• Chae, Jong-Chul (Department of Physics and Astronomy, Seoul National University)
  • Received : 2010.03.27
  • Accepted : 2010.04.06
  • Published : 2010.06.30


We investigate how plasma structures in the solar chromosphere and corona can extend to altitudes much above hydrostatic scale heights from the solar surface even under the force of gravity. Using a simple modified form of equation of motion in the vertical direction, we argue that there are two extreme ways of non-hydrostatic support: dynamical support and magnetic support. If the vertical acceleration is downward and its magnitude is a significant fraction of gravitational acceleration, non-hydrostatic support is dynamical in nature. Otherwise non-hydrostatic support is static, and magnetic support by horizontal magnetic fields is the only other possibility. We describe what kind of observations are needed in the clarification of the nature of non-hydrostatic support. Observations available so far seem to indicate that spicules in the quiet regions and dynamic fibrils in active regions are dynamically supported whereas the general chromosphere as well as prorninences is magnetically supported. Moreover, it appears that magnetic support is required for plasma in some coronal loops as well. We suspect that the identification of a coronal loop with a simple magnetic flux tube might be wrong in this regard.


magnetohydrodynamics (MHD);Sun: atmosphere;Sun: chromosphere;Sun: corona


  1. Aschwanden, M. J., Nightingale, R. W., & Alexander, D. 2000, Evidence for Nonuniform Heating of Coronal Loops Inferred from Multithread Modeling of TRACE Data, ApJ, 541, 1059
  2. Aschwanden, M. J., Schrijver, C. J., & Alexander, D. 2001, Modeling of Coronal EUV Loops Observed with TRACE. I. Hydrostatic Solutions with Nonuniform Heating, ApJ, 550, 1036
  3. Casini, R., Lopez Ariste, A., Paletou, F., & Leger, L. 2009, Multi-Line Stokes Inversion for Prominence Magnetic-Field Diagnostics, ApJ, 703, 114
  4. Chae, J., Denker, C., Spirock, T. J., Wang, H., & Goode, P. R. 2000, High-Resolution Ho: Observations of Proper Motion in NOAA 8668: Evidence for Filament Mass Injection by Chromospheric Reconnection, Sol. Phys., 195, 333
  5. Chae, J. 2003, The Formation of a Prominence in NOAA Active Region 8668. II. Trace Observations of Jets and Eruptions Associated with Canceling Magnetic Features, ApJ, 584, 1084
  6. Chae, J., Park, Y.-D., & Park, H.-M. 2006, Imaging Spectroscopy of a Solar Filament Using a Tunable H$\alpha$ Filter, Sol. Phys., 234, 115
  7. Chae, J., Park, H.-M., & Park, Y.-D. 2007, H$\alpha$ Spectral Properties of Velocity Threads Constituting a Quiescent Solar Filament, JKAS, 40, 67
  8. Chae, J., Ahn, K., Lim, E.-K., Choe, G. S., & Sakurai, T. 2008, Persistent Horizontal Flows and Magnetic Support of Vertical Threads in a Quiescent Prominence, ApJ, 689, L 73
  9. Chae, J., & Sakurai, T. 2008, A Test of Three Optical Flow Techniques-LCT, DAVE, and NAVE, ApJ, 689, 593
  10. Chae, J. 2010, Dynamics of Vertical Threads and Descending Knots in a Hedgerow Prominence, ApJ, in press
  11. Christopoulou, E. B., Georgakilas, A. A., & Koutchmy, S. 2001, Fine Structure of the Magnetic Chromosphere: Near-Limb Imaging, Data Processing and Analysis of Spicules and Mottles, Sol. Phys., 199, 61
  12. De Pontieu, B., Hansteen, V. H., Rouppe van der Voort, L., van Noort, M., & Carlsson, M. 2007, HighResolution Observations and Modeling of Dynamic Fibrils, ApJ, 655, 624
