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| Titel |
Type II radio bursts with triple harmonic structure at frequencies 10-30 MHz. |
| VerfasserIn |
Vladimir Dorovskyy, Valentin Melnik, Alexander Konovalenko, Helmut Rucker, Eduard Abranin |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250040225
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| Zusammenfassung |
| In this presentation we report about the first observations of Type II bursts with three
harmonics in frequency range 10 — 30 MHz. The most representative of them was registered
on June 4, 2004 with the UTR-2 radio telescope and consisted of three lanes. Wide frequency
band of the analysis allowed to observe all three harmonics of the burst at one moment of
time (7h53m50s UT). The observational properties, which confirm the harmonic structure of
the burst, are discussed. The frequency ratios of the harmonics at fixed moment of time
were f2-f1=2 and f3-f1=2.8, where f1, f2 and f3 are the harmonic frequencies.
All three harmonics of the observed Type II burst had fine structure in the form of
fast drifting sub-bursts. The durations of sub-bursts of different harmonics were
also different (in average 7 s for fundamental, 3 s for second and 1-2 s for third
harmonic). The frequency drift rates at fixed moment of time appeared to be -10
kHz/s for fundamental (f=10 MHz), -30 kHz/s for second harmonic (f=20 MHz) and
-50 kHz/s for third harmonic (f=30 MHz). The consistency of the three harmonics
hypothesis was tested in the frames of four different corona models. For each model
corresponding source velocities were calculated. The connection between the observed
Type-II burst and CMEs was analyzed. The extension of this Type II burst at lower
frequencies (WIND data at frequencies 1–11 MHz) was also found. Some other
examples of Type II bursts possibly having the triple harmonic structure are shown. |
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