Coloquio IRyA 2020.06.11 - Pavel Kroupa
Channel: Coloquio IRyA
Date: 2020-09-14

Speaker info:
Title: Early cluster evolution
Abstract:
Milky Way stars can be modelled as being formed as multiple systems, formed at the same time (monolithically) in spherical embedded clusters. Observational constraints imply these to be very compact with half mass radii rh/pc = 0.1(M/Msun)^0.13 and a wide range of stellar masses M (10 up to many millions of Msun). The derived radii are impressively consistent with the cross sections of molecular cloud filaments. These embedded clusters need to expand within a few Myr to achieve the radii of open and globular clusters and this can only be achieved by the expulsion of a significant amount of residual gas. The stellar-dynamical processes within the embedded clusters shape the multiplicity properties of Galactic-field stars and low-mass dwarf galaxies ought to have a much higher binary fraction than massive elliptical galaxies. Massive stars, formed in the mass segregated embedded clusters, eject each other efficiently from their birth clusters. These stellar-dynamical processes may be important for the emergence of multiple populations in embedded clusters which are not older than a few Myr by modulating infalling molecular gas into the cluster along molecular cloud filaments. They result in a field-population of runaway and slow moving O stars which is largely consistent with the observed isolated O stars. The Orion Nebula Cluster is discussed in particular.