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Journal of Physical Studies 7(4), 461–467 (2003)
DOI: https://doi.org/10.30970/jps.07.461 CHEMICAL COMPOSITION OF GALACTICAL PLANETARY NEBULAEV. V. Holovatyy1, N. V. Havrylova2
1Department for Astrophysics and 2Astronomical Observatory,
Ivan Franko National University of Lviv |
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This work starts the research of the chemical composition of planetary nebulae taking into account versatile inhomogeneities of gas density in planetary nebulae shells. We have determined the chemical composition of planetary nebulae using the radial distribution of gas density, which is close enough to the real distribution. The data for the chemical composition of 200 galactical planetary nebulae are presented. Abundances of He, C, N, O, Ne, Mg, Si, S and Ar are determined for a number of planetary nebulae 175, 64, 190, 200, 170, 13, 40, 173 and 187, respectively. Both the compositions for all 200 planetary nebulae and for photoionization models (to calculate ionization-correction factors) were obtained using the same method and the same atomic data. Observational data have been compiled from 105 papers published by other authors. The $Y$-$Z$ diagrams for combination of IIa,b planetary nebulae and the HII regions in the blue compact dwarf galaxies are analyzed. From the relation between $Y$ and $Z$, the primordial helium abundance $Y_{p}$ and the enrichment ratio $dY/dZ$ are obtained. The radial abundance gradients in the galactic disk for He, N, O, Ne, S and Ar are determined. The gradients obtained for these elements are somewhat lower in comparison with the data of other authors.
PACS number(s): 98.38.Am, 98.38.Ly