The VMC survey - XVI. Spatial variation of the cluster-formation activity in the innermost regions of the Large Magellanic Cloud

A.E. PIATTI; ET AL. (8 AUTORES)

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2015 vol. 454 p. 839 - 848

0035-8711

We present results based on Y JKs photometry of star clusters in the Large Magel-lanic Cloud (LMC), distributed throughout the central part of the galaxy?s bar andthe 30 Doradus region. We analysed the field-star decontaminated colour?magnitudediagrams of 313 clusters to estimate their reddening values and ages. The clusters areaffected by a mean reddening of E(B − V ) ∈ [0.2, 0.3] mag, where the average internalLMC reddening amounts to ∼ 0.1?0.2 mag. The region covering 30 Doradus includesclusters with reddening values in excess of E(B − V ) = 0.4 mag. Our cluster samplespans the age range 7.0 log(t yr−1 ) < 9.0, represents an increase of 30 per cent interms of the number of clusters with robust age estimates and comprises a statisticallycomplete sample in the LMC regions of interest here. The resulting cluster frequen-cies suggest that the outermost regions of the LMC bar first experienced enhancedcluster formation ? log(t yr−1 ) ∈ [8.5, 9.0] ? before the activity proceeded, although ina patchy manner, to the innermost regions, for log(t yr−1 ) < 7.7. Cluster frequenciesin the 30 Doradus region show that the area is dominated by very recent cluster for-mation. The derived star-formation frequencies suggest that the cluster and field-starpopulations do not seem to have fully evolved as fully coupled systems during the last∼ 100 Myr.