Possible bending mechanisms of protostellar jets

Observations of several bipolar jet flows from young stellar objects reveal a slight difference in the apparent direction of propagation for jet and counter jet. In this paper, possible mechanisms leading to such a jet deflection are investigated. We discuss various effects, such as the motion of the jet source within a binary system, gravitational pull due to an asymmetric external mass distribution, dynamical pressure of the external medium, inertial effects due to proper motion of the jet source, an inclined interstellar magnetic field, and the coupling between a magnetic jet and an external magnetic field. We find that for typical protostellar jet parameters the most likely mechanisms leading to a bent jet structure are Lorentz forces on the magnetic jet and/or motion of the jet source in a binary system. Dynamical pressure of a dense external medium or a stellar wind from a companion star cannot be excluded as source of jet bending.