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Solar Physics

, Volume 143, Issue 2, pp 301–316 | Cite as

A new investigation of microbursts at meter-decameter wavelengths

  • K. R. Subramanian
  • N. Gopalswamy
  • Ch. V. Sastry
Article

Abstract

We report on a new investigation of microbursts at meter-decameter wavelengths observed using the Broad Band Array at Gauribidanur Radio Observatory. This is an independent set of observations of microbursts: previous observations had been obtained only by the Clark Lake multifrequency radioheliograph. We confirm several properties of microbursts reported earlier. In addition, we have studied some new properties of microbursts such as time profile characteristics, flux density and energy spectra for comparison with the corresponding properties of normal type III bursts. The present study supports the idea that the microbursts and the normal type III bursts are generated by electron beams of similar characteristics. We interpret the low brightness temperature of microbursts as follows: plasma waves generated by the electron beams through beam-plasma instability are quickly isotropized as they scatter on the density fluctuations in the corona. The resulting low levels of plasma waves are converted into transverse radiation of low brightness temperature. One important consequence of the isotropization is that the second harmonic plasma emission dominates the fundamental and hence the microbursts are expected to be predominantly a harmonic plasma emission.

Keywords

Electron Beam Energy Spectrum Flux Density Broad Band Time Profile 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Kluwer Academic Publishers 1993

Authors and Affiliations

  • K. R. Subramanian
    • 2
  • N. Gopalswamy
    • 1
  • Ch. V. Sastry
    • 2
  1. 1.Dept. of AstronomyUniversity of MarylandUSA
  2. 2.Indian Institute of AstrophysicsBangaloreIndia

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