Questions and Conjectures on the Origin of Stellar and Galactic Magnetic Fields

  • Eugene Parker
Part of the NATO ASI Series book series (ASIC, volume 481)

Abstract

The magnetic fields of the Sun and the Galaxy, as prototypes of the fields of other stars and galaxies, appear to originate in some form or variant of the well known αω-dynamo. However, the αω-dynamo can function only in the presence of irreversible diffusion and dissipation of the small-scale internal magnetic fields. requiring effective diffusion coefficients of the order of 1012 and 1025 cm2/sec for the Sun and Galaxy, respectively. The internal motions of scale l and velocity v provide the product lv with these magnitudes, but the effect is not one of irreversible diffusion. So the αω-dynamo does not work in the manner conventionally associated with turbulent diffusion. It is hypothesized instead that the magnetic field of the Sun is in an intensely fibril state throughout the convective zone, with rapid reconnection wherever nonparallel fibrils are pressed together by the fluid motions. The result of this scenario would seem to be a sufficiently rapid irreversible interdiffusion of fields for successful operation of the solar dynamo. For the Galaxy it is hypothesized that rapid reconnection between the extended magnetic lobes or Ω-loops that form the halo accomplished the irreversibility necessary for the operation of the galactic dynamo. However, it must be emphasized that until these conjectures are firmly established, it cannot be said that we understand the origin of the magnetic fields of stars and galaxies. The fact that there is at present no known alternative to the αω-dynamo is not to say that the αω-dynamo operation is fully understood.

Keywords

Solar Dynamo Galactic Halo Poloidal Field Gaseous Disk Galactic Magnetic Field 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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References

