# PSP Bibliography

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## Found 118 entries in the Bibliography.

### Showing entries from 1 through 50

 2022 Parker Solar Probe Observations of Near-f $_Ce$ Harmonic Emissions in the Near-Sun Solar Wind and Their Dependence on the Magnetic Field Direction Wave emissions at frequencies near electron gyrofrequency harmonics are observed at small heliocentric distances below about 40 R $_\ensuremath\odot$ and are known to occur in regions with quiescent magnetic fields. We show the close connection of these waves to the large-scale properties of the magnetic field. Near electron gyrofrequency harmonic emissions occur only when the ambient magnetic field points to a narrow range of directions bounded by polar and azimuthal angular ranges in the RTN coordinate system of correspond ... Tigik, Sabrina; Vaivads, Andris; Malaspina, David; Bale, Stuart; Published by: \apj      Published on: sep YEAR: 2022     DOI: 10.3847/1538-4357/ac8473 Direct First Parker Solar Probe Observation of the Interaction of Two Successive Interplanetary Coronal Mass Ejections in 2020 November We investigate the effects of the evolutionary processes in the internal magnetic structure of two interplanetary coronal mass ejections (ICMEs) detected in situ between 2020 November 29 and December 1 by the Parker Solar Probe (PSP). The sources of the ICMEs were observed remotely at the Sun in EUV and subsequently tracked to their coronal counterparts in white light. This period is of particular interest to the community as it has been identified as the first widespread solar energetic particle event of solar cycle 25. The ... Nieves-Chinchilla, Teresa; Alzate, Nathalia; Cremades, Hebe; ia, Laura; Santos, Luiz; Narock, Ayris; Xie, Hong; Szabo, Adam; Palmerio, Erika; Krupar, Vratislav; Pulupa, Marc; Lario, David; Stevens, Michael; Wilson, Lynn; Kwon, Ryun-Young; Mays, Leila; St. Cyr, Chris; Hess, Phillip; Reeves, Katharine; Seaton, Daniel; Niembro, Tatiana; Bale, Stuart; Kasper, Justin; Published by: \apj      Published on: may YEAR: 2022     DOI: 10.3847/1538-4357/ac590b Intermittency in the Expanding Solar Wind: Observations from Parker Solar Probe (0.16 au), Helios 1 (0.3-1 au), and Voyager 1 (1-10 au) We examine statistics of magnetic-field vector components to explore how intermittency evolves from near-Sun plasma to radial distances as large as 10 au. Statistics entering the analysis include autocorrelation, magnetic structure functions of the order of n (SF$_ n$), and scale-dependent kurtosis (SDK), each grouped in ranges of heliocentric distance. The Goddard Space Flight Center Space Physics Data Facility provides magnetic-field measurements for resolutions of 6.8 ms for Parker Solar Probe, 6 s for Helios, and 1.92 s ... Cuesta, Manuel; Parashar, Tulasi; Chhiber, Rohit; Matthaeus, William; Published by: \apjs      Published on: mar YEAR: 2022     DOI: 10.3847/1538-4365/ac45fa Core Electron Heating by Triggered Ion Acoustic Waves in the Solar Wind Perihelion passes on Parker Solar Probe orbits 6-9 have been studied to show that solar wind core electrons emerged from 15 solar radii with a temperature of 55 \ensuremath\pm 5 eV, independent of the solar wind speed, which varied from 300 to 800 km s$^-1$. After leaving 15 solar radii and in the absence of triggered ion acoustic waves at greater distances, the core electron temperature varied with radial distance, R, in solar radii, as 1900R $^-4/3$ eV because of cooling produced by the adiabatic expansion. The coefficient ... Mozer, F.~S.; Bale, S.~D.; Cattell, C.~A.; Halekas, J.; Vasko, I.~Y.; Verniero, J.~L.; Kellogg, P.~J.; Published by: \apjl      Published on: mar YEAR: 2022     DOI: 10.3847/2041-8213/ac5520 Statistical Analysis of Intermittency and its Association with Proton Heating in the Near-Sun Environment We use data from the first six encounters of the Parker Solar Probe and employ the partial variance of increments (PVI) method to study the statistical properties of coherent structures in the inner heliosphere with the aim of exploring physical connections between magnetic field intermittency and observable consequences such as plasma heating and turbulence dissipation. Our results support proton heating localized in the vicinity of, and strongly correlated with, magnetic structures characterized by PVI \ensuremath\geq 1. W ... Sioulas, Nikos; Velli, Marco; Chhiber, Rohit; Vlahos, Loukas; Matthaeus, William; Bandyopadhyay, Riddhi; Cuesta, Manuel; Shi, Chen; Bowen, Trevor; Qudsi, Ramiz; Stevens, Michael; Bale, Stuart; Published by: \apj      Published on: mar YEAR: 2022     DOI: 10.3847/1538-4357/ac4fc1 Langmuir-Slow Extraordinary Mode Magnetic Signature Observations with Parker Solar Probe Radio emission from interplanetary shocks, planetary foreshocks, and some solar flares occurs in the so-called plasma emission framework. The generally accepted scenario begins with electrostatic Langmuir waves that are driven by a suprathermal electron beam on the Landau resonance. These Langmuir waves then mode-convert to freely propagating electromagnetic emissions at the local plasma frequency f $_ pe$ and/or its harmonic 2f $_ pe$. However, the details of the physics of mode conversion are unclear, and so far the ... Larosa, A.; de Wit, Dudok; Krasnoselskikh, V.; Bale, S.