# Hierarchical Star Formation in Turbulent Media: Evidence from Young Star Clusters

## TL;DR

This study analyzes young star clusters across eight galaxies, revealing hierarchical spatial and temporal patterns in star formation driven by turbulence and influenced by galactic shear.

## Contribution

It provides empirical evidence linking star formation hierarchy to turbulence and galactic environment, with quantitative relations between age differences and separations.

## Key findings

- Age difference increases with separation to the 0.25-0.6 power.
- Maximum correlated star formation size ranges from ~200 pc to ~1 kpc.
- Cluster formation is hierarchical in space and time.

## Abstract

We present an analysis of the positions and ages of young star clusters in eight local galaxies to investigate the connection between the age difference and separation of cluster pairs. We find that star clusters do not form uniformly but instead are distributed such that the age difference increases with the cluster pair separation to the 0.25-0.6 power, and that the maximum size over which star formation is physically correlated ranges from ~200 pc to ~1 kpc. The observed trends between age difference and separation suggest that cluster formation is hierarchical both in space and time: clusters that are close to each other are more similar in age than clusters born further apart. The temporal correlations between stellar aggregates have slopes that are consistent with turbulence acting as the primary driver of star formation. The velocity associated with the maximum size is proportional to the galaxy's shear, suggesting that the galactic environment influences the maximum size of the star-forming structures.