Special Universe Talk: The many scales of triggered star formation

by Matthias Gritschneder (U California, Lick Observatory, USA)

Monday 25 Jun 2012, 15:00 → 16:30 Europe/Berlin

seminar room basement (Universe Cluster, Boltzmannstr. 2, 85748 Garching)

We study the structural evolution of molecular clouds under the influence of ionizing radiation emitted from a nearby massive star. First, we will briefly review the underlying physics of ionization and previous simulation work in that field. Then, we go on to apply these concepts to the evolution and current state of the Pipe Nebula. We propose that the Pipe Nebula is an HII region shell swept up by theta Ophiuchi. We are able to show that the current size, mass and pressure of the region can be explained in this scenario. We investigate the configuration today and come to the conclusion that the Pipe Nebula can be best described by a three phase medium in pressure equilibrium. The pressure support is provided by the ionized gas and mediated by an atomic component to confine the cores at the observed current pressure. In the future, star formation in these cores is likely to be either triggered by feedback of the most massive, gravitationally bound cores as soon as they collapse or by the supernova explosion of theta Ophiuchi itself. Finally, we investigate the future evolution of the pillars as soon as the massive star explodes in a supernova. We are able to show that a surviving core at the border of the HII region (D~5pc) is getting enriched sufficiently with supernova material and is triggered into collapse fast enough to be consistent with the tight constraints put by meteoritic data of e.g. Al-26 on the formation of our Solar System. We therefore propose that the formation of the Solar System was triggered by the shock wave of a type IIa supernova interacting with surviving cold structures similar to the Pillars of Creation at the border of HII-regions.