Universiteit Leiden

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The assembly history of the milky way nuclear star cluster

Promotor: P. T. de Zeeuw, Co-promotor: N. Neumayer; G. van de Ven

A. Krause-Feldmeier
13 september 2016
Thesis in Leiden Repository

We study the assembly history of the nuclear star cluster in the Milky Way. Dense nuclear star clusters form distinct components in ~75% of nearby galaxies. Because the Milky Way nuclear star cluster is at a distance of only 8 kpc, we can spatially resolve its stellar populations and kinematics much better than possible in external galaxies. We study the large-scale stellar kinematics using long-slit spectroscopic data in the near-infrared. We extract stellar kinematic maps from the integrated light, and detect the complex kinematic structure of the star cluster. We set up dynamical models to derive the cluster’s mass. Further, we study stellar populations using integral-field spectroscopic data. From these data we extract more than 1,000 spectra from individual stars. We study the spatial distribution of young and old stars, and the metallicity distribution of cool stars. We found indications for two different formation mechanisms of the Milky Way nuclear star cluster. On the one hand, gas was accreted to the Galaxy’s centre and stars formed in-situ. On the other hand, stars formed in star clusters outside the centre. These star clusters fell into the Galaxy’s nucleus and contributed to the assembly of the Milky Way nuclear star cluster.