Abstract
To overcome the difficulty in effective dissipation of currents in electromagnetic flare models associated with high gas-kinetic conductivity of the solar plasma, attention is given to the possibility of a local decrease in conductivity in the places of highly developed MHD turbulence near the neutral lines of photospheric magnetic configurations. The concept of redistribution of electrical conductivity, which is based on the following physical effects and conditions known from the observations in the solar atmosphere, is proposed: (1) A decrease in the electrical conductivity parameter (increase in the resistivity) in a turbulent medium. (2) Magnetic suppression of turbulence under the influence of strong magnetic fields. (3) Excitation of a large-scale electric field by macroscopic plasma motions in the photosphere in the presence of a magnetic field (photospheric dynamo). (4) The observable spatial inhomogeneous structure of magnetic configurations in the vicinity of sunspot groups, which leads to the formation of current layers with zero (neutral) magnetic fields lines. The calculated values of the MHD-turbulent conductivity near neutral magnetic lines in the photosphere turn out to be almost three orders of magnitude smaller than the values of the regular gas-kinetic conductivity in the places of strong magnetic fields in the vicinity of sunspots. A significantly reduced conductivity in the regions of highly developed MHD turbulence can contribute to accelerated Joule current dissipation, whose energy is consistent with the characteristics of thermal flares.
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REFERENCES
S. I. Vainshtein, Ya. B. Zel’dovich, and A. A. Ruzmaikin, Turbulent Dynamo in Astrophysics, (Nauka, Moscow, 1980) [in Russian].
V. N. Krivodubskii, “Electric conductivity of the substance in below-photospherics layers on the Sun,” Probl. Kosm. Fiz. 8, 3–15 (1973).
V. N. Krivodubskii, “On turbulent conductivity and magnetic permeability of solar plasma,” Soln. Dannye, No. 7, 99–109 (1982).
V. N. Obridko, Sunspots and Complexes of Activity (Nauka, Moscow, 1985) [in Russian].
A. V. Stepanov, “Fundamental models of flares,” in Plasma Heliogeophysics, Vol. 1, Ed. by L. M. Zelenyi and I. S. Veselovskii (Fizmatlit, Moscow, 2008) [in Russian].
S.-I. Akasofu, “An electric-current description of solar flares,” Astrophys. Space Sci. 144, 303–309 (1988).
H. Alfvén and P. Carlqvist, “Currents in the solar atmosphere and a theory of solar flares,” Sol. Phys. 1, 220–228 (1967).
O. Gingerich, R. W. Noyes, W. Kalkofen, and Y. Cuny, “The Harvard-Smithsonian reference atmosphere,” Sol. Phys. 18, 347–365 (1971).
R. G. Giovanelli, “A theory of chromospheric flares,” Nature 158, 81–82 (1946).
R. G. Giovanelli, “Magnetic and electric phenomena in the Sun’s atmosphere associated with sunspot,” Mon. Not. R. Astron. Soc. 107, 338–355 (1947).
R. G. Giovanelli, “Chromospheric flares,” Mon. Not. R. Astron. Soc. 108, 163–176 (1948).
T. Gold and F. Hoyle, “On the origin of solar flares,” Mon. Not. R. Astron. Soc. 120, 89–105 (1960).
J. Heyvaerts, E. Priest, and D. Rust, “An emerging flux model for the solar flare phenomenon,” Astrophys. J. 216, 213–231 (1977).
J. R. Kan, S.-I. Akasofu, and L. S. Lee, “A dynamo theory of solar flares,” Sol. Phys. 84, 153–167 (1983).
M. Kopecky and G. V. Kuklin, “On a more precise calculation of the electric conductivity in the photosphere and in sunspot,” Sol. Phys. 6, 241–250 (1969).
A. G. Kosovichev and V. V. Zharkova, “Magnetic energy release and transients in the solar flare of 2000 July 14,” Astrophys. J. 550, L105–L108 (1991).
F. Krause and K.-H. Rädler, Mean Field Magnetohydrodynamics and Dynamo Theory (Pergamon, Oxford, 1980).
V. N. Krivodubskij, “Turbulent dynamo near tachocline and reconstruction of azimuthal magnetic field in the solar convection zone,” Astron. Nachr. 326, 61–74 (2005).
V. N. Krivodubskij, “Turbulent effects of sunspot magnetic field reconstruction,” Kinematics Phys. Celestial Bodies 28, 232–238 (2012).
D. B. Melrose, “Solar flares — Current dissipation or magnetic annihilation?,” Aus. J. Phys. 46, 167–193 (1993).
E. R. Priest, Solar Magnetohydrodynamics (Reidel, Dordrecht, 1982).
E. Priest and T. Forbes, Magnetic Reconnection: MHD Theory and Applications (Cambridge Univ. Press, Cambridge, 2000).
H. K. Sen and M. L. A. White, “Physical mechanism for the production of solar flares,” Sol. Phys. 23, 146–154 (1972).
A. B. Severny, “Solar magnetic fields,” Space Sci. Rev. 3, 451–486 (1964).
B. V. Somov, Physical Processes in Solar Flares (Kluwer, Dordrecht, 1992).
B. V. Somov, “On the magnetic reconnection of electric currents in solar flares,” Astron. Lett. 38, 128–138 (2012).
M. Stix, The Sun, 2nd ed. (Springer-Verlag, Berlin, 2002).
V. V. Zaitsev and A. V. Stepanov, “On the dynamo theory of solar flares,” Sov. Astron. 35, 189–193 (1991).
Ya. V. Zeldovich, A. A. Ruzmaikin, and D. D. Sokoloff, Magnetic Fields in Astrophysics (Gordon and Breach, New York, 1983).
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Translated by M. Chubarova
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Krivodubskij, V.N. On the Role of MHD Turbulence in the Decrease of Electrical Conductivity of Plasma in the Sun’s Active Magnetic Region. Kinemat. Phys. Celest. Bodies 35, 124–128 (2019). https://doi.org/10.3103/S0884591319030048
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DOI: https://doi.org/10.3103/S0884591319030048