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Coordinated measurements of auroral processes at Saturn from the Cassini spacecraft and HST
Mitchell, D. G.; Kurth, William; Hospodarsky, G. B. et al.
2008AGU Fall Meeting
 

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Keywords :
2704 Auroral phenomena (2407); 2784 Solar wind/magnetosphere interactions; 2788 Magnetic storms and substorms (7954); 5706 Aurorae; 5737 Magnetospheres (2756)
Abstract :
[en] One of the primary Cassini mission objectives at Saturn is to characterize Saturn's aurora-its spatial morphology, associated particle energization, radio wave generation, and magnetospheric currents, relationship with solar wind pressure and magnetic field, and its large scale mapping to the magnetosphere. By design, the Cassini orbital tour included high inclination and low periapsis orbits late in the prime mission specifically to address many of these topics. In this presentation, we will provide a snapshot of the current state of our investigation into the relationship between magnetospheric measurements of particles and fields, and the aurora. For in situ data, we will show measurements of upward traveling light ion conics (~30 keV to 200 keV), often accompanied by electron beams (<20 keV to ~1 MeV) and enhanced broadband noise (10 Hz to a few kHz), throughout the outer magnetosphere on field lines that nominally map from well into the polar cap (dipole L > 50) to well into the closed field region (dipole L < 10). Sometimes the particle phenomena and the broadband noise occur in pulses of roughly five-minute duration, separated by tens of minutes. At other times they are relatively steady over an hour or more. Magnetic signatures associated with some of the pulsed events are consistent with field aligned current structures. Correlative observations of solar wind (Cassini) and aurora (HST) have established a strong relationship between solar wind pressure and auroral activity (brightness) (Crary et al., Nature, 2005; Clarke et al., JGR, 2008). A similar correspondence between bright auroral arcs and ring current ion acceleration will be shown here. So while some auroral forms seem to be associated with the open/closed field boundary (i.e. in the cusp-Bunce et al., JGR, 2008), we also demonstrate that under some magnetospheric conditions for which protons and oxygen ions are accelerated once per Saturn magnetosphere rotation at a preferred local time between midnight and dawn, simultaneous auroral observations by the HST reveal a close correlation between these dynamical magnetospheric events and dawn-side transient auroral brightenings. Likewise, many of the recurrent energetic neutral atom enhancements coincide closely with bursts of Saturn kilometric radiation, again suggesting a linkage with high latitude auroral processes. Finally, we will show some intriguing results of auroral movie sequences from the Cassini UVIS instrument with corresponding ring current movies from the Magnetospheric Imaging Instrument Ion and Neutral Camera (MIMI/INCA).
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Mitchell, D. G.;  Johns Hopkins University > Applied Physics Laboratory
Kurth, William;  University of Iowa > Department of Physics and Astronomy
Hospodarsky, G. B.;  University of Iowa > Department of Physics and Astronomy
Gurnett, D. A.;  University of Iowa > Department of Physics and Astronomy
Krupp, N.;  Max-Planck-Institut für Sonnensystemforschung
Saur, J.;  Universität zu Köln > Institut für Geophysik and Meteorologie
Mauk, B. A.;  Johns Hopkins University > Applied Physics Laboratory
Carbary, J. F.;  Johns Hopkins University > Applied Physics Laboratory
Krimigis, S. M.;  Johns Hopkins University > Applied Physics Laboratory
Brandt, P. C.;  Johns Hopkins University > Applied Physics Laboratory
Dougherty, M. K.;  Imperial College (United Kingdom) > Blackett Laboratory
Clarke, J. T.;  Boston University > Center for Space Physics
Nichols, J. D.;  University of Leicester > Department of Physics and Astronomy
Gérard, Jean-Claude  ;  Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Labo de physique atmosphérique et planétaire (LPAP)
Grodent, Denis  ;  Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Labo de physique atmosphérique et planétaire (LPAP)
Pryor, W. R.;  Central Arizona College > Department of Science
Bunce, E. J.;  University of Leicester > Department of Physics and Astronomy
Crary, F. J.;  Southwest Research Institute
More authors (8 more) Less
Language :
English
Title :
Coordinated measurements of auroral processes at Saturn from the Cassini spacecraft and HST
Publication date :
01 December 2008
Event name :
AGU Fall Meeting
Event organizer :
AGU
Event place :
San Francisco, United States
Audience :
International
Available on ORBi :
since 22 December 2009

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