Auroral Processes

Kurth, W. S.; Bunce, E. J.; Clarke, J. T.; Crary, F. J.; Grodent, Denis; Ingersoll, Andrew P.; Dyudina, Ulyana A.; Lamy, Laurent; Mitchell, D. G.; Persoon, A. M.; Pryor, W. R.; Saur, Joachim; Stallard, T.

doi:10.1007/978-1-4020-9217-6_12

Cited by 34 publications

(19 citation statements)

References 108 publications

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“…by Stallard et al (2007a, b) and Kurth et al (2009), the physical processes which result in the generation of Saturn's auroras are not yet well established. With increasing equatorial distance from the planet, field-aligned currents and auroras could firstly result from corotation breakdown in the Enceladus torus through plasma production and transport processes analogous to those at Jupiter discussed by Hill (1979) and Pontius and Hill (1982).…”

Section: Introductionmentioning

confidence: 98%

Magnetospheric mapping of the dayside UV auroral oval at Saturn using simultaneous HST images, Cassini IMF data, and a global magnetic field model

et al. 2011

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Abstract.We determine the field-aligned mapping of Saturn's auroras into the magnetosphere by combining UV images of the southern dayside oval obtained by the Hubble Space Telescope (HST) with a global model of the magnetospheric magnetic field. The model is tailored to simulate prevailing conditions in the interplanetary medium, corresponding to high solar wind dynamic pressure and variable interplanetary magnetic field (IMF) strength and direction determined from suitably lagged field data observed just upstream of Saturn's dayside bow shock by the Cassini spacecraft. Two out of four images obtained in February 2008 when such simultaneous data are available are examined in detail, exemplifying conditions for northward and southward IMF. The model field structure in the outer magnetosphere and tail is found to be very different in these cases. Nevertheless, the dayside UV oval is found to have a consistent location relative to the field structure in each case. The poleward boundary of the oval is located close to the open-closed field boundary and thus maps to the vicinity of the magnetopause, consistent with previous results. The equatorward boundary of the oval then maps typically near the outer boundary of the equatorial ring current appropriate to the compressed conditions prevailing. Similar results are also found for related images from the January 2004 HST data set. These new results thus show that the mapped dayside UV oval typically spans the outer magnetosphere between the outer part of the ring current and the magnetopause. It does not encompass the region of primary corotation flow breakdown within the inner Enceladus torus.

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Section: Introductionmentioning

confidence: 98%

Magnetospheric mapping of the dayside UV auroral oval at Saturn using simultaneous HST images, Cassini IMF data, and a global magnetic field model

et al. 2011

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“…The Saturnian plasma is sub-corotating outside the orbit of Enceladus in the magnetodisk but the "corotation breakdown region" at Saturn is usually not as important to explain the main auroral oval emissions at Saturn and the associated current systems (Badman et al 2014;Bunce et al 2008). Saturn's Krimigis et al 2005) aurora is most probably be related to the location of the open-closed magnetic field line boundary in the ionosphere (Cowley and Bunce 2003), similar to the situation at Earth (Kurth et al 2009). Similar to the footprints of Io, Europa and Ganymede at Jupiter, the footprint of Enceladus has also been found (Pryor et al 2011) in UV and particle data.…”

Section: Middle Magnetosphere and Magnetodiskmentioning

confidence: 99%

“…In both magnetospheres we find strong dipolar intrinsic magnetic fields in the innermost magnetospheres, the region of the radiation belts populated with the high-energy electrons and ions with different origins. A nice review of outer planets radiation belts can be found in Mauk and Fox (2010) or in Bolton et al (2004), Kurth et al (2009) and in Krupp (2014) (accepted).…”

Section: Introductionmentioning

confidence: 99%

“…Figure 2 shows the coverage of the more than 150 orbits. Results have been summarized in various books and Four dedicated chapters about the Kronian magnetosphere and the aurora of Saturn (Gombosi et al 2009;Mitchell et al 2009;Mauk et al 2009;Kurth et al 2009) have been published in Dougherty et al (2009) where the understanding of the Kronian magnetosphere is very nicely summarized.…”

