Reddening and age of 6 poorly studied star clusters of the Large Magellanic Cloud derived from integrated spectra

MINNITI, J. H.; AHUMADA, A. V.; CLARIÁ, J. J.; BENÍTEZ-LLAMBAY, A.

ASTRONOMY AND ASTROPHYSICS

EDP SCIENCES S A

Lugar: Paris; Año: 2014 vol. 565 p. 49 - 57

0004-6361

In oder to increase the number of studied star clusters (SCs) of the Large Magellanic Cloud (LMC), we present flux-calibrated integrated spectra in the optical range (lmbda = 3700-6800 Å) for six poorly studied LMC SCs of IVA type in the sequence defined by Searle et al. (1980). Such type corresponds to the age range between 200 and 400 Myr. We also aim at creating a new template spectrum representative of this age range at the metallicity level of the LMC. Methods. Foreground reddening E(B-V) values and ages are derived applying the template matching method that consists of comparing the line strengths and continuum distribution of the cluster spectra with those of template cluster spectra with known properties. The equivalent width (EW) of the Balmer lines as well as diagnostic diagrams involving the sum of EWs of selected spectral lines were also employed as age indicators. Results. We provide for the first time estimates of the clusters reddenings and ages. As expected, all the clusters appear to be of nearly the same age, their mean value being (400 ± 100) Myr, while the resulting mean E(B-V) values range between 0.00 and 0.10 mag. Conclusions. The present cluster sample complements previous ones, in an effort to gather a spectral library with several clusters per age bin. By averaging the reddening-corrected integrated spectra, weighted by their signal-to-noise (S /N) ratios, a new high S /N ratio template spectrum of 400 Myr has been created.