  1. Babcock, H. W. and Babcock, H. C. 1955, The Sun’s magnetic field 1952 — 1954, Astrophys. J. 121, 349.ADSCrossRefGoogle Scholar
  2. Backus, G.E. 1958, A class of self-sustaining dissipative spherical dynamos, Ann. Phys. 4, 372.MathSciNetADSMATHCrossRefGoogle Scholar
  3. Battaner, E., Florido, E. and Sanchez-Saavedra, M.L. 1990, Intergalactic magnetic fields and the morphology of spiral galaxies, in Galactic and Intergalactic Magnetic Fields, IAU Symp. No. 140, Heidelberg. 19–23 June, 1989, Kluwer Academic Publishers, Dordrecht, ed. R. Beck, P.P. Kronberg, and R. Wielebinski, p. 504.CrossRefGoogle Scholar
  4. Beck, R., Kronberg, P.P., and Wielenbinski, R. eds. 1990, Galactic and Intergalctic Magnetic Fields, Kluwer Academic Publishers, Dordrecht.Google Scholar
  5. Braginskii, S. I. 1964a, self-excitation of a magnetic field during the motion of a highly conducting fluid, Sov. Phys. JETP 20, 726.MathSciNetGoogle Scholar
  6. Braginskii, S.I. 1964b, Theory of the hydromagnetic dynamo, Sov. Phys. JETP 20, 1462.MathSciNetGoogle Scholar
  7. Braginskii, S.I. 1975, Nearly axis-symmetric model of the hydromagnetic dynamo of the Earth, Geoniag. Aeron. 15, 122.Google Scholar
  8. Clark, A. 1965, Production and dissipation of magnetic fields by differential fluid motions, Phys. Fluids 7, 1299.ADSCrossRefGoogle Scholar
  9. Cowling, T.G. 1933, The magnetic field of sunspots, Mon. Not. Roy. Astron. Soc. 94, 39.ADSMATHGoogle Scholar
  10. Donner, K. J, Bradenburg, A., and Thomasson, M. 1993, Galactic dynamos and dynamics in The Cosmic Dynamo, IAU Symp. No. 157, Potsdam, 7–11, September, 1992, Kluwer Academic Publishers, Dordrecht, ed. F. Krause, K.W. Rädler, and G. Rüdiger, p. 333.Google Scholar
  11. D’Silva, S. 1993, Can equipartition fields produce the titlts of bipolar magnetic regions? Astrophys. J. 407, 395.Google Scholar
  12. D’Silva, S. and Choudhuri, A.R. 1993, A theoretical model for tilts of bipolar magnetic regions, Astron. Astrophys. 272, 621.ADSGoogle Scholar
  13. Elsasser, W.M. 1946a, Induction effects in terrestrial magnetism. Part I. Theory Phys. Rev. 69, 106.MathSciNetADSMATHCrossRefGoogle Scholar
  14. Elsasser, W.M. 1946b, Induction effects in terrestrial magnetism. Part II. The secular variation, Phys. Rev. 70, 202.MathSciNetADSMATHCrossRefGoogle Scholar
  15. Elsasser, W.M. 1947, Induction effects in terrestrial magnetism. Part III. Electric modes, Phys. Rev. 72, 821.MathSciNetADSMATHCrossRefGoogle Scholar
  16. Elsasser, W.M. 1950a, The hydromagnetic equations, Phys. Rev. 79, 183.ADSMATHCrossRefGoogle Scholar
  17. Elsasser, W.M. 1950b, The Earth’s interior and geomagnetism, Rev. Mod. Phys. 22, 1.ADSCrossRefGoogle Scholar
  18. Elsasser, W.M. 1954, Dimensional relations in magnetohydrodynamics, Phys. Rev. 95, 1.MathSciNetADSMATHCrossRefGoogle Scholar
  19. Elsasser, W.M. 1956, Hydromagnetic dynamo theory, Rev. Mod. Phys. 28, 135.MathSciNetADSMATHCrossRefGoogle Scholar
  20. Elsasser, W.M. 1957, The terrestrial dynamo, Proc. Natl. Acad. Sci. 43, 14.ADSCrossRefGoogle Scholar
  21. Fan, Y., Fisher, G.H., and DeLuca, E.E. 1993, The origin of morphological asymmetries in bipolar active regions, Astrophys. J. 405, 390.ADSCrossRefGoogle Scholar
  22. Fujimoto, M. and Sawa, T. 1989, Generation and maintenance of bisymmetric spiral magnetic fields and interaction with spiral density waves, Geophys. Astrophys. Fluid Dyn 50, 159.ADSCrossRefGoogle Scholar
  23. Gilman, P.A. 1969a, A Rossby wave dynamo for the Sun. I, Solar Phys. 8, 316.ADSCrossRefGoogle Scholar
