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Solar Physics

, Volume 42, Issue 1, pp 135–156 | Cite as

The structure and evolution of coronal holes

  • A. F. Timothy
  • A. S. Krieger
  • G. S. Vaiana
Article
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Revised:

Abstract

When observed at soft X-ray wavelengths coronal holes are seen as open features, devoid of X-ray emission and bounded by apparently divergent coronal loop structures. Inspection of the topology of the photospheric magnetic fields associated with these features suggests that holes are formed when the remnants of active region fields, emerging in both hemispheres over a period of several solar rotations, combine to form a large area of essentially unipolar field. Remnants of opposite polarity fields surround these features resulting in a divergent magnetic configuration at the hole boundaries. Holes are seen to form and evolve while the large scale divergent field pattern is reinforced and to close when large scale remnants occur which disrupt the general field pattern. Two types of holes are observed in the early Skylab observations. The first are elongated features which are aligned approximately north-south extending from one solar pole to a polar filament channel in the opposite hemisphere. The polar holes and somewhat lower latitude holes appear to lie in unipolar areas which are completely confined by opposite polarity fields.

Studies of the rotation properties of an elongated hole, which extended from the north pole to a latitude of approximately 20° S, showed it to rotate with a synodic rate of (13.25±0.03)−(0.4±0.1 sin2φdeg day−1. Possible explanations for the almost rigid rotational characteristics of this feature are discussed.

Keywords

Coronal Hole Coronal Loop Field Pattern Polar Filament Hole Boundary 
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. Altschuler, M. D., Trotter, D. E. and Orrall, F. Q.: 1972, Solar Phys. 26, 354.Google Scholar
  2. Antonucci, E. and Svalgaard, L.: 1974, Solar Phys. 34, 3.Google Scholar
  3. Babcock, H. W.: 1961, Astrophys. J. 133, 572.Google Scholar
  4. Bumba, V. and Howard, R.: 1969, Solar Phys. 7, 28.Google Scholar
  5. Dodson-Prince, H. W. and Hedeman, E. R. : 1968, in K. O. Kiepenheuer (ed.), ‘Structure and Development of Solar Active Regions’, IAU Symp. 35, 56.Google Scholar
  6. Dulk, G. A. and Sheridan, K. V.: 1974, Solar Phys. 36, 191.Google Scholar
  7. Golub, L., Krieger, A. S., Silk, J. K., Timothy, A. F., and Vaiana, G. S.: 1974, Astrophys. J. 189, L93.Google Scholar
  8. Hansen, R. T., Hansen, S. F., and Loomis, H. G.: 1969, Solar Phys. 10, 135.Google Scholar
  9. Harvey, J., Krieger, A. S., Timothy, A. F., and Vaiana, G. S.: 1974, ‘Comparison of Skylab X-ray and Ground Based Helium Observations’, to be published in the Proceedings of the Working Session on the Preliminary Results of the Skylab Solar Experiments and Correlated Ground Observations, Arcetri Astrophysical Observatory, Florence, Italy.Google Scholar
  10. Krieger, A. S., Timothy, A. F., and Roelof, E. C.: 1973, Solar Phys. 29, 505.Google Scholar
  11. Krieger, A. S., Timothy, A. F., Vaiana, G. S., Lazarus, A. J., and Sullivan, J. D.: 1974, in Proceedings of the Third Solar Wind Conference at Asilomar Conference Grounds, California.Google Scholar
  12. Leighton, R. B.: 1964, Astrophys. J. 140, 1547.Google Scholar
  13. Munro, R. H. and Withbroe, G. L.: 1972, Astrophys. J. 176, 511.Google Scholar
  14. Neupert, W. M. and Pizzo, V.: 1974, to be published in J. Geophys. Res. Google Scholar
  15. Newkirk, G. A.: 1967, Ann. Rev. Astron. Astrophys. 5, 213.Google Scholar
  16. Newkirk, G., Jr., Trotter, D. E., Altschuler, M. D., and Howard, R.: 1973. ‘A Microfilm Atlas of Magnetic Fields in the Solar Corona’, NCAR Technical Note, NCAR-TN/STR-85.Google Scholar
  17. Newton, H. W. and Nunn, M. L.: 1951, Monthly Notices Roy. Astron. Soc. 111, 413.Google Scholar
  18. Pneuman, G. W.: 1971, Solar Phys. 19, 16.Google Scholar
  19. Svalgaard, L.: 1972, J. Geophys. Res. 77, 4027.Google Scholar
  20. Švestka, Z.: 1968, Solar Phys. 4, 18.Google Scholar
  21. U.S. Department of Commerce, Environmental Science Services Administration: 1973, Solar Geophyscial Data, pp. 345–7.Google Scholar
  22. Vaiana, G. S., Krieger, A. S., and Timothy, A. F.: 1973a, Solar Phys. 32, 81.Google Scholar
  23. Vaiana, G. S., Davis, J. M., Giacconi, R., Krieger, A. S., Silk, J. K., Timothy, A. F., and Zombeck, M.: 1973b, Astrophys. J. 185, L47.Google Scholar
  24. Van Speybroeck, L. P., Krieger, A. S., and Vaiana, G. S.: 1970, Nature 227, 818.Google Scholar
  25. Weber, E. J.: 1969, Solar Phys. 9, 150.Google Scholar
  26. Weber, E. J. and Davis, L., Jr.: 1967, Astrophys. J. 148, 217.Google Scholar
  27. Wilcox, J. M. and Howard, R.: 1970, Solar Phys. 13, 251.Google Scholar
  28. Wilcox, J. M. and Tannenbaum, A. S.: 1971, Space Sci. Lab. Rep. Ser. 12.Google Scholar
  29. Wilcox, J. M., Schatten, K. H., Tannenbaum, A. S., and Howard, R.: 1970, Solar Phys. 14, 255.Google Scholar

Copyright information

© D. Reidel Publishing Company 1975

Authors and Affiliations

  • A. F. Timothy
    • 1
  • A. S. Krieger
    • 1
  • G. S. Vaiana
    • 2
  1. 1.American Science and Engineering, Inc.CambridgeU.S.A.
  2. 2.Center for AstrophysicsCambridgeU.S.A.

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