Modeling the formation of protostellar systems in Giant Molecular Cloud environment
By Michael Küffmeier
Tuesday 12 Feb
Place: Seminari DAM
Stars predominantly occur clustered among other stars embedded in Giant Molecular Clouds. Contrary to models of individual stars forming due to the collapse of one isolated core, we account for the molecular cloud environment during the epoch of star and protoplanetary disk formation. Using state-of-the art zoom-simulations with the magnetohydrodynamical codes RAMSES, we investigate the accretion process of young stars that are embedded in such different environments during their first ~100 kyr after formation. Starting initially from a turbulent (40 pc)^3 Giant Molecular Cloud, efficient use of the Adaptive Mesh Refinement technique allows us to resolve the processes inside of protoplanetary disks with a resolution down to 0.06 AU, thus covering a range of spatial scales of more than eight orders of magnitude. We find that the accretion process of stars is heterogeneous in space, time and among different protostars with a tendency of more violent accretion for deeply embedded objects. We show that large-scale infall can trigger accretion bursts and thus cause enhanced protostellar luminosities. Apart from that, we investigate the formation of wide companions at distances of ~1000 au due to turbulent fragmentation for one of the objects. A comparison with observations shows that filamentary structures connecting two protostellar sources, such as the 'bridge' observed for IRAS16293-2422, appear to be transient phenomena of multiple star formation. Finally, we suggest that protostellar companions initially form as wide companions (separation ~1000 au) and migrate to smaller separations of ~100 au on time scales of ~10 kyr after their formation.