Jets from Accreting Magnetic Young Stellar Objects. I. Comparison of Observations and High‐Resolution Simulation Results

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Abstract
High-resolution numerical magnetohydrodynamic (MHD) simulations of a new model for the formation of jets from magnetic accreting young stellar objects (YSOs) are presented and compared with observations. The simulation results corroborate a previously laid out conceptual mechanism for forming jets, wherein the interaction of the stellar magnetosphere with a surrounding accretion disk leads to an outflow. The high resolution of the numerical simulation allows optical condensations, which form in the region close to the star to be seen. The optical condensations and the episodic behavior of the jet are effects that are inherent to the jet-launching mechanism itself. A disk wind arises as well. The simulated outflow is compared with observations, and it is shown that simulated images in the forbidden lines [S II] λλ6716+6731 have morphology consistent with recent observations of the jet source HH 30. Furthermore, velocity spectra of the simulated outflow in [S II] λλ6716+6731 and mass weighted by n clearly show a two-component outflow, in agreement with observed outflows from T Tauri stars such as DG Tauri. The mechanism produces a highly collimated fast jet and a slower disk wind. While the match between existing observations and the simulated system are not perfect (the time- and size scales of the jet differ from those in HH 30 by an order of magnitude), the morphology associated with both imagery and velocity spectra of the jet are matched well. A companion paper lays out the physics that control the timescale for knot production and defines the controlling parameters of the jet-launching mechanism in general.