# Catching a Grown-Up Starfish Planetary Nebula: I. Morpho-Kinematical study of PC 22

## TL;DR

This study provides a detailed morpho-kinematical analysis of the planetary nebula PC 22, revealing its multipolar structure, high-velocity outflows, and inhomogeneous central region, suggesting a wind-shell interaction shaping its morphology.

## Contribution

First detailed morpho-kinematical analysis of PC 22 using deep imaging and spectroscopy, identifying its multipolar structure and proposing a wind-shell interaction model.

## Key findings

- PC 22 is a multipolar planetary nebula with non-symmetric outflows.
- Outflows have de-projected velocities > 100 km/s.
- Central region shows inhomogeneity with low ionization knots.

## Abstract

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.