Journal of The Korean Astronomical Society (천문학회지)

The Korean Astronomical Society (한국천문학회)
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[ Hα ] SPECTRAL PROPERTIES OF VELOCITY THREADS CONSTITUTING A QUIESCENT SOLAR FILAMENT

  • Published : 2007.09.30
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Abstract

The basic building block of solar filaments/prominences is thin threads of cool plasma. We have studied the spectral properties of velocity threads, clusters of thinner density threads moving together, by analyzing a sequence of $H{\alpha}$ images of a quiescent filament. The images were taken at Big Bear Solar Observatory with the Lyot filter being successively tuned to wavelengths of -0.6, -0.3, 0.0, +0.3, and +0.6 ${\AA}$ from the centerline. The spectra of contrast constructed from the image data at each spatial point were analyzed using cloud models with a single velocity component, or three velocity components. As a result, we have identified a couple of velocity threads that are characterized by a narrow Doppler width($\Delta\lambda_D=0.27{\AA}$), a moderate value of optical thickness at the $H{\alpha}$ absorption peak($\tau_0=0.3$), and a spatial width(FWHM) of about 1". It has also been inferred that there exist 4-6 velocity threads along the line of sight at each spatial resolution element inside the filament. In about half of the threads, matter moves fast with a line-of-sight speed of $15{\pm}3km\;s^{-1}$, but in the other half it is either at rest or slowly moving with a line-of-sight velocity of $0{\pm}3km\;s^{-1}$. It is found that a statistical balance approximately holds between the numbers of blue-shifted threads and red-shifted threads, and any imbalance between the two numbers is responsible for the non-zero line-of-sight velocity determined using a single-component model fit. Our results support the existence not only of high speed counter-streaming flows, but also of a significant amount of cool matter either being at rest or moving slowly inside the filament.

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References

  1. Chae, J., Yun, H. S., & Poland, A. I. 1998, Temperature Dependence of Ultraviolet Line Average Doppler Shifts in the Quiet Sun, ApJS, 114, 151 https://doi.org/10.1086/313064
  2. Chae, J., Denker, C., Spirock, T. J., Wang, H., & Goode, P. R. 2000, High-Resolution $H_\alpha$, Observations of Proper Motion in NOAA 8668: Evidence for Filament Mass Injection by Chromospheric Reconnection, Sol. Phys., 195, 333
  3. 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 https://doi.org/10.1086/345739
  4. Chae, J., Moon, Y.-.J., & Park, Y.-D. 2005, The Magnetic Structure of Filament Barbs, ApJ, 626, 574 https://doi.org/10.1086/429797
  5. 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 (Paper I) https://doi.org/10.1007/s11207-006-0047-z
  6. Engvold, O. 1976, The fine structure of prominences. I - Observations - H-alpha filtergrams, Sol. Phys., 49, 283
  7. Engvold, O., Malville, J. M., & Livingston, W. 1978, The fine structure of prominences. V - Active edges of quiescent prominences, Sol. Phys., 60, 57
  8. Engvold, O., Jensen, E., Zhang, Y., & Brynildsen, N. 1989, Distribution of velocities in the Pre-Eruptive Phase of a Quiscent Prominence, Hvar Observatory Bulletin, 13, 205
  9. Karpen, J. T., Antiochos, S. K., & Klimchuk, J. A. 2006, The Origin of High-Speed Motions and Threads in Prominences, ApJ, 637, 531 https://doi.org/10.1086/498237
  10. Kubota, J., & Uesugi, A. 1986, The vertical motion of matter in a prominence observed on May 7, 1984, PASJ, 38, 903
  11. 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 https://doi.org/10.1023/A:1022900604972
  12. Kucera, T. A., & Landi, E. 2006, Ultraviolet Observations of Prominence Activation and Cool Loop Dynamics, ApJ, 645, 1525 https://doi.org/10.1086/504398
  13. Kulidzanishvili, V. I. 1989, Mass Motions in a Quiescent Prominence and an Active One, Hvar Observatory Bulletin, 13, 215
  14. Lin, Y., Engvold, O. R., & Wiik, J. E. 2003, Counterstreaming in a Large Polar Crown Filament, Sol. Phys., 216, 109 https://doi.org/10.1023/A:1026150809598
  15. Lin, Y., 2004, Ph. D thesis, University of Oslo
  16. 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 https://doi.org/10.1007/s11207-005-6876-3
  17. Malherbe, J. M., Schmieder, B., & Mein, P. 1981,Dynamics in the filaments. I - Oscillations in a quiescent filament, A&A, 102, 124
  18. Martres, M.-J., Mein, P., Schmieder, B., & Soru-Escaut, I. 1981, Structure and evolution of velocities in quiescent filaments, Sol. Phys., 69, 301
  19. Mein, P. 1977, Multi-channel subtractive spectrograph and filament observations, solphys, 54, 45
  20. Mein, P. 1994, Fine Structure of Prominences and Filaments, IAU Colloq. 144: Solar Coronal Structures, 289
  21. Mein, P., & Mein, N. 1991, Dynamical fine structure of a quiescent prominence, Sol. Phys., 136, 317 https://doi.org/10.1007/BF00146539
  22. Mein, P., Mein, N., Schmieder, B., & Noens, J. C. 1989, Dynamical Structure of a Quiescent Prominence, Hvar Observatory Bulletin, 13, 113
  23. Mein, N., Mein, P., & Wiik, J. E. 1994, Dynamical fine structure of a quiescent filament, Sol. Phys., 151, 75 https://doi.org/10.1007/BF00654083
  24. Mein, N., Schmieder, B., DeLuca, E. E., Heinzel, P., Mein, P., Malherbe, J. M., & Staiger, J. 2001, A Study of Hydrogen Density in Emerging Flux Loops from a Coordinated Transition Region and Coronal Explorer and Canary Islands Observation Campaign, ApJ, 556, 438 https://doi.org/10.1086/321488
  25. Schmieder, B., Raadu, M. A., & Wiik, J. E. 1991, Fine structure of solar filaments. II - Dynamics of threads and footpoints, A&A, 252, 353
  26. Simon, G., Schmieder, B., Demoulin, P., & Poland, A. I. 1986, Dynamics of solar filaments. VI - Center-to-limb study of H-alpha and C IV velocities in a quiescent filament, A&A, 166, 319
  27. Wallace, L., Hinkle, K., & Livingston, W. 1998, An atlas of the spectrum of the solar photosphere from 13,500 to 28,000 cm-1 (3570 to 7405 A), Publisher: TUcson, AZ:National Optical Astronomy Observatories, 1998
  28. Wang, Y.-M. 1999, The Jetlike Nature of HE II lambda304 Prominences, ApJ, 520, L71
  29. You, J.-Y. & Engvold, O. 1989, Vertical Flows in a Quiescent Filament, Hvar Observatory Bulletin, 13, 197
  30. Zirker, J. B., & Koutchmy, S. 1990, Prominence fine structure, Sol. Phys., 127, 109 https://doi.org/10.1007/BF00158516
  31. Zirker, J. B., & Koutchmy, S. 1991, Prominence fine structure. II - Diagnostics, Sol. Phys., 131, 107
  32. 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

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