Catching a Grown-Up Starfish Planetary Nebula: I. Morpho-Kinematical
  study of PC 22
  We present the first part of an investigation on the planetary nebula (PN) PC
22 which focuses on the use of deep imaging and high resolution echelle
spectroscopy to perform a detailed morpho-kinematical analysis. PC 22 is
revealed to be a multipolar PN emitting predominantly in [O III] and displaying
multiple non-symmetric outflows. Its central region is found to be also
particularly inhomogeneous with a series of low ionization structures (knots)
located on the path of the outflows. The morpho-kinematical model obtained with
SHAPE indicates that i) the de-projected velocities of the outflows are rather
large, > 100 km/s, while the central region has expansion velocities in the
range ~25 to ~45 km/s following the "Wilson effect", ii) the majority of the
measured structures share similar inclination, ~100 degrees, i.e. they are
coplanar, and iii) all outflows and lobes are coeval (within the
uncertainties). All these results make us to suggest that PC 22 is an evolved
starfish PN. We propose that the mechanism responsible for the morphology of PC
22 consists of a wind-shell interaction, where the fast post-AGB wind flows
through a filamentary AGB shell with some large voids.