~D.; Agapitov, O.; Bonnell, J.; Froment, C.; Goetz, K.; Harvey, P.; Halekas, J.; Kretzschmar, M.; MacDowall, R.; Malaspina, David; Moncuquet, M.; Niehof, J.; Pulupa, M.; Revillet, C.; Published by: \apj      Published on: mar YEAR: 2022     DOI: 10.3847/1538-4357/ac4e85 The Kinetic Expansion of Solar-wind Electrons: Transport Theory and Predictions for the Very Inner Heliosphere We propose a transport theory for the kinetic evolution of solar-wind electrons in the heliosphere. We derive a gyro-averaged kinetic transport equation that accounts for the spherical expansion of the solar wind and the geometry of the Parker spiral magnetic field. To solve our three-dimensional kinetic equation, we develop a mathematical approach that combines the Crank-Nicolson scheme in velocity space and a finite-difference Euler scheme in configuration space. We initialize our model with isotropic electron distribution ... Jeong, Seong-Yeop; Verscharen, Daniel; Vocks, Christian; Abraham, Joel; Owen, Christopher; Wicks, Robert; Fazakerley, Andrew; Stansby, David; Ber\vci\vc, Laura; Nicolaou, Georgios; Rueda, Jeffersson; Bakrania, Mayur; Published by: \apj      Published on: mar YEAR: 2022     DOI: 10.3847/1538-4357/ac4805 Energy Transfer, Discontinuities, and Heating in the Inner Heliosphere Measured with a Weak and Local Formulation of the Politano-Pouquet Law The solar wind is a highly turbulent plasma for which the mean rate of energy transfer ɛ has been measured for a long time using the Politano-Pouquet (PP98) exact law. However, this law assumes statistical homogeneity that can be violated by the presence of discontinuities. Here, we introduce a new method based on the inertial dissipation $D _I^{\sigma }$ whose analytical form is derived from incompressible magnetohydrodynamics; it can be considered as a weak and local (in space) formulation of the PP98 law whose expressio ... David, V.; Galtier, S.; Sahraoui, F.; Hadid, L.~Z.; Published by: \apj      Published on: mar YEAR: 2022     DOI: 10.3847/1538-4357/ac524b Features of Magnetic Field Switchbacks in Relation to the Local-field Geometry of Large-amplitude Alfv\ enic Oscillations: Wind and PSP Observations In this Letter, we report observations of magnetic switchback (SB) features near 1 au using data from the Wind spacecraft. These features appear to be strikingly similar to the ones observed by the Parker Solar Probe mission closer to the Sun: namely, one- sided spikes (or enhancements) in the solar-wind bulk speed V that correlate/anticorrelate with the spikes seen in the radial- field component B $_ R$. In the solar-wind streams that we analyzed, these specific SB features near 1 au are associated with large-amplitude Alf ... Bourouaine, Sofiane; Perez, Jean; Raouafi, Nour; Chandran, Benjamin; Bale, Stuart; Velli, Marco; Published by: \apjl      Published on: jun YEAR: 2022     DOI: 10.3847/2041-8213/ac67d9 Radial Evolution of Thermal and Suprathermal Electron Populations in the Slow Solar Wind from 0.13 to 0.5 au: Parker Solar Probe Observations We develop and apply a bespoke fitting routine to a large volume of solar wind electron distribution data measured by Parker Solar Probe over its first five orbits, covering radial distances from 0.13 to 0.5 au. We characterize the radial evolution of the electron core, halo, and strahl populations in the slow solar wind during these orbits. The fractional densities of these three electron populations provide evidence for the growth of the combined suprathermal halo and strahl populations from 0.13 to 0.17 au. Moreover, the ... Abraham, Joel; Owen, Christopher; Verscharen, Daniel; Bakrania, Mayur; Stansby, David; Wicks, Robert; Nicolaou, Georgios; Whittlesey, Phyllis; Rueda, Jeffersson; Jeong, Seong-Yeop; Ber\vci\vc, Laura; Published by: \apj      Published on: jun YEAR: 2022     DOI: 10.3847/1538-4357/ac6605 Isotropization and Evolution of Energy-containing Eddies in Solar Wind Turbulence: Parker Solar Probe, Helios 1, ACE, WIND, and Voyager 1 We examine the radial evolution of correlation lengths perpendicular ( $\lambda _C^\perp$ ) and parallel ( $\lambda _C^\parallel$ ) to the magnetic-field direction, computed from solar wind magnetic-field data measured by Parker Solar Probe (PSP) during its first eight orbits, Helios 1, Advanced Composition Explorer (ACE), WIND, and Voyager 1 spacecraft. Correlation lengths are grouped by an interval s alignment angle; the angle between the magnetic-field and solar wind velocity vectors (\ensuremath\Theta$_BV$). Parallel a ... Cuesta, Manuel; Chhiber, Rohit; Roy, Sohom; Goodwill, Joshua; Pecora, Francesco; Jarosik, Jake; Matthaeus, William; Parashar, Tulasi; Bandyopadhyay, Riddhi; Published by: \apjl      Published on: jun YEAR: 2022     DOI: 10.3847/2041-8213/ac73fd Growth of Outward