The Location of the High-Density Boundary in Saturn’s Inner Magnetosphere (extended abstract). Planetary Radio Emissions| PLANETARY RADIO EMISSIONS VII 7|
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28 décembre 2011
- handle: 10670/1.tw5bmu
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Mots-clés
Mathematics, Physics and Space ResearchSujets proches
Wireless (Radio) Telephone, Wireless Wireless telephone (Early radio) Density, Plasma Very-low-frequency hiss Auroral hiss Density, Electron Distribution, Electron Electron densityCiter ce document
A. M. Persoon et al., « The Location of the High-Density Boundary in Saturn’s Inner Magnetosphere (extended abstract). Planetary Radio Emissions| PLANETARY RADIO EMISSIONS VII 7| », Elektronisches Publikationsportal der Österreichischen Akademie der Wissenschafte, ID : 10670/1.tw5bmu
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Résumé
Electron density measurements from the Cassini RPWS Langmuir Probe instrument have identified a sharply-defined region of low plasma densities in Saturn’s magnetosphere outside a dipole L-shell of ~15. Gradients in the density profiles define a boundary identified as the plasmapause [Gurnett et al., 2010] that separates the region of higher plasma density from the region of very low plasma density. During seven consecutive high-latitude passes in the northern hemisphere from September through December 2006, Cassini followed a series of trajectories that skimmed along high-latitude magnetic field lines for several days. The orientation of these trajectories made it possible for the RPWS to detect modulations in the high-latitude auroral hiss emissions at a 10.6 hour rotational modulation rate [Gurnett et al., 2009] and for the RPWS Langmuir Probe instrument to detect modulations in the electron density profiles that were anti-correlated with the hiss emissions [Gurnett et al., 2010]. The strong and periodic modulations in the density profiles indicate that Cassini is passing in and out of a plasma region of higher densities. One example during this seven-orbit time interval is shown in Figure 1. The periodic modulations in the density profile are shown in the bottom panel and are clearly anti-correlated with the periodic occurrence of intense auroral hiss emissions shown in the upper panel. The highest densities in this high-latitude region are 0.1 cm-3, two orders of magnitude greater than the lowest densities in this part of Saturn’s magnetosphere but well below the densities seen inside Saturn’s plasma disk [Morooka et al., 2009;Persoon et al., 2009].