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ENA periodicities at Saturn
Krimigis, S. M.; Mitchell, D. G.; Paranicas, C. +2 more
The Magnetospheric Imaging Instrument (MIMI) on the Cassini spacecraft has observed energetic neutral atoms (ENA) at Saturn for three years from 2004 to 2007. The 20-50 keV hydrogen and 64-144 keV oxygen neutrals were examined for periodic behavior by projecting their images onto a plane perpendicular to Saturn's equatorial plane and summing the e…
Venus Express observes a new type of shock with pure kinematic relaxation
Zhang, T. L.; Balikhin, M. A.; Gedalin, M. +2 more
Collisionless shocks are present in the vicinity of many astrophysical objects such as supernova remnants, space jets, stars and planets immersed in the supersonic flow of stellar winds. Understanding the shock structure is crucial for understanding the processes of the redistribution of the upstream flow energy into accelerated particles and form…
Discovery of a transient radiation belt at Saturn
Krupp, N.; Jones, G. H.; Roussos, E. +7 more
Radiation belts have been detected in situ at five planets. Only at Earth however has any variability in their intensity been heretofore observed, in indirect response to solar eruptions and high altitude nuclear explosions. The Cassini spacecraft's MIMI/LEMMS instrument has now detected systematic radiation belt variability elsewhere. We report t…
CAWSES November 7-8, 2004, superstorm: Complex solar and interplanetary features in the post-solar maximum phase
Tsurutani, Bruce T.; Echer, Ezequiel; Guarnieri, Fernando L. +1 more
The complex interplanetary structures during 7 to 8 Nov 2004 are analyzed to identify their properties as well as resultant geomagnetic effects and the solar origins. Three fast forward shocks, three directional discontinuities and two reverse waves were detected and analyzed in detail. The three fast forward shocks ``pump'' up the interplanetary …
Large-scale structure of Saturn's E-ring
Morfill, Gregor E.; Horányi, Mihály; Juhász, Antal
Geysers on the recently discovered, geologically active south-polar region of the moon Enceladus are now recognized as the dominant source of material in Saturn's E ring. The ring was traditionally thought to span the region between 3 to 8 R S , where R S is the radius of Saturn. However, new in situ dust measurements indi…
Distribution of the O2 infrared nightglow observed with VIRTIS on board Venus Express
Hueso, R.; Sánchez-Lavega, A.; Erard, S. +5 more
We present characteristics of the statistical horizontal distribution of the O2 infrared nightglow over most of the southern hemisphere observed with the VIRTIS instrument over a period spanning nearly 11 months of low solar activity. We show that the distribution is inhomogeneous with the regions of brightest emission reaching ~3 MegaR…
First identification of mirror mode waves in Venus' magnetosheath?
Zhang, T. L.; Glassmeier, K. -H.; Baumjohann, W. +3 more
In this paper first time observations of mirror mode like structures in Venus' magnetosheath are presented. Using magnetometer data from the Venus Express spacecraft it is shown that in two regions in the Venusian magnetosheath strong compressional waves exist, which propagate nearly perpendicular to the ambient magnetic field. They are most likel…
Electron properties of high-speed solar wind from polar coronal holes obtained by Ulysses thermal noise spectroscopy: Not so dense, not so hot
McComas, D. J.; Issautier, K.; MacDowall, R. J. +4 more
We present radio observations of Ulysses' third fast latitude scan near the 2007 solar activity minimum of cycle 23. We deduce in situ measurements of the electron density and temperature using the method of quasi-thermal noise spectroscopy. We study the large-scale properties of the fast solar wind coming from polar coronal holes and compare our …
Cassini detection of water-group pick-up ions in the Enceladus torus
Thomsen, M. F.; Wilson, R. J.; Tokar, R. L. +8 more
This study reports direct detection by the Cassini plasma spectrometer of freshly-produced water-group pick-up ions within the proposed Enceladus torus, a radially narrow toroidal region surrounding Saturn that contains a high density of water-group neutrals. This torus is produced by the icy plumes observed near the south pole of Enceladus. The i…
Auroral polar dawn spots: Signatures of internally driven reconnection processes at Jupiter's magnetotail
Bonfond, B.; Clarke, J. T.; Gérard, J. -C. +2 more
We report the presence of polar spots located in the dawn auroral region, based on the HST ACS 2007 campaign. We study the location of these features in the equatorial plane as well as their time scales and periodicities, based on a comprehensive series of images taken between February 21 and June 11, 2007. It is shown that the majority of polar d…