Abundance patterns in planetary nebulae
نویسندگان
چکیده
منابع مشابه
The iron abundance in four planetary nebulae
We have observed the high excitation planetary nebulae NGC 7027, NGC 6543 and the low excitation planetaries Hu 2-1 and Cn 3-1 in the optical & near IR with the aim to contribute accurate measurements of their gaseous iron abundances. Use was made of multi-level atomic models of iron ions to interpret the observed forbidden lines of various iron ions. The resulting total abundances are: N(Fe)/N...
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We have collected photometric and spectroscopic data on planetary nebulae (PNe) in 5 galaxies: the Milky Way (bulge), M 31 (bulge), M 32, the LMC and the SMC. We have computed the abundances of O, Ne and N and compared them from one galaxy to another. In each Galaxy, the distribution of oxygen abundances has a large dispersion. The average O/H ratio is larger in the M 31 and the Galactic bulge ...
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Presentamos observaciones de ĺıneas de recombinación de O II en diez nebulosas planetarias brillantes, y mediciones de O II y [O III] con resolución espacial en NGC 6720. Esto es con el fin de estudiar la discrepancia entre las abundancias calculadas con ĺıneas de recombinación de O II y aquellas derivadas de ĺıneas de excitación colisional de [O III]. Observamos una gran variación en la discre...
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Radial abundance gradients of the element ratios O/H, Ne/H, S/H, and Ar/H are determined on the basis of a sample of disk planetary nebulae. The behaviour of the gradients at large distances from the galactic centre, R > R0 = 7.6 kpc, is emphasized. It is concluded that the derived gradients are consistent with an approximately constant slope in the inner parts of the Galaxy, and some flattenin...
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ژورنال
عنوان ژورنال: The Astrophysical Journal
سال: 1990
ISSN: 0004-637X,1538-4357
DOI: 10.1086/168833