Abstract
The observational difficulties of obtaining the magnetic field distribution in the chromosphere and corona of the Sun has led to methods of extending photospheric magnetic measurements into the solar atmosphere by mathematical procedures. A new approach to this problem presented here is that a constant alpha force-free field can be uniquely determined from the tangential components of the measured photospheric flux alone. The vector magnetographs now provide measurements of both the solar photospheric tangential and the longitudinal magnetic field. This paper presents derivations for the computation of the solar magnetic field from these type of measurements. The fields considered are assumed to be a constant alpha force-free fields or equivalent, producing vanishing Lorentz forces. Consequently, magnetic field lines and currents are related by a constant and hence show an identical distribution. The magnetic field above simple solar regions are described from the solution of the field equations.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Alissandrakis, C. E.: 1981, Astron. Astrophys. 100, 197.
Buchholz, H.: 1969, The Confluent Hypergeometric Function, Springer-Verlag, New York, p. 71.
Chandrasekhar, S.: 1961, Hydrodynamic and Hydromagnetic Stability, Clarendon Press, Oxford, p. 622.
Chiu, Y. T. and Hilton, H. H.: 1977, Astrophys. J. 212, 873.
Hagyard, M. J., Cumings, N. P., West, E. A., and Smith, J. E.: 1982, Solar Phys. 80, 33.
Jackson, J. P.: 1963, Classical Electrodynamics, John Wiley and Sons, Inc., New York, pp. 18 and 285.
Morse, P. M. and Feshbach, H.: 1953, Methods of Theoretical Physics, McGraw-Hill Book Co., Inc., New York, p. 1456.
Nakagawa, Y. and Raadu, M. A.: 1972, Solar Phys. 25, 127.
Nakagawa, Y., Raadu, M. A., Billings, D. E., and McNamara, D.: 1971, Solar Phys. 19, 72.
Parker, E. N.: 1979, Cosmical Magnetic Fields, Clarendon Press, Oxford, p. 76.
Priest, E. R.: 1982, Solar Magnetohydrodynamics, D. Reidel Publ. Co., Dordrecht, Holland, p. 137.
Schmidt, H. U.: 1964, in AAS-NASA Symposium on the Physics of Solar Flares, NASA SP-50, Washington, D.C., p. 167.
Semel, M.: 1967, Ann. Astrophys. 30, 513.
Stratton, J. A.: 1941, Electromagnetic Theory, McGraw-Hill Book Co., Inc., New York, Sections 4.14–4.16.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Hannakam, L., Gary, G.A. & Teuber, D.L. Computation of solar magnetic fields from photospheric observations. Sol Phys 94, 219–234 (1984). https://doi.org/10.1007/BF00151314
Received:
Revised:
Issue Date:
DOI: https://doi.org/10.1007/BF00151314