Jets from accreting magnetic young stellar objects. I. Comparison of observations and high-resolution simulation results

High-resolution numerical magnetohydrodynamic (MHD) simulations of a new mo del for the formation of jets from magnetic accreting young stellar objects (YSOs) are presented and compared with observations. The simulation result s corroborate a previously laid out conceptual mechanism for forming jets, wherein the interaction of the stellar magnetosphere with a surrounding acc retion disk leads to an outflow. The high resolution of the numerical simul ation allows optical condensations, which form in the region close to the s tar 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 observatio ns, and it is shown that simulated images in the forbidden lines [S II] lam bda lambda 6716+6731 have morphology consistent with recent observations of the jet source HH 30. Furthermore, velocity spectra of the simulated outfl ow in [S II] lambda lambda 6716+6731 and mass weighted by n clearly show a two-component outflow, in agreement with observed outflows from T Tauri sta rs such as DG Tauri. The mechanism produces a highly collimated fast jet an d 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 dif fer from those in HH 30 by an order of magnitude), the morphology associate d with both imagery and velocity spectra of the jet are matched well. A com panion paper lays out the physics that control the timescale for knot produ ction and defines the controlling parameters of the jet-launching mechanism in general.