Composition and Dynamics of Plasma in Saturn's Magnetosphere

Young, D. T.; Berthelier, Jean‐Jacques; Blanc, Michel; Burch, J. L.; Bolton, S. J.; Coates, A. J.; Crary, F. J.; Goldstein, R.; Grandé, M.; Hill, T. W.; Johnson, R. E.; Baragiola, R. A.; Kelhä, Väinö; McComas, D. J.; Мурсула, К.; Sittler, E. C.; Svenes, K.; Szegö, K.; Tanskanen, P.; Thomsen, M. F.; Bakshi, Srinivasa Rao; Barraclough, B. L.; Bebesi, Z.; Delapp, D.; Dunlop, M. W.; Gosling, J. T.; Furman, Judith D.; Gilbert, L. K.; Glenn, D. R.; Holmlund, Christer; Illiano, J. M.; Lewis, G. R.; Linder, Dietmar; Maurice, S.; McAndrews, H. J.; Narheim, B. T.; Pallier, E.; Reisenfeld, D. B.; Rymer, A. M.; Smith, H. T.; Tokar, R. L.; Vilppola, J.; Zinsmeyer, C.

doi:10.1126/science.1106151

Cited by 279 publications

(306 citation statements)

References 32 publications

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“…Bagenal, 1994;Radioti et al, 2005), while at Saturn it will be dominated by oxygen and hydrogen originating from the icy moons (e.g. Young et al, 2005). The hot plasma in the Dungey-cycle "return" region, however, results from the heating of tail lobe plasma downstream from the tail reconnection site, and will thus consist principally of light ions, hydrogen and helium, originating either from the planet's ionosphere via the polar wind (potentially containing singly-charged helium), or from the solar wind (containing doubly-charged helium).…”

Section: Identification Of Dungey-cycle Flows In the Equatorial Magnementioning

confidence: 99%

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Significance of Dungey-cycle flows in Jupiter's and Saturn's magnetospheres, and their identification on closed equatorial field lines

2007

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Abstract. We consider the contribution of the solar winddriven Dungey-cycle to flux transport in Jupiter's and Saturn's magnetospheres, the associated voltages being based on estimates of the magnetopause reconnection rates recently derived from observations of the interplanetary medium in the vicinity of the corresponding planetary orbits. At Jupiter, the reconnection voltages are estimated to be ∼150 kV during several-day weak-field rarefaction regions, increasing to ∼1 MV during few-day strong-field compression regions.The corresponding values at Saturn are ∼25 kV for rarefaction regions, increasing to ∼150 kV for compressions. These values are compared with the voltages associated with the flows driven by planetary rotation. Estimates of the rotational flux transport in the "middle" and "outer" magnetosphere regions are shown to yield voltages of several MV and several hundred kV at Jupiter and Saturn respectively, thus being of the same order as the estimated peak Dungeycycle voltages. We conclude that under such circumstances the Dungey-cycle "return" flow will make a significant contribution to the flux transport in the outer magnetospheric regions. The "return" Dungey-cycle flows are then expected to form layers which are a few planetary radii wide inside the dawn and morning magnetopause. In the absence of significant cross-field plasma diffusion, these layers will be characterized by the presence of hot light ions originating from either the planetary ionosphere or the solar wind, while the inner layers associated with the Vasyliunas-cycle and middle magnetosphere transport will be dominated by hot heavy ions originating from internal moon/ring plasma sources. The temperature of these ions is estimated to be of the order of a few keV at Saturn and a few tens of keV at Jupiter, in both layers.

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Section: Identification Of Dungey-cycle Flows In the Equatorial Magnementioning

confidence: 99%

“…A similar body of information is currently being gathered at Saturn by the Cassini orbiter (e.g. Bunce et al, 2005;Dougherty et al, 2005;Gurnett et al, 2005;Young et al, 2005), now also including energetic neutral atom imaging of magnetospheric dynamics (e.g. Krimigis et al, 2005;Paranicas et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

Significance of Dungey-cycle flows in Jupiter's and Saturn's magnetospheres, and their identification on closed equatorial field lines

2007

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“…20R s ). Thus, energetic particles in Saturn's magnetosphere can interact with the ionosphere region and inject energy causing ionization and heating; they can also alter the composition by direct injection of particles from the magnetosphere (characterized by an oxygen-rich composition; Young et al 2005). Similarly, Titan can act as a source of particles for the magnetosphere, e.g.…”

Section: Introduction: Titan's Space Environmentmentioning

confidence: 99%

Interaction of Titan's ionosphere with Saturn's magnetosphere

Coates

2008

Phil. Trans. R. Soc. A.

