Abstract
Simple analytic models for the passive evolution of arcade-like magnetic fields through a series of force-free equilibria are presented. At the photospheric boundary, the normal magnetic field component is prescribed together with either the longitudinal field component or the photospheric shear. Analytic progress is made by considering either cylindrically symmetric solutions or using the separation of variables technique.
Two distinct cylindrically symmetric force-free fields are obtained that possess the same normal field component and photospheric shear. The scond field contains a magnetic bubble. As the shear increases beyond a critical value, so the magnetic energy of the first configuration exceeds that of the second. The possibility is therefore suggested of an eruption of the first field outwards towards the second. Such an eruptive instability is proposed as the origin of a two-ribbon solar flare.
A new analytic solution to the force-free field equations, of separable form, is discovered and it is pointed out that the existence of shear in a magnetic field does not preclude it from being potential.
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References
Alfvén, H. and Carlqvist, P.: 1967 Solar Phys. 1, 220.
Barnes, C. W. and Sturrock, P. A.: 1972, Astrophys. J. 174, 659.
Birn, J., Goldstein, H., and Schindler, K.: 1978 Solar Phys. 57, 81.
Chen, F. F.: 1974, Introduction to Plasma Physics, Plenum Press, New York.
Giachetti, R., Van Hoven, G., and Chiuderi, C.: 1977, Solar Phys. 55, 371.
Heyvaerts, J., Priest, E. R., and Rust, D. M.: 1977 Astrophys. J. 216, 123.
Heyvaerts, J., Lasry, J. M., Schatzman, M., and Witomsky, G.: 1980, in press.
Hood, A. W. and Priest, E. R.: 1979a, Astron. Astrophys. 77, 233.
Hood, A. W. and Priest, E. R.: 1979b, Solar Phys. 64, 303.
Jockers, K.: 1978, Solar Phys. 56, 37.
Kruskal, M. D.: 1954, U.S. Atomic Energy Commission Report No. NYO-6015.
Low, B. C.: 1977, Astrophys. J. 212, 234.
Low, B. C. and Nakagawa, Y.: 1975, Astrophys. J. 199, 237.
Priest, E. R.: 1976a, ‘Physics of Solar Planetary Environment’, in D. M. Williams (ed.), American Geophysical Union, Vol. 1, p. 144.
Priest, E. R.: 1976b, Solar Phys. 47, 41.
Raadu, M. A.: 1972, Solar Phys. 22, 425.
Sakurai, T.: 1976, Publ. Astron. Soc. Japan 28, 177.
Smith, S. F. and Ramsey, H. E.: 1964, Z. Astrophys. 60, 1.
Spicer, D. S.: 1977, Solar Phys. 53, 305.
Sturrock, P. A. (ed.): 1980, Proceedings of the Skylab Workshop on Solar Flares, in press.
Sturrock, P. A. and Woodbury, E. T.: 1967, in P. A. Sturrock (ed.), Rendiconti della Scuola Internazionale de Fisica, ‘Enrico Fermi’, 39 Corso, New York, London, p. 160.
Švestka, Z.: 1976, Solar Flares, D. Reidel Publ. Co., Dordrecht, Holland.
Tur, T. J. and Priest, E. R.: 1978, Solar Phys. 58, 181.
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Now at AWRE, Aldermaston, Reading, Berkshire.
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Priest, E.R., Milne, A.M. Force-free magnetic arcades relevant to two-ribbon solar flares. Sol Phys 65, 315–346 (1980). https://doi.org/10.1007/BF00152797
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DOI: https://doi.org/10.1007/BF00152797