  24. Gilman, P.A. 1969b, A Rossby wave dynamo for the Sun. II, Solar Phys. 9, 3.ADSCrossRefGoogle Scholar
  25. Giovannini, G., Kim, K.T., Kronberg, P.P. and Venturi, T. 1990, Evidence for a largescale magnetic field in the Coma-Al367 super cluster, in Galactic and Intergalactic magnetic fields, IAU symp. No. 140, Heidelberg, 19–23 June 1989, Kluwer Academic Publishers, Dordrecht, ed. R. Beck, P.P. Kronberg, and R. Wielebinski, p. 492.CrossRefGoogle Scholar
  26. Goldreich and SridharGoogle Scholar
  27. Hartquist, T.W. and Morfill, G.E. 1986, A model of static cosmic-ray supported galactic coronae, Astrophys. J. 311, 518.ADSCrossRefGoogle Scholar
  28. Jokipii, J.R. and Parker, E.N. 1969, Cosmic-ray life and the stochastic nature of the galactic magnetic field, Astrophys. J. 155, 799.ADSCrossRefGoogle Scholar
  29. Kim, K.T. and Kronberg, P.P. 1990, The strength and structure of the intercluster magnetic field in the coma-cluster of galaxies, in Galactic and Intergalactic Magnetic Fields. IAU Symp. No 140, Heidelberg, 19–23 April, 1989. Kluwer Academic Publishers, Dordrecht, ed. R. Beck, P.P. Kronberg, and R. Wielebinski, p. 483.CrossRefGoogle Scholar
  30. Ko, C.M. 1990, A study of the kinematic dynamo equation with time dependent coefficients, Astrophys. J. 360, 151.ADSCrossRefGoogle Scholar
  31. Ko, C.M. 1993, A similarity solution to the kimenatic a2u; dynamo equation with time dependent coefficients, Astrophys. J. 410, 128.ADSCrossRefGoogle Scholar
  32. Ko, C.M. and Parker, E.N. 1988, Intermittent behavior of galactic dynamo activity, Astrophys. J. 341, 828.ADSCrossRefGoogle Scholar
  33. Krause, F.K. and Rädler, K.H. 1980, Mean-Field Magnetohydrodynamics and Dynamo Theory, Pergamon Press, New York.MATHGoogle Scholar
  34. Krause, F., Rädler, K.H., and Rüdiger, G. editors. 1993, The Cosmic Dynamo, IAU Symp. No. 157, Potsdam 7–11 Sept. 1992, Kluwer Academic Publishers, Dordrecht.Google Scholar
  35. Kronberg, P.P. 1987, in Interstellar Magnetic Fields, Springer, Berlin, ed. R. Beck and R. Graves, p. 86.Google Scholar
  36. Kulsrud, R.M. 1990, The present state of a primordial magnetic field, in Galactic and Intergalactic Magnetic Fields. IAU Symp. No. 140, Heidelburg, 19–23 June, 1989, Kluwer Academic Publishers, Dordrecht, ed. R. Beck, P.P. Kronberg, and R. Wielebinski, p. 527.Google Scholar
  37. Kulsrud, R.M. and Anderson, S.W. 1992, The spectrum of random magnetic fields in the mean field dynamo theory of the galactic magnetic field, Astrophys. J. 396, 606.ADSCrossRefGoogle Scholar
  38. Leighton, R.B. 1969, A magneto-kinematic model of the solar cycle, Astrophys. J. 156, 1.ADSCrossRefGoogle Scholar
  39. Lerche, I. and Parker, E.N. 1966, Nonrelativistic equations of bulk motion of a relativistic gas, Astrophys. J. 145, 106.ADSCrossRefGoogle Scholar
  40. Lin, C.C., Yuan, C. and Shu, F.H. 1968, On the spiral structure of disk galaxies. Ill Comparison with observations, Astrophys. J. 155, 721, erratum 156, 797.ADSCrossRefGoogle Scholar
  41. Moffatt, H.K. 1978, magnetic Field Generation in Electrically Conducting Fluids, Cambridge University Press, Cambridge.Google Scholar
  42. Moss, D., Brandenburg, A., Donner, K. J., and Thomasson, M. 1993, in the Cosmic Dynamo, IAU Symp. No. 157, Potsdam, 7–11 Sept., 1992. Kluwer Academic Publishers, Dordrecht, ed. F. Krause, K.H. Rädler, and G. Rüdiger, p. 339.CrossRefGoogle Scholar
  43. Parker, E.N. 1955, Hydromagnetic dynamo models, Astrophysic. J. 122, 293.ADSCrossRefGoogle Scholar
