Things that go bump in the night : the dynamics & hydrodynamics of stellar clusters

I examine some of the dynamical interactions which occur in stellar clusters. I examine how a population of brown dwarfs will evolve within a cluster, in an attempt to explain the discrepancy between observational results and theoretical models regarding the number of brown dwarfs in a stellar cluster. I find that it is unlikely that the entire brown dwarf population could be expelled from the cluster in less than many dynamical relaxation times. Instead I propose that it is likely that the majority of the brown dwarfs are instead in binary systems with brighter companions which hide them from view. I have also modeled the formation of blue stragglers through the collision of two main-sequence stars. I propose that the angular momentum problem that other authors have found with blue stragglers formed via off-axis collisions can be resolved by considering the angular momentum loss associated with a stellar wind or locking to a disc. I show that both can quickly reduce the angular momentum of the merged object to the point where it can contract down to the main-sequence. I have examined the possibility of explaining the apparent paucity of red giants in the cores of post-core-collapse globular clusters through collisions with binary systems and with single stars. I show that such collisions often result in a bound system, where the red giant envelope acts as a common envelope and is eventually dispersed. I also show that such collisions can remove up to 17% of the red giant population.