A Comparative Study of Two Planetary Nebulae

Andra-Laura Pieptea

doi:10.59973/emjsr.394

Authors

Andra-Laura Pieptea School of Mathematics and Physics, University of Portsmouth, PO1 3QL Portsmouth, UK

DOI:

https://doi.org/10.59973/emjsr.394

Keywords:

Planetary Nebulae, Spectroscopy, Wolf-rayet-type central stars, Nebular emission line analysis

Abstract

Planetary nebulae are important astrophysical objects that provide insight into stellar evolution, ionisation processes, and chemical enrichment within galaxies. Although many planetary nebulae appear visually similar, their physical properties and central stars can differ significantly. This study investigates whether spectral analysis can reveal distinctions that are not immediately apparent through imaging alone. The aim of this project was to compare two morphologically contrasting planetary nebulae, NGC 2346 and NGC 1501, and to demonstrate the effectiveness of spectroscopy in determining their true physical nature. NGC 2346 is a bipolar planetary nebula containing a spectroscopic binary central system, while NGC 1501 is a bright, spherical planetary nebula hosting a [WR]-type central star. Imaging and spectroscopic observations were obtained at Clanfield Observatory using a 610 mm Ritchey–Chr´etien telescope equipped with a ZWO ASI2600MC (colour) camera, and a Shelyak Lhires Littrow High Resolution Spectrograph and ZWO ASI2600MM (monochrome) camera respectively. Spectral analysis, Gaussian fitting, and nebular diagnostic calculations were performed to determine elemental compositions, Balmer decrements, extinction coefficients, dereddened intensities, electron temperatures and densities, excitation classes, and central star classifications. The results revealed significant spectral differences between the two nebulae. NGC 1501 lacked several nebular emission lines present in NGC 2346, including [N II] and [S II], while exhibiting broader stellar emission features consistent with a [WR]-type central star. In contrast, NGC 2346 displayed hydrogen Balmer absorption lines characteristic of an A5V-type central star and showed a more typical planetary nebula spectrum. These findings demonstrate that visual morphology alone is insufficient for fully understanding planetary nebulae. Spectral analysis provides a more reliable method for investigating their physical properties, evolutionary states, and central star characteristics.

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