Solar Physics

, Volume 81, Issue 2, pp 253–280 | Cite as

High resolution EUV structure of the chromosphere-corona transition region above a sunspot

  • K. R. Nicolas
  • O. Kjeldseth-Moe
  • J. D. F. Bartoe
  • G. E. Brueckner


Ion emission line intensities between 1170 and 1700 Å allow one to determine the differential emission measure (DEM) and electron pressure of the plasma in the solar transition region (TR). These line intensities together with their Doppler shifts and line widths are measured simultaneously for the first time above a sunsport from data obtained with the NRL High Resolution Telescope and Spectrograph with 0.06 Å spectral and 1″ spatial resolution.

The Doppler shifts show both subsonic and supersonic flow in the same line of sight over the umbra. The temperature structure for 40 resolution elements in the sunspot umbra and penumbra is derived from the DEM and the observed electron pressures.

Extrapolation of the emission measure curves supports the previous EUV and X-ray observations that coronal plasma above sunspots with Te>106 K is reduced while emission from TR plasma between 2×105 and 106 K is greatly enhanced relative to quiet or active regions. This enhancement shifts the minimum of the DEM to lower temperatures and increases the slope at 2×105 K by a factor of two.

New pressure diagnostics using the emission line intensity ratios of C iv to N iv are presented, and applied to the data.

The energy balance in the TR for the sunspot umbra is dominated by radiative losses from the large amount of TR plasma.

An estimate of the energy budget shows that an energy input is required to balance the radiative energy losses above the umbra. The observed divergence of the enthalpy flux for the umbral downflows can balance these radiative losses for Te between 30000 and 200 000 K.

A typical umbral model of Te versus reduced mass column density is compared with one for chromospheric temperatures determined from the Ca H and K lines.


