The collimated outflows of the planetary nebula Hu1-2: proper motion and radial velocity measurements

Hu,1-2 is a planetary nebula that contains an isolated knot located northwestern of the main nebula, which could be related to a collimated outflow. We present a subsarcsecond H$\alpha$+[N,{\sc ii}] image and a high-resolution, long-slit spectrum of Hu,1-2 that allow us to identify the southeastern counterpart of the northwestern knot and to establish their high velocity ($>$ 340 km,s${}^{-1}$), collimated bipolar outflow nature. The detection of the northwestern knot in POSS red plates allows us to carry out a proper motion analysis by combining three POSS red plates and two narrow-band H$\alpha$+[N,{\sc ii}] CCD images, with a time baseline of $\simeq$ 57 yr. A proper motion of 20 $\pm$ 6,mas,yr${}^{-1}$ along position angle 312${}^{\circ }$ $\pm$ 15${}^{\circ }$, and a dynamical age of 1375${}^{+590}$\llap{${}_{-320}$},yr are obtained for the bipolar outflow. The measured proper motion and the spatio-kinematical properties of the bipolar outflow yield a lower limit of 2.7,kpc for the distance to Hu,1-2.