Talk Details

Wednesday, October 31, 2007 - 3:15pm

Dr. Stefan Schmeja (ZAH/ITA):

"The Structures of Star Clusters"

Abstract. Star clusters show a wide variety of structures from hierarchical configurations showing fractal substructure to centrally condensed clusters with relatively smooth radial density profiles. While the structures of embedded clusters may hold clues to their formation mechanism, the structures of open clusters probably reflect their dynamical evolution. In this talk I will present the analysis of observed embedded and open clusters as well as results from numerical simulations. Their structures are analysed using different statistical methods like nearest neighbour maps and minimum spanning trees. Star clusters build up from several subclusters evolving from a structured to a more centrally condensed stage. Open clusters, on the other hand, show on average, less central concentration, which indicates that due to the dynamical evolution the cluster may again develop a more hierarchical structure. The structures do not only depend on the evolutionary stage, but also on the mass of the objects. Massive stars are usually centrally concentrated, while lower-mass stars are more randomly distributed, reflecting the effect of mass segregation.