The VISCACHA survey - structure of outer MC star clusters

Abstract

The Magellanic Clouds (MCs) constitute an interacting pair of galaxies influenced by the Milky Way gravitational field. Several studies have shown the effects of the changing tidal field on the structure of both Clouds. How the varying tidal field affects their stellar populations may be gauged via star clusters, where this connection may be more confidently stablished due to the accurate determination of the clusters astrophysical properties. Our objective is to perform an analysis of the structural parameters of 56 Large Magellanic Cloud (LMC) and 34 Small Magellanic Cloud (SMC) clusters located in the galaxies outskirts searching for signatures of tidal- dynamical effects eventually altering their evolution. To achieve our goal, AO assisted observations in BVI bands with the 4.1m SOAR telescope have been carried out, in the scope of the VISCACHA (VIsible Soar photometry of star Clusters in tApii and Coxi HuguA) survey, in which an homogeneous, deep and high quality photometry is being produced. The structural parameters central stellar density, central surface brightness, core and tidal radius were obtained from King model fittings to the surface brightness and radial density profiles. By grouping clusters according to different regions we found that (i) the westernmost LMC clusters, the nearest ones to the SMC, have a larger dispersion of their core radius than those of the clusters located elsewhere; (ii) older clusters present a spread of core radius, similar to results from studies of inner MCs populous clusters.