Propagating Fast-magnetosonic/Whistler Waves in the Inner Heliosphere Observed by Parker Solar Probe The solar wind in the inner heliosphere has been observed by Parker Solar Probe (PSP) to exhibit abundant wave activities. The cyclotron wave modes responding to ions or electrons are among the most crucial wave components. However, their origin and evolution in the inner heliosphere close to the Sun remains a mystery. Specifically, it remains unknown whether it is an emitted signal from the solar atmosphere or an eigenmode growing locally in the heliosphere due to plasma instability. To address and resolve this controversy, ... He, Jiansen; Wang, Ying; Zhu, Xingyu; Duan, Die; Verscharen, Daniel; Zhao, Guoqing; Published by: \apj      Published on: jul YEAR: 2022     DOI: 10.3847/1538-4357/ac6c8e The Dynamic Evolution of Solar Wind Streams Following Interchange Reconnection Interchange reconnection is thought to play an important role in determining the dynamics and material composition of the slow solar wind that originates from near coronal-hole boundaries. To explore the implications of this process we simulate the dynamic evolution of a solar wind stream along a newly-opened magnetic flux tube. The initial condition is composed of a piecewise continuous dynamic equilibrium in which the regions above and below the reconnection site are extracted from steady-state solutions along open and clo ... Scott, Roger; Bradshaw, Stephen; Linton, Mark; Published by: \apj      Published on: jul YEAR: 2022     DOI: 10.3847/1538-4357/ac7144 MHD Turbulent Power Anisotropy in the Inner Heliosphere We study anisotropic magnetohydrodynamic (MHD) turbulence in the slow solar wind measured by Parker Solar Probe (PSP) and Solar Orbiter (SolO) during its first orbit from the perspective of variance anisotropy and correlation anisotropy. We use the Belcher \& Davis approach (M1) and a new method (M2) that decomposes a fluctuating vector into parallel and perpendicular fluctuating vectors. M1 and M2 calculate the transverse and parallel turbulence components relative to the mean magnetic field direction. The parallel turbulen ... Adhikari, L.; Zank, G.~P.; Zhao, L.; Telloni, D.; Published by: \apj      Published on: jul YEAR: 2022     DOI: 10.3847/1538-4357/ac70cb Taylor Microscale and Effective Reynolds Number near the Sun from PSP The Taylor microscale is a fundamental length scale in turbulent fluids, representing the end of fluid properties and onset of dissipative processes. The Taylor microscale can also be used to evaluate the Reynolds number in classical turbulence theory. Although the solar wind is weakly collisional, it approximately behaves as a magnetohydrodynamic (MHD) fluid at scales larger than the kinetic scale. As a result, classical fluid turbulence theory and formalisms are often used to study turbulence in the MHD range. Therefore, a ... Phillips, C.; Bandyopadhyay, R.; McComas, D.~J.; Published by: \apj      Published on: jul YEAR: 2022     DOI: 10.3847/1538-4357/ac713f Quasi-periodic Energy Release and Jets at the Base of Solar Coronal Plumes Coronal plumes are long, ray-like, open structures that have been considered as possible sources of the solar wind. Their origin in the largely unipolar coronal holes has long been a mystery. Earlier spectroscopic and imaging observations revealed blueshifted plasma and propagating disturbances (PDs) in plumes that are widely interpreted in terms of flows and/or propagating slow-mode waves, but these interpretations (flows versus waves) remain under debate. Recently we discovered an important clue about plume internal struct ... Kumar, Pankaj; Karpen, Judith; Uritsky, Vadim; Deforest, Craig; Raouafi, Nour; DeVore, Richard; Published by: \apj      Published on: jul YEAR: 2022     DOI: 10.3847/1538-4357/ac6c24 Multipoint Interplanetary Coronal Mass Ejections Observed with Solar Orbiter, BepiColombo, Parker Solar Probe, Wind, and STEREO-A We report the result of the first search for multipoint in situ and imaging observations of interplanetary coronal mass ejections (ICMEs) starting with the first Solar Orbiter (SolO) data in 2020 April-2021 April. A data exploration analysis is performed including visualizations of the magnetic-field and plasma observations made by the five spacecraft SolO, BepiColombo, Parker Solar Probe (PSP), Wind, and STEREO-A, in connection with coronagraph and heliospheric imaging observations from STEREO-A/SECCHI and SOHO/LASCO. We id ... Möstl, Christian; Weiss, Andreas; Reiss, Martin; Amerstorfer, Tanja; Bailey, Rachel; Hinterreiter, Jürgen; Bauer, Maike; Barnes, David; Davies, Jackie; Harrison, Richard; von Forstner, Johan; Davies, Emma; Heyner, Daniel; Horbury, Tim; Bale, Stuart; Published by: \apjl      Published on: jan YEAR: 2022     DOI: 10.3847/2041-8213/ac42d0 Inertial-range Magnetic-fluctuation Anisotropy Observed from Parker Solar Probe s First Seven Orbits Solar wind turbulence is anisotropic with respect to the mean magnetic field. Anisotropy leads to ambiguity when interpreting in situ turbulence observations in the solar wind because an apparent change in the measurements could be due to either the change of intrinsic turbulence properties or to a simple change of the spacecraft sampling direction. We demonstrate the ambiguity using the spectral index and magnetic compressibility in the inertial range observed by the Parker Solar Probe during its first seven orbits ranging ... Zhao, L.; Zank, G.