Collision of protostellar jets in the star-forming region IC 1396N.
  Analysis of knot proper motions
  The bright-rimmed cloud IC 1396N is believed to host one of the few known
cases where two bipolar CO outflows driven by young stellar objects actually
collide. The CO outflows are traced by chains of knots of H_2 emission, with
enhanced emission at the position of the possible collision.
  The aim of this work is to use the proper motions of the H_2 knots to confirm
the collision scenario.
  A second epoch H_2 image was obtained, and the proper motions of the knots
were determined with a time baseline of ~11 years. We also performed
differential photometry on the images to check the flux variability of the
knots.
  For each outflow (N and S) we classified the knots as pre-collision or
post-collision. The axes of the pre-collision knots, the position of the
possible collision point, and the axes of the post-collision knots were
estimated. The difference between the proper motion direction of the
post-collision knots and the position angle from the collision point was also
calculated. For some of the knots we obtained the 3D velocity by using the
radial velocity derived from H_2 spectra.
  The velocity pattern of the H_2 knots in the area of interaction
(post-collision knots) shows a deviation from that of the pre-collision knots,
consistent with being a consequence of the interaction between the two
outflows. This favours the interpretation of the IC 1396N outflows as a true
collision between two protostellar jets instead of a projection effect.
