Abstract
Excess heating of the active region solar atmosphere is interpreted by the decay of MHD slow-mode waves produced in the corona through the non-linear coupling of Alfvén waves supplied from subphotospheric layers. It is stressed that the Alfvén-mode waves may be very efficiently generated directly in the convection layer under the photosphere in magnetic regions, and that such magnetic regions, at the same time, provide the ‘transparent windows’ for Alfvén waves in regard to the Joule and frictional dissipations in the photospheric and subphotospheric layers. Though the Alfvén waves suffer considerable reflection in the chromosphere and in the transition layer, a certain fraction of this large flux is propagated out to the corona, and a large velocity amplitude exceeding the local Alfvén velocity is attained during the propagation along the magnetic tubes of force into a region of lower density and weaker magnetic field. The otherwise divergence-free velocity field in Alfvén waves gets involved in such a case with a compressional component (slow-mode waves) which again is of considerable velocity amplitude relative to the local acoustic velocity when estimated by using the formulation for non-linear coupling between MHD wave modes derived by Kaburaki and Uchida (1971). Therefore, the compressional waves thus produced through the non-linear coupling of Alvén waves will eventually be thermalized to provide a heat source. The introduction of this non-linear coupling process and the subsequent thermalization of thus produced slow-mode waves may provide means of converting the otherwise dissipation-free Alfvén mode energy into heat in the corona. The liberated heat will readily be redistributed by conduction along the magnetic lines of force, with higher density as a consequence of increased scale height, and thus the loop-like structure of the coronal condensations (or probably also the thread-like feature of the general corona) may be explained in a natural fashion.
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References
Alfvén, H.: 1947, Monthly Notices Roy. Astron. Soc. 107, 211.
Alfvén, H. and Falthammer, C.-G.: 1963, Cosmical Electrodynamics, Oxford University Press, London, p. 85.
Altschuler, M. D., Trotter, D. E., and Orrall, F. Q.: 1972, Solar Phys. 26, 354.
Athay, R. G.: 1966, Astrophys, J. 146, 223.
Bahng, J. and Schwarzschild, M.: 1963, Astrophys. J. 137, 901.
Beckers, J. M. and Schultz, R. B.: 1972, Solar Phys. 27, 61.
Biermann, L.: 1948, Z. Astrophys. 25, 161.
Billings, D. E.: 1966, A Guide to the Solar Corona, Academic Press, New York.
Danielson, R. E.: 1964, Astrophys. J. 139, 45.
de Jager, C. and Kuperus, M.: 1961, Bull. Astron. Soc. Neth. 16, 71.
Dunn, R. B.: 1972, private communication.
Ferraro, V. C. A. and Plumpton, C.: 1958, Astrophys. J., 127, 459.
Giovanelli, R. G.: 1972, Solar Phys. 27, 71.
Howard, R. F.: 1959, Astrophys. J. 130, 193.
Jordan, S.: 1970, Astrophys. J. 161, 1189.
Kaburaki, O. and Uchida, Y.: 1971, Publ. Astron. Soc. Japan 23, 405.
Kakinuma, T. and Swarup, G.: 1962, Astrophys. J. 136, 975.
Kato, S.: 1968, Publ. Astron. Soc. Japan 20, 59.
Kopp, R.: 1968, Thesis, Harvard University, Cambridge, Mass.
Kulsrud, R. M.: 1955, Astrophys. J. 121, 461.
Kuperus, M.: 1965, Thesis, University of Utrecht, Utrecht, Holland.
Lighthill, M. J.: 1952, Proc. Roy. Soc. A221, 564.
McKenzie, J. F.: 1971, Astron. Astrophys. 15, 450.
Morse, P. M.: 1948, Vibration and Sound, McGraw-Hill, New York, p. 110.
Musman, S.: 1967, Astrophys. J. 149, 201
Newkirk, G.: 1967, Ann. Rev. Astron. Astrophys. 5, 213.
Noyes, R. B.: 1967, in R. N. Thomas (ed.), ‘Aerodynamical Phenomena in Stellar Atmospheres’, IAU Symp. 28.
Osterbrock, D. E.: 1961, Astrophys. J. 134, 347.
Piddington, J. H.: 1956, Monthly Notices Roy. Astron. Soc. 116, 314.
Saito, K. and Billings, D. E.: 1964, Astrophys. J. 140, 760.
Savage, B. D.: 1969, Astrophys. J. 156, 707.
Schatzman, E.: 1949, Ann. Astrophys. 12, 203.
Schwarzschild, M.: 1948, Astrophys. J. 107, 1.
Sheeley, N. R. Jr. and Engvold, O.: 1970, Solar Phys. 12, 69.
Stein, R. F.: 1971, Astrophys. J. Suppl. 22, 410.
Takakura, T.: 1964, Publ. Astron. Soc. Japan 16, 230.
Takakura, T.: 1967, Solar Phys. 1, 304.
Thomas, J. H., Clark, P. A., and Clark Jr., A.: 1971, Solar Phys. 16, 51.
Tsubaki, T.: 1967, Publ. Astron. Soc. Japan 19, 96.
Uchida, Y. 1963, Publ. Astron. Soc. Japan 15, 376.
Uchida, Y. 1965, Astrophys. J. 142, 335.
Uchida, Y. 1967, Astrophys. J. 147, 181.
Uchida, Y. 1969, Publ. Astron. Soc. Japan 21, 128.
Uchida, Y.: 1974a, in R. G. Athay (ed.), ‘Chromospheric Fine Structures’, IAU Symp. 56, to be published.
Uchida, Y., 1974b, ‘Comment Made to Giovanelli's Paper’ in R. G. Athay (ed.), ‘Chromospheric Fine Structures’, IAU Symp. 56, to be published.
Ulmschneider, P.: 1967, Z. Astrophys. 67, 193.
van de Hulst, H. C.: 1951, Problems of Cosmical Aerodynamics, Central Air Document Office, Dayton.
Veeder, G. J. and Zirin, H.: 1970, Solar Phys. 12, 391.
Wilson, P. R.: 1971, Solar Phys. 22, 434.
Withbroe, G.: 1973, Proc. Third Orbiting Solar Observatory Workshop, held in Stanford, 1972.
Yun, H. S.: 1970, Astrophys. J. 162, 975.
Zirin, H.: 1966, The Solar Atmosphere, Blaisdell, Waltham, Mass.
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Tokyo Astronomical Observatory, University of Tokyo, Mitaka, Tokyo.
High Altitude Observatory, National Center for Atmospheric Research, Boulder, Colorado, is sponsored by the National Science Foundation.
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Uchida, Y., Kaburaki, O. Excess heating of corona and chromosphere above magnetic regions by non-linear Alfvén waves. Sol Phys 35, 451–466 (1974). https://doi.org/10.1007/BF00151968
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DOI: https://doi.org/10.1007/BF00151968