~P.; Adhikari, L.; Nakanotani, M.; Published by: \apjl      Published on: jan YEAR: 2022     DOI: 10.3847/2041-8213/ac4415 Anomalous Cosmic-Ray Oxygen Observations into 0.1 au The Integrated Science Investigation of the Sun instrument suite onboard NASA s Parker Solar Probe mission continues to measure solar energetic particles and cosmic rays closer to the Sun than ever before. Here, we present the first observations of cosmic rays into 0.1 au (21.5 solar radii), focusing specifically on oxygen from \raisebox-0.5ex\textasciitilde2018.7 to \raisebox-0.5ex\textasciitilde2021.2. Our energy spectra reveal an anomalous cosmic-ray-dominated profile that is comparable to that at 1 au, across multiple so ... Rankin, J.~S.; McComas, D.~J.; Leske, R.~A.; Christian, E.~R.; Cohen, C.~M.~S.; Cummings, A.~C.; Joyce, C.~J.; Labrador, A.~W.; Mewaldt, R.~A.; Schwadron, N.~A.; Stone, E.~C.; Strauss, R.~D.; Wiedenbeck, M.~E.; Published by: \apj      Published on: jan YEAR: 2022     DOI: 10.3847/1538-4357/ac348f Parker Solar Probe Evidence for the Absence of Whistlers Close to the Sun to Scatter Strahl and to Regulate Heat Flux Using the Parker Solar Probe FIELDS bandpass-filter data and SWEAP electron data from Encounters 1 through 9, we show statistical properties of narrowband whistlers from \raisebox-0.5ex\textasciitilde16 R $_s$ to \raisebox-0.5ex\textasciitilde130 R $_s$, and compare wave occurrence to electron properties including beta, temperature anisotropy, and heat flux. Whistlers are very rarely observed inside \raisebox-0.5ex\textasciitilde28 R $_s$ (\raisebox-0.5ex\textasciitilde0.13 au). Outside 28 R $_s$, they occur within a narrow ... Cattell, C.; Breneman, A.; Dombeck, J.; Hanson, E.; Johnson, M.; Halekas, J.; Bale, S.~D.; de Wit, Dudok; Goetz, K.; Goodrich, K.; Malaspina, D.; Pulupa, M.; Case, T.; Kasper, J.~C.; Larson, D.; Stevens, M.; Whittlesey, P.; Published by: \apjl      Published on: jan YEAR: 2022     DOI: 10.3847/2041-8213/ac4015 Numerical Modeling of Suprathermal Electron Transport in the Solar Wind: Effects of Whistler Turbulence with a Full Diffusion Tensor The electron VDF in the solar wind consists of a Maxwellian core, a suprathermal halo, a field-aligned component strahl, and an energetic superhalo that deviates from the equilibrium. Whistler wave turbulence is thought to resonantly scatter the observed electron velocity distribution. Wave-particle interactions that contribute to Whistler wave turbulence are introduced into a Fokker-Planck kinetic transport equation that describes the interaction between the suprathermal electrons and the Whistler waves. A recent numerical ... Tang, Bofeng; Zank, Gary; Kolobov, Vladimir; Published by: \apj      Published on: jan YEAR: 2022     DOI: 10.3847/1538-4357/ac36c9 Strong Perpendicular Velocity-space Diffusion in Proton Beams Observed by Parker Solar Probe The SWEAP instrument suite on Parker Solar Probe (PSP) has detected numerous proton beams associated with coherent, circularly polarized, ion-scale waves observed by PSP s FIELDS instrument suite. Measurements during PSP Encounters 4-8 revealed pronounced complex shapes in the proton velocity distribution functions (VDFs), in which the tip of the beam undergoes strong perpendicular diffusion, resulting in VDF level contours that resemble a hammerhead. We refer to these proton beams, with their attendant hammerhead fe ... Verniero, J.~L.; Chandran, B.~D.~G.; Larson, D.~E.; Paulson, K.; Alterman, B.~L.; Badman, S.; Bale, S.~D.; Bonnell, J.~W.; Bowen, T.~A.; de Wit, Dudok; Kasper, J.~C.; Klein, K.~G.; Lichko, E.; Livi, R.; McManus, M.~D.; Rahmati, A.; Verscharen, D.; Walters, J.; Whittlesey, P.~L.; Published by: \apj      Published on: jan YEAR: 2022     DOI: 10.3847/1538-4357/ac36d5 Two Correlations with Enhancement Near the Proton Gyroradius Scale in Solar Wind Turbulence: Parker Solar Probe (PSP) and Wind Observations Based on the Parker Solar Probe mission, this paper presents the observations of two correlations in solar wind turbulence near the Sun for the first time, demonstrating the clear existence of the following two correlations. One is positive correlation between the proton temperature and turbulent magnetic energy density. The other is negative correlation between the spectral index and magnetic helicity. It is found that the former correlation has a maximum correlation coefficient (CC) at the wavenumber k \ensuremath\rho $_ p ... Zhao, G.~Q.; Lin, Y.; Wang, X.~Y.; Feng, H.~Q.; Wu, D.~J.; Kasper, J.