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

TL;DR

This paper presents detailed proper motion and velocity measurements of collimated bipolar outflows in the planetary nebula Hu1-2, revealing their high velocities, age, and a lower limit on the nebula's distance.

Contribution

It provides the first proper motion analysis of Hu1-2's outflows, combining multi-epoch imaging to determine their velocity, age, and distance.

Findings

High-velocity bipolar outflows exceeding 340 km/s.

Proper motion of 20 ± 6 mas/yr indicating outflow dynamics.

Dynamical age of approximately 1375 years and a distance lower limit of 2.7 kpc.

Abstract

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.