Ehangiad ardaloedd bywiog o’r Haul i’r gofod

Ehangiad ardaloedd bywiog o’r Haul i’r gofod
(The expansion of solar active regions into space)

Huw Morgan

The Sun’s complex magnetic field permeates through the photosphere (the Sun’s surface) and into the corona (the Sun’s atmosphere). New magnetic fluxes arise from the photosphere in the form of closed loops which expand into the corona. This is a typical process of coronal active regions which creates and replenishes the coronal field. Magnetic field and plasma (energetic ionised gas) are transported through the corona and flow with the solar wind into the heliosphere (the region of space influenced by the Sun including the solar system). Transportation of this kind is seen during explosive events from the Sun. According to current thinking, the only transport of material from the closed field of active regions is through eruptive events, so in the absence of eruptions the active region plasma is isolated from the solar wind. This article presents evidence to the contrary. The observations show the first evidence of the direct, quiescent expansion of active region closed field into the extended corona without an eruption, thus forming an important part of the solar wind. The evidence is gained through the application of new image processing techniques to coronagraph observations. The observations are presented, and their implications are discussed in the context of the current model of Sun-heliospheric connections.


  	Huw Morgan, 'Ehangiad ardaloedd bywiog o’r Haul i’r gofod', Gwerddon, 18, September 2014, 10-22.


    Sun, photosphere, corona, magnetic field, magnetic debris.


  1. Antiochos, S. K., Linker, J. A., Lionello, R., et al. (2012), ‘The Structure and Dynamics of the Corona-Heliosphere Connection’, Space Science Reviews, 172, 169-85.
  2. Aschwanden, M. J., Boerner, P., Schrijver, C. J., et al. (2011), ‘Automated Temperature and Emission Measure Analysis of Coronal Loops and Active Regions Observed with the Atmospheric Imaging Assembly on the Solar Dynamics Observatory (SDO/AIA)’, Solar Physics, 283, 5-30.
  3. Byrne, J. P., Morgan, H., Seaton, D. B., et al. (2014), ‘Bridging EUV and white-light observations: evidence for the breakout model in a two-stage solar eruptive event’, Solar Physics,, 18 tudalen.
  4. Fisk, L. A. (2003), ‘Acceleration of the solar wind as a result of the reconnection of open magnetic flux with coronal loops’, Journal of Geophysical Research (Space Physics), 108, SSH 7-1–SSH 7-8.
  5. Gopalswamy, N., Mäkelä, P., Akiyama, S., et al. (2013), ‘The Solar Connection of Enhanced Heavy Ion Charge States in the Interplanetary Medium: Implications for the Flux-Rope Structure of CMEs’, Solar Physics, 284, 17-46.
  6. Gosling, J. T., Baker, D. N., Bame, S. J., et al. (1987), ‘Bidirectional solar wind electron heat flux events’, Journal of Geophysical Research, 92, 8519-35.
  7. Harra, L. K., Sakao, T., Mandrini, C. H., et al. (2008), ‘Outflows at the Edges of Active Regions: Contribution to Solar Wind Formation’, The Astrophysical Journal, 676, L147-L150.
  8. Kojima, M., Fujiki, K., Ohmi, T., et al. (1999), ‘Low-speed solar wind from the vicinity of solar active regions’, Journal Geophysical Research, 104, 16993-17004.
  9. Kojima, M., Fujiki, K., Hakamada, K., et al. (2000), ‘Low-Speed Solar Wind Associations with Active Regions Near Solar Minimum’, Advances in Space Research, 25, 1893-96.
  10. Lavraud, B., Opitz, A., Gosling, J. T., et al. (2010), ‘Statistics of counter-streaming solar wind suprathermal electrons at solar minimum: STEREO observations’, Annales Geophysicae, 28, 233-46.
  11. Morgan, H. (2013), ‘An observation of solar active region expansion into the heliosphere’, Monthly Notices of the Royal Astronomical Society, 433, L74-L78.
  12. Morgan, H., Byrne, J. P., a Habbal, S. R. (2012), ‘Automatically Detecting and Tracking Coronal Mass Ejections. I. Separation of Dynamic and Quiescent Components in Coronagraph Images’, The Astrophysical Journal, 752 (id144), 14 tudalen.
  13. Morgan, H., Jeska, L., a Leonard, A. (2013), ‘The Expansion of Active Regions into the Extended Solar Corona’, The Astrophysical Journal Supplement, 206 (id19), 10 tudalen.
  14. Morgan, H., a Druckmuller, M. (2014), ‘Multiscale Gaussian Normalization for solar image processing’, Solar Physics, 289 (8), 2945-55.
  15. Neugebauer, M., Liewer, P. C., Smith, E. J., et al. (2002), ‘Sources of the solar wind at solar activity maximum’, Journal of Geophysical Research (Space Physics), 107 (A12), SSH 13-1– SSH 13-15.
  16. Sheeley, Jr, N. R., Lee, D. D. H., Casto, K. P., et al. (2009), ‘The Structure of Streamer Blobs’, The Astrophysical Journal, 694 (2), 1471-80.
  17. Slemzin, V., Harra, L., Urnov, A., et al. (2013), ‘Signatures of Slow Solar Wind Streams from Active Regions in the Inner Corona’, Solar Physics, 286 (1), 157-84.
  18. Uchida, Y., McAllister, A., Strong, K. T., et al. (1992), ‘Continual expansion of the activeregion corona observed by the YOHKOH Soft X-ray Telescope’, Publications of the Astronomical Society of Japan, 44 (5), L155-L160.
  19. Wang, Y. M., Ko, Y. K., a Grappin, R. (2009), ‘Slow Solar Wind from Open Regions with Strong Low-Coronal Heating’, The Astrophysical Journal, 691 (1), 760-9.
  20. Wang, Y. M., a Sheeley, Jr, N. R. (2006), ‘Observations of Flux Rope Formation in the Outer Corona’, The Astrophysical Journal, 650 (2), 1172-83.