Research Area B: The Matter Cycle and Star Formation in the Milky Way
Research Area B aims at understanding the complex interplay between stars, dust, and gas and the different feedback loops that connect them on various levels and scales.
We want to comprehend under which conditions star-forming clouds originate from the turbulent interstellar medium with its highly complex morphological, kinematical, and chemical structure, how stars can form in the interior of such clouds, and which feedback processes connect these components. The theoretical approach requires profound knowledge of gas physics (turbulence, hydrodynamics), astrochemistry (to describe the various phases of the ISM and their chemical properties), radiation physics (radiation transfer in the ISM, radiative feedback from massive stars), stellar evolution, and gravity. Key observables are the spatial and velocity structure of the various components of the ISM, the location, kinematics and chemical composition of stars in clusters and the field, and the various correlations between the gaseous and stellar components. Research Area A is inextricably linked to B through the flow of baryons in gas into and back from stars, which is a central Galactic evolutionary process.
We concentrate on the following subprojects in Research Area B:
Subproject B1: Star Formation and Global Matter Cycle of the Milky Way. Numerical study of the coupled evolution of stars and gas in the disk on a Galactic scale to constrain the interplay between star formation, feedback and gravitational instabilities.
Subproject B2: Molecular Clouds in the Milky Way and Their Ability to Form Stars. Simulations of molecular cloud formation, evolution and destruction, including the assembly of clouds from converging flows of warm atomic hydrogen, the formation of stars within the clouds, and the eventual dispersal of the clouds. Constraints on cloud lifetimes, star formation rates, and the properties of embedded star clusters.
Subproject B3: The chemical evolution from diffuse clouds to dense cores. Theoretical and observational multi-spatial-scale study of the chemistry within the ISM, including the evolution of complex molecules from the low-density molecular clouds to high-density star-forming regions, of fractional ionization of the ISM, and of the chemistry as a function of Galactocentric distance.
Subproject B4: Feedback and Interstellar Turbulence. Numerical simulations of effects of feedback from protostars, massive stars, and supernovae on the nearby environment. Simulations of outflow-driven feedback by implementing detailed jet/disk-wind models, and investigation of the various feedback processes regulating regulate star formation.
Subproject B5: Open Star Clusters in the Milky Way. Open clusters as tracers of the evolution of the Galactic disk and their contribution to the stellar content of the disk at every stage of a clusters' life. Census and properties of open star clusters in the Milky Way. Determination of cluster dispersal rate and importance for the build-up of field populations. Recent star formation history of the disk as traced by clusters.
Subproject B6: The Mass Function of Low-Mass Stars and Substellar Objects. Extension of the determination of the mass function to the end of the main sequence and into the brown dwarf regime in field populations and selected nearby star clusters and associations. Star formation history of the Solar neighborhood. Complete census of substellar objects down to very low masses.
