Abstract
Magnetic reconnection can take place between two plasma regions with antiparallel magnetic field components. In a time-dependent reconnection event, the plasma outflow region consists of a leading bulge region and a trailing reconnection layer. Magnetohydrodynamic (MHD) discontinuities, including rotational discontinuities, can be formed in both the bulge region and the trailing layer. In this paper, we suggest that the rotational discontinuities observed in the solar wind may be generated by magnetic reconnection associated with microflares in coronal holes. The structure of the reconnection layer is studied by solving the one-dimensional Riemann problem for the evolution of an initial current sheet after the onset of magnetic reconnection as well as carrying out two-dimensional MHD simulations. As the emerging magnetic flux reconnects with ambient open magnetic fields in the coronal hole, rotational discontinuities are generated in the region with open field lines. It is also found that in the solar corona with a low plasma beta (β ∼ 0.01), the magnetic energy is converted through magnetic reconnection mostly into the plasma bulk-flow energy. Since more microflares will generate more rotational discontinuities and also supply more energy to the solar wind, it is expected that the number of rotational discontinuities observed in the solar wind would be an increasing function of solar wind speed. The observation rate of rotational discontinuities generated by microflares is estimated to be dN RD/dt ∼- f/63 000 s (f > 1) at 1 AU. The present mechanism favors the generation of rotational discontinuities with a large shock normal angle.
Similar content being viewed by others
References
Alexander, C. J., Neugebauer, M., Smith, E. J., and Bame, S. J.: 1987, Tech. Note NCAR/TN-306 and Proc. Nat. Conf. for Atmos. Res., Boulder, Colorado, p. 341.
Axford, W. I. and McKenzie, J. F.: 1992, in E. Marsch and R. Schwenn (eds.), Solar Wind Seven, Pergamon Press, Oxford, p. 1.
Barnes, A.: 1979, in E. N. Parker, C. F. Kennel, and L. J. Lanzerotti (eds.), Solar System Plasma Phys. 1, North-Holland Co., p. 249.
Biernat, H. K., Heyn, M. F., Rijnbeek, R. P., Semenov, V. S., and Farrugia, C. J.: 1989, J. Geophys. Res. 94, 287.
Biernat, H. K. et al.: 1992, J. Geophys. Res. 92, 3392.
Burlaga, L. F.: 1971, J. Geophys. Res. 76, 4360.
Burlaga, L. F., Lemaire, J. E, and Turner, J. M.: 1977, J. Geophys. Res. 82, 3191.
Cohen, R. H. and Kulsrud, R. R.: 1974, Phys. Fluids 17, 2215.
Dere, K. P.: 1992, in E. Marsch and R. Schwenn (eds.), Solar Wind Seven, Pergamon Press, Oxford, p. 11.
Dungey, J. W.: 1961, Phys. Rev. Letters 6, 47.
Goodrich, C. C. and Cargill, P. J.: 1991, Geophys. Res. Letters 18, 65.
Habbal, S. R.: 1992, in E. Marsch and R. Schwenn (eds.), Solar Wind Seven, Pergamon Press, Oxford, p. 41.
Hau, L.-N. and Sonnerup, B. U. O.: 1989, J. Geophys. Res. 94, 6539.
Hau, L.-N. and Sonnerup, B. U. O.: 1991, J. Geophys. Res. 96, 15767.
Heyn, M. F., Biernat, H. K., Rijnbeek, P. P., and Semenov, V. S.: 1988, J. Plasma Phys. 40, 235.
Heyvaerts, J., Priest, E. R., and Rust, D. M.: 1977, Astrophys. J. 216, 123.
Jeffrey, A. and Taniuti, T.: 1964, Non-Linear Wave Propagation, Academic, Orlando.
Kennel, C. F., Buti, B., Hada, T., and Pellat, R.: 1988, Phys. Fluids 31, 1949.
Kentrowitz, A. R. and Petschek, H. E.: 1966, in W. B. Kunkel (ed.), Plasma Physics in Theory and Application, MacGraw-Hill, New York, p. 148.
Landau, L. D. and Lifshitz, E. M.: 1960, Electrodynamics of Continuous Media, Pergamon Press, London.
LaBelle-Hamer, A., Otto, A., and Lee, L. C.: 1994, Phys. Plasmas 1, 706.
Lee, L. C. and Kan, J. R.: 1982, J. Geophys. Res. 87, 139.
Lee, L. C., Huang, L. and Chao, J. K.: 1989, J. Geophys. Res. 94, 8813.
Lepping, R. P. and Behannon, K. W.: 1980, NASA Tech. Memo. 82036, NASA Goddard Space Flight Center, Greenbelt, Md.
Lepping, R. P. and Behannon, K. W.: 1986, J. Geophys. Res. 91, 8725.
Levy, R. H., Petschek, H. E., and Siscoe, G. L.: 1964, AIAA J. 2, 2065.
Lin, Y. and Lee, L. C.: 1993, J. Geophys. Res. 98, 3919.
