Disentangling the physical reality of star cluster candidates projected towards the inner disc of the Large Magellanic Cloud

A.E. PIATTI

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2014 vol. 440 p. 3091 - 3099

0035-8711

     We have used Washington photometry for 90 star cluster candidates of smallangular size -typically ∼ 11′′ in radius- distributed within nine selected regions inthe inner disc of the Large Magellanic Cloud (LMC) to disentangle whether theyare genuine physical system, and to estimate the ages for the confirmed clusters. Inorder to avoid a misleading interpretation of the cluster colour-magnitude diagrams(CMDs), we applied a subtraction procedure to statistically clean them from field starcontamination. Out of the 90 candidate clusters studied, 61 of them resulted to begenuine physical systems, whereas the remaining ones were classified as possible non-clusters since either their CMDs and/or the distribution of stars in the respective fieldsdo not resemble those of stellar aggregates. We statistically show that ∼ (13 ± 6)% ofthe catalogued clusters in the inner disc could be possible non-clusters, independentlyof their deprojected distances. We derived the ages for the confirmed clusters from thefit of theoretical isochrones to the cleaned cluster CMDs. The derived ages resultedto be in the age range 7.8 log(t) 9.2. Finally, we built cluster frequencies for thedifferent studied regions and found that there exists some spatial variation of the LMCCF throughout the inner disc. Particularly, the innermost field contains a handful ofclusters older than ∼ 2 Gyr, while the wider spread between different CFs has takenplace during the most recent 50 Myr of the galaxy lifetime.