The VMC Survey. XXIX. Turbulence-Controlled Hierarchical Star Formation in the Small Magellanic Cloud

TL;DR

This study analyzes the hierarchical and turbulent nature of star formation in the Small Magellanic Cloud by examining young stellar structures and their properties, revealing patterns consistent with turbulence-regulated star formation.

Contribution

It provides the first detailed clustering analysis of young stars in the SMC using VMC survey data, highlighting turbulence's role in hierarchical star formation.

Findings

Young stellar structures are hierarchically organized.

Structures exhibit power-law mass-size relations.

Properties mirror turbulent interstellar medium characteristics.

Abstract

In this paper we report a clustering analysis of upper main-sequence stars in the Small Magellanic Cloud, using data from the VMC survey (the VISTA near-infrared YJKs survey of the Magellanic system). Young stellar structures are identified as surface overdensities on a range of significance levels. They are found to be organized in a hierarchical pattern, such that larger structures at lower significance levels contain smaller ones at higher significance levels. They have very irregular morphologies, with a perimeter-area dimension of 1.44 +/- 0.02 for their projected boundaries. They have a power-law mass-size relation, power-law size/mass distributions, and a lognormal surface density distribution. We derive a projected fractal dimension of 1.48 +/- 0.03 from the mass-size relation, or of 1.4 +/- 0.1 from the size distribution, reflecting significant lumpiness of the young stellar structures. These properties are remarkably similar to those of a turbulent interstellar medium (ISM), supporting a scenario of hierarchical star formation regulated by supersonic turbulence.