INVESTIGADORES
AHUMADA Andrea Veronica
artículos
Título:
Integrated spectral analysis of 18 concentrated star clusters in the Small Magellanic Cloud
Autor/es:
PIATTI, A. E.; SANTOS, J. F. C., JR.; CLARIÁ, J. J.; BICA, E.; AHUMADA, A. V.; PARISI, M. C.
Revista:
ASTRONOMY AND ASTROPHYSICS
Editorial:
EDP SCIENCES S A
Referencias:
Lugar: Paris; Año: 2005 vol. 440 p. 111 - 120
ISSN:
0004-6361
Resumen:
We present in this study flux-calibrated integrated spectra in the range
(3600-6800) Å for 18 concentrated SMC clusters. Cluster reddening
values were estimated by interpolation between the extinction maps of
Burstein & Heiles (1982, AJ, 87, 1165) and Schlegel et al. (1998,
ApJ, 500, 525). The cluster parameters were derived from the template
matching procedure by comparing the line strengths and continuum
distribution of the cluster spectra with those of template cluster
spectra with known parameters and from the equivalent width (EW) method.
In this case, new calibrations were used together with diagnostic
diagrams involving the sum of EWs of selected spectral lines. A very
good agreement between ages derived from both methods was found. The
final cluster ages obtained from the weighted average of values taken
from the literature and the present measured ones range from 15 Mr (e.g.
L 51) to 7 Gyr (K 3). Metal abundances have been derived for only 5
clusters from the present sample, while metallicity values directly
averaged from published values for other 4 clusters have been adopted.
Combining the present cluster sample with 19 additional SMC clusters
whose ages and metal abundances were put onto a homogeneous scale, we
analyse the age and metallicity distributions in order to explore the
SMC star formation history and its spatial extent. By considering the
distances of the clusters from the SMC centre instead of their
projections onto the right ascension and declination axes, the present
age-position relation suggests that the SMC inner disk could have been
related to a cluster formation episode which reached the peak ~2.5 Gyr
ago. Evidence for an age gradient in the inner SMC disk is also
presented.