|
Notice:
|
Found 14 entries in the Bibliography.
Showing entries from 1 through 14
| 2020 |
|
Alfv\ enic fluctuations in solar wind are an intrinsic property of fast streams, while slow intervals typically have a very low degree of Alfv\ enicity, with much more variable parameters. However, sometimes a slow wind can be highly Alfv\ enic. Here we compare three different regimes of solar wind, in terms of Alfv\ enic content and spectral properties, during a minimum phase of the solar activity and at 0.3 au. We show that fast and Alfv\ enic slow intervals share some common characteristics. This would suggest a simila ... Perrone, D.; D\textquoterightAmicis, R.; De Marco, R.; Matteini, L.; Stansby, D.; Bruno, R.; Horbury, T.; Published by: Astronomy \& Astrophysics Published on: 01/2020 YEAR: 2020 DOI: 10.1051/0004-6361/201937064 parker solar probe; plasmas; Solar Probe Plus; Solar wind; Sun: corona; Sun: heliosphere; turbulence |
| 2019 |
|
Does Turbulence Turn off at the Alfv\ en Critical Surface? The\ Parker Solar Probe\ (PSP) will eventually reach and cross the Alfv\ en point or surface as it provides us with direct in situ measurements of the solar atmosphere. The Alfv\ en surface is the location at which the large-scale bulk solar wind speed\ Published by: The Astrophysical Journal Published on: Jan-05-2019 YEAR: 2019 DOI: 10.3847/1538-4357/ab141c |
|
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 |
|
Contextual Predictions for the Parker Solar Probe . I. Critical Surfaces and Regions The solar corona and young solar wind may be characterized by critical surfaces\textemdashthe sonic, Alfv\ en, and first plasma-β unity surfaces\textemdashthat demarcate regions where the solar wind flow undergoes certain crucial transformations. Global numerical simulations and remote sensing observations offer a natural mode for the study of these surfaces at large scales, thus providing valuable context for the high-resolution in situ measurements expected from the recently launched Parker Solar Probe (PSP). The prese ... Chhiber, Rohit; Usmanov, Arcadi; Matthaeus, William; Goldstein, Melvyn; Published by: The Astrophysical Journal Supplement Series Published on: 03/2019 YEAR: 2019 DOI: 10.3847/1538-4365/ab0652 Astrophysics - Solar and Stellar Astrophysics; magnetohydrodynamics: MHD; Parker Data Used; parker solar probe; Physics - Space Physics; Solar Probe Plus; Solar wind; Sun: corona; turbulence |
| 2018 |
|
On slow solar wind with high Alfv\ enicity: from composition and microphysics to spectral properties Alfv\ enic fluctuations are very common features in the solar wind and are found especially within the main portion of fast-wind streams while the slow wind usually is less Alfv\ enic and more variable. In general, the fast and slow winds show many differences, which span from the large-scale structure to small-scale phenomena, including also a different turbulent behaviour. Recent studies, however, have shown that even the slow wind can sometimes be highly Alfv\ enic, with fluctuations as large as those of the fast wind. ... textquoterightAmicis, Raffaella; Matteini, Lorenzo; Bruno, Roberto; Published by: Monthly Notices of the Royal Astronomical Society Published on: 3/2019 YEAR: 2018 DOI: 10.1093/mnras/sty3329 Astrophysics - Solar and Stellar Astrophysics; methods: data analysis; parker solar probe; Physics - Data Analysis; Physics - Plasma Physics; Physics - Space Physics; Solar Probe Plus; Solar wind; Statistics and Probability; turbulence |
| 2017 |
|
A Zone of Preferential Ion Heating Extends Tens of Solar Radii from the Sun The extreme temperatures and nonthermal nature of the solar corona and solar wind arise from an unidentified physical mechanism that preferentially heats certain ion species relative to others. Spectroscopic indicators of unequal temperatures commence within a fraction of a solar radius above the surface of the Sun, but the outer reach of this mechanism has yet to be determined. Here we present an empirical procedure for combining interplanetary solar wind measurements and a modeled energy equation including Coulomb relax ... Kasper, J.; Klein, K.; Weber, T.; Maksimovic, M.; Zaslavsky, A.; Bale, S.; Maruca, B.; Stevens, M.; Case, A.; Published by: The Astrophysical Journal Published on: 11/2017 YEAR: 2017 DOI: 10.3847/1538-4357/aa84b1 acceleration of particles; Astrophysics - Solar and Stellar Astrophysics; magnetic fields; parker solar probe; Physics - Plasma Physics; Physics - Space Physics; plasmas; Solar Probe Plus; Solar wind; Sun: corona; turbulence |
| 2016 |
|
MEASURING COLLISIONLESS DAMPING IN HELIOSPHERIC PLASMAS USING FIELD\textendashPARTICLE CORRELATIONS An innovative field-particle correlation technique is proposed that uses single-point measurements of the electromagnetic fields and particle velocity distribution functions to investigate the net transfer of energy from fields to particles associated with the collisionless damping of turbulent fluctuations in weakly collisional plasmas, such as the solar wind. In addition to providing a direct estimate of the local rate of energy transfer between fields and particles, it provides vital new information about the distribut ... Published by: The Astrophysical Journal Published on: 08/2016 YEAR: 2016 DOI: 10.3847/2041-8205/826/2/L30 Astrophysics - Solar and Stellar Astrophysics; parker solar probe; Physics - Plasma Physics; Physics - Space Physics; plasmas; Solar Probe Plus; Solar wind; turbulence; waves |