~C.; Published by: \apj Published on: jan YEAR: 2022 DOI: 10.3847/1538-4357/ac3747 A Study of an Equatorial Coronal Hole Observed at the First Parker Solar Probe Perihelion In this study, we present an observational analysis of a coronal hole (CH) observed on 2018 November 1 and solar wind (SW) that originated from it, using the Solar Dynamics Observatory, the Parker Solar Probe (PSP) observations at 68 solar radii, ACE and WIND data at 1 au, and interplanetary scintillation (IPS) observations from 0.2 to 1 au. The CH-originated SW stream was observed by L1 on 2018 November 4 and by PSP on 2018 November 15. We examined the CH for nine Carrington Rotations (CR) and find that the SW stream to rea ... Karna, Nishu; Berger, Mitchell; Asgari-Targhi, Mahboubeh; Paulson, Kristoff; Fujiki, Ken; Published by: \apj Published on: jan YEAR: 2022 DOI: 10.3847/1538-4357/ac3c46 Three-Dimensional Anisotropy and Scaling Properties of Solar Wind Turbulence at Kinetic Scales in the Inner Heliosphere: Parker Solar Probe Observations We utilize the data from the Parker Solar Probe mission at its first perihelion to investigate the three-dimensional (3D) anisotropies and scalings of solar wind turbulence for the total, perpendicular, and parallel magnetic-field fluctuations at kinetic scales in the inner heliosphere. By calculating the five-point second-order structure functions, we find that the three characteristic lengths of turbulence eddies for the total and the perpendicular magnetic-field fluctuations in the local reference frame$(\hatL_\perp ,\ha ... Zhang, J.; Huang, S.~Y.; He, J.~S.; Wang, T.~Y.; Yuan, Z.~G.; Deng, X.~H.; Jiang, K.; Wei, Y.~Y.; Xu, S.~B.; Xiong, Q.~Y.; Lin, R.~T.; Yu, L.; Published by: \apjl      Published on: jan YEAR: 2022     DOI: 10.3847/2041-8213/ac4027 Simulation of Plasma Emission in Magnetized Plasmas The recent Parker Solar Probe observations of type III radio bursts show that the effects of the finite background magnetic field can be an important factor in the interpretation of data. In the present paper, the effects of the background magnetic field on the plasma-emission process, which is believed to be the main emission mechanism for solar coronal and interplanetary type III radio bursts, are investigated by means of the particle-in-cell simulation method. The effects of the ambient magnetic field are systematically s ... Lee, Sang-Yun; Yoon, Peter; Lee, Ensang; Tu, Weichao; Published by: \apj      Published on: jan YEAR: 2022     DOI: 10.3847/1538-4357/ac32bb Small-scale Magnetic Flux Ropes and Their Properties Based on In Situ Measurements from the Parker Solar Probe We report small-scale magnetic flux ropes via the in situ measurements from the Parker Solar Probe during the first six encounters, and present additional analyses to supplement our prior work in Chen et al. These flux ropes are detected by the Grad-Shafranov-based algorithm, with their durations and scale sizes ranging from 10 s to \ensuremath\lesssim1 hr and from a few hundred kilometers to 10$^-3$ au, respectively. They include both static structures and those with significant field-aligned plasma flows. Most structures t ... Chen, Yu; Hu, Qiang; Published by: \apj      Published on: jan YEAR: 2022     DOI: 10.3847/1538-4357/ac3487 Improving the Alfv\ en Wave Solar Atmosphere Model Based on Parker Solar Probe Data In van der Holst et al. (2019), we modeled the solar corona and inner heliosphere of the first encounter of NASA s Parker Solar Probe (PSP) using the Alfv\ en Wave Solar atmosphere Model (AWSoM) with Air Force Data Assimilative Photospheric flux Transport- Global Oscillation Network Group magnetograms, and made predictions of the state of the solar wind plasma for the first encounter. AWSoM uses low-frequency Alfv\ en wave turbulence to address the coronal heating and acceleration. Here, we revise our simulations, by introdu ... van der Holst, B.; Huang, J.; Sachdeva, N.; Kasper, J.~C.; Manchester, W.~B.; Borovikov, D.; Chandran, B.~D.~G.; Case, A.~W.; Korreck, K.~E.; Larson, D.; Livi, R.; Stevens, M.; Whittlesey, P.; Bale, S.~D.; Pulupa, M.; Malaspina, D.~M.; Bonnell, J.~W.; Harvey, P.~R.; Goetz, K.; MacDowall, R.~J.; Published by: \apj      Published on: feb YEAR: 2022     DOI: 10.3847/1538-4357/ac3d34 Alpha-Proton Differential Flow of the Young Solar Wind: Parker Solar Probe Observations The velocity of alpha particles relative to protons can vary depending on the solar wind type and distance from the Sun. Measurements from the previous spacecraft provided the alpha-proton differential velocities down to 0.3 au. The Parker Solar Probe (PSP) now enables insights into differential flows of the newly accelerated solar wind closer to the Sun for the first time. Here we study the difference between proton and alpha bulk velocities near PSP perihelia of encounters 3-7 when the core solar wind is in the field of vi ... Mostafavi, P.; Allen, R.~C.; McManus, M.~D.; Ho, G.~C.; Raouafi, N.~E.; Larson, D.~E.; Kasper, J.~C.; Bale, S.