Abstract
We identify the Balmer 9 and 11 lines of He ii at 959 Å and 942 Å in solar spectra. These lines are produced mainly by recombination following photoionization of He ii by coronal XUV radiation. From analysis of the line intensities, we confirm the theoretical model of Avrett et al. (1976), who found that an appreciable amount of He++ is present at temperatures of 1–2 × 104 K and that the anomalously strong He ii λ304 line is produced primarily by collisional excitation. We also confirm the suggestion of Kohl (1977) that the photoionization-recombination process is more important in active regions than in the quiet Sun, and we find that the λ304 line is produced largely by recombination in solar flares.
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Avrett, E. H., Vernazza, J. E., and Linsky, J. L.: 1976, Astrophys. J. Letters 207, L199.
Garcia, J. D. and Mack, J. E.: 1965, J. Opt. Soc. Am. 55, 654.
Johnson, L. C.: 1972, Astrophys. J. 174, 227.
Jordan, C.: 1969, Monthly Notices Roy. Astron. Soc. 142, 501.
Jordan, C.: 1975, Monthly Notices Roy. Astron. Soc. 170, 429.
Kohl, J. L.: 1977, Astrophys. J. 211, 958.
McWhirter, R. P. W.: 1965, in Plasma Diagnostic Techniques, Academic Press, New York, p. 201.
Morton, D. C. and Underhill, A. B.: 1977, Astrophys. J. Suppl. 33, 83.
Noyes, R. W.: 1979, in preparation.
Pengelly, R. M. and Seaton, M. J.: 1964, Monthly Notices Roy. Astron. Soc. 126, 165.
Raymond, J. C.: 1978, Astrophys. J. 224, 259.
Raymond, J. C.: 1979, Astrophys. J. Suppl., in press.
Reeves, E. M., Huber, M. C. E., and Timothy, J. G.: 1977, Appl. Opt. 16, 837.
Seaton, M. J.: 1959, Monthly Notices Roy. Astron. Soc. 119, 81.
Shine, R., Gerola, W., and Linsky, J. L.: 1975, Astrophys. J. Letters 202, L101.
Summers, H. P.: 1974, Internal Memo 367, Appleton Laboratory, Culham Laboratory, Ditton Park, Slough, England.
Timothy, J. G.: 1979, in preparation.
Tworkowski, A.: 1976, Astrophys. Letters 17, 27.
Weisheit, J. C., Tarter, C. B., Scofield, J. H., and Richards, L. M.: 1976, J. Quant. Spectrosc. Radiat. Transfer 16, 659.
Vernazza, J. E. and Reeves, E. M.: 1978, Astrophys. J. Suppl. 37, 485.
Zirin, H.: 1975, Astrophys. J. Letters 199, L63.
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Raymond, J.C., Noyes, R.W. & Stopa, M.P. The Balmer 9 and Balmer 11 lines of He ii in the Sun. Sol Phys 61, 271–277 (1979). https://doi.org/10.1007/BF00150411
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DOI: https://doi.org/10.1007/BF00150411