INVESTIGADORES
PIATTI Andres Eduardo
artículos
Título:
Formation and Evolution of the Large Magellanic Cloud: The Old Star Cluster Candidates
Autor/es:
PIATTI, ANDRÉS E.; GEISLER, DOUG; BICA, EDUARDO; DOTTORI, HORACIO; CLARIA OLMEDO, JUAN JOSÉ; SANTOS JR, JOÂO F.C.
Revista:
Proc. Workshop "Science with GEMINI: a South American Perspective"
Editorial:
B. Barbuy, E. Lapasset, R. Baptista, R. Cid Fernandez
Referencias:
Año: 1998 p. 230 - 232
Resumen:
We report the first results of a color-magnitude diagram survey of 25
candidate old LMC clusters. For almost all of the sample, it was possible to
reach the turnoff region, and in many clusters we have several magnitudes of
the main sequence. Age estimates based on the magnitude difference $\delta T_1$
between the giant branch clump and the turnoff revealed that no new old
clusters were found. The candidates turned out to be of intermediate age (1-3
Gyr) We show that the apparently old ages as inferred from integrated UBV
colors can be explained by a combination of stochastic effects produced by
bright stars and by photometric errors for faint clusters lying in crowded
fields. The relatively metal poor candidates from the CaII triplet spectroscopy
also turned out to be of intermediate age. This, combined with the fact that
they lie far out in the disk, yields interesting constraints regarding the
formation and evolution of the LMC disk. We also study the age distribution of
intermediate age and old clusters This homogeneous set of accurate relative
ages allows us to make an improved study of the history of cluster
formation/destruction for ages $>1$Gyr. We confirm previous indications that
there was apparently no cluster formation in the LMC during the period from 3-8
Gyr ago, and that there was a pronounced epoch of cluster formation beginning 3
Gyrs ago that peaked at about 1.5 Gyrs ago. Our results suggest that there are
few, if any, genuine old clusters in the LMC left to be found.