~D.; Published by: \apjl      Published on: feb YEAR: 2022     DOI: 10.3847/2041-8213/ac51e1 Turbulence in the Sub-Alfv\ enic Solar Wind The Parker Solar Probe (PSP) entered a region of sub-Alfv\ enic solar wind during encounter 8, and we present the first detailed analysis of low-frequency turbulence properties in this novel region. The magnetic field and flow velocity vectors were highly aligned during this interval. By constructing spectrograms of the normalized magnetic helicity, cross-helicity, and residual energy, we find that PSP observed primarily Alfv\ enic fluctuations, a consequence of the highly field-aligned flow that renders quasi-2D fluctuation ... Zank, G.~P.; Zhao, L.; Adhikari, L.; Telloni, D.; Kasper, J.~C.; Stevens, M.; Rahmati, A.; Bale, S.~D.; Published by: \apjl      Published on: feb YEAR: 2022     DOI: 10.3847/2041-8213/ac51da An Improved Technique for Measuring Plasma Density to High Frequencies on the Parker Solar Probe The correlation between the plasma density measured in space and the surface potential of an electrically conducting satellite body with biased electric field detectors has been recognized and used to provide density proxies. However, for Parker Solar Probe, this correlation has not produced quantitative density estimates over extended periods of time because it depends on the energy-dependent exponential variation of the photoemission spectrum, the electron temperature, the ratio of the biased surface area to the conducting ... Mozer, F.~S.; Bale, S.~D.; Kellogg, P.~J.; Larson, D.; Livi, R.; Romeo, O.; Published by: \apj      Published on: feb YEAR: 2022     DOI: 10.3847/1538-4357/ac4f42 Modeling Ion Beams, Kinetic Instabilities, and Waves Observed by the Parker Solar Probe near Perihelia Recent in situ observations from the Parker Solar Probe (PSP) mission in the inner heliosphere near perihelia show evidence of ion beams, temperature anisotropies, and kinetic wave activity, which are likely associated with kinetic heating and acceleration processes of the solar wind. In particular, the proton beams were detected by PSP/Solar Probe Analyzers-Ion (SPAN-I) and related magnetic fluctuation spectra associated with ion-scale waves were observed by the FIELDS instrument. We present the ion velocity distribution fu ... Ofman, Leon; Boardsen, Scott; Jian, Lan; Verniero, Jaye; Larson, Davin; Published by: \apj      Published on: feb YEAR: 2022     DOI: 10.3847/1538-4357/ac402c Multiband Electrostatic Waves below and above the Electron Cyclotron Frequency in the Near-Sun Solar Wind Using the Parker Solar Probe measurements, this Letter reports two new types of multiband electrostatic waves in and near the heliospheric current sheet. They are classified into the f < f $_ce$ and f > f $_ce$ multiband electrostatic waves, in which most (or all) of the bands in the former type are lower than f $_ce$, and all of the bands in the latter type are higher than f $_ce$, where f and f $_ce$ denotes the wave frequency and the electron cyclotron frequency, respectively. This Letter also exhibits observational evide ... Shi, Chen; Zhao, Jinsong; Malaspina, David; Bale, Stuart; Dong, Xiangcheng; Wang, Tieyan; Wu, Dejin; Published by: \apjl      Published on: feb YEAR: 2022     DOI: 10.3847/2041-8213/ac4d37 The Stability of the Electron Strahl against the Oblique Fast-magnetosonic/Whistler Instability in the Inner Heliosphere We analyze the micro-kinetic stability of the electron strahl in the solar wind depending on heliocentric distance. The oblique fast- magnetosonic/whistler (FM/W) instability has emerged in the literature as a key candidate mechanism for the effective scattering of the electron strahl into the electron halo population. Using data from the Parker Solar Probe (PSP) and Helios, we compare the measured strahl properties with the analytical thresholds for the oblique FM/W instability in the low- and high-\ensuremath\beta _\ensur ... Jeong, Seong-Yeop; Abraham, Joel; Verscharen, Daniel; Ber\vci\vc, Laura; Stansby, David; Nicolaou, Georgios; Owen, Christopher; Wicks, Robert; Fazakerley, Andrew; Rueda, Jeffersson; Bakrania, Mayur; Published by: \apjl Published on: feb YEAR: 2022 DOI: 10.3847/2041-8213/ac4dff The Singular Behavior of the Solar Wind Scaling Features during Parker Solar Probe-BepiColombo Radial Alignment At the end of 2020 September, the Parker Solar Probe (PSP) and BepiColombo were radially aligned: PSP was orbiting near 0.17 au and BepiColombo near 0.6 au. This geometry is of particular interest for investigating the evolution of solar wind properties at different heliocentric distances by observing the same solar wind plasma parcels. In this work, we use the magnetic field observations from both spacecraft to characterize both the topology of the magnetic field at different heliocentric distances (scalings, high-order sta ... Alberti, Tommaso; Milillo, Anna; Heyner, Daniel; Hadid, Lina; Auster, Hans-Ulrich; Richter, Ingo; Narita, Yasuhito; Published by: \apj Published on: feb YEAR: 2022 DOI: 10.3847/1538-4357/ac478d Sub-Alfv\ enic Solar Wind Observed by the Parker Solar Probe: Characterization of Turbulence, Anisotropy, Intermittency, and Switchback In the lower solar coronal regions where the magnetic field is dominant, the Alfv\ en speed is much higher than the wind speed. In contrast, the near-Earth solar wind is strongly super- Alfv\ enic, i.e., the wind speed greatly exceeds the Alfv\ en speed. The transition between these regimes is classically described as the Alfv\ en point but may in fact occur in a distributed Alfv\ en critical region. NASA s Parker Solar Probe (PSP) mission has entered this region, as it follows a series of orbits that gradually approach ... Bandyopadhyay, R.; Matthaeus, W.