INVESTIGADORES
PIATTI Andres Eduardo
artículos
Título:
Ages and metallicities of star clusters: New calibrations and diagnostic diagrams from visible integrated spectra
Autor/es:
SANTOS JR, JOÂO F.C.; PIATTI, ANDRÉS E.
Revista:
ASTRONOMY AND ASTROPHYSICS
Referencias:
Año: 2004 vol. 428 p. 79 - 88
ISSN:
0004-6361
Resumen:
We present homogeneous scales of ages and metallicities for star
clusters from very young objects, through intermediate-age ones up to
the oldest known clusters. All the selected clusters have integrated
spectra in the visible range, as well as reliable determinations of
their ages and metallicities. From these spectra equivalent widths (EWs)
of K Ca II, G band (CH) and Mg I metallic, and Hδ, Hγ and
Hβ Balmer lines have been measured homogeneously. The analysis of
these EWs shows that the EW sums of the metallic and Balmer H lines,
separately, are good indicators of cluster age for objects younger than
10 Gyr, and that the former is also sensitive to cluster metallicity for
ages greater than 10 Gyr. We propose an iterative procedure for
estimating cluster ages by employing two new diagnostic diagrams and age
calibrations based on the above EW sums. For clusters older than 10 Gyr,
we also provide a calibration to derive their overall metal contents.