Name of the Speaker(s): Dr S. G. Lucek
Institution: Imperial College (United Kingdom)
Title of the communication: Magnetohydrodynamic Jet formation
Preliminary abstract (12 lines max.): (please see attatched note for more details) 2 and 3 D numerical solutions for the time-dependent, ideal MHD, equations suggest that jets may be readily formed by a number of different processes. Two related processes are examined here, i) the rotation of an accretion disk in a magnetic field and ii) the pinching of a wind from a stationary disk by an azimuthal magnetic field. In the first case, the accretion disk loses angular momentum and falls into a gravitational well, building up the pressure near the centre of the well, which ejects a jet along the rotation axis. The jet is collimated partly by hydrodynamic funnelling and partly by the axial component of the magnetic field, which is compressed and amplified by the infall of the disk. In the second case, idealised calculations of the generic problem of collimation by an azimuthal field indicate that, whilst a jet is readily formed, it is prone to large m=1 (kink) instabilities which disrupt the jet.