~H.; McComas, D.~J.; Chhiber, R.; Usmanov, A.~V.; Huang, J.; Livi, R.; Larson, D.~E.; Kasper, J.~C.; Case, A.~W.; Stevens, M.; Whittlesey, P.; Romeo, O.~M.; Bale, S.~D.; Bonnell, J.~W.; de Wit, Dudok; Goetz, K.; Harvey, P.~R.; MacDowall, R.~J.; Malaspina, D.~M.; Pulupa, M.; Published by: \apjl Published on: feb YEAR: 2022 DOI: 10.3847/2041-8213/ac4a5c Magnetic Field Intermittency in the Solar Wind: Parker Solar Probe and SolO Observations Ranging from the Alfv\ en Region up to 1 AU Parker Solar Probe (PSP) and SolO data are utilized to investigate magnetic field intermittency in the solar wind (SW). Small-scale intermittency (20-100 d_ i $) is observed to radially strengthen when methods relying on higher-order moments are considered (SF$_ q $; SDK), but no clear trend is observed at larger scales. However, lower-order moment-based methods (e.g., partial variance of increments; PVI) are deemed more appropriate for examining the evolution of the bulk of coherent structures (CSs), PVI \ensuremath\geq 3 ... Sioulas, Nikos; Huang, Zesen; Velli, Marco; Chhiber, Rohit; Cuesta, Manuel; Shi, Chen; Matthaeus, William; Bandyopadhyay, Riddhi; Vlahos, Loukas; Bowen, Trevor; Qudsi, Ramiz; Bale, Stuart; Owen, Christopher; Louarn, P.; Fedorov, A.; c, Milan; Stevens, Michael; Case, Anthony; Kasper, Justin; Larson, Davin; Pulupa, Marc; Livi, Roberto; Published by: \apj Published on: aug YEAR: 2022 DOI: 10.3847/1538-4357/ac7aa2 Solar Chromospheric Network as a Source for Solar Wind Switchbacks Recent studies suggest that the magnetic switchbacks (SBs) detected by the Parker Solar Probe carry information on the scales of solar supergranulation (large scale) and granulation (medium scale). We test this claim using high-resolution H\ensuremath\alpha images obtained with the visible spectropolarimeters of the Goode Solar Telescope in Big Bear Solar Observatory. As possible solar sources, we count all the spicule-like features standing along the chromospheric networks near the coronal hole boundary visible in the H\ens ... Lee, Jeongwoo; Yurchyshyn, Vasyl; Wang, Haimin; Yang, Xu; Cao, Wenda; Oliveros, Juan; Published by: \apjl Published on: aug YEAR: 2022 DOI: 10.3847/2041-8213/ac86bf Preferential Heating of Protons over Electrons from Coherent Structures during the First Perihelion of the Parker Solar Probe The solar wind undergoes significant heating as it propagates away from the Sun; the exact mechanisms responsible for this heating remain unclear. Using data from the first perihelion of the Parker Solar Probe mission, we examine the properties of proton and electron heating occurring within magnetic coherent structures identified by means of the Partial Variance of Increments (PVI) method. Statistically, regions of space with strong gradients in the magnetic field, PVI \ensuremath\geq 1, are associated with strongly enhance ... Sioulas, Nikos; Shi, Chen; Huang, Zesen; Velli, Marco; Published by: \apjl Published on: aug YEAR: 2022 DOI: 10.3847/2041-8213/ac85de Linking Small-scale Solar Wind Properties with Large-scale Coronal Source Regions through Joint Parker Solar Probe-Metis/Solar Orbiter Observations The solar wind measured in situ by Parker Solar Probe in the very inner heliosphere is studied in combination with the remote-sensing observation of the coronal source region provided by the METIS coronagraph aboard Solar Orbiter. The coronal outflows observed near the ecliptic by Metis on 2021 January 17 at 16:30 UT, between 3.5 and 6.3 R$_\ensuremath\odot$above the eastern solar limb, can be associated with the streams sampled by PSP at 0.11 and 0.26 au from the Sun, in two time intervals almost 5 days apart. The two pla ... Telloni, Daniele; Zank, Gary; Sorriso-Valvo, Luca; Amicis, Raffaella; Panasenco, Olga; Susino, Roberto; Bruno, Roberto; Perrone, Denise; Adhikari, Laxman; Liang, Haoming; Nakanotani, Masaru; Zhao, Lingling; Hadid, Lina; anchez-Cano, Beatriz; Verscharen, Daniel; Velli, Marco; Grimani, Catia; Marino, Raffaele; Carbone, Francesco; Mancuso, Salvatore; Biondo, Ruggero; Pagano, Paolo; Reale, Fabio; Bale, Stuart; Kasper, Justin; Case, Anthony; de Wit, Thierry; Goetz, Keith; Harvey, Peter; Korreck, Kelly; Larson, Davin; Livi, Roberto; MacDowall, Robert; Malaspina, David; Pulupa, Marc; Stevens, Michael; Whittlesey, Phyllis; Romoli, Marco; Andretta, Vincenzo; Da Deppo, Vania; Fineschi, Silvano; Heinzel, Petr; Moses, John; Naletto, Giampiero; Nicolini, Gianalfredo; Spadaro, Daniele; Stangalini, Marco; Teriaca, Luca; Capobianco, Gerardo; Capuano, Giuseppe; Casini, Chiara; Casti, Marta; Chioetto, Paolo; Corso, Alain; De