Evolución espectral integrada de cúmulos abiertos de nuestra Galaxia

PIATTI, A. E.; BICA, E.; CLARIÁ, J. J.; SANTOS, J. F. C., JR.; AHUMADA, A. V.

Congreso; 45o Reunion de la Asoc. Arg. de Astronomia; 2002

We study the integrated spectral evolution in the range 3600 Å < λ < 7400 Å of 47 Galactic open clusters, including both very young ones associated to gas emission and ages as old as a few Gyrs. The great majority of the spectra used in the present work were obtained at CASLEO (San Juan, Argentina) over a period of several years. In all, we succeeded in building twenty new templates, characterized by a high S/N ratio. These templates represent cluster evolutionary stages with ages in the following ranges: 2-4, 5-10, 20-40, 45-75, 100-150, 200-350, 500, 1000 and 3000 Myr. Additionally, we present the flux-calibrated integrated spectrum of the loose open cluster Ruprecht 83, also known as BH 80. Using the equivalent widths of the Balmer lines and comparing the cluster spectrum for Ruprecht 83 with cluster spectra of well known parameters, we derive E(B-V) = 0.40 ± 0.15 and an age of 55 ± 20 Myr. Using this new template library, we revise the fundamental parameters of the small angular size open clusters NGC 2635, Hogg 12 and BH 217. In particular, the latter is a clear example of the need to rely on a complete sample of template spectra of open clusters in order to enhance the estimated cluster fundamental parameters. The present template sequence represents the integrated spectral evolution of a solar metallicity stellar population. Thus it will be applicable to studies of stellar population synthesis as well as in the interpretation of composite stellar populations in galaxies with large star-formation regions.