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Titan is the only Moon in the Solar System with a significant permanent atmosphere. Within this nitrogen-methane atmosphere, an ionosphere forms. Titan has no significant magnetic dipole moment, and is usually located inside Saturn's magnetosphere. Atmospheric particles are ionized both by sunlight and by particles from Saturn's magnetosphere, mainly electrons, which reach the top of the atmosphere. So far, the Cassini spacecraft has made over 45 close flybys of Titan, allowing measurements in the ionosphere and the surrounding magnetosphere under different conditions. Here we review how Titan's ionosphere and Saturn's magnetosphere interact, using measurements from Cassini low-energy particle detectors. In particular, we discuss ionization processes and ionospheric photoelectrons, including their effect on ion escape from the ionosphere. We also discuss one of the unexpected discoveries in Titan's ionosphere, the existence of extremely heavy negative ions up to 10 000 amu at 950 km altitude.

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“…Solar radiation and energetic plasma from Saturn's magnetosphere ionizes the neutral molecules in Titan's ionosphere, creating an ionosphere at altitudes above about 400 km (Bird et al 1997;Wahlund et al 2005;Young et al 2005;Keller et al 1992;Gan et al 1992;Galand et al 1999;Banaskiewicz et al 2000;Molina-Cuberos et al 2001;Lilensten et al 2005a;Agren et al 2007;Cravens et al 2008, Kliore et al, 2008). Titan's neutral atmosphere consists mainly of molecular nitrogen and methane but the relatively minor amounts of many hydrocarbon and nitrogen-bearing species play an important role in the upper atmosphere and ionosphere Vuitton et al 2006Vuitton et al , 2007Fox and Yelle 1997;Keller et al 1998;Waite et al 2007).…”

Section: Introductionmentioning

confidence: 99%

Model-data comparisons for Titan's nightside ionosphere

Cravens

Robertson

Waite

et al. 2009

Icarus

112

144

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Solar and x-ray radiation and energetic plasma from Saturn's magnetosphere interact with the upper atmosphere producing an ionosphere at Titan. The highly coupled ionosphere and upper atmosphere system mediates the interaction between Titan and the external environment.A model of Titan's nightside ionosphere will be described and the results compared with data from the Ion and Neutral Mass Spectrometer (INMS) and the Langmuir probe (LP) part of the Radio and Plasma Wave (RPWS) experiment for the T5 and T21 nightside encounters of the Cassini Orbiter with Titan.Electron impact ionization associated with the precipitation of magnetospheric electrons into the upper atmosphere is assumed to be the source of the nightside ionosphere, at least for altitudes above 1000 km. Magnetospheric electron fluxes measured by the Cassini electron spectrometer (CAPS ELS) are used as an input for the model. The model is used to interpret the observed composition and structure of the T5 and T21 ionospheres. The densities of many ion species (e.g., CH 5 + and C 2 H 5 + ) measured during T5 exhibit temporal and/or spatial variations apparently associated with variations in the fluxes of energetic electrons that precipitate into the atmosphere from Saturn's magnetosphere.

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Composition and Dynamics of Plasma in Saturn's Magnetosphere

Cited by 279 publications

References 32 publications

Significance of Dungey-cycle flows in Jupiter's and Saturn's magnetospheres, and their identification on closed equatorial field lines

Significance of Dungey-cycle flows in Jupiter's and Saturn's magnetospheres, and their identification on closed equatorial field lines

Interaction of Titan's ionosphere with Saturn's magnetosphere

Model-data comparisons for Titan's nightside ionosphere

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