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H. Shang, A. Allen, J. Liu (ASIAA), Z.-Y. Li, M.-Y. Chou, J. Anderson (U Va)
We develop a unified model for molecular outflows in star formation. The model incorporates essential features expected of the primary wind that is thought to be driven magnetocentrifugally from close to the central stellar object, and the ambient core material shaped by magnetized collapse. The primary wind is modelled as a toroidally magnetized fast outflow moving radially away from the origin, with an angle-dependent density distribution: a dense axial jet surrounded by a more tenuous wide-angle component, as expected in the X-wind model. If dynamically significant magnetic fields are present, the star-forming core would collapse faster along the field lines than across, forming a toroid-like structure. We approximate the structure with a singular isothermal toroid whose density distribution can be obtained analytically. The interaction of the laterally stratified wind and the ambient toroid is followed using the Zeus2D MHD code. We find that the lobes produced by the interaction resemble many systematics observed in molecular outflows from very young stars, ranging from Class 0 to I sources. In particular, both the dense axial jet and the wide-angle component participate in the wind-ambient interaction. In our model, the jet- and wind-driven pictures of molecular outflows are unified. We discuss observational implications of the unified picture, including the possibility of detecting the primary jet/wind directly.
The author(s) of this abstract have provided an email address for comments about the abstract: shang@asiaa.sinica.edu.tw
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Bulletin of the American Astronomical Society, 37 #4
© 2005. The American Astronomical Soceity.