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Found 8 entries in the Bibliography.
Showing entries from 1 through 8
| 2021 |
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One of the key challenges in solar and heliospheric physics is to understand the acceleration of the solar wind. As a super-sonic, super-Alfv\ enic plasma flow, the solar wind carries mass, momentum, energy, and angular momentum from the Sun into interplanetary space. We present a framework based on two-fluid magnetohydrodynamics to estimate the flux of these quantities based on spacecraft data independent of the heliocentric distance of the location of measurement. Applying this method to the Ulysses dataset allows us to st ... Verscharen, Daniel; Bale, Stuart; Velli, Marco; Published by: \mnras Published on: jul YEAR: 2021 DOI: 10.1093/mnras/stab2051 Solar wind; Sun: heliosphere; Magnetohydrodynamics; plasmas; methods: data analysis |
| 2020 |
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Polytropic Behavior of Solar Wind Protons Observed by Parker Solar Probe A polytropic process describes the transition of a fluid from one state to another through a specific relationship between the fluid density and temperature. The value of the polytropic index that governs this relationship determines the heat transfer and the effective degrees of freedom during a specific process. In this study, we analyze\ solar\ wind proton plasma measurements, obtained by the Faraday cup instrument on board the\ Parker\ Solar\ Probe. We examine the large-scale variations of the ... Nicolaou, Georgios; Livadiotis, George; Wicks, Robert; Verscharen, Daniel; Maruca, Bennett; Published by: The Astrophysical Journal Published on: 09/2020 YEAR: 2020 DOI: 10.3847/1538-4357/abaaae Parker Data Used; parker solar probe; Solar Physics; Solar Probe Plus; Solar wind; Space plasmas |
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Turbulence, a ubiquitous phenomenon in interplanetary space, is crucial for the energy conversion of space plasma at multiple scales. This work focuses on the propagation, polarization, and wave composition properties of the\ solar\ wind turbulence within 0.3 au, and its variation with heliocentric distance at magnetohydrodynamic scales (from 10 s to 1000 s in the spacecraft frame). We present the probability density function of propagation wavevectors (PDF (k(parallel to),k)) for\ solar\ wind turbulen ... Zhu, Xingyu; He, Jiansen; Verscharen, Daniel; Duan, Die; Bale, Stuart; Published by: The Astrophysical Journal Published on: 09/2020 YEAR: 2020 DOI: 10.3847/2041-8213/abb23e Alfv\ en waves; Heliosphere; interplanetary turbulence; Parker Data Used; parker solar probe; Slow solar wind; Solar Probe Plus |
| 2019 |
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Self-induced Scattering of Strahl Electrons in the Solar Wind We investigate the scattering of strahl electrons by microinstabilities as a mechanism for creating the electron halo in the solar wind. We develop a mathematical framework for the description of electron-driven microinstabilities and discuss the associated physical mechanisms. We find that an instability of the oblique fast-magnetosonic/whistler (FM/W) mode is the best candidate for a microinstability that scatters strahl electrons into the halo. We derive approximate analytic expressions for the FM/W instability thresho ... Verscharen, Daniel; Chandran, Benjamin; Jeong, Seong-Yeop; Salem, Chadi; Pulupa, Marc; Bale, Stuart; Published by: The Astrophysical Journal Published on: 12/2019 YEAR: 2019 DOI: 10.3847/1538-4357/ab4c30 Astrophysics - Solar and Stellar Astrophysics; instabilities; parker solar probe; Physics - Geophysics; Physics - Plasma Physics; Physics - Space Physics; plasmas; Solar Probe Plus; Solar wind; Sun: corona; turbulence; waves |
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A step closer to the Sun\textquoterights secrets NASA\textquoterights Parker Solar Probe is currently making a series of close encounters with the Sun. Initial observations from the spacecraft have improved our understanding of both the Sun and its environment. Published by: Nature Published on: 12/2019 YEAR: 2019 DOI: 10.1038/d41586-019-03665-3 |
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The Fluid-like and Kinetic Behavior of Kinetic Alfv\ en Turbulence in Space Plasma Kinetic Alfv\ en waves (KAWs) are the short-wavelength extension of the magnetohydrodynamics Alfv\ en-wave branch in the case of highly oblique propagation with respect to the background magnetic field. Observations of space plasma show that small-scale turbulence is mainly KAW-like. We apply two theoretical approaches, a collisional two-fluid theory and a collisionless linear kinetic theory, to obtain predictions for the KAW polarizations depending on\ β\ p\ (the ratio of the proton th ... Wu, Honghong; Verscharen, Daniel; Wicks, Robert; Chen, Christopher; He, Jiansen; Nicolaou, Georgios; Published by: The Astrophysical Journal Published on: 01/2019 YEAR: 2019 DOI: 10.3847/1538-4357/aaef77 magnetohydrodynamics: MHD; plasmas; solar-terrestrial relations; turbulence; waves; Physics - Space Physics; Astrophysics - Solar and Stellar Astrophysics; Physics - Plasma Physics |
| 2015 |
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A MODIFIED VERSION OF TAYLOR\textquoterightS HYPOTHESIS FOR SOLAR PROBE PLUS OBSERVATIONS The Solar Probe Plus (SPP) spacecraft will explore the near-Sun environment, reaching heliocentric distances less than 10 R☉ . Near Earth, spacecraft measurements of fluctuating velocities and magnetic fields taken in the time domain are translated into information about the spatial structure of the solar wind via Taylor\textquoterights \textquotedblleftfrozen turbulence\textquotedblright hypothesis. Near the perihelion of SPP, however, the solar-wind speed is comparable to the Alfv\ en speed, and Taylor\text ... Klein, Kristopher; Perez, Jean; Verscharen, Daniel; Mallet, Alfred; Chandran, Benjamin; Published by: The Astrophysical Journal Published on: 03/2015 YEAR: 2015 DOI: 10.1088/2041-8205/801/1/L18 Astrophysics - Solar and Stellar Astrophysics; Parker Data Used; parker solar probe; Physics - Plasma Physics; Physics - Space Physics; plasmas; Solar Probe Plus; Solar wind; Sun: corona; turbulence |
| 2013 |
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Stochastic Heating, Differential Flow, and the Alpha-to-proton Temperature Ratio in the Solar Wind Chandran, B.~D.~G.; Verscharen, D.; Quataert, E.; Kasper, J.~C.; Isenberg, P.~A.; Bourouaine, S.; Published by: \apj Published on: 10/2013 YEAR: 2013 DOI: 10.1088/0004-637X/776/1/45 Parker Data Used; plasmas; Solar wind; Sun: corona; turbulence; waves; Astrophysics - Solar and Stellar Astrophysics; Physics - Plasma Physics; Physics - Space Physics |
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