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

Abstract

Hu1-2 is a planetary nebula that contains an isolated knot located north-west of the main nebula, which could be related to a collimated outflow. We present a subarcsecond Hα+[Nii] image and a high-resolution, long-slit spectrum of Hu1-2 that allow us to identify the south-eastern counterpart of the north-western knot and to establish their high-velocity (>340 kms -1), collimated bipolar outflow nature. The detection of the north-western knot in Palomar Observatory Sky Atlas (POSS) red plates allows us to carry out a proper motion analysis by combining three POSS red plates and two narrow-band Hα+[Nii] CCD images, with a time baseline of ≃57yr. A proper motion of 20 ± 6masyr -1 along position angle 312°± 15° and a dynamical age of 1375yr are obtained for the bipolar outflow. The measured proper motion and the spatio-kinematical properties of the bipolar outflow yield a lower limit of 2.7kpc for the distance to Hu1-2. © 2012 The Authors Monthly Notices of the Royal Astronomical Society © 2012 RAS.