The Dynamics of Star Clusters

Astronomy Unit Seminars
Nick Wright
Izaskun Jimenez-Serra
November 24th, 2017 at 14:30
GO Jones Room 610

The formation and evolution of young star clusters is fundamental to our understanding of the star formation process, the conditions faced by young binary and planetary systems, and the formation of long-lived open and globular clusters. Despite this our understanding of the physical processes that drive this evolution has been limited by the static nature of most observations. This is all changing thanks to a revolution in kinematic data quality from large-scale radial velocity surveys and new astrometric facilities such as Gaia. These observations have the potential to reveal the dynamical state of these systems and constrain their past evolution. I will present recent kinematic observations of OB association that show they have considerable kinematic substructure and no evidence for the radial expansion pattern predicted by theories such as residual gas expulsion. This means that, contrary to the standard view of OB associations as expanded star clusters, these systems could never have been dense star clusters in the past and were most likely born as extended and highly substructured groups of stars. This places strong constraints on the frequency of clustered vs non-clustered star formation and the conditions faced by young planetary systems.