Abstract
We measure the separation velocity of opposite poles from 24 new bipoles on the Sun. We find that the measured velocities range from about 0.2 to 1 km s−1. The fluxes of the bipoles range over more than two orders of magnitude, and the mean field strength and the sizes range over one order of magnitude. The measured separation velocity is not correlated with the flux and the mean field strength of the bipole. The separation velocity predicted by the present theory of magnetic buoyancy is between 7.4Ba −1/4 cot θ and 13 cot θ km s−1, where θ is the elevation angle of the flux tube at the photosphere (see Figure 9), B is the mean field strength, and a is the radius of the observed bipole. The rising velocity of the top of flux tubes predicted by the theory of magnetic buoyancy is between 3.7Ba −1/4 and 6.5 km s−1. The predicted separation velocity is about one order of magnitude higher than those measured, or else the flux tubes are almost vertical at the photosphere. There is no correlation between the measured separation velocity and the theoretical value, 7.4Ba −1/4. The predicted rising velocity is also higher than the vertical velocity near the line of inversion in emerging flux regions observed by other authors.
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References
Akasofu, S.-I.: 1984, Planetary Space Sci. 32, 1257.
Born, R.: 1974, Solar Phys. 38, 127.
Brants, J. J.: 1985, Solar Phys. 98, 197.
Frazier, E. N.: 1972, Solar Phys. 26, 130.
Harvey, K. L. and Martin, S. F.: 1973, Solar Phys. 32, 389.
Kawaguchi, I. and Kitai, R.: 1976, Solar Phys. 46, 125.
Kiepenheuer, K. O.: 1953, in G. P. Kuiper (ed.), The Sun, The University of Chicago Press, Chicago, p. 322.
Landau, L. D. and Lifshitz, E. M.: 1959, Fluid Mechanics, Pergamon, London, Chap. 2.
Livi, S. H. B., Wang, J., and Martin, S. F.: 1985, Australian J. Phys. 38, 222.
Martin, S. F.: 1983, in S. Keil (ed.), Sacramento Peak Workshop on Small Scale Dynamical Processes, Proc, Nat. Solar Obs. Conf. Sunspot. NM, p. 30.
Martin, S. F., Livi, S. H. B., Wang, J., and Shi, Z.: 1985, in M. J. Hagyard(ed.), Measurements of Solar Vector Magnetic Fields, NASA Conference Publication 2374, NASA, Washington DC, p. 403.
Moreno-Insertis, F.: 1983, Astron. Astrophys. 122, 241.
Parker, E. N.: 1955, Astrophys. J. 121, 491.
Parker, E. N.: 1975, Astrophys. J. 198, 205.
Parker, E. N.: 1979, Cosmical Magnetic Fields, Oxford, New York, Chap. 8 and 10.
Roberts, P. H.: 1970, ‘Velocity Fiels in Magnetically Disturbed Regions of the Hα Chromosphere’, Thesis, Calif. Inst. of Technology.
Schmidt, H. U., Simon, G. W., and Weiss, N. O.: 1985, Astron. Astrophys. 148, 191.
Schüssler, M.: 1977, Astron. Astrophys. 56, 439.
Schüssler, M.: 1979, Astron. Astrophys. 71, 79.
Shi, Z., Wang, J., and Patterson, A.: 1986, ‘Calibration of Dopplergrams and Magnetograms at BBSO’, BBSO Preprint No. 257, Calif. Inst. of Technology.
Simon, G. W. and Leighton, R. B.: 1964, Ap. J. 140, 1120.
Simon, G. W. and Wilson, P. R.: 1985, Ap. J. 295, 241.
Spruit, H. C.: 1974, Solar Phys. 34, 277.
Topka, K. and Tarbell, T.: 1983, in S. Keil (ed.), Small-Scale Dynamical Processes in Quiet Stellar Atmospheres, Proc. Nat. Solar Obs. Conf, Sunspot, NM, p. 278.
Tritton, D. J.: 1977, Physical Fluid Dynamics, Van Nostrand Reinhold, England, Chap. 3.
Tsinganos, K. C.: 1980, Ap. J. 239, 746.
Unno, W. and Ribes, E.: 1976, Ap. J. 208, 222.
van Ballegooijen, A. A.: 1982, Astron. Astrophys. 106, 43.
Wang, H.: 1987, in preparation.
Wilson, P. R. and Simon, G. W.: 1983, Ap. J. 273, 805.
Wilson, P. R.: 1986, Solar Phys. 106, 1.
Zirin, H.: 1972, Solar Phys. 22, 34.
Zirin, H.: 1985, Australian J. Phys. 38, 961.
Zirin, H.: 1986, private communication.
Zwaan, C.: 1978, Solar Phys. 60, 213.
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Chou, DY., Wang, H. The separation velocity of emerging magnetic flux. Sol Phys 110, 81–99 (1987). https://doi.org/10.1007/BF00148204
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DOI: https://doi.org/10.1007/BF00148204