paper

Outflows and Jets from Collapsing Magnetized Cloud Cores

arXiv:astro-ph/0508374 · doi:10.1086/500496

Abstract

Star formation is usually accompanied by outflow phenomena. There is strong evidence that these outflows and jets are launched from the protostellar disk by magneto-rotational processes. Here, we report on our three dimensional, adaptive mesh, magneto-hydrodynamic simulations of collapsing, rotating, magnetized Bonnor-Ebert-Spheres whose properties are taken directly from observations. In contrast to the pure hydro case where no outflows are seen, our present simulations show an outflow from the protodisk surface at ~ AU and a jet at ~ 0.07 AU after a strong toroidal magnetic field build up. The large scale outflow, which extends up to ~ AU at the end of our simulation, is driven by toroidal magnetic pressure (spring), whereas the jet is powered by magneto-centrifugal force (fling). At the final stage of our simulation these winds are still confined within two respective shock fronts. Furthermore, we find that the jet-wind and the disk-anchored magnetic field extracts a considerable amount of angular momentum from the protostellar disk. The initial spin of our cloud core was chosen high enough to produce a binary system. We indeed find a close binary system (separation ~ 3 R_sol) which results from the fragmentation of an earlier formed ring structure. The magnetic field strength in these protostars reaches ~ 3 kG and becomes about 3 G at 1 AU from the center in agreement with recent observational results.

revised version, accepted for publication in ApJ, a higher resolution version of this paper can be downloaded at http://www.physics.mcmaster.ca/~banerjee/outflows.pdf

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