The HCO+ molecular outflow in NGC 2071

We present high angular resolution and multitransition HCO+ observations to ward the NGC 2071 molecular outflow. Comparison of the high-velocity (HV) H CO+ and the near-IR H-2 in the molecular outflow shows a clear correlation. At high HCO flow velocities the spatial coincidence is especially remarkab le. In addition, the HV HCO+ presents clear morphological and kinematical d ifferences with the CO outflow. These differences appear not only in the HV HCO+ emission associated with the H-2 but in the overall outflow. There is a clear HCO+ emission enhancement, relative to CO, at increasing flow velo cities. This enhancement is probably due to an abundance enhancement produc ed by a velocity-dependent chemistry in the shocks. An overabundance of CH in low Mach shocks may cause the HCO+ abundance enhancement. Because of the short cooling time for H-2, the correlation between the HCO+ and the H-2 i mplies that HCO+ emission can provide a useful tool to study in detail the current interactions of protostellar winds with the dense ambient medium. A t the position of the extremely high velocity (EHV) CO component in the red lobe we detect HCO+ (J = 3 --> 2) emission within the velocity range of th e EHV CO gas. This emission is roughly compatible with the expected HCO+ em ission associated with EHV gas arising from behind dissociative shocks.