A loop-top hard X-ray source in a compact solar flare as evidence for magnetic reconnection

Article metrics

Abstract

SOLAR flares are thought to be the result of magnetic reconnection — the merging of antiparallel magnetic fields and the consequent release of magnetic energy. Flares are classified into two types1: compact and two-ribbon. The two-ribbon flares, which appear as slowly-developing, long-lived large loops, are understood theoretically2–6 as arising from an eruption of a solar prominence that pulls magnetic field lines upward into the corona. As the field lines form an inverted Y-shaped structure and relax, the reconnection of the field lines takes place. This view has been supported by recent observations7–10. A different mechanism seemed to be required, however, to produce the short-lived, impulsive compact flares. Here we report observations made with the Yohkoh11 Hard X-ray Telescope12 and Soft X-ray Telescope13, which show a compact flare with a geometry similar to that of a two-ribbon flare. We identify the reconnection region as the site of particle acceleration, suggesting that the basic physics of the reconnection process (which remains uncertain) may be common to both types of flare.

Access optionsAccess options

Rent or Buy article

Get time limited or full article access on ReadCube.

from$8.99

All prices are NET prices.

References

  1. 1

    Pallavicini, R. Phil. Trans. R. Soc. A336, 389–400 (1991).

  2. 2

    Carmichael, H. in AAS-NASA Symp. on the Physics of Solar Flares, NASA-SP 5O (ed. Hess, W. N.) 451–456 (NASA, Washington DC, 1964).

  3. 3

    Sturrock, P. A. Nature 211, 695–697 (1966).

  4. 4

    Hirayama, T. Sol. Phys. 34, 323–338 (1974).

  5. 5

    Kopp, R. A. & Pneuman, G. W. Sol. Phys. 50, 85–98 (1976).

  6. 6

    Hayvaerts, J., Priest, E. R. & Rust, D. M. Astrophys. J. 216, 123–137 (1977).

  7. 7

    Tsuneta, S. et al. Publs astr. Soc. Japan 44, L63–L69 (1992).

  8. 8

    Tsuneta, S. in The Magnetic and Velocity Fields of Solar Active Regions, IAU Colloq. 141 (eds Zirin, H., Ai, G. & Wang, H.) 239–248 (Astr. Soc. Pacific, San Francisco, 1993).

  9. 9

    Tsuneta, S. in X-Ray Solar Physics from Yohkoh (eds Uchica, Y., Watanabe, T., Shibata, K. & Hudson, H. S.) 115–119 (Universal Academy Press, Tokyo, 1994).

  10. 10

    Tsuneta, S. et al. Publs astr. Soc. Japan 44, L211–L214 (1992).

  11. 11

    Ogawara, Y. et al. Sol. Phys. 136, 1–16 (1991).

  12. 12

    Kosugi, T. et al. Sol. Phys. 136, 17–36 (1991).

  13. 13

    Tsuneta, S. et al. Sol. Phys. 136, 37–67 (1991).

  14. 14

    Hoyng, P. et al. Astrophys. J. 244, L153–L156 (1981).

  15. 15

    Duijveman, A., Hoyng, P. & Machado, M. E. Sol. Phys. 81, 137–157 (1982).

  16. 16

    Sakao, T. thesis, Univ. Tokyo (1994).

  17. 17

    Hudson, H. S. et al. Astrophys. J. 422, L25–L27 (1994).

  18. 18

    Hudson, H. S. in High-Energy Solar Phenomena—A New Era of Spacecraft Measurements AIP Conf. Proc. 294 (eds Ryan, J. M. & Vestrand, W. T.) 151–161 (AIP, New York, 1994).

  19. 19

    Haisch, B., Strong, K. T. & Rodono, M. A. Rev. Astr. Astrophys. 29, 275–324 (1991).

  20. 20

    Brown, J. C. Sol. Phys. 18, 489–502 (1971).

  21. 21

    Hudson, H. S., Canfield, R. C. & Kane, S. R. Sol. Phys. 60, 137–142 (1978).

  22. 22

    Masuda, S. thesis, Univ. Tokyo (1994).

Download references

Author information

Rights and permissions

Reprints and Permissions

About this article

Further reading

Comments

By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.