Abstract details

By using synthetic integrated spectral energy distribution (ISED) of open clusters and a new evolutionary scenario involving interactive binaries, new models of simple stellar populations (SSPs) are presented. For young and intermediate age stellar populations (10^8 y to several Gyrs) represented by Galactic open clusters, a certain number of blue straggler with very good measurements of member-ship are commonly present and following a statistics as studies in our previous work. These stars are usually around 2 magnitudes brighter and much bluer than the MS turn-off of the cluster, and they certainly belong to the same population as the host cluster. Considering the cluster as the nearest counterpart the concept of SSP, inclusion of such stars may have significant consequences on the integrated of properties of the population. We are showing in the present work that if one is to fit the real stellar population using the classical model based only on single star evolution theory, large errors in either age or metallicity (or both) can be made. The new theoretical SSP incorporated with interactive binaries can explain part of the difference between classical SSP model and synthetic ISED built up with open clusters. This suggests that the formation of blue stragglers in real clusters is more complicated as usually assumed in binary stellar population synthesis.