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Treatments of the radio scattering due to density turbulence in the solar wind typically employ asymptotic approximations to the phase structure function. We use a general structure function (GSF) that straddles the asymptotic limits and…

Solar and Stellar Astrophysics · Physics 2015-09-28 Madhusudan Ingale

In the absence of efficient collisions, deviations from thermal equilibrium of plasma particle distributions are controlled by the self-generated instabilities. The whistler instability is a notorious example, usually responsible for the…

Space Physics · Physics 2019-10-15 M. Lazar , R. A. Lopez , S. M. Shaaban , S. Poedts , H. Fichtner

We investigate possible links between the large-scale and small-scale features of solar wind fluctuations across the frequency break separating fluid and kinetic regimes. The aim is to correlate the magnetic field fluctuations polarization…

Space Physics · Physics 2017-01-26 D. Telloni , R. Bruno

The fast solar wind's high speeds and nonthermal features require that significant heating occurs well above the Sun's surface. Two leading theories seem incompatible: low-frequency "Alfv\'enic" turbulence, which transports energy outwards…

Solar and Stellar Astrophysics · Physics 2022-02-25 Jonathan Squire , Romain Meyrand , Matthew W. Kunz , Lev Arzamasskiy , Alexander A. Schekochihin , Eliot Quataert

Intensive studies have been conducted to understand the anisotropy of solar wind turbulence. However, the anisotropy of Els\"asser variables ($\textbf{Z}^\pm$) in 2D wave-vector space has yet to be investigated. Here we first verify the…

Solar and Stellar Astrophysics · Physics 2016-05-04 Limei Yan , Jiansen He , Lei Zhang , Chuanyi Tu , Eckart Marsch , Christopher H. K. Chen , Xin Wang , Linghua Wang , Robert T. Wicks

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

We analyse velocity fluctuations in the solar wind at magneto-fluid scales in two datasets, extracted from Wind data in the period 2005-2015, that are characterised by strong or weak expansion. Expansion affects measurements of anisotropy…

Solar and Stellar Astrophysics · Physics 2019-04-24 Andrea Verdini , Roland Grappin , Olga Alexandrova , Luca Franci , Simone Landi , Lorenzo Matteini , Emanuele Papini

Various remote sensing observations have been used so far to probe the turbulent properties of the solar wind. Using the recently reported density modulation indices that are derived using angular broadening observations of Crab Nebula…

Solar and Stellar Astrophysics · Physics 2021-06-30 K. Sasikumar Raja , Prasad Subramanian , Madhusudan Ingale , R. Ramesh , Milan Maksimovic

For more than five decades, a notable spread in the low frequencies of velocity and temperature spectra, scaled using inertial subrange properties and Monin-Obukhov similarity theory, has been observed in unstable stratification. A large…

Fluid Dynamics · Physics 2023-11-08 Claudine Charrondière , Ivana Stiperski

The power spectrum of the evolving solar wind shows evidence of a spectral break between an inertial range of turbulent fluctuations at higher frequencies and a "$1/f$" like region at lower frequencies. In the ecliptic plane at $\sim 1$ AU,…

Solar and Stellar Astrophysics · Physics 2009-09-24 R. M. Nicol , S. C. Chapman , R. O. Dendy

The interpretation of single-point spacecraft measurements of solar wind turbulence is complicated by the fact that the measurements are made in a frame of reference in relative motion with respect to the turbulent plasma. The Taylor…

Solar and Stellar Astrophysics · Physics 2015-06-19 G. G. Howes , K. G. Klein , J. M. TenBarge

Statistical classification of the Helios solar wind observations into several populations sorted by bulk speed has revealed an outward acceleration of the wind. The faster the wind is, the smaller is this acceleration in the 0.3 - 1 au…

Solar and Stellar Astrophysics · Physics 2023-04-19 Dakeyo , Maksimovic , Démoulin , Halekas , Stevens

Cosmic ray propagation in the Milky Way and other galaxies is largely diffusive, with mean free path determined primarily by pitch angle scattering from hydromagnetic waves with wavelength of order the cosmic ray gyroradius. In the theory…

High Energy Astrophysical Phenomena · Physics 2020-02-19 Ellen G. Zweibel

Due to non-homogeneous mass distribution and non-uniform velocity rate inside the Sun, the solar outer shape is distorted in latitude. In this paper, we analyze the consequences of a temporal change in this figure on the luminosity. To do…

Solar and Stellar Astrophysics · Physics 2011-08-31 Z. Fazel , J. P. Rozelot , S. Lefebvre , A. Ajabshirizadeh , S. Pireaux

We tackle the question of how anisotropy in flows subject to background rotation favours structures elongated along the rotation axis, especially in turbulent flows. A new, wave-free mechanism is identified that challenges the current…

Fluid Dynamics · Physics 2020-04-22 J. A. Brons , P. J. Thomas , A. Potherat

Motivated by recent observations of distinct parallel and perpendicular signatures in magnetic helicity measurements segregated by wave period and angle between the local magnetic field and the solar wind velocity, this paper undertakes a…

Plasma Physics · Physics 2015-06-19 Kristopher G. Klein , Gregory G. Howes , Jason M. TenBarge , John J. Podesta

The selfgenerated wave fluctuations are particularly interesting in the solar wind and magnetospheric plasmas, where Coulomb collisions are rare and cannot explain the observed states of quasi-equilibrium. Linear theory predicts that the…

Solar and Stellar Astrophysics · Physics 2015-06-16 M. Lazar , S. Poedts , R. Schlickeiser , D. Ibscher

Using two-dimensional hybrid expanding box simulations we study the competition between the continuously driven parallel proton temperature anisotropy and fire hose instabilities in collisionless homogeneous plasmas. For quasi radial…

Space Physics · Physics 2017-02-15 Petr Hellinger

Anisotropy and multifractality in velocity and temperature time series sampled at multiple heights in the roughness sublayer (RSL) over a boreal mixed-coniferous forest are reported. In particular, a turbulent-stress invariant analysis…

We use a luminous fast magnetic rotator model to analyze the influence of a magnetic field on the linear waves induced in the wind of a massive star by the radiative instability. We show that a twisted magnetic field can drive a strong wind…

Astrophysics · Physics 2007-05-23 Henning Seemann , Peter L. Biermann