Skip to main content
Log in

The Magnetic Structure and Generation of EUV Flare Ribbons

  • Published:
Solar Physics Aims and scope Submit manuscript

Abstract

The `ribbons' of two-ribbon flares show complicated patterns reflecting the linkages of coronal magnetic field lines through the lower solar atmosphere. We describe the morphology of the EUV ribbons of the July 14, 2000 flare, as seen in SOHO, TRACE, and Yohkoh data, from this point of view. A successful co-alignment of the TRACE, SOHO/MDI and Yohkoh/HXT data has allowed us to locate the EUV ribbon positions on the underlying field to within ∼ 2′′, and thus to investigate the relationship between the ribbons and the field, and also the sites of electron precipitation. We have also made a determination of the longitudinal magnetic flux involved in the flare reconnection event, an important parameter in flare energetic considerations. There are several respects in which the observations differ from what would be expected in the commonly-adopted models for flares. Firstly, the flare ribbons differ in fine structure from the (line-of-sight) magnetic field patterns underlying them, apparently propagating through regions of very weak and probably mixed polarity. Secondly, the ribbons split or bifurcate. Thirdly, the amount of line-of-sight flux passed over by the ribbons in the negative and positive fields is not equal. Fourthly, the strongest hard X-ray sources are observed to originate in stronger field regions. Based on a comparison between HXT and EUV time-profiles we suggest that emission in the EUV ribbons is caused by electron bombardment of the lower atmosphere, supporting the hypothesis that flare ribbons map out the chromospheric footpoints of magnetic field lines newly linked by reconnection. We describe the interpretation of our observations within the standard model, and the implications for the distribution of magnetic fields in this active region.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Similar content being viewed by others

References

  • Berger, T. E., De Pontieu, B., Fletcher, L., Schrijver, C. J., Tarbell, T. D., and Title, A. M.: 1999, Solar Phys. 190, 409.

    Article  ADS  Google Scholar 

  • Berger, T. E., Lites, B., Martinez-Pillet, V. Tarbell, T., and Title, A.: 2001, Solar Phys. (in preparation).

  • Bruzek, A.: 1964, Astrophys. J. 140, 746.

    Article  ADS  Google Scholar 

  • Czaykowska, A., Alexander, D., and De Pontieu, B.: 2001, Astrophys. J. 552, 849.

    Article  ADS  Google Scholar 

  • Czaykowska, A., De Pontieu, B., Alexander, D., and Rank, G.: 1999, Astrophys. J. 521, L75.

    Article  ADS  Google Scholar 

  • Domingo, V., Fleck, B., and Poland, A. I.: 1995, Solar Phys. 162, 1.

    Article  ADS  Google Scholar 

  • Fletcher, L. and De Pontieu, B.: 1999, Astrophys. J. 520, L135.

    Article  ADS  Google Scholar 

  • Kane, S. R. and Donnelly, R. F.: 1971, Astrophys. J. 164, 151.

    Article  ADS  Google Scholar 

  • Kane, S. R., Frost, K. J., and Donnelly, R. F.: 1979, Astrophys. J. 234, 669.

    Article  ADS  Google Scholar 

  • Keller C. U.: 1992, Nature 359, 307.

    Article  ADS  Google Scholar 

  • Klimchuk, J.: 1997, in R. D. Bentley and J. Mariska (eds.), ‘Magnetic Reconnection in the Solar Atmosphere’ ASP Conf. Proc. 111, 319.

  • Kopp, R. and Pneuman, G.: 19976, Solar Phys. 50, 85.

    ADS  Google Scholar 

  • Li, P., Emslie, A. G., and Mariska, J. T.: 1993, Astrophys. J. 471, 313.

    Article  ADS  Google Scholar 

  • Martens, P. C. H., Kankelborg, C. C., and Berger, T. E.: 2000, Astrophys. J. 537, 471.

    Article  ADS  Google Scholar 

  • Masuda, S.: 1994, Ph.D. Thesis, University of Tokyo.

  • Masuda, S., Kosugi, T., and Hudson, H. S.: 2001, Solar Phys., this issue.

  • McKenzie, D. E. and Hudson, H. S.: 1999, Astrophys. J. 519, L93.

    Article  ADS  Google Scholar 

  • Melrose, D. B.: 1997, Astrophys. J. 486, 521.

    Article  ADS  Google Scholar 

  • Scherrer, P.H., Bogart, R.S., Bush, R.I., Hoeksema, J.T., Kosovichev, A.G.et al.: 1995, Solar Phys. 162, 129.

    Article  ADS  Google Scholar 

  • Sakao, T.: 1994, Ph.D. Thesis, University of Tokyo.

  • Švestka, Z.: 1976, Solar Flares, Reidel, Dordrecht, Holland.

    Google Scholar 

  • Woodgate, B. E., Shine, R. A., Poland, A. I., and Orwig, L. E.: 1983, Astrophys. J. 265, 530.

    Article  ADS  Google Scholar 

Download references

Author information

Authors and Affiliations

Authors

Rights and permissions

Reprints and permissions

About this article

Cite this article

Fletcher, L., Hudson, H. The Magnetic Structure and Generation of EUV Flare Ribbons. Sol Phys 204, 69–89 (2001). https://doi.org/10.1023/A:1014275821318

Download citation

  • Issue Date:

  • DOI: https://doi.org/10.1023/A:1014275821318

Keywords

Navigation