|
SOLAR WIND COLLISIONAL AGE FROM A GLOBAL MAGNETOHYDRODYNAMICS SIMULATION Simple estimates of the number of Coulomb collisions experienced by the interplanetary plasma to the point of observation, I.e., the \textquotedblleftcollisional age\textquotedblright, can be usefully employed in the study of non-thermal features of the solar wind. Usually these estimates are based on local plasma properties at the point of observation. Here we improve the method of estimation of the collisional age by employing solutions obtained from global three-dimensional magnetohydrodynamics simulations. This enable ... Chhiber, R; Usmanov, AV; Matthaeus, WH; Goldstein, ML; Published by: The Astrophysical Journal Published on: 04/2016 YEAR: 2016 DOI: 10.3847/0004-637X/821/1/34 magnetohydrodynamics: MHD; methods: numerical; parker solar probe; plasmas; scattering; Solar Probe Plus; Solar wind; turbulence |
|
EVOLUTION OF THE PROTON VELOCITY DISTRIBUTION DUE TO STOCHASTIC HEATING IN THE NEAR-SUN SOLAR WIND We investigate how the proton distribution function evolves when the protons undergo stochastic heating by strong, low-frequency, Alfv\ en-wave turbulence under the assumption that β is small. We apply our analysis to protons undergoing stochastic heating in the supersonic fast solar wind and obtain proton distributions at heliocentric distances ranging from 4 to 30 solar radii. We find that the proton distribution develops non-Gaussian structure with a flat core and steep tail. For r\gt 5 RS, the proton distr ... Klein, Kristopher; Chandran, Benjamin; Published by: The Astrophysical Journal Published on: 03/2016 YEAR: 2016 DOI: 10.3847/0004-637X/820/1/47 Astrophysics - Solar and Stellar Astrophysics; parker solar probe; Physics - Plasma Physics; plasmas; Solar Probe Plus; Solar wind; turbulence; waves |
| 2015 |
|
ION-SCALE TURBULENCE IN THE INNER HELIOSPHERE: RADIAL DEPENDENCE The evolution of the ion-scale plasma turbulence in the inner heliosphere is studied by associating the plasma parameters for hybrid-code turbulence simulations to the radial distance from the Sun via a Solar wind model based mapping procedure. Using a mapping based on a one-dimensional solar wind expansion model, the resulting ion-kinetic scale turbulence is related to the solar wind distance from the Sun. For this purpose the mapping is carried out for various values of ion beta that correspond to the heliocentric dista ... sel, H.; Motschmann, U.; üchner, J.; Narita, Y.; Nariyuki, Y.; Published by: The Astrophysical Journal Published on: 10/2015 YEAR: 2015 DOI: 10.1088/0004-637X/812/2/175 parker solar probe; plasmas; Solar Probe Plus; Solar wind; turbulence; waves |
|
We extend the kinetic guiding-center model of collisionless coronal hole protons presented in Isenberg \& Vasquez to consider driving by imbalanced spectra of obliquely propagating ion-cyclotron waves. These waves are assumed to be a small by-product of the imbalanced turbulent cascade to high perpendicular wavenumber, and their total intensity is taken to be 1\% of the total fluctuation energy. We also extend the kinetic solutions for the proton distribution function in the resulting fast solar wind to heliocentric d ... Isenberg, Philip; Vasquez, Bernard; Published by: The Astrophysical Journal Published on: 08/2015 YEAR: 2015 DOI: 10.1088/0004-637X/808/2/119 parker solar probe; plasmas; Solar Probe Plus; Solar wind; Sun: corona; turbulence; waves |
|
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 |
| 2014 |
|
THE VIOLATION OF THE TAYLOR HYPOTHESIS IN MEASUREMENTS OF SOLAR WIND TURBULENCE Motivated by the upcoming Solar Orbiter and Solar Probe Plus missions, qualitative and quantitative predictions are made for the effects of the violation of the Taylor hypothesis on the magnetic energy frequency spectrum measured in the near-Sun environment. The synthetic spacecraft data method is used to predict observational signatures of the violation for critically balanced Alfv\ enic turbulence or parallel fast/whistler turbulence. The violation of the Taylor hypothesis can occur in the slow flow regime, leading to a ... Klein, K.; Howes, G.; TenBarge, J.; Published by: The Astrophysical Journal Published on: 08/2014 YEAR: 2014 DOI: 10.1088/2041-8205/790/2/L20 Astrophysics - Solar and Stellar Astrophysics; parker solar probe; Physics - Plasma Physics; Physics - Space Physics; plasmas; Solar Probe Plus; Solar wind; turbulence; waves |
|
VALIDITY OF THE TAYLOR HYPOTHESIS FOR LINEAR KINETIC WAVES IN THE WEAKLY COLLISIONAL SOLAR WIND 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 hypothesis\textemdashthat temporal fluctuations measured by a stationary probe in a rapidly flowing fluid are dominated by the advection of spatial structures in the fluid rest frame\textemdashis often assumed to simplify the analysis. But measurements of turbulence in upcoming missions, such ... Howes, G.; Klein, K.; TenBarge, J.; Published by: The Astrophysical Journal Published on: 07/2014 YEAR: 2014 DOI: 10.1088/0004-637X/789/2/106 Astrophysics - Solar and Stellar Astrophysics; parker solar probe; Physics - Plasma Physics; Solar Probe Plus; Solar wind; turbulence |
\ and the Alfv\ en speed\ 
Adhikari, L.; 1
