SCYON Abstract

Received on September 15 2008

Evolution of stellar structure in the Small Magellanic Cloud

Authors	M. Gieles (¹), N. Bastian (^2,3), and B. Ercolano (^2,4)
Affiliation	(¹) ESO/Santiago (²) IoA Cambridge (³) UCL (⁴) CfA
Accepted by	Monthly Notices of the Royal Astronomical Society
Contact	mgieles@eso.org
URL	http://arxiv.org/abs/0809.2295
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Abstract

The projected distribution of stars in the Small Magellanic Cloud (SMC) from the Magellanic Clouds Photometric Survey is analysed. Stars of different ages are selected via criteria based on V magnitude and V-I colour, and the degree of `grouping' as a function of age is studied. We quantify the degree of structure using the two-point correlation function and a method based on the Minimum Spanning Tree and find that the overall structure of the SMC is evolving from a high degree of sub-structure at young ages (~10 Myr) to a smooth radial density profile. This transition is gradual and at ~75 Myr the distribution is statistically indistinguishable from the background SMC distribution. This time-scale corresponds to approximately the dynamical crossing time of stars in the SMC. The spatial positions of the star clusters in the SMC show a similar evolution of spatial distribution with age. Our analysis suggests that stars form with a high degree of (fractal) sub-structure, probably imprinted by the turbulent nature of the gas from which they form, which is erased by random motions in the galactic potential on a time-scale of a galactic crossing time.