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N. A. Yakovkin 《Solar physics》1972,27(2):493-495
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The statistical equilibrium equations for the continuum and first 10 levels of a hydrogen atom show that the radiation of a bright prominence (the brightness of the H line has attained 56 mÅ of the disc centre spectrum) is completely due to scattering of the Sun radiation. The basic unknowns are separated with certainty: electron concentration (n
e = 3.0 × 1010 cm–3), effective thickness (l = 4.2 × 108 cm) and electron temperature (T
e = 5000 K).Radiation of a very bright prominence (A
(H) = 213 mÅ; T
e = 7300 K; n
e = 5.0 × 1011 cm–3; l = 1.3 × 107 cm) is on account of electron impacts (40%) and the Sun radiation scattering (60%).The parameters are shown to depend greatly on the prominence optical thickness in the lines of the first subordinate series of a hydrogen atom. In the course of determination all the parameters and 100 interconnected integral equations of the radiation diffusion have been thickness-averaged; the population of levels has been calculated by observations using the self-absorption factors. 相似文献
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It is shown that the emission of quiescent and loop prominences in the helium D3 line and in the 4686 Å line of He+ respectively, occurs at low temperatures, of the order of 7000 K.The ionization of neutral helium is produced by short-wave solar radiation, which is absorbed in the outer layers of filaments composing a prominence. The population of helium triplet levels in prominences is determined by recombinations and subsequent resonance scattering of photospheric radiation. Transitions from triplet to singlet levels caused by electron collisions considerably reduce the line brightness.Emission of ionized helium in the 4686 Å line arises in prominence surface layers as well. In quiescent prominences the emission is very faint and is due to recombination; the second ionization is caused by the far ultraviolet radiation.In flare-like events ionized helium emits due to charge-exchange collisions. The symmetrical resonance charge-exchange of -particles is caused by helium ions in corpuscular streams which are probably generated in photospheric layers. Due to increased radiation losses the temperature of the prominence under the action of the stream is negligibly increased. With a stream density equal to 5 × 108 cm-3 and velocity 300 km/s the theoretical intensity of the 4686 He+ line is some hundreds of microängströms and agrees with observations of Goldberg-Rogozinskaya (1962, 1965) and others. 相似文献
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The following is shown on the basis of a solution of the integral diffusion equations for radiation in a multilevel helium atom under low-temperature plasma conditions (T
e = 7000 K) in the Vertical slab model: (a) Neutral helium is ionized by coronal radiation mainly in the 100–300 Å spectral region; the degree of helium ionization is maximum at the boundary planes, (b) The photorecombinations to the 23
S and 21
S levels and the photoionizations by the Balmer continuum of the Sun are very nearly balanced and this determines the population of these levels. The 23
S level is destroyed by electron impacts (this reduces the brightness of the triplet lines), and the 21
S level decays via the escape of the quanta of 584 through the 21
P level, (c) Emission in the resonance line 584 (21
P 11
S) occurs due to recombination to 21
S with subsequent absorption of quanta of infrared radiation 20581. This is a rare case. (d) The radiation of helium is generated in the vicinity of the boundary planes in the region of penetration of radiation with 200 Å, where the density of matter decreases gradually down to the coronal value. In the subordinate lines, the radiation is conditioned by the quasi-resonance scattering of photospheric radiation, (e) The calculated absolute values of the intensities of the helium and hydrogen lines are in good agreement with the observations (see Figure 6).The helium to hydrogen number ratio is close to 0.05. 相似文献
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The present work is a review of papers related to the theory of prominence radiation. Special attention is paid to stationary equations and the theory of radiation diffusion in the lines and continua of hydrogen, helium and metals.We conclude that prominences are low-temperature formations T
e
7000 K, of low density 1012 particles per cm3, n
e
1011 cm–3, effective thickness 109 cm, and that the chemical composition of prominences and that of the Sun's atmosphere are the same. The prominence radiation in the lines of hydrogen, helium and metals is due mainly to quasiresonance scattering of the photospheric radiation. 相似文献
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