INVESTIGADORES
PIATTI Andres Eduardo
artículos
Título:
Ages and metallicities of eight star clusters and their surrounding fields in the inner disc of the Large Magellanic Cloud
Autor/es:
GEISLER, DOUG; PIATTI, ANDRÉS E.; BICA, EDUARDO; CLARIA OLMEDO, JUAN JOSÉ
Revista:
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
Referencias:
Año: 2003 vol. 341 p. 771 - 784
ISSN:
0035-8711
Resumen:
We present Washington system colour-magnitude diagrams for 8 star
clusters and their surrounding fields which, with one exception, lie
within the inner parts of the Large Magellanic Cloud (LMC) disc. Careful
attention is paid to separating out the cluster and field star
distributions. Ages and metallicities are then determined in a
consistent manner for both populations in two different ways. We first
compare the colour-magnitude diagrams (CMDs) with new theoretical
isochrones in the Washington system. We also derive ages using the
magnitude difference between the red clump and the turnoff, and derive
metallicities by comparing the giant branches to standard calibrating
clusters. For this latter metallicity derivation, we present
age-dependent metallicity corrections for intermediate age clusters
(IACs) based on the new isochrones. The two methods for both age and
metallicity determination are in good agreement with each other. All
clusters are found to be IACs (1-3 Gyr), with [Fe/H] from -0.4 to -0.9.
We find that the stellar population of each star cluster is generally
quite similar to that of the field where it is embedded, sharing its
mean age and metallicity. Combining the present sample with a revision
of that of Bica et al. studied similarly, we find that our metallicities
for IACs are intermediate in metallicity to those for clusters of
similar age studied by Olszewski et al. and by Beasley, Hoyle &
Sharples. A combined age-metallicity relation is presented which shows
that LMC clusters formed between 1-3 Gyr ago with a mean metallicity
(-0.5 dex) and metallicity spread (0.23 dex) independent of age. Good
agreement is found with the bursting model of Pagel & Tautvaisiene.
No evidence for a metallicity gradient is found.