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... Show moreWe 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. Show less
This thesis presents the results from the analysis and characterisation of the water and mid-J (J<11) 12CO, 13CO and C18O observations for a large sample of low-, intermediate-, and high-mass... Show moreThis thesis presents the results from the analysis and characterisation of the water and mid-J (J<11) 12CO, 13CO and C18O observations for a large sample of low-, intermediate-, and high-mass young stellar objects (YSOs). The studied molecular transitions have been observed with the HIFI instrument on board of Herschel Space Observatory and within the context of the Herschel key programme __WISH__. These species and transitions constitute unambiguous tracers of specific physical conditions within the inner and warmer regions of the YSO environment. The sample of sources, composed by more than 120 YSOs, covers a large range of bolometric luminosities, several evolutionary stages within the embedded phase, and different physical scales. The aim of this work is to explore the differences and similarities between low- and high-mass star-forming regions. In particular, this study focuses on investigating the physical and dynamical structure of dense warm gas within protostellar environments by characterising the velocity-resolved H2O and CO spectra in terms of line profile and line luminosity. The ultimate goal is to contribute to the understanding of the star formation process without imposing luminosity boundaries, and to put in context these processes on Galactic and extragalactic scales. Show less
