An Interpretation of Hydrogen and Helium Line Spectra of the Loop Prominence Observed on November 3, 1973
The H I, He I, and He ii emission lines of the loop prominence observed on November 3, 1973 in the rapidly developing phase are analyzed. The difference in widths of these lines suggests they do not originate in the same volume. The estimated Te (8000-9000 K) and e ( 2x 1012 cm-3) in the loop from the Balmer lines do not change appreciably with time everywhere in the loop during our observation ( UT). The degree of ionization of hydrogen is estimated to be in the range of 0.8 to 1.0. The ionizing mechanism may be attributed to the UV radiation ( 912A) from the underlying flare region. Local thermodynamic equilibrium (LTE) is approximately established in the excited levels of He I, but the singlet levels are somewhat overpopulated. The UV radiation field ( ) from the surrounding coronal condensation is estimated from microwave and X-ray flux measurements of SOLRAD 9. The ionization of He I (ionization degree 0.1-0.2) is mainly controlled by UV radiation from the coronal condensation. An adequate thread structure model of the loop prominence is suggested. Key words: Coronal condensation; Loop prominence; Spectra.
Publications of the Astronomical Society of Japan
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