INVESTIGADORES
PIATTI Andres Eduardo
artículos
Título:
Tracing the formation history of intermediate-age star clusters in the Small Magellanic Cloud
Autor/es:
PIATTI, ANDRÉS E.; SARAJEDINI, A.; GEISLER, DOUG; SEGUEL, J.; CLARK, D.
Revista:
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
Referencias:
Año: 2005 vol. 358 p. 1215 - 1230
ISSN:
0035-8711
Resumen:
Colour-magnitude diagrams (CMDs) are presented for the first time for 10
star clusters projected on to the Small Magellanic Cloud (SMC). The
photometry was carried out in the Washington system C and T1
filters allowing the determination of ages by means of the magnitude
difference between the red giant clump and the main-sequence turnoff
(MSTO), and metallicities from the red giant branch (RGB) locus. The
clusters all have ages in the range 1.5-4 Gyr and metallicities between
-1.3 < [Fe/H] < -0.6, with respective errors of ~0.5 Gyr and 0.3
dex. This increases substantially the sample of intermediate-age
clusters in the SMC with well-derived parameters. We combine our results
with those for other clusters in the literature to derive as large and
homogeneous a data base as possible (totalling 26 clusters) in order to
study global effects. We find evidence for two peaks in the age
distribution of SMC clusters, at ~6.5 and 2.5 Gyr, in good agreement
with previous hints involving smaller samples. The most recent peak
occurs at a time that corresponds to a very close encounter between the
Large Magellanic Cloud (LMC) and the SMC according to the recent
dynamical models of Bekki et al. that they used to explain the
enhancement of LMC clusters with this age. It appears cluster formation
may have been similarly stimulated in the SMC by this encounter as well.
We also find very good agreement between cluster ages and metallicities
and the prediction from a bursting model from Pagel and
Tautvaiienė with a burst that occurred 3 Gyr ago. These two
lines of evidence together favour a bursting cluster formation history
as opposed to a continuous one for the SMC.