文章基本信息

标题：The Kinematics of the Permitted C ii λ6578 Line in a Large Sample of Planetary Nebulae* **
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作者：Michael G. Richer ; Genaro Suárez ; José Alberto López 等
期刊名称：The Astronomical journal
印刷版ISSN：0004-6256
电子版ISSN：1538-3881
出版年度：2017
卷号：153
期号：3
DOI：10.3847/1538-3881/aa5f53
语种：English
出版社：American Institute of Physics
摘要：We present spectroscopic observations of the C ii λ6578 permitted line for 83 lines of sight in 76 planetary nebulae at high spectral resolution, most of them obtained with the Manchester Echelle Spectrograph on the 2.1 m telescope at the Observatorio Astronómico Nacional on the Sierra San Pedro Mártir. We study the kinematics of the C ii λ6578 permitted line with respect to other permitted and collisionally excited lines. Statistically, we find that the kinematics of the C ii λ6578 line are not those expected if this line arises from the recombination of C2+ ions or the fluorescence of C+ ions in ionization equilibrium in a chemically homogeneous nebular plasma, but instead its kinematics are those appropriate for a volume more internal than expected. The planetary nebulae in this sample have well-defined morphology and are restricted to a limited range in Hα line widths (no large values) compared to their counterparts in the Milky Way bulge; both these features could be interpreted as the result of young nebular shells, an inference that is also supported by nebular modeling. Concerning the long-standing discrepancy between chemical abundances inferred from permitted and collisionally excited emission lines in photoionized nebulae, our results imply that multiple plasma components occur commonly in planetary nebulae.
关键词：cosmological parameters;galaxies: abundances;ISM: abundances;ISM: kinematics and dynamics