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arXiv · 1804.01652

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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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.

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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. 2018-04-05. The VMC Survey. XXIX. Turbulence-Controlled Hierarchical Star Formation in the Small Magellanic Cloud. https://doi.org/10.3847/1538-4357%2Faabc50

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