interstellar medium that drives the star formation process, correlating the components in unbound star-forming complexes in a hierarchical manner, dispersing shortly after formation, suggestive of a single, continuous mode of star formation across all galaxies.