Schedule Jan 17, 2009
Accounting for Stochastic Fluctuations in the Analysis of Cluster Properties
Morgan Fouesneau (Obs. de Strasbourg)

The integrated spectrophotometric properties of all but the most massive star clusters are distributed in non trivial ways around the average properties predicted by standard population synthesis models. This is due to the stochastic mass distribution of the finite (small) number of luminous stars in each cluster, stars which may be either particularly blue or particularly red. The distribution is most extended and usually far from Gaussian for the colors of young and intermediate age star clusters.

We are developing a Bayesian approach to the study of ages and luminous masses of star clusters that cannot be resolved into stars. Based on Monte-Carlo simulations, we explore the distributions of acceptable properties of star clusters with a given photometry.

We will present first a short review of the main stochastic effects, then results based on the analysis of synthetic star clusters, as well as an application to star clusters in a star forming galaxy. Finally we will discuss the perspectives offered by this approach.

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