Abstract
The equilibrium and stability of a loop in which energy storage occurs prior to a solar flare is discussed. Working on the hypothesis, that the onset of the flare begins only after sufficient magnetic energy has been stored in the loop typical values of parameters which describe the equilibrium are found for a magnetic field with a constant twist. The stability of this configuration is examined next and it is shown that for the force-free case, the structure is always unstable to kinking for any degree of twist. However, a slight deviation from the force-free configuration, through the presence of a small positive transverse pressure gradient, can stabilize the loops for moderate degrees of twist. The range of wave-numbers for which instability occurs and the maximum growth rates are also presented. Lastly, it is shown that the pressure gradients required to stabilize a pre-flare loop do not lead to conflict with observations.
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References
Alfvén, H. and Carlquist, P.: 1967, Solar Phys. 1, 220.
Altschuler, M. D.: 1974, in G. Newkirk, Jr. (ed.), ‘Coronal Disturbances’, IAU Symp. 57, 3.
Anzer, U.: 1968, Solar Phys. 3, 298.
Bernstein, I. B., Frieman, E. A., Kruskal, M. D., and Kulsrud, R. M.: 1958, Proc. Roy. Soc. A244, 17.
Brueckner, G. E., Patterson, N. P., and Scherrer, V. E.: 1976, Solar Phys. 47, 127.
Cheng, C. C. and Widing, K.: 1975, Astrophys. J. 201, 735.
Foukal, P. V.: 1975, Solar Phys. 43, 327.
Foukal, P. V.: 1976, Astrophys. J. 210, 575.
Giachetti, R., Van Hoven, G., and Chiuderi, C.: 1977, Solar Phys. 55, 371.
Goedbloed, J. P. and Hagebuk, E. J.: 1972, Phys. Fluids 15, 1090.
Harvey, K. O. and Harvey, J. W.: 1973, Solar Phys. 28, 61.
Hasan, S. S.: 1977, unpublished D. Phil. thesis, Oxford.
Hasan, S. S.: 1978, IAU Colloq. 44, 233.
Jordan, C.: 1976, Phil. Trans. Roy. Soc. London A281, 391.
Kahler, S. W., Krieger, A. S., and Vaina, G. S.: 1975, Astrophys. J. Letters 199, L57.
Krall, A. N. and Trivelpiece, A. W.: 1973, Principles of Plasma Physics, McGraw-Hill, pp. 241–246.
Livingston, W. and Harvey, J. W.: 1969, Solar Phys. 10, 294.
Lundquist, S.: 1950, Ark. Fys. 2, 361.
Lust, R. and Hain, K.: 1958, Z. Naturforsch. 13a, 936.
Moreton, G. and Severney, A. B.: 1968, Solar Phys. 3, 282.
Pallavicini, R., Serio, S., and Vaiana, G. S.: 1977, Astrophys. J. 216, 108.
Petrasso, R. D., Kahler, S. W., Krieger, A. S., Silk, J. K., and Vaiana, G. S.: 1975, Astrophys. J. Letters 199, L127.
Rust, D. M. and Bar, V.: 1973, Solar Phys. 33, 445.
Severny, A. B.: 1965, Astron. Zh. 42, 217.
Spicer, D. B.: 1977, NRL Report 8036.
Van Hoven, G., Chiuderi, C., and Giachetti, R.: 1977, Astrophys. J. 213, 869.
Vorpahl, J. A., Gibson, E. G., Landecker, P. B., McKenzie, D. L., and Underwood, J. H.: 1975, Solar Phys. 45, 199.
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Hasan, S.S. Magnetohydrodynamic equilibrium and stability of pre-flare loops. Sol Phys 67, 267–283 (1980). https://doi.org/10.1007/BF00149807
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DOI: https://doi.org/10.1007/BF00149807