Search Publications
Evidence of Superdiffusive Transport of Electrons Accelerated at Interplanetary Shocks
Perri, S.; Zimbardo, G.
We study the transport properties of energetic electrons accelerated at corotating interaction regions in the solar wind considering the possibility of anomalous diffusion. It is shown that the particle time decay has a power-law behavior when a non-Gaussian propagator, appropriate for superdiffusive transport, is assumed for particles accelerated…
A Floor in the Solar Wind Magnetic Field
Cliver, E. W.; Svalgaard, L.
Long-term (~130 years) reconstruction of the interplanetary magnetic field (IMF) based on geomagnetic indices indicates that the solar wind magnetic field strength has a ``floor,'' a baseline value in annual averages that it approaches at each 11 yr solar minimum. In the ecliptic plane at 1 AU, the IMF floor is ~4.6 nT, a value substantiated by di…
Density and Magnetic Field Signatures of Interplanetary 1/f Noise
Romoli, M.; Bemporad, A.; Poletto, G. +4 more
We investigate the occurrence of 1/f noise in the interplanetary density and the magnetic field at varying heliocentric latitudes. The characteristic spectral amplitudes can be found in Ulysses density and magnetic data in the expected frequency ranges at all available latitudes, ranging from the ecliptic plane to more than 80°. Average spectra in…
Encounter of the Ulysses Spacecraft with the Ion Tail of Comet MCNaught
Geiss, J.; McComas, D. J.; Smith, E. J. +12 more
Comet McNaught was the brightest comet observed from Earth in the last 40 years. For a period of five days in early 2007 February, four instruments on the Ulysses spacecraft directly measured cometary ions and key properties of the interaction of the comet's ion tail with the high-speed solar wind from the polar regions of the Sun. Because of the …
Monte Carlo Simulation of Directivity of Interplanetary Radio Bursts
MacDowall, R. J.; Kaiser, M. L.; Thejappa, G.
We have developed a Monte Carlo simulation code to study the effects of refraction due to spatial variation of the solar wind density and scattering due to random density fluctuations on directivities, time profiles, and sizes and positions of the apparent sources of the interplanetary type II and type III radio bursts excited at the fundamental (…
The Width of a Solar Coronal Mass Ejection and the Source of the Driving Magnetic Explosion: A Test of the Standard Scenario for CME Production
Moore, Ronald L.; Sterling, Alphonse C.; Suess, Steven T.
We show that the strength (BFlare) of the magnetic field in the area covered by the flare arcade following a CME-producing ejective solar eruption can be estimated from the final angular width (Final θCME) of the CME in the outer corona and the final angular width (θFlare) of the flare arcade: BFlare~1.4…
Comparative Study of the Initial Spikes of Soft Gamma-Ray Repeater Giant Flares in 1998 and 2004 Observed with Geotail: Do Magnetospheric Instabilities Trigger Large-Scale Fracturing of a Magnetar's Crust?
Kawai, N.; Tanaka, Y. T.; Yoshikawa, I. +5 more
We present the unsaturated peak profile of the giant flare from SGR 1900+14 on 1998 August 27. This was obtained by the particle counters of the Low Energy Particles instrument on board the Geotail spacecraft. The observed peak profile revealed four characteristic features: an initial steep rise, an intermediate rise to the peak, an exponential de…
Cool-Plasma Jets that Escape into the Outer Corona
Moore, Ronald L.; Sterling, Alphonse C.; Poletto, Giannina +2 more
We report on observations acquired in 2003 May during a SOHO-Ulysses quadrature campaign. The UVCS slit was set normal to the radial of the Sun along the direction to Ulysses at 1.7 Rsolar, at a northern latitude of 14.5°. From May 25 to May 28, UVCS acquired spectra of several short-lived ejections that represent the extension at highe…
Angular Momentum Transport and Proton-Alpha-Particle Differential Streaming in the Solar Wind
Li, Xing; Habbal, Shadia Rifai; Li, Bo
The interplay between the proton-alpha-particle differential flow speed, vαp, and angular momentum transport in the solar wind is explored by using a three-fluid model. The force introduced by the azimuthal components is found to play an important role in the force balance for ions in interplanetary space, bringing the radial flow speed…
Diffusive Compression Acceleration of Energetic Particles with an Application to Shock Acceleration near Injection Energies
Zhang, Ming
The behavior of energetic charged particles accelerated by a continuous plasma compression profile is explored in the framework of diffusion. At high enough energies, the accelerated particles have a power-law spectrum with a slope generally steeper than a shock spectrum with the same compression ratio. The spectral slope depends on the ratio of t…