A sample of relatively unstudied star clusters in the Large Magellanic Cloud: fundamental parameters determined from Washington photometry

PALMA, T.; CLARIA, J.J.; GEISLER, D.; PIATTI, ANDRÉS E.; AHUMADA, A.V.

ASTRONOMY AND ASTROPHYSICS

EDP SCIENCES S A

Lugar: Paris; Año: 2013 vol. 555 p. 131 - 140

0004-6361

Aims. In order to enlarge our growing sample of well-studied Large Magellanic Cloud (LMC) star clusters, we present CCDWashington CT1 photometry down to T1 ∼ 23 in the fields of twenty three mostly unstudied clusters located in the inner disc andouter regions of the LMC.Methods. We estimate cluster radii from star counts. Using the clusterWashington (T1,C-T1) colour-magnitude diagrams, statisticallycleaned from field star contamination, we derive cluster ages and metallicities from a comparison with theoretical isochrones of thePadova group. Whenever possible, we also derive ages using T1 -the magnitude difference between the red giant clump and the mainsequence turnoff- and estimate metallicities from the standard giant branch procedure. We enlarge our sample by adding clusters withpublished ages and metallicities determined on a similar scale applying the same methods. We examine relationships between theirpositions in the LMC, ages and metallicities.Results. We find that the two methods for both age and metallicity determination are in good agreement with each other. Fourteenclusters are found to be intermediate-age clusters (1-2 Gyr), with [Fe/H] values ranging from -0.4 to -0.7. The remaining nine clustersturn out to be younger than 1 Gyr, with metallicities between 0.0 and -0.4.Conclusions. Our 23 clusters represent an increase of ∼ 30% in the current total amount number of well-studied LMC clusters usingWashington photometry. In agreement with previous studies, we find no evidence for a metallicity gradient. We also find that theyounger clusters were formed closer to the LMC centre than the older ones.