Advertisement

Solar Physics

, Volume 284, Issue 2, pp 579–588 | Cite as

Instability of Electrons Trapped by the Coronal Magnetic Field and Its Evidence in the Fine Structure (Zebra Pattern) of Solar Radio Spectra

  • E. Y. ZlotnikEmail author
ADVANCES IN EUROPEAN SOLAR PHYSICS

Abstract

Solar radio emission is a significant source of information regarding coronal plasma parameters and the processes occurring in the solar atmosphere. High resolution frequency, space, and time observations together with the developed theory make it possible to retrieve physical conditions in the radiation source and recognize the radiation mechanisms responsible for various kinds of solar radio emission. In particular, the high brightness temperature of many bursts testifies to coherent radiation mechanisms, that is, to plasma instabilities in the corona.

As an example, the fine structure of solar radio spectra looking like a set of quasi-harmonic stripes of enhanced and lowered radiation, which is observed against the type IV continuum at the post-flare phase of activity, is considered. It is shown that such emission arises from a trap-like source filled with a weakly anisotropic equilibrium plasma and a small addition of electrons which have a shortage of small velocities perpendicular to the magnetic field. For many recorded events with the mentioned fine spectral structure the instability processes responsible for the observed features are recognized. Namely, the background type IV continuum is due to the loss-cone instability of hot non-equilibrium electrons, and the enhanced striped radiation results from the double-plasma-resonance effect in the regions where the plasma frequency f p coincides with the harmonics of electron gyrofrequency f B ; f p=sf B . Estimations of the electron number density and magnetic field in the coronal magnetic traps, as well as the electron number density and velocities of hot electrons necessary to excite the radiation with the observed fine structure, are given. It is also shown that in some cases several ensembles of non-equilibrium electrons can coexist in magnetic traps during solar flares and that its radio signature sensitively depends on the parameters of the distribution functions of the various ensembles.

Keywords

Corona Radio emission Energetic particles Electrons Instabilities Waves Plasma 

Notes

Acknowledgements

The work was supported in part by the Russian Foundation for Basic Research (Project No. 10-02-00265).

References

  1. Altyntsev, A.T., Kuznetsov, A.A., Meshalkina, N.S., Rudenko, G.V., Yan, Y.: 2005, Astron. Astrophys. 431, 1037. ADSCrossRefGoogle Scholar
  2. Aschwanden, M.: 2005, Physics of the Solar Corona. An Introduction with Problems and Solutions, Praxis, Chichester. Google Scholar
  3. Aurass, H., Klein, K.-L., Zlotnik, E.Ya., Zaitsev, V.V.: 2003, Astron. Astrophys. 410, 1001. ADSCrossRefGoogle Scholar
  4. Aurass, H., Vrs̆nak, B., Hoffmann, A., Rudz̆jak, V.: 1999, Solar Phys. 190, 267. ADSCrossRefGoogle Scholar
  5. Berney, M., Benz, A.O.: 1978, Astron. Astrophys. 65, 369. ADSGoogle Scholar
  6. Chen, B., Bastian, T.S., Gary, D.E., Jing, J.: 2011, Astrophys. J. 736, 64. ADSCrossRefGoogle Scholar
  7. Chen, B., Yan, Y.: 2007, Solar Phys. 246, 431. ADSCrossRefGoogle Scholar
  8. Chernov, G.: 2006, Space Sci. Rev. 127, 195. MathSciNetADSCrossRefGoogle Scholar
  9. Chernov, G., Poquerusse, M., Bougeret, J.-P., Zlobec, P.: 1999, In: Proc. of the 9th European Meeting on Solar Physics SP-448. ESA, Noordwijk, 765. Google Scholar
  10. Dory, R., Guest, G., Harris, E.: 1965, Phys. Rev. Lett. 14, 131. ADSCrossRefGoogle Scholar
  11. Elgaroy, O.: 1961, Astrophys. Nor. 7, 23. Google Scholar
  12. Hankins, T.H., Eilek, J.A.: 2007, Astrophys. J. 670, 693. ADSCrossRefGoogle Scholar
  13. Kuijpers, J.: 1975, Astron. Astrophys. 410, 405. ADSGoogle Scholar
  14. Kuijpers, J.: 1980, In: Radio Physics of the Sun, IAU Symp. 86, 341. CrossRefGoogle Scholar
  15. Kuznetsov, A.A.: 2005, Astron. Astrophys. 438, 341. ADSCrossRefGoogle Scholar
  16. Kuznetsov, A.A.: 2008, Solar Phys. 253, 103. ADSCrossRefGoogle Scholar
  17. Kuznetsov, A.A., Tsap, Yu.: 2007, Solar Phys. 241, 127. ADSCrossRefGoogle Scholar
  18. Slottje, C.: 1972, Solar Phys. 25, 210. ADSCrossRefGoogle Scholar
  19. Tao, X., Thorne, R.N., Horne, R.B., Grimald, S., Arridge, C.S., Hospodarsky, G.B., Gurnett, D.A., Coates, A.J., Crary, F.J.: 2010, J. Geophys. Res. 115, A12204. ADSCrossRefGoogle Scholar
  20. Titova, E.E., Demekhov, A.G., Pasmanik, D.L. Trakhtengerts, V.Y., Manninen, J., Turunen, T., Rycroft, M.J.: 2007, Geophys. Res. Lett. 34, L02112. ADSCrossRefGoogle Scholar
  21. Winglee, R.M., Dulk, G.: 1986, Astrophys. J. 307, 808. ADSCrossRefGoogle Scholar
  22. Zaitsev, V.V., Stepanov, A.V.: 1975, Astron. Astrophys. 45, 135. ADSGoogle Scholar
  23. Zheleznyakov, V.V., Zlotnik, E.Ya.: 1975a, Solar Phys. 43, 441. ADSCrossRefGoogle Scholar
  24. Zheleznyakov, V.V., Zlotnik, E.Ya.: 1975b, Solar Phys. 44, 461. ADSCrossRefGoogle Scholar
  25. Zlotnik, E.Ya.: 2009, Cent. Eur. Astrophys. Bull. 33, 281. ADSGoogle Scholar
  26. Zlotnik, E.Ya., Zaitsev, V.V., Aurass, H., Mann, G.: 2009, Solar Phys. 255, 273. ADSCrossRefGoogle Scholar
  27. Zlotnik, E.Ya., Zaitsev, V.V., Aurass, H., Mann, G., Hofmann, A.: 2003, Astron. Astrophys. 410, 1011. ADSzbMATHCrossRefGoogle Scholar
  28. Zlotnik, E.Ya., Sher, E.M.: 2009, Radiophys. Quantum Electron. 52, 88. ADSCrossRefGoogle Scholar
  29. Zlotnik, E.Ya., Zaitsev, V.V., Aurass, H.: 2011a, Cent. Eur. Astrophys. Bull. 35, 161. ADSGoogle Scholar
  30. Zlotnik, E.Ya., Zaitsev, V.V., Aurass, H.: 2011b, Astrophys. J. Lett. 37, 508. Google Scholar

Copyright information

© Springer Science+Business Media Dordrecht 2012

Authors and Affiliations

  1. 1.Institute of Applied Physics RASNizhny NovgorodRussia

Personalised recommendations