Dynamik und mineralogische Zusammensetzung von Jupiter- und Saturn-Stromteilchen
Zusammenfassung der Projektergebnisse
The goal of this project was to utilize the Cassini Cosmic Dust Analyser (CDA) measurements to achieve a comprehensive understanding of the dynamics, the composition, and the origin of stream particles. Stream particles are nanometer-sized dust particles ejected from both the Jovian and Saturnian systems with speed faster than ∼ 100 km/ second. Among various types of cosmic dust, stream particles are definitely at the extremes. Studying these fast nanodust particles thus will provide us unique insights to their host system and their interactions between the environment. The dynamics and composition of Saturnian stream particles measured by the Cosmic Dust Analyser (CDA) onboard the Cassini spacecraft was analysed. To reconstruct the dynamical properties of Saturnian stream particles, we adopted a backward tracing method with in situ solar wind measurements to filter out the influence of the interplanetary magnetic field. Our results showed that stream particles from Saturn have sizes ranging from 2 to 8 nm (radius) with ejection velocities between 50 and 200 km s^−1 . Our results showed that stream particles from Saturn have sizes ranging from 2 to 8 nm (radius) with ejection velocities between 50 and 200 kms^−1 . Moreover, the derived “ejection region” of stream particles in the outer part of Saturn’s E ring is indicative of the dust charging condition profile in the planet’s magnetosphere. By using the Cassini magnetospheric plasma measurements as input, our ejection model considers stochastic charging and well reproduces the dynamical properties of stream particles derived from backward simulations. An updated analysis of CDA stream particle mass spectra confirms that the silicateous material is the most probable composition of Saturnian stream particles, in contrast to E ring particles whose composition is dominated by water ice. This compositional discrepancy can be reproduced by our model if the different sputter efficiencies of silicateous material and water ice are considered. We suggest that silicateous impurities released from icy grains at the outer E ring are the most probable source of Saturnian stream particles.
Projektbezogene Publikationen (Auswahl)
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2010, Interaction of the Solar Wind and Stream Particles, Results from the Cassini Dust Detector, “Twelfth International Solar Wind Conference”, AIP Conf. Proc., 1216, 510- 513
H.-W. Hsu, S. Kempf, F. Postberg, R. Srama, C. M. Jackman, G. Moragas-Klostermeyer, S. Helfert, and E. Grün
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2010, Observation of Saturnian Stream Particles in the Interplanetary Space, Icarus, 206, 653-661
H.-W. Hsu, S. Kempf, and C. M. Jackman
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Dynamics, Composition, and Origin of Jovian and Saturnian Dust Stream Particles, in Nanodust in the Solar System: Discoveries and Interpretations, edited by I. Mann, N. Meyer-Vernet, A. Czechowski, pp. 77-117, Astrophysics and Space Science Library of Springer, 2012, Vol. 385
H.-W. Hsu, H. Krüger, and F. Postberg
