Astrophysical Bulletin

, Volume 63, Issue 2, pp 156–168 | Cite as

Reversal of the polarization of cyclotron radiation in a hot coronal loop

  • T. I. Kaltman
  • O. A. Sheiner
  • E. Ya. Zlotnik
Article
  • 31 Downloads

Abstract

Spectropolarimetric features of thermal cyclotron radiation of solar coronal loops and the possibility of interpretation of the observed reversal of the sense of polarization of centimeter and decimeter waves are discussed. To this end, thermal cyclotron radiation is computed in terms of the simplest model of a three-dimensional hot loop (a half-torus). Such a loop is shown to be capable of changing appreciably the properties of the radiation of a solar active region at centimeter and decimeter wavelengths. A detailed analysis is performed to determine the conditions under which the radiation spectrum of an active region containing a coronal loop may have a complex pattern with several maxima or relatively narrow-band cyclotron lines, and the sense of polarization may change several times in the wavelength interval considered. These conditions are modelled by such parameters as the structure of the magnetic field, electron density, and size of the loop. The results of the computations of two-dimensional brightness temperature distributions at different wavelengths for ordinary and extraordinary waves at fixed points of the loop and the integrated parameters of the flux and polarization of radiation in terms of the model discussed are reported. Cases are considered where the line of sight is crossed by one or two loops. The expected distribution of polarization across the source in the model considered is compared to the results of RATAN-600 observations of the solar active region AR 7962 made on May 12–14, 1996.

PACS numbers

96.60.Tf 95.30.Gv 96.60.P- 95.75.Pq 

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Copyright information

© MAIK Nauka 2008

Authors and Affiliations

  • T. I. Kaltman
    • 1
  • O. A. Sheiner
    • 2
  • E. Ya. Zlotnik
    • 3
  1. 1.St.Petersburg Branch of the Special Astrophysical ObservatoryRussian Academy of SciencesPulkovoRussia
  2. 2.Radiophysical Research InstituteNizhnii NovgorodRussia
  3. 3.Institute of Applied PhysicsRussian Academy of SciencesNizhnii NovgorodRussia

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