The jet-driven molecular outflow of HH 211

We present high angular resolution (down to similar to 1.5 ") interferometr ic maps of the CO J = 1 --> 0 and J = 2 --> 1 emission in the molecular out flow associated with the extremely young HH 211 jet, which is located in th e IC 348 molecular complex. At velocities close to the systemic velocity, t he CO emission traces the outflow cavities, while an extremely collimated, continuous jet-like structure is observed at high CO velocities. The contin uum emission reveals a similar to 0.2 M. dust condensation surrounding the central exciting (Class 0) protostar, clearly resolved and elongated perpen dicular to the jet axis. The strong (bow-)shocks observed in vibrationally excited H-2 emission are located at the terminal ends of the jet and the lo w-velocity CO cavities are precisely situated in their wake. Hence, the ove rall structure of HH 211 perfectly fits into the picture of a jet-driven fl ow and strongly supports shock-entrainment models as the formation mechanis ms of young, embedded molecular outflows. The shape of the cavities traced by the low-velocity CO emission can actually be (surprisingly well) reprodu ced by a simple, semi-analytical toy-model of a jet-driven flow, in which p rompt entrainment occurs at the head of a travelling bow-shock. The estimat ed jet mass and mass loss rate yield a timescale of order one thousand year s, in agreement with the kinematical age. Finally, we discuss the physical properties of the different parts of the outflow, and especially the actual nature of the high-velocity CO jet.