By analyzing the data from the HASH database, astronomers have conducted a comprehensive study of nearly 1,500 planetary nebulae in the Milky Way galaxy. Results of the study, published October 15 on the arXiv preprint server, improve our knowledge regarding the physical and chemical properties of these sources.
In general, planetary nebulae (PNe) are expanding shells of gas and dust that have been ejected from a star during the process of its evolution from a main sequence star into a red giant or white dwarf. They are relatively rare, but are important for astronomers investigating the composition of the interstellar medium (ISM).
The Hong Kong/Australian Astronomical Observatory/Strasbourg Observatory H𝛼 Planetary Nebula (HASH) database is a huge collection of photometric and spectral data for different objects, including nearly 2,600 planetary nebulae. A team of astronomers led by Nurullah Erzincan of the Çukurova University in Adana, Turkey, has recently combed through this database to inspect more than a thousand galactic PNe, hoping to get more insights into their properties.
“A comprehensive analysis of 1,449 out of 2,591 PNe from the HASH database was conducted in this study to examine their physical and chemical properties across different galactic components,” the researchers write.
The study found that angular sizes and morphologies, including elliptical, bipolar, and asymmetric types of the investigated PNe were predominantly distributed within the Milky Way’s disk, with median angular sizes of approximately 1.47 light years. The PNe in the galactic halo exhibit larger angular dimensions, indicating distinct characteristics compared to other components of our galaxy.
The results indicate that the PNe sample studied in the paper have median values of extinction coefficient, electron temperature and electron density of 1.5, 9,900 K, and 1,200 cm−3, respectively. It was noted that the extinction coefficient values in the galactic bulge and thin disk regions are higher than the overall median for PNe.
When it came to the chemical composition, it turned out that the elemental abundance distributions for hydrogen, helium, nitrogen, oxygen, neon, sulfur, chlorine and argon show Gaussian-like patterns. However, it was found that thin disk PNe show higher abundances than average, except for oxygen and neon, while halo PNe have the lowest values.
The study also identified strong correlations between elements, with sulfur and nitrogen showing a particularly high correlation of about 0.87. In addition, comparisons with previous studies revealed discrepancies in elemental abundance ratios, particularly in the galactic halo.
Summing up the results, the authors of the paper underlined the importance of their study in the context of disentangling the properties of the galactic PNe population.
“This study underscores the importance of leveraging large datasets to uncover trends in PNe properties and provides a foundation for future investigations into their role in galactic chemical evolution,” the scientists conclude.
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More information:
N. Erzincan et al, Analysis of Planetary Nebulae in the Milky Way: Physical Properties, Chemical Abundances, and Galactic Distributions, arXiv (2025). DOI: 10.48550/arxiv.2510.14149
Journal information:
arXiv
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Comprehensive study examines properties of 1,449 planetary nebulae across the Milky Way (2025, October 23)
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