Arquivo do trabalho - IAG - USP

AbstractIn this work, we have investigated the effects of shocks (induced by supernovae) andmagnetohydrodynamical turbulenceintheprocessofstarformation. Consideringfirst, theimpact of a supernova remnant (RSN) with a neutral magnetized cloud we derived analyticallya set of conditions through which these interactions can lead to the formation ofdense structures able to become gravitationally unstable and form stars. Using these conditions,we have built diagrams of the RSN radius, R RSN , versus the initial cloud density,n c , thatconstrain a domainintheparameter space where star formationisallowed. Thesediagrams have been also tested by means of three-dimensional magneto-hydrodynamical(3D MHD) numerical simulations where the space-time evolution of a RSN interactingwith a self-gravitating cloud is followed. We find that the numerical analysis is in agreementwith the results predicted by the diagrams. We have also found that the effects of aweak homogeneous magnetic field (∼ 1 µG) approximately perpendicular to the impactvelocity of the RSN results only a small decrease of the allowed zone for star formationin the diagrams when compared with the diagrams with non-magnetized clouds. A largermagnetic field (∼ 10 µG) on the other hand, causes a significant shrinking of the starformation zone, as one should expect.Although derived from simple analytical considerations, these diagrams provide a usefultool for identifying sites where star formation could be triggered by the impact of a SNblast wave. Applications of them to a few regions of our own Galaxy (e.g., the large COshell in the direction of Scorpious, and the Edge Cloud 2 in the direction of the Cassiopeiaconstellation) have revealed that star formation in those sites could have been triggeredby shock waves from SNRs in a recent past, when considering specific values of the RSNradius and the initial conditions in the neutral clouds.We have also evaluated the effective star formation efficiency for this sort of interacvii