Hostname: page-component-7bb8b95d7b-l4ctd Total loading time: 0 Render date: 2024-09-21T23:01:05.529Z Has data issue: false hasContentIssue false
  • English
  • Français

Small-Scale Structures in Active Regions

Published online by Cambridge University Press:  12 April 2016

Christoph U. Keller
Christoph U. Keller*
Affiliation:
Institute of Astronomy, ETH-Zentrum, CH-8092 Zürich, Switzerland

Extract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

Within the last few years significant progress has been made in our understanding of the small-scale structures in active regions. Here I present some of the newest findings obtained by using speckle interferometric techniques. There exist continuum bright points with a contrast of about 30% that are cospatial with strong magnetic fields. The observations are consistent with the assumption that some facular and network bright points are the white-light signature of magnetic fluxtubes with a diameter of about 200 km. Magnetic elements larger than about 300 km are mainly darker than the average quiet sun. Their properties are similar to what has been called magnetic knots or invisible sunspots. In highly magnetic areas there is no clear relationship between continuum intensity and magnetogram signal at the smallest spatial scales. The magnetic field of pores extends beyond the dark umbra. There radially elongated structures may appear that are similar to penumbral filaments in sunspots.

Type
Session 1. Structure of Active Regions
Information
International Astronomical Union Colloquium , Volume 141: The Magnetic and Velocity Fields of Solar Active Regions , 1993 , pp. 3 - 10
Copyright
Copyright © Astronomical Society of the Pacific 1993

References

Auffret, H., and Muller, R. 1991, A&A, 246, 264 Google Scholar
Beckers, J. M., and Schröter, E.-H. 1968, Solar Physics, 4, 142 Google Scholar
Bray, R. J., and Loughhead, R. E. 1964, Sunspots, The Int. Astrophys. Ser. VII, Chapman and Hall, London Google Scholar
Bünte, M., Steiner, O., and Pizzo, V. J. 1992, A&A, (in press)Google Scholar
Choudhuri, A. R., Auffret, H., and Priest, E. R. 1992, (in press)Google Scholar
Dunn, R. B., and Zirker, J. B. 1973, Solar Physics, 33, 281 Google Scholar
Engvold, O., and Andersen, T. 1990, Status of the Design of the Large Earth-based Solar Telescope, LEST Foundation Google Scholar
Frank, Z. A., Scharnier, G. B., Keller, C. U., and Lundstedt, H. 1991, BAAS, 23, 1052 Google Scholar
Frazier, E. N., and Stenflo, J. O. 1972, Solar Physics, 27, 330 Google Scholar
Harvey, J. W., and Livingston, W. C. 1969, Solar Physics, 10, 283 Google Scholar
Keller, C. U. 1992, Nature, 359, 307 Google Scholar
Keller, C. U., and von der, LüO. 1992a, in High Resolution Imaging by Interferometry II, Beckers, J. M. and Merkle, F., ESO, (in press)Google Scholar
Keller, C. U., and von der, Lühe O. 1992b, A&A, 261, 321 Google Scholar
Keller, C. U., Solanki, S. K., Steiner, O., and Stenflo, J. O. 1990a, A&A, 233, 583 Google Scholar
Knölker, M., and Schüssler, M. 1988, A&A, 202, 275 Google Scholar
Mehltretter, J. P. 1974, Solar Physics, 38, 43 CrossRefGoogle Scholar
Muller, R. 1983, Solar Physics, 85, 113 CrossRefGoogle Scholar
Muller, R., Roudier, Th., and Hulot, J.C. 1989, Solar Physics, 119, 229 Google Scholar
Rabin, D. 1992, ApJ, 391, 832 Google Scholar
Ramsey, H. E., Schoolman, S. A., and Title, A. M. 1977, ApJ, 215, L41 Google Scholar
Rüedi, I., Solanki, S. K., Livingston, W., and Stenflo, J. O. 1992, A&A, 263, 323 Google Scholar
Schmidt, H. U., Spruit, H. C., and Weiss, N. O. 1986, A&A, 158, 351 Google Scholar
Schüssler, M. 1984, A&A, 140, 453 Google Scholar
Schüssler, M. 1990, in Solar Photosphere: Structure, Convection, Magnetic Fields, Stenflo, J. O., Proc. IAU Symp. 138, Dordrecht: Kluwer, 161 Google Scholar
Solanki, S. K., 1990, in Solar Photosphere: Structure, Convection, Magnetic Fields, Stenflo, J. O., Proc. IAU Symp. 138, Dordrecht: Kluwer, 103 Google Scholar
Solanki, S. K., and Brigljević, V. 1992, A&A, 262, L29 Google Scholar
Spruit, H. C., Zwaan, C. 1981, Solar Physics, 70, 207 Google Scholar
Stenflo, J. O. 1973, Solar Physics, 32, 41 Google Scholar
Stenflo, J. O. 1989, A&AR, 1, 3 Google Scholar
Title, A. M., Tarbell, T. D., Topka, K. P., et al. 1990, in Physics of Magnetic Flux Ropes, Russell, C. T., Priest, E. R., and Lee, L. C., Geophysical Monograph 58, 171 Google Scholar
Title, A. M., Topka, K. P., Tarbell, T. D., Schmidt, W., Balke, C., and Scharmer, G. B. 1992, ApJ, 393, 782 Google Scholar
Topka, K. P., Tarbell, T. D., and Title, A. M. 1992, ApJ, 396, 351 Google Scholar
Zirin, H., and Wang, H. 1992, ApJ, 385, L27 CrossRefGoogle Scholar