Space Science Reviews

, Volume 26, Issue 1, pp 3–38 | Cite as

The emission mechanisms for solar radio bursts

  • D. B. Melrose
Article

Abstract

Emission mechanisms for meter-λ solar radio bursts are reviewed with emphasis on fundamental plasma emission.

The ‘standard’ version of fundamental plasma emission is due to scattering of Langmuir waves into transverse waves by thermal ions. It may be treated semi-quantitatively by analogy with Thomson scattering provided induced scattering is unimportant. A physical interpretation of induced scattering is given and used to derive the transfer equation in a semi-quantitative way. Solutions of the transfer equation are presented and it is emphasized that ‘standard’ fundamental emission with brightness temperatures ≫109 K can be explained only under seemingly exceptional circumstances.

Two alternative fundamental emission mechanisms are discussed: coalescence of Langmuir waves with low-frequency waves and direct conversion due to a density inhomogeneity. It is pointed out for the first time that the coalescence process (actually a related decay process) can lead to amplified transverse waves. The coalescence process saturates when the effective temperature Tt of the transverse waves reaches the effective temperature Tl of the Langmuir waves. This saturation occurs provided the energy density in the low-frequency waves exceeds a specific value which is about 10-9 of the thermal energy density for emission from the corona at ≈100 MHz. It is suggested that direct emission has been dismissed as a possible alternative without adequate justification.

Second harmonic plasma emission is discussed and compared with fundamental plasma emission. It also saturates at TtTl, and this saturation should occur in the corona roughly for Tl ≳ 1015 K. If fundamental plasma emission is attributed to coalescence with low-frequency waves, then for Tl ≳ 1015 K the brightness temperatures at the two harmonics should be equal and equal to Tl. This offers a natural explanation for the approximate equality of the two brightness temperature often found in type II and type III bursts.

