Search Publications
Energetic Ion Moments and Polytropic Index in Saturn's Magnetosphere using Cassini/MIMI Measurements: A Simple Model Based on κ-Distribution Functions
Krupp, Norbert; Krimigis, Stamatios M.; Mitchell, Donald G. +7 more
Moments of the charged particle distribution function provide a compact way of studying the transport, acceleration, and interactions of plasma and energetic particles in the magnetosphere. We employ κ-distributions to describe the energy spectra of H+ and O+, based on >20 keV measurements by the three detectors of Cassini…
Planetary Period Oscillations in Saturn's Magnetosphere: Cassini Magnetic Field Observations Over the Northern Summer Solstice Interval
Dougherty, M. K.; Cowley, S. W. H.; Bunce, E. J. +3 more
We determine properties of Saturn's planetary period oscillations from Cassini magnetic measurements over the 2-year interval from September 2015 to end of mission in September 2017, spanning Saturn northern summer solstice in May 2017. Phases of the northern system oscillations are derived over the whole interval, while those of the southern syst…
Field-Aligned Currents in Saturn's Nightside Magnetosphere: Subcorotation and Planetary Period Oscillation Components During Northern Spring
Dougherty, M. K.; Alexeev, I. I.; Belenkaya, E. S. +7 more
We newly analyze Cassini magnetic field data from the 2012/2013 Saturn northern spring interval of highly inclined orbits and compare them with similar data from late southern summer in 2008, thus providing unique information on the seasonality of the currents that couple momentum between Saturn's ionosphere and magnetosphere. Inferred meridional …
Field-Aligned Currents in Saturn's Magnetosphere: Observations From the F-Ring Orbits
Dougherty, M. K.; Cowley, S. W. H.; Bunce, E. J. +3 more
We investigate the azimuthal magnetic field signatures associated with high-latitude field-aligned currents observed during Cassini's F-ring orbits (October 2016-April 2017). The overall ionospheric meridional current profiles in the northern and southern hemispheres, that is, the regions poleward and equatorward of the field-aligned currents, dif…
Recurrent Magnetic Dipolarization at Saturn: Revealed by Cassini
Coates, A. J.; Krupp, N.; Dougherty, M. K. +17 more
Planetary magnetospheres receive plasma and energy from the Sun or moons of planets and consequently stretch magnetic field lines. The process may last for varied timescales at different planets. From time to time, energy is rapidly released in the magnetosphere and subsequently precipitated into the ionosphere and upper atmosphere. Usually, this …
Statistical Planetary Period Oscillation Signatures in Saturn's UV Auroral Intensity
Badman, S. V.; Cowley, S. W. H.; Provan, G. +3 more
Saturn's auroral emissions are a good measure of field-aligned current (FAC) systems in the planet's magnetospheric environment. Previous studies based on magnetic field data have identified current systems rotating with the planetary period oscillations (PPOs) in both hemispheres, superimposed onto the local time-invariant current system producin…
The Dusty Plasma Disk Around the Janus/Epimetheus Ring
Gurnett, D. A.; Persoon, A. M.; Kurth, W. S. +5 more
We report on the electron, ion, and dust number densities and the electron temperatures obtained by the Radio and Plasma Wave Science instruments onboard Cassini during the Ring-Grazing orbits. The numerous ring passage observations show a consistent picture as follows: (1) Beyond 0.1 RS above and below the equator the electron and ion …
Statistical Study of the Energetic Proton Environment at Titan's Orbit From the Cassini Spacecraft
Coates, A. J.; Luhmann, J. G.; Krupp, N. +9 more
A statistical study of the energetic proton environment at Titan's orbit as captured by the MIMI/LEMMS and MIMI/CHEMS instruments is performed. The data analyzed cover all the dedicated flybys of Titan by Cassini as well as the orbit crossings that happen far from the moon. The energetic environment is found to be highly variable on timescales com…
Cassini RPWS Dust Observation Near the Janus/Epimetheus Orbit
Gurnett, D. A.; Persoon, A. M.; Hospodarsky, G. B. +7 more
During the Ring Grazing orbits near the end of Cassini mission, the spacecraft crossed the equatorial plane near the orbit of Janus/Epimetheus ( 2.5 Rs). This region is populated with dust particles that can be detected by the Radio and Plasma Wave Science (RPWS) instrument via an electric field antenna signal. Analysis of the voltage waveforms re…
The Periodic Flapping and Breathing of Saturn's Magnetodisk During Equinox
Dougherty, M. K.; Arridge, C. S.; Guio, P. +3 more
Periodic variations have been observed in many field and particle properties in Saturn's magnetosphere, modulated at a period close to the planetary rotation rate. Magnetic field observations by Cassini's magnetometer instrument suggest that in the outer magnetosphere (beyond ∼12 Saturn radii) Saturn's current sheet is periodically displaced with …