Universe Colloquium: Shell fragmentation and self-propagating star formation

by Eva Ntormousi (USM)

Wednesday 23 May 2012, 16:30 → 18:00 Europe/Berlin

seminar room (basement) (Universe Cluster, Garching)

Eva will review the picture of self-propagating star formation, mostly from a theoretical point of view. In particular, the talk will be focused on the hydrodynamical instabilities relevant to the fragmentation of an expanding thin shock, such as the Vishniac, the thermal instability and the gravitational instability. Eva will discuss which of them become important at each stage of the shell expansion, with an eye towards the timescales for triggered star formation. Eva's and her colleague's simulation results will be highlighted in this context, showing the two- and three-dimensional growth (and saturation) of these instabilities with different seeding (small-scale noise vs background turbulence), as well as the creation of a multi-phase interstellar medium (ISM) from the collision of such socks: Cold, dynamical filaments arise naturally in such an environment, strengthening the view that converging flows are a very efficient mechanism for structure formation in the ISM. Finally, she will comment on metal mixing in such an environment and the timescales for metal enrichment of newly-formed cold clumps that will participate in the next round of star formation.