Search Publications
A giant periodic flare from the soft γ-ray repeater SGR1900+14
Cline, T.; Hurley, K.; Golenetskii, S. +11 more
Soft γ-ray repeaters are transient sources of high-energy photons; they emit sporadic and short (about 0.1s) bursts of `soft' γ-rays during periods of activity, which are often broken by long stretches of quiescence. These objects are associated with neutron stars in young supernova remnants. The event of 5 March 1979 was the most intense burst to…
Formation and Evolution of Corotating Interaction Regions and their Three Dimensional Structure
Gosling, J. T.; Pizzo, V. J.
Corotating interaction regions are a consequence of spatial variability in the coronal expansion and solar rotation, which cause solar wind flows of different speeds to become radially aligned. Compressive interaction regions are produced where high-speed wind runs into slower plasma ahead. When the flow pattern emanating from the Sun is roughly t…
Magnetohydrodynamic modeling of the solar corona during Whole Sun Month
Thompson, B. J.; Forsyth, R. J.; Biesecker, D. A. +7 more
The Whole Sun Month campaign (August 10 to September 8, 1996) brought together a wide range of space-based and ground-based observations of the Sun and the interplanetary medium during solar minimum. The wealth of data collected provides a unique opportunity for testing coronal models. We develop a three-dimensional magnetohydrodynamic (MHD) model…
A Markov Stochastic Process Theory of Cosmic-Ray Modulation
Zhang, Ming
This paper introduces the use of Markov stochastic process theory to study heliospheric modulation of cosmic rays. The basic cosmic-ray transport equation is reformulated with a set of stochastic differential equations that describe the guiding center and momentum of individual charged particles randomly walking in the heliospheric magnetic field.…
Dust in the Local Interstellar Wind
Zank, Gary P.; Slavin, Jonathan D.; Geiss, Johannes +13 more
The gas-to-dust mass ratios found for interstellar dust within the solar system, versus values determined astronomically for the cloud around the solar system, suggest that large and small interstellar grains have separate histories and that large interstellar grains preferentially detected by spacecraft are not formed exclusively by mass exchange…
Acceleration of the fast solar wind by the emergence of new magnetic flux
Schwadron, N. A.; Zurbuchen, T. H.; Fisk, L. A.
Recent observations have shown that small magnetic loops are continuously emerging within supergranules in the solar photosphere. The subsequent reconnection of this emerging flux with field lines which open into the corona should define the Poynting's vector and mass flux into the corona. These two quantities uniquely determine the final energy f…
A review of discontinuities and Alfvén waves in interplanetary space: Ulysses results
Tsurutani, Bruce T.; Ho, Christian M.
The Ulysses mission is the first to explore our heliosphere at all latitudes up to +/-80° and therefore is an ideal mission to study potential gradients in heliolatitude (and radial distance) of discontinuity occurrence rates and types. Directional discontinuities (DDs) are shown to be dependent on the type of solar wind streams that they are embe…
Three-dimensional propagation of coronal mass ejections in a structured solar wind flow 2. CME launched adjacent to the streamer belt
Pizzo, V. J.; Odstrčil, D.
A three-dimensional (3-D) numerical hydrodynamic model is used to investigate the evolution of coronal mass ejections (CMEs) launched at several heliographic positions into a tilted-dipole ambient solar wind (SW) flow, which is appropriate around solar activity minimum and declining phase. The CME is injected as an overpressured plasma cloud. Resu…
Heliospheric magnetic field polarity inversions at high heliographic latitudes
Balogh, A.; Horbury, T. S.; Lucek, E. A. +2 more
The heliospheric magnetic field over the poles of the sun has been examined to identify intervals when the polarity of the magnetic field deviates significantly from the calculated Parker spiral, using Ulysses observations in 1994 and 1995, near solar minimum. Intervals with deviation > 90° have been identified, corresponding to magnetic field …
CIR Morphology, Turbulence, Discontinuities, and Energetic Particles
Tsurutani, B. T.; Lucek, E.; Crooker, N. U. +18 more
Corotating interaction regions (CIRs) in the middle heliosphere have distinct morphological features and associated patterns of turbulence and energetic particles. This report summarizes current understanding of those features and patterns, discusses how they can vary from case to case and with distance from the Sun and possible causes of those va…