"Toward a Comprehensive Picture of the Galactic Open Star Clusters' Age Distribution"

A.E. PIATTI

Horizons in World Physics

Noba Publishers

Año: 2014; p. 203 - 216

<!-- @page { size: 21cm 29.7cm; margin: 2cm } P { margin-bottom: 0.21cm } --> In this work we revisited some particular issues related to the Galactic open star clusters´ age distribution. As is well know photometric and spectroscopic techniques have long been used to estimate their ages. From the photometric side, color-magnitude diagrams firstly require to be cleaned from field star contamination by means of statistical methods that make use of variable cells; that do not need to know whether a star is placed close to the cluster center to infer its membership; and that take into account the star field density. The cleaned open cluster color-magnitude diagrams can then be matched to those previously calibrated in terms of age, with empirical isochrones traced using the most populated regions along the open star cluster sequences. On the spectro <!-- @page { size: 21cm 29.7cm; margin: 2cm } P { margin-bottom: 0.21cm } -->star clusters by matching their integrated spectra to template spectra. The latter must satisfy the requirement of having, within the respective age group, comparable continuum energy distributions and spectral absorption features. Some age ranges could also show the existence of relatively short periods in the open star cluster spectral evolution, in which the integrated light becomes dominated by brighter stars with particular spectral signatures. Finally, once the photometric/spectroscopic age estimates are put into a homogeneous scale, it is necessary to perform a sound analysis of them in order to build the intrinsic age distribution of the open star cluster sample considered. For that purpose, the uncertainties in the age estimates should be taken into account to define the age intervals along the whole open star cluster age range, as well as to bear in mind that any individual point in the age distribution diagram may fall in the respective age bin or in any of the adjacent bins, due to its errors.scopic side, the integrated spectroscopy allows us to estimate ages of compact open