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

Authors:
  • ASAtul Kumar Singh
    Atul Kumar Singh
  • SSSaurabh Sharma
    Saurabh Sharma
  • RARahul Kumar Anand
    Rahul Kumar Anand
  • AGArpan Ghosh
    Arpan Ghosh
  • TCTarak Chand
    Tarak Chand
  • SRShantanu Rastogi
    Shantanu Rastogi

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.