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Mapping of coma anisotropies to plasma structures of weak comets: a 3-D hybrid simulation study

Gortsas, Nikolaos und Motschmann, Uwe und Kührt, Ekkehard und Knollenberg, Jörg und Simon, Sven und Boesswetter, Alexander (2009) Mapping of coma anisotropies to plasma structures of weak comets: a 3-D hybrid simulation study. Annales Geophysicae, 27 (4), Seiten 1555-1572. Copernicus Publications. ISSN 0992-7689.

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Offizielle URL: http://www.ann-geophys.net/27/1555/2009/

Kurzfassung

The effects of coma anisotropies on the plasma environment of comets have been studied by means of a 3-D hybrid model which treats electrons as a massless, charge-neutralizing fluid, whereas ion dynamics are covered by a kinetic approach. From Earth-based observations as well as from in-situ spacecraft measurements the shape of the coma of many comets is ascertained to be anisotropic. However, most plasma simulation studies deploy a spherically symmetric activity pattern. In this paper anisotropy is studied by considering three different coma shape models. The first model is derived from the Haser model and is characterised by spherically symmetry. This reference model is then compared with two different neutral gas shape models: the dayside restricted model with no nightside activity and a cone shaped model with opening angle of π/2. In all models the integrated surface activity is kept constant. The simulations have been done for the Rosetta target comet 67P/Churyumov-Gerasimenko for two heliocentric distances, 1.30 AU and 3.25 AU. It is found that shock formation processes are modified as a result of increasing spatial confinement. Characteristic plasma structures of comets such as the bow shock, magnetic barrier region and the ion composition boundary exhibit a shift towards the sun. In addition, the cone shaped model leads to a strong increase of the mass-loaded region which in turn leads to a smooth deceleration of the solar wind flow and an increasing degree of mixture between the solar wind and cometary ion species. This creates an additional transport channel of the magnetic field from the magnetic barrier region away which in turn leads to a broadening of this region. In addition, it leads to an ion composition boundary which is only gradually developed.

Dokumentart:Zeitschriftenbeitrag
Titel:Mapping of coma anisotropies to plasma structures of weak comets: a 3-D hybrid simulation study
Autoren:
AutorenInstitution oder E-Mail-Adresse der Autoren
Gortsas, NikolaosNICHT SPEZIFIZIERT
Motschmann, UweDLR und TU Braunschweig
Kührt, EkkehardNICHT SPEZIFIZIERT
Knollenberg, JörgNICHT SPEZIFIZIERT
Simon, SvenTU Braunschweig
Boesswetter, AlexanderTU Braunschweig
Datum:2 April 2009
Erschienen in:Annales Geophysicae
Referierte Publikation:Ja
In Open Access:Ja
In SCOPUS:Ja
In ISI Web of Science:Ja
Band:27
Seitenbereich:Seiten 1555-1572
Herausgeber:
HerausgeberInstitution und/oder E-Mail-Adresse der Herausgeber
European Geosciences Union, NICHT SPEZIFIZIERT
Verlag:Copernicus Publications
ISSN:0992-7689
Status:veröffentlicht
Stichwörter:Comets, Plasma Simulations, Numerical Simulation Studies, Kometen, Plasmasimulationen, Numerik
HGF - Forschungsbereich:Verkehr und Weltraum (alt)
HGF - Programm:Weltraum (alt)
HGF - Programmthema:W EW - Erforschung des Weltraums
DLR - Schwerpunkt:Weltraum
DLR - Forschungsgebiet:W EW - Erforschung des Weltraums
DLR - Teilgebiet (Projekt, Vorhaben):W - Vorhaben Asteroiden und Kometen (alt)
Standort: Berlin-Adlershof
Institute & Einrichtungen:Institut für Planetenforschung > Asteroiden und Kometen
Hinterlegt von: Nikolaos Gortsas
Hinterlegt am:07 Apr 2009
Letzte Änderung:04 Apr 2013 15:50

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