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Filamented ion tail structures at Titan: A hybrid simulation study

Feyerabend, M. and Simon, S. and Motschmann, U. and Liuzzo, L. (2015) Filamented ion tail structures at Titan: A hybrid simulation study. Planetary and Space Science, 117, pp. 362-376. Elsevier. DOI: 10.1016/j.pss.2015.07.008 ISSN 0032-0633

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Abstract

This study investigates the processes that lead to the detection of split signatures in ion density during several crossings of the Cassini spacecraft through Titan's mid-range plasma tail (T9, T63, and T75). During each of these flybys, the Cassini Plasma Spectrometer detected Titan's ionospheric ion population twice; i.e., the spacecraft passed through two spatially separated regions where cold ions were detected, with the regions also being dominated by ions of different masses in the case of T9. Whether this filamented tail structure is an omnipresent feature of Titan's plasma interaction or a result of non-stationary upstream conditions during specific flybys is still unclear. To explain these features, we apply the hybrid simulation code AIKEF (kinetic ions and fluid electrons). Our model includes chemical reactions as well as a realistic photoionization model for a sophisticated description of the ionospheric composition of Titan. Our simulations show that the filamentation of Titan's tail is indeed a common feature of the moon's plasma interaction. Light ionospheric species escape along draped magnetic field lines to form a parabolically shaped filament structure, which is mainly seen in planes that contain the upstream magnetospheric magnetic field and the upstream flow direction. In addition, transport of ions of all species from the ramside towards downstream produces a cone structure behind Titan, with a region of decreased density inside and filaments of 1–2 RT (RT¼2575 km) thickness and enhanced density at the surface of the cone. Spacecraft trajectories that penetrate these structures allow for the detection of split signatures in the tail. The orientation of the upstream magnetic field and plasma flow as well as local time effects (i.e., Titan's orbital position) influence the location of the filaments in the tail and can also cause asymmetries in their sizes and densities. The detection of the split signatures along a spacecraft trajectory may therefore be made possible or completely prevented by moving the narrow filaments in or out of the way of the spacecraft. Our results imply that the detections of split signatures during T9, T63 and T75 are consistent by Cassini penetrating through parts of these filament structures.

Item URL in elib:https://elib.dlr.de/100829/
Document Type:Article
Title:Filamented ion tail structures at Titan: A hybrid simulation study
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Feyerabend, M.feyerabend (at) geo.uni-koeln.deUNSPECIFIED
Simon, S.Institut für Geophysik und Extraterrestrische Physik der Technischen Universität Braunschweig, Braunschweig, GermanyUNSPECIFIED
Motschmann, U.uwe.motschmann (at) dlr.deUNSPECIFIED
Liuzzo, L.School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, USAUNSPECIFIED
Date:2015
Journal or Publication Title:Planetary and Space Science
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In SCOPUS:Yes
In ISI Web of Science:Yes
Volume:117
DOI :10.1016/j.pss.2015.07.008
Page Range:pp. 362-376
Publisher:Elsevier
ISSN:0032-0633
Status:Published
Keywords:Titan, Cassini, Moon–magnetosphere interactions, Hybrid plasmasimulation
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Space Science and Exploration
DLR - Research area:Raumfahrt
DLR - Program:R EW - Erforschung des Weltraums
DLR - Research theme (Project):R - Vorhaben Exploration des Sonnensystems
Location: Berlin-Adlershof
Institutes and Institutions:Institute of Planetary Research > Asteroids and Comets
Deposited By: Kührt, Dr.rer.nat. Ekkehard
Deposited On:06 Jan 2016 16:49
Last Modified:08 Mar 2018 18:48

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