  44. Parker, E.N. 1957, The solar hydromagnetic dynamo, Proc. nati. Acad. Sci. 43, 8.ADSCrossRefGoogle Scholar
  45. Parker, E.N. 1963, Kinematical hydromagnetic theory and its application to the low solar photosphere, Astrophys. J. 138, 552.ADSMATHCrossRefGoogle Scholar
  46. Parker, E.N. 1965, Cosmic rays and their formation of a galactic halo, Astrophys. J. 142, 584.ADSCrossRefGoogle Scholar
  47. Parker, E.N. 1966a, The kinetic properties of the cosmic ray gas, Astrophys. J. 144, 916.ADSCrossRefGoogle Scholar
  48. Parker, E.N. 1966b, The dynamical state of the interstellar gas and field, Astrophys. J. 145, 811.ADSCrossRefGoogle Scholar
  49. Parker, E.N. 1966c, General dynamical effects of cosmic rays in the Galaxy, in Proc. of the Ninth International Conference on Cosmic Rays, Vol 1, 126, The Physical Society, London.Google Scholar
  50. Parker, E.N. 1967, Dynamical state of the interstellar gas and field. II. Nonlinear growth of clouds and forces in three dimensions, Astrophys. J. 149, 517.ADSCrossRefGoogle Scholar
  51. Parker, E.N. 1968, Dynamical properties of cosmic rays, Chap. 14 in Nebulae and Interstellar Matter, Vol. VII Stars and Stellars Systems. University of Chicago Press, Chicago, ed. B.M. Middlehurst and L.H. Aller.Google Scholar
  52. Parker, E.N. 1969, the galactic effects of the cosmic-ray gas, Space Sci. Rev. 9, 651.ADSGoogle Scholar
  53. Parker, E.N. 1970, The generation of magnetic fields in astrophysical bodies: I. The dynamo equations, Astrophys. J. 162, 665.ADSCrossRefGoogle Scholar
  54. Parker, E.N. 1971a, The generation of magnetic fields in astrophysical bodies: II. The galactic field, Astrophys. J. 163, 255.ADSCrossRefGoogle Scholar
  55. Parker, E.N. 1971b, The generation of magnetic fields in astrophysical bodies: IV. The solar and terrestrial dynamos, Astrophysic. J. 164, 491.ADSCrossRefGoogle Scholar
  56. Parker, E.N. 1979, Cosmical Magnetic Fields, Oxford, Clarendon Press.Google Scholar
  57. Parker, E.N. 1984a, Stellar fibril magnetic systems. I. Reduced energy state, Astrophys. J. 283, 343.ADSCrossRefGoogle Scholar
  58. Parker, E.N. 1984b, Stellar fibril magnetic fields. II. Two dimensional magnetohydrodynamic equations, Astrophys. J. 294, 47.ADSCrossRefGoogle Scholar
  59. Parker, E.N. 1984c, Stellar fibril magnetic fields. III. Convective counterflow, Astrophys. J. 293, 57.Google Scholar
  60. Parker, E.N. 1990, Spontaneous discontinuties in galactic magnetic fields and the creation of galactic radio halos, in Galactic and Integalactic Magnetic Fields. Proc. IAU Symp. No. 140, Heidelberg, June 19–23, 1989, Kluwer Academic Publishers, Dordrecht, ed. R. Beck, P.P. Kronberg, and R. Wielebinski, P. 169.CrossRefGoogle Scholar
  61. Parker, E.N. 1992, Fast dynamos cosmic rays and the galactic magnetic field, Astrophys. J. 401, 137.ADSCrossRefGoogle Scholar
  62. Parker, E.N. 1993a, Galactic cosmic rays and galactic halo X-ray emission, in Currents in Astrophysics and Cosmology, Cambridge University Press, Cambridge, ed. G.G. Fazio and R. Silberberg, p. 3.Google Scholar
  63. Parker, E.N. 1993b, A solar dynamo surface wave at the interface between convection and nonuniform rotation, Astrophys. J. 408, 707.ADSCrossRefGoogle Scholar
  64. Parker, E.N. 1996Google Scholar
  65. Rüdiger, G., Elstner, D. and Schultz, M. 1993, The galactic dynamo: modes and models in The Cosmic Dynamo, IAU Symp. No. 157, Potsdam, 7–11 Spet. 1992, Kluwer Academic Publishers, Dordrecht, ed. F. Krause, K.H. Rädler, and G. Rüdiger, p. 321.Google Scholar
