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High-speed solar wind streams emanating from coronal holes are frequently impinging on the Earth's magnetosphere causing recurrent, medium-level geomagnetic storm activity. Modeling high-speed solar wind streams is thus an essential element…

Fast (>700 km/s) and slow (~400 km/s) winds stream from the Sun, permeate the heliosphere and influence the near-Earth environment. While the fast wind is known to emanate primarily from polar coronal holes, the source of the slow wind…

Solar and Stellar Astrophysics · Physics 2016-06-01 David H. Brooks , Ignacio Ugarte-Urra , Harry P. Warren

Alfv\'en waves, considered one of the primary candidates for heating and accelerating the fast solar wind, are ubiquitous in spacecraft observations, yet their origin remains elusive. In this study, we analyze data from the first 19…

Four decades have gone by since the discovery that the solar wind at 1 AU seems to exist in two relatively distinct states: slow and fast. There is still no universal agreement concerning the primary physical cause of this apparently…

Astrophysics · Physics 2007-05-23 Steven R. Cranmer

This Letter addresses the first Solar Orbiter (SO) -- Parker Solar Probe (PSP) quadrature, occurring on January 18, 2021, to investigate the evolution of solar wind from the extended corona to the inner heliosphere. Assuming ballistic…

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

Switchbacks -- abrupt reversals of the magnetic field within the solar wind -- have been ubiquitously observed by Parker Solar Probe (PSP). Their origin, whether from processes near the solar surface or within the solar wind itself, remains…

Solar and Stellar Astrophysics · Physics 2022-12-14 Zade Johnston , Jonathan Squire , Alfred Mallet , Romain Meyrand

By explicitly taking into account effects of Alfven waves, I derive from a simple energetics argument a fundamental relation which predicts solar wind (SW) speeds in the vicinity of the earth from physical properties on the sun. Kojima et…

Astrophysics · Physics 2009-11-11 Takeru K. Suzuki

One of the striking observations from the Parker Solar Probe (PSP) spacecraft is the prevalence in the inner heliosphere of large amplitude, Alfv\'enic magnetic field reversals termed 'switchbacks'. These $\delta B_R/B \sim \mathcal{O}(1$)…

Radio waves are strongly scattered in the solar wind, so that their apparent sources seem to be considerably larger and shifted than the actual ones. Since the scattering depends on the spectrum of density turbulence, better understanding…

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

Data obtained from Parker Solar Probe (PSP) since 2021 April have shown the first in situ observation of the solar corona, where the solar wind is formed and accelerated. Here we investigate the alpha-proton differential flow and its…

Solar and Stellar Astrophysics · Physics 2024-01-22 Hao Ran , Ying D. Liu , Chong Chen , Parisa Mostafavi

Characterizing compressible fluctuations in the solar wind is essential for understanding their role in solar wind acceleration and heating, yet their origin and evolution across different turbulence regimes remain poorly understood. In…

Plasma Physics · Physics 2026-04-13 C. A. Gonzalez , C. Gonzalez , A. Tenerani

We present a first theoretical modeling of joint Parker Solar Probe (PSP) - Metis/Solar Orbiter (SolO) quadrature observations Telloni et al 2022c. The combined observations describe the evolution of a slow solar wind plasma parcel from the…

Solar and Stellar Astrophysics · Physics 2022-10-05 Laxman Adhikari , Gary P. Zank , Daniele Telloni , Lingling Zhao

The nature of solar wind (SW) turbulence below the proton gyroscale is a topic that is being investigated extensively nowadays. Although recent observations gave evidence of the dominance of Kinetic Alfv\'en Waves (KAW) at sub-ion scales…

Solar and Stellar Astrophysics · Physics 2015-05-30 Fouad Sahraoui , Gérard Belmont , Melvyn Goldstein

In its first encounter at solar distances as close as r = 0.16AU, Parker Solar Probe (PSP) observed numerous local reversals, or inversions, in the heliospheric magnetic field (HMF), which were accompanied by large spikes in solar wind…

Solar and Stellar Astrophysics · Physics 2021-01-06 Allan R Macneil , Mathew J Owens , Robert T Wicks , Mike Lockwood

Energy supply sources for the heating process in the slow solar wind remain unknown. The Parker Solar Probe (PSP) mission provides a good opportunity to study this issue. Recently, PSP observations have found that the slow solar wind…

Space Physics · Physics 2020-11-23 Honghong Wu , Chuanyi Tu , Xin Wang , Jiansen He , Liping Yang

Alfv\'enicity is a well-known property, common in the solar wind, characterized by a high correlation between magnetic and velocity fluctuations. Data from the Parker Solar Probe (PSP) enable the study of this property closer to the Sun…

Because of its distinctive compositional properties and variability, low-speed ($\lesssim 450$ km s$^{-1}$) solar wind is widely believed to originate from coronal streamers, unlike high-speed wind, which comes from coronal holes. An…

Solar and Stellar Astrophysics · Physics 2021-04-16 Y. -M. Wang , Y. -K. Ko