The evolution of O/B associations - A quasi-Markovian approach

In this paper the spatio-temporal evolution of initially compact groups of O/B associations is studied. A probabilistic theory is developed using the concept of Markov chains. The local influence of shocks and the global influence of star density is taken into account in this theory. It appears that even in this simplified treatment the possibilities in the spatio-temporal evolution of associations are varied: O/B formation may stay strictly localized, but spatial spreading may occur as well; oscillations in time in O/B star numbers may occur in a periodic fashion. The relation between these phenomena and the parameters of the model is established.