SIMBAD references

We deal with the question whether the deflection of stellar jets/outflows that is observed for example in L 1221 can be caused by strong ambient magnetic fields. We present results of fully three-dimensional (3D) numerical magnetohydrodynamics (MHD) simulations of adiabatic jets propagating into an initially homogeneous medium containing an oblique magnetic field. In our model, the jet is longitudinally magnetized by a field of the strength of the x-component of the ambient magnetic field. We varied the jet velocity v_j (in the range 2 to 40km/s), the ambient magnetic field strength B_a (50, 100 µG), and the angle α (10° to 70°) between the initial jet velocity and the ambient field to find the dependence of the critical velocity v_cr (up to which a jet is deflected by the magnetic field) on B_a and α. Our numerical results indicate that v_cr is a decreasing function of the field angle α. We find a nearly linear dependence of v_cr on the ambient field strength B_a. Our numerical results are in good qualitative and rough quantitative agreement with an analytical model derived from a two-dimensional consideration of the ram pressure balance governing the motion of the jet head. This model predicts an unrealistically high ambient field strength of ∼ 1000 µG to deflect a jet of 100km/s (appropriate to stellar jets). Applying our results to L 1221 and HH 110/HH 270 we thus suggest that in these sources the jet/outflow must interact with a relatively strong magnetic field (≥100 µG) contained in a dense clump of ambient gas (n≥10⁴cm^–3) if deflection is to be caused by magnetic forces. In the case of L 1221 two other possible explanations of the observational data can be given by assuming (i) that only a low speed wind surrounding the driving jet is bent by an ambient field while the outflow-driving jet itself remains straight and invisible due to high obscuration by ambient material, or (ii) that the outflow contains no high speed driving jet at all and can therefore be deflected by a moderate ambient field (≲200 µG).