Spike-like Bursts as Fine Structure of Zebras |
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| Authors: | P Zlobec M Karlický |
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| Institution: | (1) INAF – Trieste Astronomical Observatory, Via G.B. Tiepolo 11, 34131 Trieste, Italy;(2) Astronomical Institute, Academy of Sciences of the Czech Republic, 251 65 Ondřejov, Czech Republic |
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| Abstract: | We studied the characteristics of the zebra-associated spike-like bursts that were recorded with high time resolution at 1420
MHz in four intervals (from 12:45 to 12:48 UT) during 5 August 2003. Our detailed analysis is based on the selection of more
than 500 such spike-like bursts and it is, at least to our knowledge, the first study devoted to such short-lived bursts.
Their characteristics are different from those pertinent to “normal” spike bursts, as presented in the paper by Güdel and
Benz (Astron. Astrophys.
231, 202, 1990); in particular, their duration (about 7.4 ms at half power) is shorter, so they should be members of the SSS (super short
structures) family (Magdalenić et al., Astrophys. J.
642, L77, 2006). The bursts were generally strongly R-polarized; however, during the decaying part of interval I a low R-polarized and L-polarized
bursts were also present. This change of polarization shows a trend that resembles the peculiar form of the zebra lines in
the spectral dominion (“V” like). A global statistical analysis on the bursts observed in the two polarimetric channels shows
that the highest cross-correlation coefficient (about 0.5) was pertinent to interval I. The zebras and the bursts can be interpreted
by the same double plasma resonance process as proposed by Bárta and Karlicky (Astron. Astrophys.
379, 1045, 2001) and Karlicky et al. (Astron. Astrophys.
375, 638, 2001); in particular, the spikes are generated by the interruption of this process by assumed turbulence (density or magnetic
field variations). This process should be present in the region close to the reconnection site (e.g., in the plasma reconnection outflows) where the density and the magnetic field vary strongly. |
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| Keywords: | Sun Radio bursts |
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