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We introduce a new solar energetic particle (SEP) transport code that aims at studying the effects of different solar wind configurations on SEP events. We focus on the influence of varying solar wind velocities on the energy changes of…

Space Physics · Physics 2019-01-29 N. Wijsen , A. Angels , J. Pomoell , S. Poedts

Physical processes in the tail of the solar wind interaction region with the partially ionized local interstellar medium are investigated in a framework of the self-consistent kinetic-gas dynamic model. It is shown that the charge exchange…

Astrophysics · Physics 2009-11-10 Vladislav V. Izmodenov , Dmitry B. Alexashov

Solar wind is probably the best laboratory to study turbulence in astrophysical plasmas. In addition to the presence of magnetic field, the differences with neutral fluid isotropic turbulence are: weakness of collisional dissipation and…

Solar and Stellar Astrophysics · Physics 2015-06-16 Olga Alexandrova , Christopher H. K. Chen , Luca Sorriso-Valvo , Timothy S. Horbury , Stuart D. Bale

Recently, we correlated the inferred structure of the solar chromospheric plasma topography with solar wind velocity and composition data measured at 1AU. We now offer a physical justification of these relationships and present initial…

Astrophysics · Physics 2011-02-11 Robert J. Leamon , Scott W. McIntosh

The relationship between the peak velocities of high-speed solar wind streams near Earth and the areas of their solar source regions, i.e., coronal holes, has been known since the 1970s, but it is still physically not well understood. We…

Solar and Stellar Astrophysics · Physics 2020-07-10 Stefan J. Hofmeister , Astrid M. Veronig , Stefaan Poedts , Evangelia Samara , Jasmina Magdalenic

We propose a new model for explaining the observations of more than mass proportional heating of heavy ions in the polar solar corona. We point out that a large number of small scale intermittent shock waves can be present in the solar…

Solar and Stellar Astrophysics · Physics 2010-12-13 Gaetano Zimbardo

Observations of interstellar scintillations at radio wavelengths reveal a Kolmogorov-like scaling of the electron density spectrum with a spectral slope of -5/3 over six decades in wavenumber space. A similar turbulent density spectrum in…

Space Physics · Physics 2015-05-13 Dastgeer Shaikh , G. P. Zank

The classic Weber-Davis model of the solar wind is reconsidered by incorporating alpha particles and by allowing the solar wind to flow out of the equatorial plane in an axisymmetrical configuration. In the ion momentum equations of the…

Astrophysics · Physics 2007-05-23 Bo Li , Xing Li

Stellar winds are an integral part of the underlying dynamo, the motor of stellar activity. The wind controls the star's angular momentum loss, which depends on the magnetic field geometry which varies significantly in time and latitude.…

Solar and Stellar Astrophysics · Physics 2021-03-16 P. Jakab , A. Brandenburg

A complete theory for the complex interaction between solar energetic particles and the turbulent interplanetary magnetic field remains elusive. In this work we aim to contribute towards such a theory by modelling the propagation of solar…

Space Physics · Physics 2019-02-27 R. D. Strauss , J. A. le Roux

Helioseismology has revealed many details of solar differential rotation and also its time variation, known as torsional oscillations. So far there is no generally accepted theoretical explanation for torsional oscillations, even though a…

Astrophysics · Physics 2008-11-26 Matthias Rempel

Space plasmas are collisionpoor and kinetic effects prevail leading to wave fluctuations, which transfer the energy to small scales: wave-particle interactions replace collisions and enhance dispersive effects heating particles and…

Solar and Stellar Astrophysics · Physics 2015-06-04 M. Lazar , V. Pierrard , S. Poedts , R. Schlickeiser

We investigate the quasilinear effects of the resonant wave-particle interaction under conditions of imbalanced turbulent heating in the collisionless coronal hole. We find that velocity-space transport of protons from the heated part of…

In fast wind or when the local Coulomb collision frequency is low, observations show that solar wind minor ions and ion sub-populations flow with different bulk velocities. Measurements indicate that the drift speed of both alpha particles…

Solar and Stellar Astrophysics · Physics 2018-09-07 B. L. Alterman , Justin C. Kasper , Michael L. Stevens , Andriy Koval

The slow solar wind exhibits strong variability on timescales from minutes to days, likely related to magnetic reconnection processes in the extended solar corona. Higginson2017b presented a numerical magnetohydrodynamic simulation which…

Solar and Stellar Astrophysics · Physics 2018-05-23 Aleida K. Higginson , Benjamin J. Lynch

We perform 2.5D hybrid simulations to investigate the origin and evolution of relative drift speeds between protons and $\alpha$ particles in the collisionless turbulent low-$\beta$ solar wind plasma. We study the generation of differential…

Space Physics · Physics 2015-06-11 Y. G. Maneva , L. Ofman , A. Viñas

Observations with {\em RHESSI} have enabled the detailed study of the structure of dense hard X-ray coronal sources in solar flares. The variation of source extent with electron energy has been discussed in the context of streaming of…

Solar and Stellar Astrophysics · Physics 2015-06-19 Natasha L. S. Jeffrey , Eduard P. Kontar , Nicolas H. Bian , A. Gordon Emslie

The 'standard solar' flare model collects all physical ingredients identified by multi-wavelength observations of our Sun: magnetic reconnection, fast particle acceleration and the resulting emission at various wavelengths, especially in…

Solar and Stellar Astrophysics · Physics 2020-06-24 Wenzhi Ruan , Chun Xia , Rony Keppens

We introduce an updated, time-dependent treatment to the split-tail ("croissant-like") heliosphere model with data-driven solar wind conditions at 1 au, to study the evolution of the heliosphere with solar-cycle variations in plasma speed,…

Solar and Stellar Astrophysics · Physics 2026-03-20 Chika Onubogu , M. Opher , E. Powell , S. Du , J. M. Sokół , J. D. Richardson , B. Van Der Holst

Observations in the solar wind suggest that the compressive component of inertial-range solar-wind turbulence is dominated by slow modes. The low collisionality of the solar wind allows for non-thermal features to survive, which suggests…

Space Physics · Physics 2017-05-19 Daniel Verscharen , Christopher H. K. Chen , Robert T. Wicks