Analytic treatments of gyro-synchrotron emission are reviewed. The application of the mechanism to moving type IV bursts is discussed in view of bursts with ≳ 1010 K at 43 MHz.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Bougeret, J. L. and Steinberg, J. L.: 1977, Astron. Astrophys. 61, 777.Google Scholar
  2. Daigne, G.: 1975a, Astron. Astrophys. 38, 141.Google Scholar
  3. Daigne, G.: 1975b, Astron. Astrophys. 42, 71.Google Scholar
  4. Daigne, G. and Møller-Pedersen, B.: 1974, Astron. Astrophys. 37, 355.Google Scholar
  5. Denisse, J. F.: 1960, Inf. Bull. Solar Radio Obs. No. 4 and URSI 13th General Assembly, London 1960.Google Scholar
  6. Dulk, G. A.: 1973, Solar Phys. 43, 491.Google Scholar
  7. Dulk, G. A. and McLean, D. J.: 1978, Solar Phys. 57, 279.Google Scholar
  8. Dulk, G. A., Melrose, D. B. and White, S. M.: 1979, Astrophys. J. 234, 1137.Google Scholar
  9. Dulk, G. A. and Suzuki, S.: 1979, ‘The Positions and Polarization of Type III Solar Bursts’, Astron. Astrophys., in press.Google Scholar
  10. Duncan, R. A.: 1979, Solar Phys. 63, 389.Google Scholar
  11. Field, G. B.: 1956, Astrophys. J. 124, 555.Google Scholar
  12. Ginzburg, V. L. and Syrovatskii, S. I.: 1965, Am. Rev. Astron. Astrophys. 3, 297.Google Scholar
  13. Ginzburg, V. L. and Zheleznyakov, V. V.: 1958, Astron. Zh. 35, 694; Soviet Astron.-A. J. 2, 653.Google Scholar
  14. Ginzburg, V. L. and Zheleznyakov, V. V.: 1959, Astron. Zh. 36, 233; Soviet Astron.-A. J. 3, 235.Google Scholar
  15. Gurnett, D. A.: 1979, in H. Rosenbauer (ed.), Plasma Waves in the Solar Wind: A Review of Observations, Solar Wind, Vol. 4, Springer (in press).Google Scholar
  16. Gurnett, D. A. and Anderson, R. R.: 1977, J. Geophys. Res. 82, 632.Google Scholar
  17. Holt, S. S. and Ramaty, R.: 1969, Solar Phys. 8, 119.Google Scholar
  18. Kai, K.: 1970, Solar Phys. 11, 456.Google Scholar
  19. Kamilov, K., Khakimov, F. Kh., Stenflo, L. and Tsytovich, V. N.: 1974, Physica Scripta 10, 191.Google Scholar
  20. Kaplan, S. A. and Tsytovich, V. N.: 1967, Astron. Zh. 44, 1036; Soviet Astron.-A. J. 11, 834 (1968).Google Scholar
  21. Kaplan, S. A. and Tsytovich, V. N.: 1973, Plasma Astrophysics, Pergamon Press, Oxford.Google Scholar
  22. Martyn, D. F.: 1947, Nature 159, 26.PubMedGoogle Scholar
  23. Melrose, D. B.: 1970a, Australian J. Phys. 32, 871.Google Scholar
  24. Melrose, D. B.: 1970b, Australian J. Phys. 23, 885.Google Scholar
  25. Melrose, D. B.: 1973, Australian J. Phys. 26, 229.Google Scholar
  26. Melrose, D. B.: 1975, Solar Phys. 43, 79.Google Scholar
  27. Melrose, D. B.: 1976, Solar Phys. 46, 511.Google Scholar
  28. Melrose, D. B.: 1977, Izv. Vyssh. Uchebn. Zaved. Radiofiz. 20, 1369; Radiophysics and Quantum Electronics 20, 945.Google Scholar
  29. Melrose, D. B.: 1979a, Plasma Astrophysics, Vol. 1, Gordon and Breach, New York.Google Scholar
  30. Melrose, D. B.: 1979b, Plasma Astrophysics, Vol. 2, Gordon and Breach, New York.Google Scholar
  31. Melrose, D. B.: 1979c, ‘Mode Coupling in the Solar Corona VI Direct Conversion of Langmuir Waves into o-mode Waves’, Australian J. Phys., in press.Google Scholar
  32. Melrose, D. B., Dulk, G. A. and Smerd, S. F.: 1978, Astron. Astrophys. 66, 315.MathSciNetMATHGoogle Scholar
  33. Melrose, D. B. and Stenhouse, J. E.: 1979, Astron. Astrophys. 73, 151.Google Scholar
  34. Melrose, D. B. and Sy, W. N.: 1972, Australian J. Phys. 25, 387.Google Scholar
  35. Melrose, D. B. and White, S. M.: 1978, Proc. Astron. Soc. Australia 3, 231.Google Scholar
  36. Mercier, C. and Rosenberg, H.: 1974, Astron. Astrophys. 39, 193.Google Scholar
  37. Pawsey, J. L. and Smerd, S. F.: 1953, in G. P. Kuiper (ed.), The Solar System, Vol. 1, Chapter 7, University of Chicago Press.Google Scholar
  38. Ramaty, R.: 1969, Astrophys. J. 158, 753.Google Scholar
  39. Ramaty, R. and Petrosian, V.: 1977, Astrophys. J. 178, 241.Google Scholar
  40. Riddle, A. C.: 1972, Proc. Astron. Soc. Australia 2, 98.Google Scholar
  41. Riddle, A. C.: 1974, Solar Phys. 35, 153.Google Scholar
  42. Robinson, R. D.: 1974, Proc. Astron. Soc. Australia 2, 258.Google Scholar
  43. Robinson, R. D.: 1977, dissertation, University of Colorado.Google Scholar
  44. Schmahl, E. J.: 1972, Proc. Astron. Soc. Australia 2, 95.Google Scholar
  45. Shklovsky, I. S.: 1946, Astr. J. U.R.S.S. 23, 333.Google Scholar
  46. Smerd, S. F.: 1976, Solar Phys. 46, 493.Google Scholar
  47. Smith, D. F.: 1976, Solar Phys. 46, 515.Google Scholar
  48. Smith, D. F.: 1970, Adv. Astron. Astrophys. 7, 147.Google Scholar
  49. Smith, D. F. and Riddle, A. C.: 1975, Solar Phys. 44, 471.Google Scholar
  50. Steinberg, J. L., Aubier-Giraud, M., Leblanc, Y. and Boischot, A.: 1971, Astron. Astrophys. 10, 362.Google Scholar
  51. Stewart, R. T., Duncan, R. A., Suzuki, S. and Nelson, G. J.: 1978, Proc. Astron. Soc. Australia 3, 247.Google Scholar
  52. Suzuki, S. and Sheridan, K. V.: 1977, Izv. Vyssh. Uchebn. Zaved. Radiofiz. 20, 1432; Radiophysics and Quantum Electrons. 20, 989.Google Scholar
  53. Takakura, T.: 1972, Solar Phys. 26, 151.Google Scholar
  54. Takakura, T. and Scalise, E., Jr.: 1970, Solar Phys. 11, 434.Google Scholar
  55. Tarnstrom, G. T.: 1976, Astron. Astrophys. 49, 31.Google Scholar
  56. Tidman, D. A. and Dupree, T. H.: 1965, Phys. Fluids 8, 1860.Google Scholar
  57. Trubnikov, B. A.: 1958, dissertation, Moscow University: ‘Magnetic Emission of High Temperature Plasmas’ (English translation 1960, USAEC Tech. Information Service AEC-tr-4073).Google Scholar
  58. Tsytovich, V. N.: 1966, Usp. Fiz. Nauk. 89, 89; Soviet Phys. Uspekhi 9, 370.Google Scholar
  59. Watson, G. N.: 1944, A Treatise on the Theory of Bessel Functions, Cambridge Univ. Press.Google Scholar
  60. Wild, J. P. and Hill, E. R.: 1971, Australian J. Phys. 24, 43.Google Scholar
  61. Wild, J. P., Murray, J. D. and Rowe, W. C.: 1953, Nature 172, 533.Google Scholar
  62. Wild, J. P., Murray, J. D. and Rowe, W. C.: 1954, Australian J. Phys. 7, 439.Google Scholar
  63. Zheleznyakov, V. V.: 1970, Radio Emission from the Sun and Planets, Pergamon Press, Oxford.Google Scholar

Copyright information

© D. Reidel Publishing Co 1980

Authors and Affiliations

  • D. B. Melrose
    • 1
  1. 1.Department of Theoretical PhysicsUniversity of SydneyN.S.W.Australia

Personalised recommendations