The VMC Survey - XXI. New star cluster candidates discovered from infrared photometry in the Small Magellanic Cloud

A.E. PIATTI + 1 COAUTOR

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2016 vol. 460 p. 383 - 395

0035-8711

We report the first search for new star clusters performed using the VISTA near-infrared Y JK s Magellanic Clouds survey (VMC) data sets. We chose a pilot field of∼ 0.4 deg 2 located in the South-West of the Small Magelllanic Cloud (SMC) bar,where the star field is among the densest and highest reddened region in the galaxy.In order to devise an appropriate automatic procedure we made use of dimensionsand stellar densities observed in the VMC data sets of the known clusters in thisarea. We executed different kernel density estimations over a sample of more than358000 stars with magnitudes measured in the three Y JK s filters. We analysed thenew cluster candidates whose colour-magnitude diagrams (CMDs), cleaned from fieldstar contamination, were used to assess the clusters? reality and estimate reddeningsand ages of the genuine systems. As a result 38 objects (≈ a 55% increase in theknown star clusters located in the surveyed field) of 0.15 - 0.40 arcmin (2.6 - 7.0 pc)in radius resulted to have near-infrared CMD features which resemble those of starclusters of young to moderate intermediate age (log(t yr −1 ) ∼ 7.5-9.0). Most of thenew star cluster candidates are hardly recognizable in optical images without the helpof a sound star field decontaminated CMD analysis. For highly reddened star clustercandidates (E(B − V ) ≥ 0.6 mag) the VMC data sets were necessary in order torecognize them.