Excitation of Metastable Levels in Low Density Nebular Plasmas: [SII] and [ArIV]
Abstract
Diagnostics of low density nebular plasma by means of its forbidden line spectrum require not only a knowledge of certain intensity ratios as a function of its density and temperature but also a knowledge of the occupation numbers of relevant ionic levels. We present the necessary data for important levels of ionized sulfur and triply ionized argon.
Footnotes
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↵ * Present address: Perkins Observatory of the Ohio State and Wesleyan Universities.
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↵ † Present address: General Physics Laboratory, Wright-Patterson Air Force Base, Fairborn, Ohio.
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↵ ‡ Requests for reprints may be addressed to Dr. Aller, Department of Astronomy, University of California, Los Angeles, Calif. 90024.
