The Dynamical Evolution of Stars and their Circumstellar Environments in Young Dense Clusters
Final Report Abstract
The objective of this project is the investigation of the dynamical evolution of young dense star clusters from their earliest gas-embedded stages, focusing on the effect of gravitational interactions among the stellar population and their protoplanetary discs. The recent finding that most stars form in star clusters makes this project a vital contribution to the understanding of star and planet formation, one of the fundamental issues of current research. The investigation is carried out via numerical simulations of star cluster models using high-order accurate direct parallel N -body codes and novel supercomputers based on special accelerator devices. The numerical findings are confronted with observational data obtained at the most advanced observational facilities for star cluster studies. Initially, the project was supposed to be driven by ambitious achievements in code development, aiming at the implementation of a scheme for cluster formation and the self-consistent simulation of stars and their circumstellar discs in a cluster environment. Unexpected technical difficulties necessitated an alternative strategy to overcome the numerical limitations by establishing effective collaborations. This fruitful approach stimulated a variety of subprojects within a broadened scientific context including detailed studies of mass segregation in star clusters, advanced cluster models with high dynamical complexity, dynamically induced mass growth of black holes in star clusters, the formation of planets in protoplanetary discs, the encounter-induced instability of planetary systems in cluster environments, and the transformation of galaxies in cluster environments (known as galaxy harassment). The milestones of the project are (i) the development and versatile application of a sensitive and geometrically independent measure for mass segregation based on the minimum spanning tree (MST), (ii) the theoretical prediction of an encounter-induced bimodal structure of circumstellar discs in the tidal tails of young star clusters, and (iii) the theoretical explanation of the observed size-distribution of dust grains in protoplanetary discs based on a consistent mathematical model.
Publications
- “A highly efficient measure of mass segregation in star clusters”, 2011, A&A, 532, A119
Olczak, C., Spurzem, R. & Henning, T.
- “Simulations of the Hyades”, 2011, A&A, 536, A64
Ernst, A., Just, A., Berczik, P. & Olczak, C.
- “The Central Blue Straggler Population in Four Outer-halo Globular Clusters”, 2012, ApJ, 754, 108
Beccari, G., Lützgendorf, N., Olczak, C. et al.
(See online at https://doi.org/10.1088/0004-637X/754/2/108) - “The Evolution of Protoplanetary Disks in the Arches Cluster”, 2012, ApJ, 756, 123
Olczak, C., Kaczmarek, T., Harfst, S. et al.
(See online at https://doi.org/10.1088/0004-637X/756/2/123) - “From dust to planetesimals: an improved model for collisional growth in protoplanetary disks”, 2013, ApJ, 764, 146
Garaud, P., Meru, F., Galvagni, M. & Olczak, C.
(See online at https://doi.org/10.1088/0004-637X/764/2/146) - “Growth of Grains in Brown Dwarf Disks”, 2013, ApJL, 774, 4
Meru, F., Galvagni, M., Olczak, C.
(See online at https://doi.org/10.1088/2041-8205/774/1/L4)