Lin, Y. and Lee, L. C.: 1994, Space Sci. Rev. 65, 59.
Lin, Y., Lee, L. C., and Kennel, C. F.: 1992, Geophys. Res. Letters 19, 229.
Lyu, L. H. and Kan, J. R.: 1989, J. Geophys. Res. 94, 6523.
Ma, Z. W., Lee, L. C., and Otto, A.: 1995, J. Geophys. Res. 100, in press.
Mariani, F., Bavassano, B., Villante, U., and Ness, N. F.: 1973, J. Geophys. Res. 78, 9011.
Martin, R. N., Belcher, J. W., and Lazarus, A. J.: 1973, J. Geophys. Res. 78, 3653.
Martin, S. F.: 1988, Solar Phys. 117, 243.
Neubauer, F. M. and Barnstorf, H.: 1981, Rep. MAPE-W-100–81–31, Lindau, Germany, p. 116.
Neugebauer, M.: 1989, Geophys. Res. Letters 16, 1261.
Neugebauer, M.: 1992, in E. Marsch and R. Schwenn (eds.), Solar Wind Seven, Pergamon Press, Oxford, p. 69.
Neugebauer, M., Clay, D. R., Goldstein, B. E., Tsurutani, B. T., and Zwickl, R. D.: 1984, J. Geophys. Res. 89, 5393.
Parker, E. N.: 1957, J. Geophys. Res. 62, 509.
Parker, E. N.: 1963, Astrophys. J. Suppl. Ser. 8, 117.
Parker, E. N.: 1991, Astrophys. J. 372, 719.
Petschek, H. E.: 1964, in AAS-NASA Symposium on the Physics of Solar Flares, NASA Spec. Publ. SP-50, 425.
Porter, J. G., Moore, R. L., Reichmann, E. J., Engvold, O., and Harvey, K. L.: 1987, Astrophys. J. 241, 394.
Priest, E. R. and Forbes, T. G.: 1986, J. Geophys. Res. 91, 5579.
Richter, P. and Scholer, M.: 1989, Geophys. Res. Letters 16, 1257.
Sato, T.: 1979, J. Geophys. Res. 84, 7177.
Scholer, M.: 1989, J. Geophys. Res. 94, 15099.
Semenov, V. S., Kubyshkin, I. V., Lebedeva, V. V., Sidneva, M. V., Biernat, H. K., Heyn, M. F., Besser, B. P., and Rijnbeek, R. P.: 1992, J. Geophys. Res. 97, 4251.
Shi, Y. and Lee, L. C.: 1990, Planetary Space. Sci. 38, 437.
Siscoe, G. L.: 1974, in C. T. Russell (ed.), Solar Wind 3 IGPP, UCLA, p. 151.
Smith, E. J.: 1973, J. Geophys. Res. 78, 2054.
Solodyna, C. V., Sari, J. W., and Belcher, J. W.: 1977, J. Geophys. Res. 82, 10.
Sonnerup, B. U. O.: 1970, J. Plasma Phys. 4, 161.
Sonnerup, B. U. O., Paschmann, G., Papamastorakis, I., Sckopke, N., Haerendel, G., Bame, S. J., Asbridge, J. R., Gosling, J. T., and Russell, C. T.: 1981, J. Geophys. Res. 86, 10049.
Sweet, P. A.: 1958, in B. Lehnert (ed.), Electromagnetic Phenomena in Cosmical Physics, Cambridge University Press, London, p. 123.
Swift, D. W. and Lee, L. C.: 1983, J. Geophys. Res. 88, 111.
Taniuti, T.: 1962, Prog. Theor. Phys. 28, 756.
Turner, J. M.: 1973, J. Geophys. Res. 78, 59.
Turner, J. M. and Siscoe, G. L.: J. Geophys. Res. 76, 1816.
Ugai, M.: 1984, Plasma Phys. Contr. Fusion 26, 1549.
Wang, D. J. and Sonnerup, B. U. O.: 1984, Phys. Fluids 27, 2828.
Withbroe, G. L.: 1988, Astrophys. J. 325, 442.
Wu, C. C.: 1990, J. Geophys. Res. 95, 8149.
Wu, C. C. and Kennel, C. F.: 1992, Phys. Rev. Letters 68, 56.
Yan, M., Lee, L. C., and Priest, E. R.: 1992, J. Geophys. Res. 97, 8277.
Yang, C-K and Sonnerup, B. U. O.: 1977, J. Geophys. Res. 82, 699.
Yeh, T. and Axford, W.: 1970, J. Plasma. Phys. 4, 207.
Zirker, J. B. (ed.): 1977, Coronal Holes and High-Speed Wind Streams, Colorado Associated University Press, Boulder, p. 1.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Lee, L.C., Lin, Y. & Choe, G.S. Generation of rotational discontinuities by magnetic reconnection associated with microflares. Sol Phys 163, 335–359 (1996). https://doi.org/10.1007/BF00148006
Received:
Revised:
Issue Date:
DOI: https://doi.org/10.1007/BF00148006