Talk Details

Wednesday, May 21, 2008 - 3:15pm

Richard Wunsch (Cardiff University):

"Fragmentation of the expanding self-gravitating shell"

Abstract. The observational evidence suggests that massive stars can have positive feedback on star formation, and this may eventually lead to self-propagating star formation. It is assumed, in the so-called collect and collapse scenario, that a group of massive stars inserts a large amount of energy into its surrounding interstellar medium (ISM) due to their powerful stellar winds, SN explosions and high number of emitted UV photons. This leads to the formation of an expanding bubble which sweeps the ambient ISM onto its surface, where it cools down and collapses into a thin shell. This shell may become gravitationally unstable, fragment and form a new generation of stars. We study the collect and collapse mode of star formation by means of three-dimensional simulations. In order to concentrate on the physics of the gravitational instability, we have explored a model of the expanding momentum-driven shell, based on the AMR code Flash. I will describe our model, in particular the new tree based gravity solver which we have developed. Finally, I will show the first results and compare them to the analytical description of the gravitational instability and to SPH simulations.