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Solar Physics

, Volume 175, Issue 2, pp 667–684 | Cite as

First View of the Extended Green-Line Emission Corona At Solar Activity Minimum Using the Lasco-C1 Coronagraph on Soho

  • R. Schwenn
  • B. Inhester
  • S. P. Plunkett
  • A. Epple
  • B. Podlipnik
  • D. K. Bedford
  • C. J. Eyles
  • G. M. Simnett
  • S. J. Tappin
  • M. V. Bout
  • P. L. Lamy
  • A. Llebaria
  • G. E. Brueckner
  • K. P. Dere
  • R. A. Howard
  • M. J. Koomen
  • C. M. Korendyke
  • D. J. Michels
  • J. D. Moses
  • N. E. Moulton
  • S. E. Paswaters
  • D. G. Socker
  • O. C. St. Cyr
  • D. Wang
Article

Abstract

The newly developed C1 coronagraph as part of the Large-Angle Spectroscopic Coronagraph (LASCO) on board the SOHO spacecraft has been operating since January 29, 1996. We present observations obtained in the first three months of operation. The green-line emission corona can be made visible throughout the instrument's full field of view, i.e., from 1.1 R⊙ out to 3.2 R⊙ (measured from Sun center). Quantitative evaluations based on calibrations cannot yet be performed, but some basic signatures show up even now: (1) There are often bright and apparently closed loop systems centered at latitudes of 30° to 45° in both hemispheres. Their helmet-like extensions are bent towards the equatorial plane. Farther out, they merge into one large equatorial ‘streamer sheet’ clearly discernible out to 32 R⊙. (2) At mid latitudes a more diffuse pattern is usually visible, well separated from the high-latitude loops and with very pronounced variability. (3) All high-latitude structures remain stable on time scales of several days, and no signature of transient disruption of high-latitude streamers was observed in these early data. (4) Within the first 4 months of observation, only one single ‘fast’ feature was observed moving outward at a speed of 70 km s-1 close to the equator. Faster events may have escaped attention because of data gaps. (5) The centers of high-latitude loops are usually found at the positions of magnetic neutral lines in photospheric magnetograms. The large-scale streamer structure follows the magnetic pattern fairly precisely. Based on our observations we conclude that the shape and stability of the heliospheric current sheet at solar activity minimum are probably due to high-latitude streamers rather than to the near-equatorial activity belt.