Section: Introductionmentioning

confidence: 99%

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Giant magnetospheres in our solar system: Jupiter and Saturn compared

Krupp

2014

Astron Astrophys Rev

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We review the current knowledge about the two biggest magnetospheres in our solar system based on the significant progress made with data from the Cassini spacecraft in orbit around Saturn since 2004, and based on the last mission to Jupiter by the Galileo spacecraft between 1995 and 2003. In addition we take into account new observations of the Hubble Space Telescope and other telescopes as well as the latest computer simulation efforts.

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“…Saturn is a planet with many types of auroral emissions (see review by Kurth et al [2009]); however, the extent to which these emissions are caused by internally driven magnetospheric processes is unknown. In ultraviolet wavelengths, the brightest of these emissions is the ‘main’ auroral emission, which exists at ∼75° latitude [ Badman et al , 2006], varies in strength and position with solar wind conditions [ Clarke et al , 2009], and is magnetically conjugate with equatorial radii of ∼18–23 R S (Saturn radii, 1 R S = 60280 km) [ Bunce et al , 2008].…”

Section: Introductionmentioning

confidence: 99%

Characterizing the limitations to the coupling between Saturn's ionosphere and middle magnetosphere

et al. 2012

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[1] Observations of Saturn's ultraviolet and infrared aurora show structures that, when traced along the planetary magnetic field, map to the inner, middle, and outer magnetosphere. From low to high latitudes the structures seen in the UV are the Enceladus footprint, which maps to an equatorial radius of 4 R S (Saturn radii); a diffuse emission that maps to a broad equatorial region from 4-11 R S on the nightside; and a bright ring of emission that maps to $15 R S . With the exception of the Enceladus spot, the magnetospheric drivers for these auroral emissions are not yet fully understood. We apply a 1D spatial, 2D velocity space Vlasov solver to flux tubes mapping from equatorial radii of 4, 6, 9, and 13 R S to Saturn's southern atmosphere. The aim is to globally characterize the field-aligned potential structure and plasma density profiles. The ionospheric properties -the field-aligned current densities at the ionospheric boundary, energy intensity profiles and fluxes of the electrons precipitating into the ionosphere -are also determined. We then couple our results to an ionospheric model to calculate the Pedersen conductances at the foot of the relevant flux tubes. We find that for a zero net potential drop between the ionosphere and magnetosphere, there exists a sharp potential drop at $1.5 R S along the magnetic field line as measured from the planetary center. The strength of this potential drop is approximately equal to that of the ambipolar potential resulting from the centrifugal confinement of the heavy, cold magnetospheric ion population. We also find that the ionospheric properties respond to changes in the magnetospheric plasma population, which are reflected in the nature of the precipitating electron population. For the flux tube mapping to 9 R S (À70 ), the incident electron energy flux into the ionosphere resulting from a magnetospheric plasma population with a small fraction of hot electrons is an order of magnitude less than that inferred from observations, implying that significant high-latitude field-aligned potentials (up to 1.5 keV) may exist in the saturnian magnetosphere. Calculated ionospheric Pedersen conductances range from 3.0-18.9 mho, and are thus not expected to limit the currents flowing between the ionosphere and magnetosphere.Citation: Ray, L. C., M. Galand, L. E. Moore, and B. Fleshman (2012), Characterizing the limitations to the coupling between Saturn's ionosphere and middle magnetosphere,

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Auroral Processes

Cited by 34 publications

References 108 publications

Magnetospheric mapping of the dayside UV auroral oval at Saturn using simultaneous HST images, Cassini IMF data, and a global magnetic field model

Magnetospheric mapping of the dayside UV auroral oval at Saturn using simultaneous HST images, Cassini IMF data, and a global magnetic field model

Giant magnetospheres in our solar system: Jupiter and Saturn compared

Characterizing the limitations to the coupling between Saturn's ionosphere and middle magnetosphere

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