Search Publications
Plasma Density and Magnetic Field Fluctuations in the Ion Gyro-Frequency Range Near the Diamagnetic Cavity of Comet 67P
Nilsson, H.; André, M.; Vaivads, A. +8 more
We report the detection of large-amplitude, quasi-harmonic density fluctuations with associated magnetic field oscillations in the region surrounding the diamagnetic cavity of comet 67P. Typical frequencies are ∼0.1 Hz, corresponding to ∼10 times the water and ≲ 0.5 times the proton gyro-frequencies, respectively. Magnetic field oscillations are n…
Dependence of Dayside Electron Densities at Venus on Solar Irradiance
Pätzold, M.; Häusler, B.; Tellmann, S. +3 more
The ionosphere of Venus is a weakly ionized plasma layer embedded in the planet's upper atmosphere. Planetary ionospheres provide an excellent opportunity to study how our variable Sun affects the planets in our solar system. Because ionospheres are reservoirs from which atmospheric species can be lost to space, studying how ionospheres respond to…
Characteristics of Reconnection Sites and Fast Flow Channels in an MHD Simulation
McPherron, R. L.; El-Alaoui, M.; Walker, R. J. +1 more
We investigate an interval of moderate magnetic activity from 0-8 UT on 14 March 2008 by using a global magnetohydrodynamics (MHD) simulation with high spatial and temporal resolution. Observations show several distinct substorms during this interval. One of these with onset at 04:44 UT occurs at 04:42 UT in the simulation. The simulation shows re…
Dependence of the Interplanetary Magnetic Field on Heliocentric Distance at 0.3-1.7 AU: A Six-Spacecraft Study
Hanneson, Cedar; Johnson, Catherine L.; Mittelholz, Anna +2 more
We use magnetometer data taken simultaneously by MESSENGER, VEX, STEREO and ACE to characterize the variation of the interplanetary magnetic field (IMF) with heliocentric distance, rh, for rh≲ 1 AU. Power law fits (a rh b) to the individual IMF components and magnitude indicate that, on average, the IMF is more tightly wound and its strength decre…
Multipoint Observations of Magnetosheath Response to Foreshock Transients
Wei, Xinhua; Cai, Chunlin
Multispacecraft observations of the magnetosheath responses to various foreshock transients in a single event on 17 March 2004 are reported in this paper. The Cluster spacecraft recorded long-standing large amplitude ULF waves with both compressive and transverse components in the magnetosheath. Additionally, two transient structures with depressi…
Plasma Turbulence at Comet 67P/Churyumov-Gerasimenko: Rosetta Observations
Halekas, J. S.; Howes, G. G.; Ruhunusiri, S.
We perform a power spectral analysis of magnetic field fluctuations measured by the Rosetta spacecraft's magnetometer at comet 67P/Churyumov-Gerasimenko. We interpret the power spectral signatures in terms of plasma turbulent processes and discover that different turbulent processes are prominent during different active phases of the comet. During…
Suprathermal Fe in the Earth's Plasma Environment: Cluster RAPID Observations
Dandouras, I.; Daly, P. W.; Haaland, S. +2 more
Baryonic matter in geospace is almost exclusively in a plasma state, with protons (H+) and to some extent ionized helium (He) and oxygen (O) being the dominant ion species. But also other heavier ion species and even molecular ions are present in geospace. The Research with Adaptive Particle Imaging Detectors (RAPID) on board the Cluste…
A Survey of Venus Shock Crossings Dominated by Kinematic Relaxation
Pope, S. A.
Collisionless shocks are one of the most effective particle accelerators in the known universe. Even low Mach number shocks could have a significant role in particle heating and acceleration. Theory suggests that kinematic collisionless relaxation, the process whereby a downstream nongyroptopic ion population becomes thermalized through collisionl…
Equatorial Magnetosonic Waves: Do Nonlinear Interactions Play a Role in Their Evolution?
Walker, S. N.; Yearby, K. H.; Balikhin, M. A. +1 more
The occurrence of nonlinear interactions between discrete wave frequencies has been shown to play a significant role in the propagation and evolution of some plasma wave modes. In this paper we take advantage of closely spaced Cluster measurements to investigate the possibility nonlinear interactions occurring between the discrete emissions that a…
Observations of Sounder Accelerated Electrons by Mars Express
Barabash, S.; Winningham, J. D.; Frahm, R. A. +5 more
The electron sensor of the Analyzer of Space Plasmas and Energetic Atoms experiment detects accelerated electrons during pulses of radio emissions from the powerful topside sounder: the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) on board the Mars Express spacecraft. Accelerated electrons are observed at energies up to 400 …