Abstract
A coronal magnetic arcade can be thought of as consisting of an assembly of coronal loops. By solving equations of isobaric thermal equilibrium along each loop and assuming a base temperature of 2 × 104 K, the thermal structure of the arcade can be found. The possible thermal equilibria can be shown to depend on two parameters L *p * and h */p * representing the ratios of cooling (radiation) to condu and heating to cooling, respectively. Arcades can contain four types of loops: hot loops with summits hotter than 400000 K; cool loops at temperatures less than 80000 K along their lengths; hot-cool loops with cool summits and cool footpoints but hotter intermediate portions; and warm loops, cooler than 80000 K along most of their lengths but with summits as hot as 400000 K. Two possibilities for coronal heating are considered, namely a heating that is independent of magnetic field and a heating that is proportional to the square of the local magnetic field. When the arcade is sheared the thermal structure of the arcade may change, leading in some cases to non-equilibrium or in other cases to the formation of a cool core.
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Antiochos, S. K.: 1979, Astrophys. J.232, L125.
Antiochos, S. K. and Noci, G.: 1986, Astrophys. J.301, 440.
Antiochos, S. K., Shoub, E. C., An, C.-H., and Emslie, A. G.: 1985, Astrophys J.298, 876.
Athay, R. G.: 1966, Astrophys. J.145, 784.
Athay, R. G.: 1984, Astrophys. J.287, 412.
Ballester, J.-L. and Priest, E. R.: 1989, Astron. Astrophys.225, 213.
Basri, G. S., Linsky, J. L., Bartoe, J.-D. F., Brueckner, G., and Van Hoosier, M. E.: 1979, Astrophys. J.230, 924.
Craig, I. J. D. and McClymont, A. N.: 1987, Astrophys. J.318, 421.
Craig, I. J. D., McClymont, A. N., and Underwood, J. H.: 1978, Astron. Astrophys.70, 1.
Craig, I. J. D., Robb, T. D., and Rollo, M. D.: 1982, Solar Phys.76, 331.
Davies, J. M. and Krieger, A. S.: 1982, Solar Phys.80, 295.
Dupree, A. K. and Goldberg, L.: 1967, Solar Phys.1, 229.
Foukal, P. V.: 1975, Solar Phys.43, 327.
Foukal, P. V.: 1976, Astrophys. J.210, 578.
Foukal, P. V.: 1978, Astrophys. J.223, 1046.
Foukal, P. V.: 1981, Astrophys. J.245, 304.
Hidner, E.: 1974, Solar Phys.35, 123.
Habbal, S. and Rosner, R.: 1979, Astrophys. J.234, 1113.
Hood, A. W. and Anzer, U.: 1988, Solar Phys.115, 61.
Hood, A. W. and Priest, E. R.: 1979, Astron. Astrophys.77, 233.
Kippenhahn, R. and Schlüter, A.: 1957, Z. Astrophys.43, 364.
Landini, M. and Monsignori Fossi, B. C.: 1975, Astron. Astrophys.42, 213.
Landini, M. and Monsignori Fossi, B. C.: 1981, Astron. Astrophys.102, 391.
Priest, E. R.: 1978, Solar Phys.58, 57.
Priest, E. R.: 1981, in F. Orral (ed.), Solar Active Regions, Colorado Ass. University Press, Boulder, p. 213.
Priest, E. R.: 1982, Solar Magnetohydrodynamics, D. Reidel Publ. Co., Dordrecht, Holland, p. 94.
Priest, E. R.: 1989, Dynamics and Structure of Quiescent Solar Prominences, Kluwer Academic Publishers, Dordrecht, Holland.
Priest, E. R. and Smith, E. A.: 1979, Solar Phys.64, 267.
Rabin, D. and Moore, R. L.: 1984, Astrophys. J.285, 359.
Rosner, R., Tucker, W. H., and Vaiana, G. S.: 1978, Astrophys. J.220, 643.
Sakurai, T. and Levine, R. H.: 1981, Astrophys. J.248, 817.
Serio, S., Vaiana, G. S., Godoli, G., Matta, S., Pirronello, V., and Zappata, R.: 1978, Solar Phys.59, 65.
She, Z. S., Malherbe, J. M., and Raadu, M. A.: 1986, Astron. Astrophys.164, 364.
Sheeley, N. R., Bohlin, J. D., Breuckner, G. E., Purcell, J. D., Sherrer, V., and Tousey, R.: 1975, Solar Phys.40, 103.
Spitzer, L.: 1962, Physics of Fully Ionised Gases, 2nd edition, Wiley, Inter-Science, New York.
Steele, C. D. C.: 1989, Ph.D. Thesis, University of St. Andrews, Scotland (Ch. 6).
Steele, C. D. C. and Priest, E. R.: 1990a, Solar Phys.125, 295.
Steele, C. D. C. and Priest, E. R.: 1990b, Solar Phys.127, 65.
Tandberg-Hanssen, E.: 1974, Solar Prominences, D. Reidel Publ. Co., Dordrecht, Holland.
Vaiana, G. S., Krieger, A. S., and Timothy, A. F.: 1973, Solar Phys.32, 81.
Vernazza, J. E., Avrett, E. H., and Loeser, R.: 1981, Astrophys. J. Suppl.45, 635.
Wragg, M. A. and Priest, E. R.: 1981, Solar Phys.70, 293.
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Steele, C.D.C., Priest, E.R. Thermal equilibria of isobaric coronal magnetic arcades. Sol Phys 134, 73–97 (1991). https://doi.org/10.1007/BF00148740
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DOI: https://doi.org/10.1007/BF00148740