Search Publications
The Electron Temperature and Anisotropy in the Solar Wind. Comparison of the Core and Halo Populations
Trávníček, P. M.; Maksimovic, M.; Štverák, Š. +3 more
Estimating the temperature of solar wind particles and their anisotropies is particularly important for understanding the origin of their deviations from thermal equilibrium and the effects this has. In the absence of energetic events, the velocity distribution of electrons reveals a dual structure with a thermal (Maxwellian) core and a supratherm…
The plasma structure of coronal hole solar wind: Origins and evolution
Borovsky, Joseph E.
Whereas slow solar wind is known to be highly structured, the fast (coronal hole origin) wind is usually considered to be homogeneous. Using measurements from Helios 1 + 2, ACE, Wind, and Ulysses, structure in the coronal hole origin solar wind is examined from 0.3 AU to 2.3 AU. Care is taken to collect and analyze intervals of "unperturbed corona…
Global Gradients for Cosmic-Ray Protons in the Heliosphere During the Solar Minimum of Cycle 23/24
Potgieter, M. S.; Vos, E. E.
Global gradients for cosmic-ray (CR) protons in the heliosphere are computed with a comprehensive modulation model for the recent prolonged solar minimum of Cycle 23/24. Fortunately, the PAMELA (Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics) and Ulysses/KET (Kiel Electron Telescope) instruments simultaneously observed pro…
Spatial gradients of GCR protons in the inner heliosphere derived from Ulysses COSPIN/KET and PAMELA measurements
Gieseler, J.; Heber, B.
Context. During the transition from solar cycle 23 to 24 from 2006 to 2009, the Sun was in an unusual solar minimum with very low activity over a long period. These exceptional conditions included a very low interplanetary magnetic field (IMF) strength and a high tilt angle, which both play an important role in the modulation of galactic cosmic ra…
Modeling the Solar Wind at the Ulysses, Voyager, and New Horizons Spacecraft
McComas, D. J.; Pogorelov, N. V.; Zank, G. P. +2 more
The outer heliosphere is a dynamic region shaped largely by the interaction between the solar wind and the interstellar medium. While interplanetary magnetic field and plasma observations by the Voyager spacecraft have significantly improved our understanding of this vast region, modeling the outer heliosphere still remains a challenge. We simulat…
Scale-dependent Normalized Amplitude and Weak Spectral Anisotropy of Magnetic Field Fluctuations in the Solar Wind Turbulence
He, Jiansen; Wang, Xin; Wang, Linghua +2 more
Turbulence in the solar wind was recently reported to be anisotropic, with the average power spectral index close to -2 when sampling parallel to the local mean magnetic field B0 and close to -5/3 when sampling perpendicular to the local B0. This result was widely considered to be observational evidence for the critical balan…
Influence of intermittency on the anisotropy of magnetic structure functions of solar wind turbulence
He, Jiansen; Wang, Xin; Wang, Linghua +4 more
Intermittency appears to be connected with the spectral anisotropy of solar wind turbulence. We use the Local Intermittency Measure to identify and remove intermittency from the magnetic field data measured by the Ulysses spacecraft in fast solar wind. Structure functions are calculated based on the time sequences as obtained before and after remo…
A 17 June 2011 polar jet and its presence in the background solar wind
Jackson, B. V.; Buffington, A.; Hick, P. P. +3 more
High-speed jet responses in the polar solar wind are enigmatic. Here we measure a jet response that emanates from the southern polar coronal hole on 17 June 2011 at the extreme speed of over 1200 km/s. This response was recorded from the Sun-Earth line in Solar Dynamics Observatory/Atmospheric Imaging Assembly (SDO/AIA) and Large Angle and Spectro…
MHD-IPS analysis of relationship among solar wind density, temperature, and flow speed
Hayashi, Keiji; Tokumaru, Munetoshi; Fujiki, Ken'ichi
The solar wind properties near the Sun are a decisive factor of properties in the rest of heliosphere. As such, determining realistic plasma density and temperature near the Sun is very important in models for solar wind, specifically magnetohydrodynamics (MHD) models. We had developed a tomographic analysis to reconstruct three-dimensional solar …
Possible gamma-ray burst radio detections by the Square Kilometre Array. New perspectives
Capozziello, Salvatore; Ruggeri, Alan Cosimo
The next generation interferometric radio telescope, the Square Kilometre Array (SKA), which will be the most sensitive and largest radio telescope ever constructed, could greatly contribute to the detection, survey and characterization of Gamma Ray Bursts (GRBs). By the SKA, it will be possible to perform the follow up of GRBs even for several mo…