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

Piatti, Andrés E.; Ivanov, Valentin D.; Rubele, Stefano; Marconi, Marcella; Ripepi, Vincenzo; Cioni, Maria-Rosa L.; Oliveira, Joana M.; Bekki, Kenji

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


Authors

Andrés E. Piatti

Valentin D. Ivanov

Stefano Rubele

Marcella Marconi

Vincenzo Ripepi

Maria-Rosa L. Cioni

Kenji Bekki



Abstract

We report the first search for new star clusters performed using the VISTA near-infrared YJKs Magellanic Clouds survey (VMC) data sets. We chose a pilot field of ~0.4 deg2 located in the South-west of the Small Magelllanic Cloud 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 dimensions and stellar densities observed in the VMC data sets of the known clusters in this area. We executed different kernel density estimations over a sample of more than 358 000 stars with magnitudes measured in the three YJKs filters. We analysed the new cluster candidates whose colour–magnitude diagrams (CMDs), cleaned from field star contamination, were used to assess the clusters’ reality and estimate reddenings and ages of the genuine systems. As a result 38 objects (˜ a 55?per?cent increase in the known 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 star clusters of young to moderate intermediate age (log(t yr-1) ~7.5–9.0). Most of the new star cluster candidates are hardly recognizable in optical images without the help of a sound star field decontaminated CMD analysis. For highly reddened star cluster candidates (E(B - V) = 0.6 mag) the VMC data sets were necessary in order to recognize them.

Journal Article Type Article
Acceptance Date Apr 25, 2016
Online Publication Date Apr 28, 2016
Publication Date Jul 21, 2016
Publicly Available Date Mar 28, 2024
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Publisher Oxford University Press
Peer Reviewed Peer Reviewed
Volume 460
Issue 1
Pages 383 - 395
DOI https://doi.org/10.1093/mnras/stw1000
Keywords Techniques: photometric; galaxies: individual: SMC; Magellanic Clouds
Publisher URL http://mnras.oxfordjournals.org/content/460/1/383

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