Wavelength-dependence of EUV continuum absorption |
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| Authors: | Takara Nishikawa |
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| Institution: | (1) Department of Astronomy, Faculty of Science, University of Kyoto, 606 Kyoto, Japan;(2) Present address: Takayama Junior College, Simobayashi-cho, Takayama, 506 Gifu, Japan |
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| Abstract: | The weakening of EUV line emission due to continuum absorptions of neutral hydrogen and neutral helium is investigated to examine its wavelength-dependence. After convolving the intensities predicted from multilevel calculations over an instrumental profile, we found a systematic, linear weakening for lines shortward of 912 Å, which can be attributed to Lyman continuum absorption in the cool chromospheric cloud. The degree of the weakening at the quiet Sun seems to be constant in the temperature range of 4.3 < log T < 5.4. We also find that the lines shortward of 504 Å are somewhat weakened by He i continuum absorption. From the comparison of both weakenings the temperature of the absorber is estimated to be rather low (T
e  7 × 103 K). |
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