18 February 2020Young bright and old dark star clusters

Sambaran BANERJEE
AIfA Bonn, Allemagne

In this talk, I discuss two of our recent studies. In the first part, I talk about our studies to explain the observed kinematic and structural properties of two well-studied very young, massive star clusters, namely, the central cluster of the Galactic starburst region NGC 3603 and the R136 cluster of the LMC. We show that the classical paradigm of episodic star cluster formation through residual gas expulsion is adequate in explaining the central velocity dispersion of R136 and its inferred present-day state of dynamical equilibrium. Such scenario also provides remarkable agreement between realistically modeled clusters computed using direct N-body integration and the detailed structural and kinematic properties of the NGC 3603 young cluster. In the next part of the talk, I discuss a predicted new class of intermediate-aged star clusters which we refer to as Òdark star clusterÓs. Such clusters form closer towards the Galactic center where they are heavily stripped by tidal forces to unveil their centrally segregated sub-populations of black holes and neutron stars, thereby appear as compact stellar populations with high mass-to-light-ratio. Our model calculations predict that a sizable population of such clusters would exist in the inner region of our Galaxy provided a significant fraction of stellar remnants survive their birth kicks.