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

TL;DR

This paper presents a detailed plasma and stellar analysis of planetary nebula PC 22, utilizing novel Monte Carlo methods, machine learning for ionization correction factors, and confirms its classification as a [WO1]-type Wolf-Rayet central star.

Contribution

It introduces new plasma diagnostics, pioneer ionization correction factors derived via machine learning, and confirms the [WO1] classification of the central star in PC 22.

Findings

Electron temperatures of ~10,800 K and ~13,000 K in different nebula regions.

First use of machine learning to calculate ionization correction factors for this nebula.

Classification of the central star as a [WO1]-type Wolf-Rayet star.

Abstract

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 to the PyNeb code for the uncertainty propagation. The innermost region of the nebula shows electronic temperatures $T_{\rm e}$ $\approx$ 10,800~K using [NII] and $\approx$ 13,000 K using [OIII] and electronic densities $n_{\rm e}$ $\approx$ 600~cm$^{-3}$. We also used for the first time a Machine Learning Algorithm to calculate Ionisation 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 database (3MdB) and the best fit model obtained with the NLTE model atmosphere code PoWR. PC 22 is therefore a new addition to the [WO1]-subtype PNe.