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Titel |
Effect of Jovian magnetic field on the beaming cone of Io-controlled decameter radio emissions |
VerfasserIn |
Patrick Galopeau, Mohammed Y. Boudjada |
Konferenz |
EGU General Assembly 2013
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Medientyp |
Artikel
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Sprache |
Englisch
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Digitales Dokument |
PDF |
Erschienen |
In: GRA - Volume 15 (2013) |
Datensatznummer |
250080551
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Zusammenfassung |
In the CML-Io phase diagram, where the occurrence probability of the Jovian decameter
radio emissions is plotted versus the central meridian longitude (CML) and the orbital
phase of Io, four zones of enhanced probability emerge: the so-called Io-controlled
sources Io-A, Io-B (emitted from the northern hemisphere), and Io-C, Io-D (emitted
from the south). Making the hypothesis that the radio emission is generated (by the
cyclotron maser instability), near the local gyrofrequency, along a magnetic field line
carried away by Io (with a lead angle δ) along its revolution around Jupiter, we
study the occurrence probability in a polar diagram linked to the local magnetic
field. We make the assumption that the magnetic field intensity gradient plays the
role of an optical axis for the wave propagation. Thus, for a given Jovian magnetic
field model, we are able to plot the four sources Io-A, Io-B, Io-C and Io-D as a
function of the colatitude angle θ relative to the gradient of the magnetic field (radial
coordinate) and an azimuth angle Ï linked to the direction of magnetic field vector. Our
previous results revealed that the angle θ is not constant and that the Jovian decameter
emission controlled by Io is radiated in a hollow cone which is not axi-symmetrical
around the magnetic field gradient but flattened in the direction of the magnetic field
vector. In the present study, we focus on the effect of the magnetic field model
on the angular distribution of the sources and the consequences for the emission
cone. |
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