The Role of Turbulence in the Process of Star Formation

Abstract

The aim of this thesis is to study the role of interstellar turbulence in the process of star formation. We demonstrate that supersonic turbulent motions significantly affect various properties of the interstellar medium (ISM). Therefore, we run numerical simulations of molecular clouds in different environments. In particular, we study typical clouds located in the Milky Way disk as well as clouds which can be found in more extreme regions in our Galaxy, e.g. in the Central Molecular Zone (CMZ) near the Galactic Center. In addition, we perform radiative transfer calculations of numerous diagnostic fine structure lines and compare our results with observational measurements. Furthermore, we analyze the influence of the turbulence on different observables, e.g. on the structure functions, the ∆-variance, the power spectra as well as the star formation efficiencies. We also study the impact of turbulent motions on the chemistry and the different phases of the ISM. Our studies about Milky Way disk clouds show that the statistical properties of the turbulence are significantly influenced by the individual gas tracers. Moreover, our investigations about CMZ-like clouds show that high levels of turbulence can significantly suppress, but never inhibit star formation, owing to local compression of gas by turbulent shocks. Finally, we show that various atomic tracers accurately reflect most of the physical properties of both the H2 and the total gas of the cloud and that they provide a very useful alternative to common molecular lines when we study the ISM in the CMZ.