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

Ning Chen Sun, Richard De Grijs, Maria Rosa L. Cioni, Stefano Rubele, Smitha Subramanian, Jacco Th Van Loon, Kenji Bekki, Cameron P.M. Bell, Valentin D. Ivanov, Marcella Marconi, Tatiana Muraveva, Joana M. Oliveira, Vincenzo Ripepi

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17 Citations (Scopus)

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 YJK s 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 log-normal 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, supporting a scenario of hierarchical star formation regulated by supersonic turbulence.

Original languageEnglish
Article number31
JournalThe Astrophysical Journal
Volume858
Issue number1
DOIs
Publication statusPublished - 1 May 2018

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