Keywords

Current Sheet Neutral Line Heliospheric Current Sheet Solar Activity Minimum Streamer Structure 
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. Alfvén, H.: 1977, J. Geoph. Res. 91, 13 679.Google Scholar
  2. Altschuler, M. D. and Newkirk, G., Jr.: 1969, Solar Phys. 9, 131.CrossRefADSGoogle Scholar
  3. Ananthakrishnan, R.: 1952, Nature 170, 158.CrossRefADSGoogle Scholar
  4. Behannon, K. W., Neubauer, F. M., and Barnstorf, H.: 1981, J. Geophys. Res. 86, 3273.ADSCrossRefGoogle Scholar
  5. Billings, D. E.: 1966, A Guide to the Solar Corona, Academic Press, New York.Google Scholar
  6. Bird, M. K. and Edenhofer, P.: 1990 in R. Schwenn and E. Marsch (eds.), Physics of the Inner Heliosphere, Springer-Verlag, Berlin, p. 13.Google Scholar
  7. Brueckner, G. E. et al.: 1995, Solar Phys. 162, 357.CrossRefADSGoogle Scholar
  8. Burgess, A. and Seaton, M.: 1964, Monthly Notices Roy. Astron. Soc. 127, 355.ADSGoogle Scholar
  9. Crooker, N. U., Siscoe, G. L., Shodhan, S., Webb, D. F., Gosling, J. T., and Smith, E. J.: 1993, J. Geophys. Res. 98, 9371.ADSCrossRefGoogle Scholar
  10. De Jager, C.: 1959, in S. Flügge (ed.), Handbuch der Physik, Springer-Verlag, Berlin, p. 80.Google Scholar
  11. Domingo, V., Fleck, B., and Poland, A. I.: 1995, Solar Phys. 162, 1.CrossRefADSGoogle Scholar
  12. Edlèn, B.: 1942, Z. Astrophys. 22, 30.ADSGoogle Scholar
  13. Esser, R., Brickhouse, N. S., Habbal, S. R., Altrock, R. C., and Hudson, H. S.: 1995, J. Geophys. Res. 100, 19 829.CrossRefADSGoogle Scholar
  14. Grotrian, W.: 1939, Naturwissenschaften 34, 87.Google Scholar
  15. Guhathakurta, M. and Fisher, R. R.: 1994, Solar Phys. 152, 181.CrossRefADSGoogle Scholar
  16. Guhathakurta, M., Fisher, R. R., and Altrock, R. C.: 1993, Astrophys. J. 414, L145.CrossRefADSGoogle Scholar
  17. Hoeksema, J. T.: 1986, in R. G. Marsden (ed.), The Sun and the Heliosphere in Three Dimensions, D. Reidel Publ. Co., Dordrecht, Holland, p. 241.Google Scholar
  18. Hoeksema, J. T.: 1995, Space Sci. Rev. 72, 137.CrossRefADSGoogle Scholar
  19. Howard, R. A., Sheeley, N. R., Jr., Koomen, M. J., and Michels, D. J.: 1985, J. Geophys. Res. 90, 8173.ADSCrossRefGoogle Scholar
  20. Koutchmy, S.: 1988, Space Sci. Rev. 47, 95.CrossRefADSGoogle Scholar
  21. Koutchmy, S. and Livshits, M.: 1992, Space Sci. Rev. 61, 393.CrossRefADSGoogle Scholar
  22. Leroy, J.-L. and Noëns, J.-C.: 1983, Astron. Astrophys. 120, L1.ADSGoogle Scholar
  23. Leroy, J.-L. and Trellis, M.: 1974, Astron. Astrophys. 35, 283.ADSGoogle Scholar
  24. Levine, R. H.: 1982, Solar Phys. 79, 203.CrossRefADSGoogle Scholar
  25. Loucif, M. L. and Koutchmy, S.: 1989, Astron. Astrophys. Suppl. Ser. 77, 45.ADSGoogle Scholar
  26. Lyot, B.: 1930, C.R. Acad. Sci. Paris 191, 834.zbMATHGoogle Scholar
  27. Mariani, F. and Neubauer, F. M.: 1990, in R. Schwenn and E. Marsch (eds.), Physics of the Inner Heliosphere, Springer-Verlag, Berlin, p. 18.Google Scholar
  28. Newkirk, G. and Bohlin, J. D.: 1963, Appl. Optics 2, 131.ADSCrossRefGoogle Scholar
  29. Picat, J. P., Fort, B., Dantel, M., and Leroy, J.-L.: 1973, Astron. Astrophys. 24, 259.ADSGoogle Scholar
  30. Raju, K. P. and Desai, J. P.: 1993, Solar Phys. 147, 255.CrossRefADSGoogle Scholar
  31. Schatten, K. H., Wilcox, J. M., and Ness, N. F.: 1969, Solar Phys. 6, 442.CrossRefADSGoogle Scholar
  32. Schulz, M.: 1973, Astrophys. Space Sci. 24, 371.ADSCrossRefGoogle Scholar
  33. Schwenn, R.: 1990, in R. Schwenn and E. Marsch (eds.), Physics of the Inner Heliosphere, Springer-Verlag, Berlin, p. 99.Google Scholar
  34. Smartt, R. N.: 1982, SPIE 331, 442.ADSGoogle Scholar
  35. Ulrich, R. K.: 1992, in M. S. Giampampa and J. A. Bookbinder (eds.), Cool Stars, Stellar Systems and the Sun, ASP, San Francisco.Google Scholar
  36. Waldmeier, M.: 1951, Die Sonnenkorona I, Birkhäuser Verlag, Basel.Google Scholar
  37. Waldmeier, M.: 1957, Die Sonnenkorona II, Birkhäuser Verlag, Basel.Google Scholar
  38. Wang, Y.-M. and Sheeley, N. R., Jr.: 1992, Astrophys. J. 392, 310.CrossRefADSGoogle Scholar
  39. Wang, Y.-M. and Sheeley, N. R., Jr.: 1995, Astrophys. J. 447, L143.ADSGoogle Scholar
  40. Zirin, H.: 1970, Sky Telescope 218, 215.ADSGoogle Scholar

Copyright information

© Kluwer Academic Publishers 1997

Authors and Affiliations

  • R. Schwenn
    • 1
  • B. Inhester
    • 1
  • S. P. Plunkett
    • 2
  • A. Epple
    • 1
  • B. Podlipnik
    • 1
  • D. K. Bedford
    • 2
  • C. J. Eyles
    • 2
  • G. M. Simnett
    • 2
  • S. J. Tappin
    • 2
  • M. V. Bout
    • 3
  • P. L. Lamy
    • 3
  • A. Llebaria
    • 3
  • G. E. Brueckner
    • 4
  • K. P. Dere
    • 4
  • R. A. Howard
    • 4
  • M. J. Koomen
    • 4
  • C. M. Korendyke
    • 4
  • D. J. Michels
    • 4
  • J. D. Moses
    • 4
  • N. E. Moulton
    • 4
  • S. E. Paswaters
    • 4
  • D. G. Socker
    • 4
  • O. C. St. Cyr
    • 4
  • D. Wang
    • 4
  1. 1.Max Planck Institut für AeronomieLindauGermany
  2. 2.Space Research Group, School of Physics and Space ResearchUniversity of BirminghamBirminghamU.K
  3. 3.Laboratoire d'Astronomie SpatialeMarseilleFrance
  4. 4.Naval Research LaboratoryE.O. Hulburt Center for Space ResearchWashington D.C.U.S.A

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