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Star Formation Studies

Snapshots of density structures
Image Credit: Shang et al.
Snapshots of density structures
Snapshots of density structures at 100 (top) and 1000 (bottom) years, respectively, for different anisotropy in the ambient mass distribution induced by magnetic field (Shang et al. 2006, ApJ, 649, 845).
One of the main features of the X-wind model is a wind driven from the innermost region of the accretion disk. The wind leaves the launch region and expands subsequently into free space at all solid angles, becoming a so-called wide-angle wind. Because of the action of magnetic stress, the density field in the wind, on the other hand, forms a cylindrical profile that leads to specific characters pertaining to the detailed model. The emission mechanisms that contribute to the observed jets in many wavelengths, especially within the context of the X-wind, are actively investigated with natural physical processes occurring around young stars. Accumulating evidences of optical and infrared properties of T-Tauri jets reveal resemblance to simulated model signatures. The links to the observed phenomena hold important tests for the popular theoretical models. Once the wide-angle wind leaves the vicinity of the protostar, it interacts with the ambient material, which is undergoing gravitational collapse under the strong influence of magnetic fields in the very early phases. We have developed a unified model to describe precisely this phenomenon. 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 anisotropic magnetic support. The numerical simulation results show the formation of molecular outflows by a wide-angle wind with jet-like density stratification, similar to one predicted by the X-wind model. The lobes produced by the interaction resemble many evolutionary systematics observed in molecular outflows from very young stars. The system of HH211 is the first example illustrating the closest signatures of jet and outflow from a deeply embedded protostar.
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