Abstract
The height distribution of hard X-ray bremsstrahlung is predicted for dissipative thermal models, involving rapid heating of many small (tearing mode) islands near the top of a magnetic arch. Emission at low energies (ɛ) originates mainly at high altitudes in the heated kernels themselves while high energy emission comes from the Maxwellian tail electrons escaping to the chromosphere.
For a power-law distribution of kernel production temperatures, the ratio of high to low altitude emissions should vary as ɛ −2. Recent stereo occultation results (Kane et al., 1979) are consistent with this prediction for a typical size of primary dissipation kernel ≃10 km/(n/1011) for kernel density n(cm−3). The prediction should also prove a useful diagnostic for SMM data.
However the small kernel size required to explain the weakness of the coronal emission demands the heating of 8 × 1036 electrons per second to above 5 keV temperatures. This is comparable to the acceleration rate above 5 keV needed in a thick target model, so that the thermal model has little energetic advantage in this event.
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References
Brown, J. C. and McClymont, A. N.: Solar Phys. 41, 135.
Brown, J. C. and Melrose, D. B.: 1977, Solar Phys. 52, 117.
Brown, J. C., Canfield, R. C., and Robertson, M. N.: 1978, Solar Phys. 57, 399.
Brown, J. C., Melrose, D. B., and Spicer, D. S.: 1979, Astrophys. J. 228, 512 (BMS).
Brown, J. C., Craig, I. J. D., and Karpen, J. T.: 1980, Solar Phys. 67, 143 (BCK).
Brown, J. C., Hayward, J., and Spicer, D. S.: 1981, Astrophys. J. Letters 245, in press (BHS).
Canfield, R. C.: 1980, preprint UCSD-SP-80-04.
Emslie, A. G.: 1981, Astrophys. J., in press.
Hoyng, P., Duijveman, A., Machado, M. E., Rust, D. M., Švestka, Z., Boelee, A., Frost, K. J., Lafleur, H., Simnett, G. M., van Beek, H. F., and Woodgate, B. E.: 1981, submitted to Astrophys. J. Letters.
Kane, S. R.: 1974, in G. A. Newkirk (ed.), ‘Coronal Disturbances’, IAU Symp. 57, 105.
Kane, S. R., Anderson, K. A., Evans, W. D., Klebesadel, R. W., and Laros, J.: 1979, Astrophys. J. Letters 233, L151.
Kane, S. R., Crannell, C. J., Datlowe, D. W., Feldman, U., Gabriel, A., Hudson, H. S., Kundu, M. R., Mätzler, C., Neidig, D., Petrosian, V., and Sheeley, N. R.: 1980, in P. A. Sturrock (ed.), Solar Flares, Colorado, Assoc. Univ. Press, p. 187.
Melrose, D. B. and Brown, J. C.: 1976, Monthly Notice Roy. Astron. Soc. 176, 15.
Mätzler, C., Bai, T., Crannell, C. J., and Frost, K. J.: 1978, Astrophys. J. 223, 1058.
Sermulina, B. J., Somov, B. V., Spektor, A. R., and Syrovatskii, S. I.: 1980, in M. Dryer and E. Tandberg-Hansen (eds.), ‘Solar and Interplanetary Dynamics’, IAU Symp. 91, 491.
Smith, D. F. and Auer, L. H.: 1980, Astrophys. J. 238, 1126.
Smith, D. F. and Brown, J. C.: 1980, Astrophys. J. 242, 799.
Smith, D. F. and Lilliequist, C. G.: 1979, Astrophys J. 232, 582.
Spicer, D. S.: 1977, Solar Phys. 53, 305.
Spitzer, L. W.: 1962, Physics of Fully Ionised Gases, Wiley Interscience, New York.
Vlahos, L. and Papadopoulos, D.: 1979, Astrophys. J. 233, 717.
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Brown, J.C., Hayward, J. Height structure of thermal hard x-ray sources on the sun. Sol Phys 73, 121–132 (1981). https://doi.org/10.1007/BF00153149
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DOI: https://doi.org/10.1007/BF00153149