  13. Ewell, M. W., Jr., Zirin, H., Jensen, J. B., & Bastian, T. S. 1993, Submillimeter Observations of the 1991 July 11 Total Solar Eclipse, ApJ, 403, 426
  14. Foukal, P. 1971, $H\alpha$ Fine Structure and the Chromospheric Field, Sol. Phys., 20, 298
  15. Johannesson, A., & Zirin, H. 1996, The Pole-Equator Variation of Solar Chromospheric Height, ApJ, 471, 510
  16. Keil, S. L., & 10 colleagues 2003, Design and development of the Advanced Technology Solar Telescope (ATST), Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series, 4853, 240
  17. Kippenhahn, R., & Schliiter, A. 1957, Eine Theorie der solar en Filamente. Mit 7 Textabbildungen, Zeitschrift fur Astrophysik, 43, 36
  18. Kucera, T. A., Tovar, M., & De Pontieu, B. 2003, Prominence Motions Observed at High Cadences in Temperatures from 10 000 to 250 000 K, Sol. Phys., 212, 81
  19. Kuperus, M., & Raadu, M. A. 1974, The Support of Prominences Formed in Neutral Sheets, A&A, 31, 189
  20. Lee, J. 2007, Radio Emissions from Solar Active Regions, Space Science Reviews, 133, 73
  21. Lin, H., Penn, M. J., & Tomczyk, S. 2000, A New Precise Measurement of the Coronal Magnetic Field Strength, ApJ, 541, L83
  22. Lin, Y., Engvold, O. R., & Wiik, J. E. 2003, Counterstreaming in a Large Polar Crown Filament, Sol. Phys., 216, 109
  23. Lin, Y., Engvold, O., Rouppe van der Voort, L., & Wiik, J. E., Berger, T. E. 2005, Thin Threads of Solar Filaments, Sol. Phys., 226, 239
  24. Lippincott, S. L. 1957, Chromospheric Spicules, Smithsonian Contributions to Astrophysics, 2, 15
  25. Litvinenko, Y. E., & Martin, S. F. 1999, Magnetic Reconnection as the Cause of a Photospheric Canceling Feature and Mass Flows in a Filament, Sol. Phys., 190, 45
  26. Litvinenko, Y. E. 2000, On the Magnetic Field Orientation and Plasma Flows in Solar Filament Barbs, Sol. Phys., 196, 369
  27. Lopez Ariste, A., & Casini, R. 2003, Improved Estimate of the Magnetic Field in a Prominence, ApJ, 582, L51
  28. Lopez Ariste, A., & Casini, R. 2005, Inference of the Magnetic Field in Spicules from Spectropolarimetry of He I D3, A&A, 436, 325
  29. November, L. J., & Simon, G. W. 1988, Precise Proper-Motion Measurement of Solar Granulation, ApJ, 333, 427
  30. Pasachoff, J. M., Jacobson, W. A., & Sterling, A. C. 2009, Limb Spicules from the Ground and from Space, Sol. Phys., 260, 59
  31. Petrie, G. J. D. 2006, Coronal Loop Widths and Pressure Scale Heights, ApJ, 649, 1078
  32. Plowman, J. E., Kankelborg, C. C., & Longcope, D. W. 2009, Coronal Loop Expansion Properties Explained Using Separators, ApJ, 706, 108
  33. Suematsu, Y., Wang, H., & Zirin, H. 1995, HighResolution Observation of Disk Spicules. 1. Evolution and Kinematics of Spicules in the Enhanced Network, ApJ, 450, 411
  34. Vernazza, J. E., Avrett, E. H., & Loeser, R. 1981, Structure of the Solar Chromosphere. III - Models of the EUV Brightness Components of the Quiet-Sun, ApJS, 45, 635
  35. Wang, Y.-M. 1999, The Jetlike Nature of HE II Lambda304 Prominences, ApJ, 520, L71
  36. Watko, J. A., & Klimchuk, J. A. 2000, Width Variations along Coronal Loops Observed by TRACE, Sol. Phys., 193, 77
  37. Winebarger, A. R., Warren, H., van Ballegooijen, A., DeLuca, E. E., & Golub, L. 2002, Steady Flows Detected in Extreme-Ultraviolet Loops, ApJ, 567, L89
  38. Zirin, H. 1988, Astrophysics of the sun, Cambridge and New York, Cambridge University Press
  39. Zirin, H. 1996, The Mystery of the Chromosphere, Sol. Phys., 169, 313
  40. Zirker, J. B., Engvold, O., & Martin, S. F. 1998., Counter-Streaming Gas Flows in Solar Prominences as Evidence for Vertical Magnetic Fields, Nature, 396, 440