Open cluster formation

Analytical and numerical models which describe the formation of bound clusters from a wide range of initial protocluster conditions are presented. Bound open cluster formation is shown to depend on star formation efficiency, gas removal time, and initial system mass density. Investigation of the rho Ophiuchus molecular cloud core is advocated. A calorimetric technique for determining the luminosity function of cluster members in the cloud is shown to be useful to obtain the luminosity function of an embedded cluster, and may be a way to study the time evolution of a cluster mass function. This method suggests a deficiency of intermediate mass stars in the rho Oph region, which may reveal how protostellar fragments grow into stars and on the mass dependence of the early stages of star formation.