Photoionization Modeling of Planetary Nebulae in the Galactic Bulge

TL;DR

This study presents detailed photoionization models for 124 Galactic bulge planetary nebulae, deriving stellar and nebular properties, elemental abundances, and evolutionary stages, providing comprehensive insights into their physical characteristics and evolution.

Contribution

It offers the most extensive photoionization modeling of Galactic bulge PNe to date, including stellar parameters, elemental abundances, and evolutionary insights, with comparisons to observational data.

Findings

Effective temperatures peak around 100,000 K.

Nebular diameters average 7% larger than observed.

Progenitor masses range from 0.8 to 4.2 solar masses.

Abstract

In this study, we present the results of photoionization modeling for 124 planetary nebulae (PNe) in the Galactic bulge. Utilizing the {\scshape cloudy} code, we derived the effective temperatures (T$_{eff}$) of the central stars, with a peak distribution around $\sim$ 100,000 K, and luminosities clustering around $\sim$ 3,000 L$\odot$. The inner radii of the ionized regions range from 0.003 to 0.31 pc, with nebula diameters varying from 1.8" to 34", averaging 7\% larger than the observed visible diameters. Elemental abundances for Helium, Nitrogen, Oxygen, Neon, Sulphur, Chlorine and Argon relative to hydrogen derived from the models show consistency within 0.5 dex, with notable variations in Sulphur, Nitrogen, and Chlorine. The study also compares elemental abundances from photoionization models with previous observations, showing overall good agreement, particularly for Cl/H, but notable discrepancies in He/H and S/H ratios. The models' goodness of fit, quantified by $\chi^{2}$ values, varies widely, with higher values linked to discrepancies in WISE photometric data. The evolutionary tracks of the central stars from H-R diagrams suggest progenitor masses ranging from 0.8 to 4.2 $M_\odot$ and progenitor final masses between 0.53 and 0.87 $M_\odot$, indicating significant mass loss during evolution. These PNe have post-AGB ages ranging from 150 to 20,000 years, consistent with the Galactic PNe distribution. Most of the PNe are in an intermediate evolutionary stage with larger nebular sizes. Our results provide the most comprehensive photoionization modeling to date, with key implications for central stars of PNe, gas, and dust.