“School of Astronomy”
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| Paper IPM / Astronomy / 14165 |
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We present results of the first ever three-dimensional (3D) magnetohydrodynamic (MHD) simulations of the
accretion�??ejection structure. We investigate the 3D evolution of jets launched symmetrically from single stars but
also jets from warped disks in binary systems. We have applied various model setups and tested them by
simulating a stable and bipolar symmetric 3D structure from a single star�??disk�??jet system. Our reference
simulation maintains a good axial symmetry and also a bipolar symmetry for more than 500 rotations of the inner
disk, confirming the quality of our model setup. We have then implemented a 3D gravitational potential (Roche
potential) due by a companion star and run a variety of simulations with different binary separations and mass
ratios. These simulations show typical 3D deviations from axial symmetry, such as jet bending outside the Roche
lobe or spiral arms forming in the accretion disk. In order to find indications of precession effects, we have also run
an exemplary parameter setup, essentially governed by a small binary separation of only ;200 inner disk radii.
This simulation shows a strong indication that we observe the onset of a jet precession caused by the wobbling of
the jet-launching disk. We estimate the opening angle of the precession cone defined by the lateral motion of the jet
axis to be about 4ð after about 5000 dynamical time steps.
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