Search Publications
Evolution of Switchbacks in the Inner Heliosphere
Velli, Marco; Matteini, Lorenzo; Sioulas, Nikos +3 more
We analyze magnetic field data from the first six encounters of Parker Solar Probe, three Helios fast streams and two Ulysses south polar passes covering heliocentric distances 0.1 ≲ R ≲ 3 au. We use this data set to statistically determine the evolution of switchbacks of different periods and amplitudes with distance from the Sun. We compare the …
An Ab Initio Approach to Antiproton Modulation in the Inner Heliosphere
Engelbrecht, N. Eugene; Moloto, K. D.
Recent advances in the detection of cosmic-ray (CR) antiproton intensities at Earth have the potential to provide valuable new insights in the search for dark matter. As such, a fuller understanding of the modulation of these particles due to the influence of the Sun is of vital importance. Valuable insights can be gained through the study of gala…
Threaded-field-line Model for the Low Solar Corona Powered by the Alfvén Wave Turbulence
Jin, Meng; Sokolov, Igor V.; Gombosi, Tamas I. +6 more
We present an updated global model of the solar corona, including the transition region. We simulate the realistic three-dimensional (3D) magnetic field using the data from the photospheric magnetic field measurements and assume the magnetohydrodynamic (MHD) Alfvén wave turbulence and its nonlinear dissipation to be the only source for heating the…
Flux Ropes, Turbulence, and Collisionless Perpendicular Shock Waves: High Plasma Beta Case
Zhao, L. L.; Zank, G. P.; Adhikari, L. +4 more
With the onset of solar maximum and the expected increased prevalence of interplanetary shock waves, Parker Solar Probe is likely to observe numerous shocks in the next few years. An outstanding question that has received surprisingly little attention has been how turbulence interacts with collisionless shock waves. Turbulence in the supersonic so…
Global Distribution of the Solar Wind Speed Reconstructed from Improved Tomographic Analysis of Interplanetary Scintillation Observations between 1985 and 2019
Kojima, Masayoshi; Tokumaru, Munetoshi; Fujiki, Ken'ichi +1 more
Computer-assisted tomography (CAT) for interplanetary scintillation (IPS) observations enables the determination of the global distribution of solar wind speed. We compared solar wind speeds derived from the CAT analysis of IPS observations between 1985 and 2019 with in situ observations conducted by the near-Earth and Ulysses spacecraft. From thi…
A Catalog of Interplanetary Coronal Mass Ejections Observed by Juno between 1 and 5.4 au
Lugaz, Noé; Winslow, Réka M.; Möstl, Christian +2 more
We use magnetic field measurements by the Juno spacecraft to catalog and investigate interplanetary coronal mass ejections (ICMEs) beyond 1 au. During its cruise phase, Juno spent about 5 yr in the solar wind between 2011 September and 2016 June, providing measurements of the interplanetary magnetic field (IMF) between 1 and 5.4 au. Juno therefore…
Time and Charge-sign Dependence of the Heliospheric Modulation of Cosmic Rays
Potgieter, M. S.; Aslam, O. P. M.; Bisschoff, D. +4 more
Simultaneous and continuous observations of galactic cosmic-ray electrons (e-) and positrons (e+) from the PAMELA and AMS02 space experiments are most suitable for numerical modeling studies of the heliospheric modulation of these particles below 50 GeV. A well-established comprehensive three-dimensional modulation model is a…
Relation of Microstreams in the Polar Solar Wind to Switchbacks and Coronal X-Ray Jets
Neugebauer, Marcia; Sterling, Alphonse C.
Ulysses data obtained at high solar latitudes during periods of minimum solar activity in 1994 and 2007 are examined to determine the relation between velocity structures called microstreams and folds in the magnetic field called switchbacks. A high correlation is found. The possibility of velocity peaks in microstreams originating from coronal X-…
Modeling Solar Wind Variations over an 11 Year Cycle with Alfvén Wave Dissipation: A Parameter Study
Réville, Victor; Hazra, Soumitra; Strugarek, Antoine +3 more
We study the behavior and properties of the solar wind using a 2.5D Alfvén wave (AW)-driven wind model. We first systematically compare the results of an AW-driven wind model with a polytropic approach. Polytropic magnetohydrodynamic wind models are thermally driven, while AWs act as additional acceleration and heating mechanisms in the AW-driven …
Solar Origin of Bare Ion Anomalies in the Solar Wind and Interplanetary Coronal Mass Ejections
Reeves, Katharine K.; Raymond, John C.; Stevens, Michael L. +3 more
Previous studies of the solar wind and interplanetary coronal mass ejections (ICMEs) have shown periods throughout solar cycle 23 when heliospheric measurements of ion composition appear anomalous. In these cases, C6+ and other bare ion densities, i.e., fully stripped ions, are unusually low, leading it to be classified as the Outlier s…