SFR history and bayesian ages of MW stars

Abstract

The increasing number of open cluster member stars with accurate estimates of their atmospheric parameters makes it now possible to derive individual stellar ages by applying a Bayesian approach as in Pont & Eyer (2004) and Jørgensen & Lindegren (2005). As described in the literature this approach removes uses "prior probabilities" to avoid the severe biases that may happen because some places on isochrones are more densely populated than others owing to the initial mass function, IMF, the time scales involved in stellar evolution, and Star Formation Rate,SFR, history. In fact, just looking for the closest match between stellar parameters and isochrone predictions, i.e. by simply ignoring the above-mentioned facts, might lead to quite unreliable stellar age estimates. In this talk we will present the results of applying a Bayesian technique to open cluster stars by adopting as "priors" different SFR histories in order to derive individual stellar ages to be compared with the published ages of the corresponding clusters as derived by Main Sequence Turn Off, MSTO, technique. The aim is to derive empirical constraints on the SFR history of open clusters by imposing the consistency of the individual stellar ages with the one of the corresponding cluster.