Evidence of a SiO collimated outflow from a massive YSO in IRAS
  17233-3606
  Studies of molecular outflows in high-mass young stellar objects reveal
important information about the formation process of massive stars. We
therefore selected the close-by IRAS 17233-3606 massive star-forming region to
perform SiO observations with the SMA interferometer in the (5-4) line and with
the APEX single-dish telescope in the (5-4) and (8-7) transitions. In this
paper, we present a study of one of the outflows in the region, OF1, which
shows several properties similar to jets driven by low-mass protostars, such as
HH211 and HH212. It is compact and collimated, and associated with extremely
high velocity CO emission, and SiO emission at high velocities. We used a
state-of-the-art shock model to constrain the pre-shock density and shock
velocity of OF1. The model also allowed us to self-consistently estimate the
mass of the OF1 outflow. The shock parameters inferred by the SiO modelling are
comparable with those found for low-mass protostars, only with higher pre-shock
density values, yielding an outflow mass in agreement with those obtained for
molecular outflows driven by early B-type young stellar objects. Our study
shows that it is possible to model the SiO emission in high-mass star-forming
regions in the same way as for shocks from low-mass young stellar objects.
