NGC 2392 and NGC 4361: Spectroscopic Diagnostics of Planetary Nebula Evolution

TL;DR

This paper conducts a detailed spectroscopic analysis of two planetary nebulae, NGC 2392 and NGC 4361, revealing their physical conditions, chemical compositions, and morphological features to understand their evolutionary histories.

Contribution

It provides new spectroscopic diagnostics and elemental abundance measurements for NGC 2392 and NGC 4361, offering insights into their progenitors and evolutionary stages.

Findings

NGC 2392 has a double-shell structure and moderate excitation.

NGC 4361 shows a diffuse elliptical shape with high excitation.

The nebulae have distinct chemical signatures indicating different progenitor histories.

Abstract

The study presents a detailed spectroscopic analysis of the planetary nebulae (PNe) NGC~2392 and NGC~4361 using optical spectra obtained from the 2-m Himalayan Chandra Telescope (HCT) and mid-infrared spectra from archival \textit{Spitzer} IRS data. The physical conditions, such as electron temperature ($T_e$) and density ($n_e$), were derived using diagnostic emission lines through the PyNeb software. Elemental abundances of key species, including He, O, N, Ne, S, Cl, and Ar, were determined for both nebulae, offering insights into their nucleosynthesis history and evolutionary status. High-resolution HST and Pan-STARRS imaging further elucidate the morphological structures of the nebulae. NGC~2392 exhibits a well-defined double-shell structure and moderate excitation characteristics, while NGC~4361 displays a diffuse elliptical morphology with high-excitation conditions and a notably low nitrogen content. The observed line spectra and derived abundances point toward distinct progenitor histories for the two PNe, with NGC~2392 originating from a younger, intermediate-mass progenitor, while NGC~4361 traces an older, metal-poor Population II star. This comparative study enhances our understanding of the evolution and chemical enrichment processes of low- to intermediate-mass stars.