THE DIRECTIVITY OF SOLAR KILOMETRIC TYPE III BURSTS: ULYSSES–ARTEMIS OBSERVATIONS IN AND OUT OF THE ECLIPTIC PLANE |
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| Authors: | HOANG S POQUÉRUSSE M BOUGERET J-L |
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| Institution: | (1) Observatoire de Paris, DESPA, URA 264, CNRS, 92195 Meudon, France |
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| Abstract: | Comparing the records of the radio spectrographs ARTEMIS (100–500 MHz) on the ground and URAP (1–1000 kHz) on the Ulysses spacecraft, we find that most type III bursts extend from the corona to the solar wind. Using the positions of the associated flares, and assuming an average intensity ratio between these two frequency ranges, we derive for the first time the average radiation pattern of interplanetary type III bursts. We find that at 800 kHz it is shifted east of the radial direction by 30° and has a half-width of about 80° at maximum/10; the shift and width increase towards lower frequencies. Ulysses high-latitude observations show that the cross-section perpendicular to the heliospheric equator is about the same. We interpret these properties by refraction effects in local density gradients. |
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