Search Publications
An approach to numerical simulation of the gas distribution in the atmosphere of Enceladus
Combi, M. R.; Tenishev, V.; Waite, J. H. +1 more
In addition to being the major source of neutral gas and dust particles for the Saturnian E-ring and, ultimately, heavy ions for the Saturnian inner magnetosphere, Enceladus exhibits geological activity that has made it an object of recent intensive study. The interest has significantly increased after Cassini flybys in 2005 provided a detailed ma…
Auroral signatures of flow bursts released during magnetotail reconnection at Jupiter
Bonfond, B.; Gérard, J. -C.; Grodent, D. +1 more
Recent studies based on Hubble Space Telescope (HST) data reported the presence of transient polar dawn spots in the Jovian auroral region and interpreted them as signatures of internally driven magnetic reconnection in the Jovian magnetotail. Even though an association of the polar dawn spots with the reconnection process has been suggested, it h…
Asymmetries in Saturn's radiation belts
Krupp, N.; Roussos, E.; Khurana, K. K. +10 more
We present both energetic proton and electron data from the main radiation belts of Saturn. When organized by L shell and equatorial pitch angle, data from Cassini's Magnetospheric Imaging Instrument reveal proton radiation belts that are highly symmetric in local time. The energetic electron radiation belts are asymmetric in two principal ways. U…
Ground-based observations of diffuse auroral frequencies in the context of whistler mode chorus
Samara, M.; Michell, R. G.
We present a case study of an active auroral event containing diffuse auroral structures. These data were collected on 04 February 2009 during a ground-based observational campaign at Poker Flat, Alaska (L ∼ 6), from January through April 2009. They were used to extract the frequencies of pulsating auroral structures that lasted many hours after s…
Dynamical and magnetic field time constants for Titan's ionosphere: Empirical estimates and comparisons with Venus
Luhmann, J. G.; Wahlund, J. -E.; Ågren, K. +12 more
Plasma in Titan's ionosphere flows in response to forcing from thermal pressure gradients, magnetic forces, gravity, and ion-neutral collisions. This paper takes an empirical approach to the ionospheric dynamics by using data from Cassini instruments to estimate pressures, flow speeds, and time constants on the dayside and nightside. The plasma fl…
Asymmetry of solar polar fields and the southward shift of HCS observed by Ulysses
Mursula, K.; Virtanen, I. I.
We study the hemispheric asymmetry of high-latitude unipolar fields and the latitudinal shift of the heliospheric current sheet (HCS) using Ulysses magnetic field observations during the perihelion passes in 1994-1995, 2001-2002, and 2007. Using the cumulative flux density and the best fit lines to its high-latitude observations in the two hemisph…
Global magnetohydrodynamic simulation of reconnection and turbulence in the plasma sheet
Goldstein, Melvyn L.; El-Alaoui, Mostafa; Walker, Raymond J. +3 more
Plasma sheet turbulence is examined by using a global MHD simulation. The simulation used idealized purely southward interplanetary magnetic field (IMF) driving conditions to eliminate the effect of solar wind and IMF variations. The results were compared with spacecraft observations of turbulence by computing power spectral densities and probabil…
The 3-D extent of the Io UV footprint on Jupiter
Bonfond, B.
The Io footprint (IFP) is the auroral signature of the electromagnetic interaction between Io and Jupiter's magnetosphere. It consists of several spots followed by an extended tail, which are located close to the feet of the magnetic field lines connecting Io to Jupiter. The size of the main spot is a controversial issue, and previously published …
Comparative analysis and variability of the Jovian X-ray spectra detected by the Chandra and XMM-Newton observatories
Bhardwaj, Anil; Branduardi-Raymont, Graziella; Lisse, Carey M. +6 more
Expanding upon recent work, a more comprehensive spectral model based on charge exchange induced X-ray emission by ions precipitating into the Jovian atmosphere is used to provide new understanding of the polar auroras. In conjunction with the Xspec spectral fitting software, the model is applied to analyze observations from both Chandra and XMM-N…
Pickup hydrogen distributions in the solar wind at ∼11 AU: Do we understand pickup ions in the outer heliosphere?
McComas, D. J.; Schwadron, N. A.; Elliott, H. A.
This study examines the detailed distribution of interstellar pickup hydrogen ions measured by the Surface Wave Process Program instrument on the New Horizons spacecraft en route to Pluto. The observations cover an 8 h interval on 15 October 2008 when the craft was at ∼11.3 AU, constituting the first detailed pickup ion measurements in the outer h…