  66. Ruzmaikin, A.A., Shukurov, A.M., and Sokoloff, D.D. 1988, Magnetic Fields of Galaxies, Kluwer Academic Publishers, Dordrecht.CrossRefGoogle Scholar
  67. Schlickeiser, R. and Rephaeli, Y. 1990, Intracluster magnetic fields from X-ray and radio measurements, in Galactic and Intergalactic Magnetic Fields, IAU Symp. No. 140, Heidelberg, 19–23 June 1989, Kluwer Academic publishers, Dordrecht, ed. R. Beck, P.P. Kronberg, and R. Wielebinski, p. 487.CrossRefGoogle Scholar
  68. Schmidt, M. 1957, Spiral structure in the inner parts of the galactic system derived from the hydrogen emission at 21 cm wave length, Bull. Astron. Inst. Netherlands 13, 247.ADSGoogle Scholar
  69. Sokoloff, D.D., Ruzmaikin, A.A. and Shukurov, A. 1990, Intermittent magnetic fields generated by turbulence in galaxies and galaxy cluster, in Galactic and Intergalactic Magnetic Fields, IAU Symp. No. 140, Heidelberg, 19–23 June 1989, Kluwer Academic Publishers, Dordrecht, ed. R. Beck, P.P. Kronberg, and R. Wielebinski, p. 499.CrossRefGoogle Scholar
  70. Soward, A.M. 1972, A kinematic theory of large magnetic Reynolds number dynamos, Phil. Trans. Roy. Soc. London 272, 431.ADSMATHCrossRefGoogle Scholar
  71. Soward, A.M. and Roberts, P.H. 1976, Magnitnaya Gidrodinanika 1, 3.Google Scholar
  72. Spruit, W.C. 1974, A model of the solar convection zone, solar Phys. 34, 277.ADSCrossRefGoogle Scholar
  73. Steenbeck, M. and Krause, F. 1969a, Zur dynamotheorie stellarer and planeterar magnet felder I. Berechnumg sonnenähnlicher Wechsel feldgeneratoren, Astron. Nachr. 291, 49.ADSMATHCrossRefGoogle Scholar
  74. Steenbeck, M. and Krause, F. 1969b, Zur dynamotheorie stellarer and planetarer magnetfelder II. Berechnung planeten ähnlicher gleich feldgeneratoren, Astron. Nachr. 291, 271.ADSMATHCrossRefGoogle Scholar
  75. Tajima, J., Cable, S., Shibata, K. and Kulsrud, R.M. 1992, On the origin of cosmical magnetic fields, Astrophys. J. 390, 309.ADSCrossRefGoogle Scholar
  76. Tosa, M. and Chiba, M. 1990, in Galactic and Intergalactic Magnetic Fieldss, IAU Symp. No. 140, Heideberg, 19–23 June 1989, ed. Kluwer Academic Publishers, Dordrecht, ed. R. Beck, P.P. Kronberg, and R. Wielebinski, p. 127.CrossRefGoogle Scholar
  77. Vainshtein, S.I., Parker, E.N. and Rosner, R. 1993, On the generation of “strong” magnetic fields, Astrophys. J. 404, 773.ADSCrossRefGoogle Scholar
  78. Vallee, J.P. 1990, A possible excess rotation measure and large-scale magnetic field in the Virgo supercluster of galaxies, Astron. J. 99, 459.ADSCrossRefGoogle Scholar
  79. Vallee, J.P., Macleod, J.M. and Broten, N.W. 1986, A large-scale magnetic field in the galaxy cluster A2319, Astron. Astrophys. 156, 386.ADSGoogle Scholar
  80. Vishniac, E.T. 1995, The dynamics of flux tubes in a high β plasma, Astrophys. J. (in press).Google Scholar
  81. Walker, M.R. and Barenghi, C.F. 1994, High resolution numerical dynamos in the limit of a thin disk galaxy, Geophys. Astrophys. Fluid Dyn. 76, 265.ADSCrossRefGoogle Scholar
  82. Weiss, N.O. 1966, The expulsion of magnetic flux by eddies, Proc. Roy. Soc. A. 293, 310.ADSCrossRefGoogle Scholar
  83. Zwaan, C. 1985, the emergence of magnetic flux, Solar Phys. 100, 397.ADSCrossRefGoogle Scholar

Copyright information

© Kluwer Academic Publishers 1996

Authors and Affiliations

  • Eugene Parker
    • 1
  1. 1.Enrico Fermi Institute and Depts. of Physics and AstronomyThe University of ChicagoChicagoUSA

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