Catching a grown-up starfish planetary nebula – II. Plasma analysis and central star properties of PC 22

After performing the morpho-kinematic analysis of the planetary nebula (PN) PC 22, we now present its nebular and stellar analysis. The plasma investigation relies on the novel use of a Monte Carlo analysis associated with the PYNEB code for the uncertainty propagation. The innermost region of the nebula shows electronic temperatures T e ≈ 10 800 K using [N II] and ≈13 000 K using [O III] and electronic densities n e ≈ 600 cm ⁻³ . We also used for the first time a machine learning algorithm to calculate ionization correction factors (ICFs) specifically adapted to PC 22. This has allowed us to have pioneer ICFs for (S ⁺ + S ⁺⁺ )/O ⁺⁺ , Cl ⁺⁺ /O ⁺⁺ , and Ar ³⁺  + Ar ⁴⁺ , as well as a possible new determination for the total abundance of neon. The study of the stellar spectrum revealed the presence of broad emission lines consistent with a Wolf–Rayet-type [WR] classification and more precisely a [WO1] subtype based on different qualitative and quantitative criteria. This classification is also coherent with the high stellar temperature derived from the reproduction of the ionization state of the gas with the Mexican Million Models data base (3MdB) and the best-fitting model obtained with the NLTE model atmosphere code PoWR. PC 22 is therefore a new addition to the [WO1]-subtype PNe.