Supersonic Flow Radiative Loss Column Density Electron Pressure Differential Emission Measure 
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.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Bartoe, J.-D. F. and Brueckner, G. E.: 1975, J. Opt. Soc. Am. 65, 13.Google Scholar
  2. Basri, G. S., Linsky, J. L., Bartoe, J.-D. F., Brueckner, G., and VanHoosier, M. E.: 1919, Astrophys. J. 230, 924.Google Scholar
  3. Beckers, J. M.: 1975, New Views of Sunspots, Sacramento Peak Obs. Cont. No. 249.Google Scholar
  4. Beckers, J. M.: 1976, Astrophys. J. 203, 739.Google Scholar
  5. Beckers, J. M. and Schneeberger, T. J.: 1977, Astrophys. J. 215, 356.Google Scholar
  6. Brueckner, G. E.: 1980, in F. Orrall (ed.), NASA-Skylab Active Region Workshop Monograph, University of Colorado Press, Boulder, Colo.Google Scholar
  7. Brueckner, G. E. and Bartoe, J.-D. F.: 1974, Solar Phys. 38, 133.Google Scholar
  8. Brueckner, G. E., Bartoe, J.-D. F., and VanHoosier, M. E.: 1978, in E. Hansen and S. Schaffner (eds.), Proceedings OSO-8 Workshop, University of Colorado Press, Boulder, Colo., p. 380.Google Scholar
  9. Bruner, E. C. Jr., Chipman, E. G., Lites, B. W., Rottman, G. J., Shine, R. A., Athay, R. G., and White, O. R.: 1976, Astrophys. J. 210, L97.Google Scholar
  10. Burton, W. M., Jordan, C., Ridgeley, A., and Wilson, R.: 1971, Phil. Trans. Roy. Soc. London A270, 81.Google Scholar
  11. Cheng, C. C. and Kjeldseth-Moe, O.: 1977, Solar Phys. 52, 327.Google Scholar
  12. Cheng, C. C., Doschek, G. A., and Feldman, U.: 1976, Astrophys. J. 210, 836.Google Scholar
  13. Chipman, E. G.: 1972, Ph.D. Thesis, Harvard University.Google Scholar
  14. Cook, J. W. and Nicolas, K. R.: 1979, Astrophys. J. 229, 1163.Google Scholar
  15. Foukal, P. V.: 1976, Astrophys. J. 210, 575.Google Scholar
  16. Foukal, P. V.: 1978, Astrophys. J. 223, 1046.Google Scholar
  17. Foukal, P. V., Huber, M. C. E., Noyes, R. W., Reeves, E. M., Schmahl, E. J., Timothy, J. G., Vernazza, J. E., and Withbroe, G. E.: 1974, Astrophys. J. 193, L134.Google Scholar
  18. Jacobs, V. L., Davis, J., Keple, P. C., and Blaha, M.: 1979a, Astrophys. J. 211, 605.Google Scholar
  19. Jacobs, V. L., Davis, J., Keple, P. C., and Blaha, M.: 1979b, Astrophys. J. 215, 605.Google Scholar
  20. Jordan, C.: 1980, Astron. Astrophys. 86, 355.Google Scholar
  21. Jordan, C., Brueckner, G. E., Bartoe, J.-D. F., Sandlin, G. D., and VanHoosier, M. E.: 1978, Astrophys. J. 226, 687.Google Scholar
  22. Kjeldseth-Moe, O. and Nicolas, K. R.: 1977, Astrophys. J. 211, 579.Google Scholar
  23. Kjeldseth-Moe, O., VanHoosier, M. E., Bartoe, J. D. F., and Brueckner, G. E.: 1976, NRL Reports 8056, 8057.Google Scholar
  24. Kjeldseth-Moe, O., Engvold, O., Nicolas, K. R., Bartoe, J. D. F., and Brueckner, G. E.: 1983, Solar Phys., in press.Google Scholar
  25. Kneer, F. and Mattig, W.: 1978, Astron. Astrophys. 65, 17.Google Scholar
  26. Kundu, M. R., Schmahl, E. J., and Rao, A. P.: 1981, Astron. Astrophys., in press.Google Scholar
  27. Lites, B. W.: 1980, Solar Phys. 68, 327.Google Scholar
  28. Maltby, P.: 1975, Solar Phys. 43, 91.Google Scholar
  29. Nicolas, K. R. and Kjeldseth-Moe, O.: 1983, in preparation.Google Scholar
  30. Nicolas, K. R., Brueckner, G. E., Tousey, R., Tripp, D. A., White, O. R., and Athay, R. G.: 1977, Solar Phys. 55, 305.Google Scholar
  31. Nicolas, K. R., Bartoe, J.-D. F., Brueckner, G. E., and VanHoosier, M. E.: 1979, Astrophys. J. 233, 741.Google Scholar
  32. Nye, A. H. and Hollweg, J. V.: 1980, Solar Phys. 68, 279.Google Scholar
  33. Pallavicini, R., Vaiana, G. S., Tofani, G., and Felli, M.: 1979, Astrophys. J. 229, 375.Google Scholar
  34. Parker, E. N.: 1979, Astrophys. J. 230, 905.Google Scholar
  35. Pneuman, G. W. and Kopp, R. A.: 1977, Astron. Astrophys. 55, 305.Google Scholar
  36. Raymond, J. C. and Doyle, J. G.: 1982, Astrophys. J., to appear.Google Scholar
  37. Ross, J. E. and Aller, L. H.: Science 191, 1223.Google Scholar
  38. Schindler, M., Kjeldseth-Moe, O., Bartoe, J.-D. F., Brueckner, G. E., and VanHoosier, M. E.: 1981, Bull. Am. Astron. Soc. 12, No. 4, 916.Google Scholar
  39. Sheeley, N. R. Jr.: 1980, Solar Phys. 66, 79.Google Scholar
  40. Solar Geophysical Data: 1975, Prompt Reports, No. 373, pt. 1, U.S. Department of Commerce; Boulder, Colo.Google Scholar
  41. Vernazza, J. E. and Reeves, E. M.: 1978, Astrophys. J. Suppl. 37, 485.Google Scholar
  42. Vernazza, J. E., Avrett, E. H., and Loeser, R.: 1981, Astrophys. J. Suppl., in press.Google Scholar
  43. Webb, D. F. and Zirin, H.: 1981, Solar Phys., in press.Google Scholar
  44. Webb, D. F.: 1981, in F. Orrall (ed.), NASA-Skylab Active Region Workshop Monograph, University of Colorado Press, Boulder, Colo.Google Scholar

Copyright information

© D. Reidel Publishing Co 1982

Authors and Affiliations

  • K. R. Nicolas
    • 1
  • O. Kjeldseth-Moe
    • 1
  • J. D. F. Bartoe
    • 1
  • G. E. Brueckner
    • 1
  1. 1.E. O. Hulburt Center for Space Research, Naval Research LaboratoryWashington, D.C.USA

Personalised recommendations