Subproject B2: Star Cluster Formation and Evolution – From Molecular Clouds to Tidal Fields

Subproject B2 focused on the formation and evolution of individual molecular clouds rather than on Galactic scales as in B1. In the first funding period, the chemical network was improved to better account for the coupling between matter and the interstellar radiation field. We now have the technical capabilities to describe the formation and evolution of star forming molecular clouds with complementary magnetohydrodynamic simulations codes (FLASH, Gadget, Arepo) coupled to a time-dependent chemical network for the most relevant atomic and molecular species in the ISM (subproject B3, completed) with a realistic link between matter and the ambient radiation field. We can use sink particles to model protostellar collapse and star formation and we have developed modules for the most important feedback processes (supernova explosions, ionizing radiation, winds and protostellar outflows; subproject B4, completed). Moreover, realistic synthetic maps can now be constructed from the simulated clouds based on detailed radiative transfer calculations with the RADMC-3D code. In B2, the first 3-D models of converging flows that self-consistently trace the formation of H2 and CO were calculated. Also, it was shown that CO cooling is not needed to form stars; C+ cooling is sufficient.

In the second funding period, we focus on one of the aspects of the original subproject B2, namely the formation and early evolution of star clusters in molecular clouds. Understanding these processes is a key problem of Milky Way research. We will develop a multi-scale, forward- and backward-approach in order to determine the typical initial conditions of star cluster formation in the Galactic disk and to characterize their subsequent dynamical evolution. We follow two complementary pathways. Firstly, we perform a large set of simulations of molecular cloud formation, evolution and destruction, consistently taking into account the impact of the clouds’ Galactic environment. Secondly, we develop a comprehensive model of the secular evolution of the star clusters, from gas expulsion to the dissolution in the tidal field of the Galactic disk. We relate both approaches to the available observational data in subproject B5.

Publications