The distribution of star-forming regions in M33

TL;DR

This study uses fractal analysis to examine the clustering of stars, gas, and clouds in M33, revealing a transition from turbulent to galactic scale behaviors and indicating a highly fragmented interstellar medium.

Contribution

It provides a systematic fractal analysis of various components in M33 across multiple scales, highlighting the transition point and the complexity of the interstellar medium.

Findings

Transition from scale-free to uniform distribution at 500-1000 pc

Fractal dimension of young stars and gas is ≤ 1.9

Interstellar medium in M33 is more fragmented than in the Milky Way

Abstract

We use fractal analysis to systematically study the clustering strength of the distribution of stars, HII regions, molecular gas, and individual giant molecular clouds in M33 over a wide range of spatial scales. We find a clear transition from a scale-free behavior at small spatial scales to a nearly uniform distribution at large scales. The transition region lies in the range 500-1000 pc and it separates the regime of small-scale turbulent motion from that of large-scale galactic dynamics. The three-dimensional fractal dimension of bright young stars and molecular gas at small spatial scales is similar to or less than 1.9 indicating that the interstellar medium in M33 is on average much more fragmented and irregular than the in the Milky Way.