On the Expansion of Large and Small Flux Tubes with Height

  • S. K. Solanki
  • I. Rüedi
  • W. Finsterle
  • W. Livingston
Part of the Astrophysics and Space Science Library book series (ASSL, volume 243)


In the solar photosphere magnetic features (e.g. magnetic elements, sunspots) are known to expand with height. In the case of sunspots this expansion is known to be very rapid, with the field forming an almost horizontal canopy. In this contribution we present new results on the superpenumbral canopy of sunspots based on fits to Stokes I and V profiles of infrared spectral lines. The new models take pressure balance across the boundary of the canopy field into account. This improvement leads to significantly lower canopy base heights than previously determined from similar data. The three investigated sunspots show rather similar canopy base heights.

Finally, we compare the sunspot results with the expansion of small flux tubes and find interesting similarities between magnetic features having magnetic fluxes that differ by 5–6 orders of magnitude.

Key words

polarization magnetic fields sun: infrared radiation sunspots faculae flux tubes 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Adams M., Solanki S.K., Hagyard M.J., Moore R.L.: 1993, Solar Phys. 148, 201ADSCrossRefGoogle Scholar
  2. Briand C., Solanki S.K.: 1995, Astron. Astrophys. 299, 596ADSGoogle Scholar
  3. Bruls J.H.M.J., Solanki S.K.: 1995, Astron. Astrophys. 293, 240ADSGoogle Scholar
  4. Bruls J.H.M.J., Solanki S.K., Carlsson M., Rutten R.J.: 1995, Astron. Astrophys. 293, 225ADSGoogle Scholar
  5. Defouw R.J.: 1976, Astrophys. J. 209, 266ADSCrossRefGoogle Scholar
  6. Degenhardt D., Wiehr E.: 1991, Astron. Astrophys. 252, 821ADSGoogle Scholar
  7. Faurobert-Scholl M.: 1993, Astron. Astrophys. 268, 765ADSGoogle Scholar
  8. Faurobert-Scholl M., Feautrier N., Machefert F., Petrovay K., Spielfiedel A.: 1995, Astron. Astrophys. 298, 289ADSGoogle Scholar
  9. Ferriz Mas A., Schüssler M.: 1989, Geophys. Astrophys. Fluid Dyn. 48, 217ADSzbMATHCrossRefGoogle Scholar
  10. Frutiger C., Solanki S.K.: 1998, Astron. Astrophys. 336, L65ADSGoogle Scholar
  11. Giovanelli R.G.: 1980, Solar Phys. 68, 49ADSCrossRefGoogle Scholar
  12. Giovanelli R.G., Jones H.P.: 1982, Solar Phys. 79, 267ADSCrossRefGoogle Scholar
  13. Jahn K.: 1989, Astron. Astrophys. 222, 264ADSGoogle Scholar
  14. Jahn K., Schmidt H.U.: 1994, Astron. Astrophys. 290, 295ADSGoogle Scholar
  15. Keppens R., Martínez Pillet V.: 1996, Astron. Astrophys. 316, 229ADSGoogle Scholar
  16. Lites B.W., Elmore D.F., Seagraves P., Skumanich A.: 1993, Astrophys. J. 418, 928ADSCrossRefGoogle Scholar
  17. Livingston W.: 1991, in Solar Polarimetry, L. November (Ed.), National Solar Obs., Sunspot, NM, p. 356Google Scholar
  18. Maltby P., Avrett E.H., Carlsson M., Kjeldseth-Moe O., Kurucz R.L., Loeser R.: 1986, Astrophys. J. 306, 284ADSCrossRefGoogle Scholar
  19. Martens P.C.H., Hurlburt N.E., Title A.M., Acton L.W.: 1996, Astrophys. J. 463, 372ADSCrossRefGoogle Scholar
  20. Pizzo V.J.: 1986, Astrophys. J. 302, 785ADSCrossRefGoogle Scholar
  21. Pizzo V.J.: 1990, Astrophys. J. 365, 764ADSCrossRefGoogle Scholar
  22. Roberts B., Webb A.R.: 1979, Solar Phys. 64, 77ADSCrossRefGoogle Scholar
  23. Rüedi I., Solanki S.K., Livingston W., Stenflo, J.O.: 1992, Astron. Astrophys. 263, 323ADSGoogle Scholar
  24. Schlichenmaier R., Jahn K., Schmidt H.U.: 1998, Astrophys. J. 493, L121ADSCrossRefGoogle Scholar
  25. Schmidt W., Hofmann A., Balthasar H., Tarbell T.D., Frank Z.A.: 1992, Astron. Astrophys. 264, L27ADSGoogle Scholar
  26. Schüssler M.: 1986, in Small Scale Magnetic Flux Concentrations in the Solar Photosphere, W. Deinzer, M. Knölker, H.H. Voigt (Eds.), Vandenhoeck & Ruprecht, Göttingen, p. 103Google Scholar
  27. Schüssler M.: 1992, in The Sun — a Laboratory for Astrophysics, J.T. Schmelz, J.C. Brown (Eds.), Kluwer, Dordrecht, p. 81CrossRefGoogle Scholar
  28. Solanki S.K.: 1998, in Space Solar Physics, J.C. Vial, K. Bocchialini, P. Boumier (Eds.), Springer Verlag, Berlin, p. 41CrossRefGoogle Scholar
  29. Solanki S.K., Brigljević V.: 1992, Astron. Astrophys. 262, L29ADSGoogle Scholar
  30. Solanki S.K., Montavon C.A.P.: 1993, Astron. Astrophys. 275, 283ADSGoogle Scholar
  31. Solanki S.K., Schmidt H.U.: 1993, Astron. Astrophys. 267, 287ADSGoogle Scholar
  32. Solanki S.K., Rüedi I., Livingston W.: 1992, Astron. Astrophys. 263, 339ADSGoogle Scholar
  33. Solanki S.K., Montavon C.A.P., Livingston W.: 1994, Astron. Astrophys. 283, 221ADSGoogle Scholar
  34. Stenflo J.O.: 1989, Astron. Astrophys. Rev. 1, 3ADSCrossRefGoogle Scholar
  35. Stenflo J.O.: 1994, Solar Magnetic Fields: Polarized Radiation Diagnostics, Kluwer, DordrechtCrossRefGoogle Scholar
  36. Title A.M., Frank Z.A., Shine R.A., Tarbell T.D., Topka K.P., Scharmer G., Schmidt W.: 1993, Astrophys. J. 403, 780ADSCrossRefGoogle Scholar
  37. Zayer I., Solanki S.K., Stenflo J.O., Keller C.U.: 1990, Astron. Astrophys. 239, 356ADSGoogle Scholar
  38. Zirin H., Popp B.: 1989, Astrophys. J. 340, 571ADSCrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media Dordrecht 1999

Authors and Affiliations

  • S. K. Solanki
    • 1
  • I. Rüedi
    • 1
  • W. Finsterle
    • 2
  • W. Livingston
    • 3
  1. 1.ETH-ZentrumInstitute of AstronomyZürichSwitzerland
  2. 2.Physikalisch Meteorologisches ObservatoriumWorld Radiation CenterDavos DorfSwitzerland
  3. 3.National Solar ObservatoryNational Optical Astronomy, ObservatoriesTucsonUSA

Personalised recommendations