Leo, Yara; Fabi, Michele; Frassati, Federica; Frassetto, Fabio; Giordano, Silvio; Guglielmino, Salvo; Jerse, Giovanna; Landini, Federico; Liberatore, Alessandro; Magli, Enrico; Massone, Giuseppe; Messerotti, Mauro; Pancrazzi, Maurizio; Pelizzo, Maria; Romano, Paolo; Sasso, Clementina; Schühle, Udo; Slemer, Alessandra; Straus, Thomas; Uslenghi, Michela; Volpicelli, Cosimo; Zangrilli, Luca; Zuppella, Paola; Abbo, Lucia; Auchère, Fr\; Cuadrado, Regina; Berlicki, Arkadiusz; Ciaravella, Angela; Lamy, Philippe; Lanzafame, Alessandro; Malvezzi, Marco; Nicolosi, Piergiorgio; o, Giuseppe; Peter, Hardi; Solanki, Sami; Strachan, Leonard; Tsinganos, Kanaris; Ventura, Rita; Vial, Jean-Claude; Woch, Joachim; Zimbardo, Gaetano; Published by: \apj Published on: aug YEAR: 2022 DOI: 10.3847/1538-4357/ac8103 Magnetic Field Dropouts and Associated Plasma Wave Emission near the Electron Plasma Frequency at Switchback Boundaries as Observed by the Parker Solar Probe The first solar encounters by the Parker Solar Probe revealed the magnetic field to be dominated by short field reversals in the radial direction, referred to as switchbacks. While radial velocity and proton temperature were shown to increase inside the switchbacks, \ensuremath\midB\ensuremath\mid exhibits very brief dropouts only at the switchback boundaries. Brief intensifications in spectral density measurements near the electron plasma frequency, f$_pe$, were also observed at these boundaries, indicating the presenc ... Rasca, Anthony; Farrell, William; Whittlesey, Phyllis; MacDowall, Robert; Bale, Stuart; Kasper, Justin; Published by: \apj Published on: aug YEAR: 2022 DOI: 10.3847/1538-4357/ac80c3 New Insights into the First Two PSP Solar Encounters Enabled by Modeling Analysis with ADAPT-WSA Parker Solar Probe s (PSP s) unique orbital path allows us to observe the solar wind closer to the Sun than ever before. Essential to advancing our knowledge of solar wind and energetic particle formation is identifying the sources of PSP observations. We report on results for the first two PSP solar encounters derived using the Wang-Sheeley-Arge (WSA) model driven by Air Force Data Assimilative Photospheric Flux Transport (ADAPT) model maps. We derive the coronal magnetic field and the 1 R$_\ensuremath\odot$source regions ... Wallace, Samantha; Jones, Shaela; Arge, Nick; Viall, Nicholeen; Henney, Carl; Published by: \apj Published on: aug YEAR: 2022 DOI: 10.3847/1538-4357/ac731c Turbulence and Waves in the Sub-Alfv\ enic Solar Wind Observed by the Parker Solar Probe during Encounter 10 During its 10th orbit around the Sun, the Parker Solar Probe sampled two intervals where the local Alfv\ en speed exceeded the solar wind speed, lasting more than 10 hours in total. In this paper, we analyze the turbulence and wave properties during these periods. The turbulence is observed to be Alfv\ enic and unbalanced, dominated by outward-propagating modes. The power spectrum of the outward-propagating Elsässer z$^+$mode steepens at high frequencies while that of the inward- propagating z$^-$mode flattens. The obse ... Zhao, L.; Zank, G.~P.; Adhikari, L.; Telloni, D.; Stevens, M.; Kasper, J.~C.; Bale, S.~D.; Raouafi, N.~E.; Published by: \apjl Published on: aug YEAR: 2022 DOI: 10.3847/2041-8213/ac8353 Patches of Magnetic Switchbacks and Their Origins Parker Solar Probe (PSP) has shown that the solar wind in the inner heliosphere is characterized by the quasi omnipresence of magnetic switchbacks ( switchback hereinafter), local backward bends of magnetic field lines. Switchbacks also tend to come in patches, with a large-scale modulation that appears to have a spatial scale size comparable to supergranulation on the Sun. Here we inspect data from the first 10 encounters of PSP focusing on different time intervals when clear switchback patches were observed by PSP. We s ... Shi, Chen; Panasenco, Olga; Velli, Marco; Tenerani, Anna; Verniero, Jaye; Sioulas, Nikos; Huang, Zesen; Brosius, A.; Bale, Stuart; Klein, Kristopher; Kasper, Justin; de Wit, Thierry; Goetz, Keith; Harvey, Peter; MacDowall, Robert; Malaspina, David; Pulupa, Marc; Larson, Davin; Livi, Roberto; Case, Anthony; Stevens, Michael; Published by: \apj Published on: aug YEAR: 2022 DOI: 10.3847/1538-4357/ac7c11 The Turbulent Properties of the Sub-Alfv\ enic Solar Wind Measured by the Parker Solar Probe For the first time, Parker Solar Probe (PSP) observed the sub- Alfv\ enic solar wind where the solar wind bulk speed drops below the local Alfv\ en speed for an extended period of time. Here, we report on the turbulent properties of the sub- Alfv\ enic region. We analyze the turbulence correlation length and the energy transfer and compare the results with nearby super-Alfv\ enic regions. As the Alfv\ en speed is larger or comparable to the solar wind speed in the intervals studied, we use a modified Taylor s hypothesis to a ... Zhao, L.; Zank, G.~P.; Telloni, D.; Stevens, M.; Kasper, J.~C.; Bale, S.~D.; Published by: \apjl Published on: apr YEAR: 2022 DOI: 10.3847/2041-8213/ac5fb0 Using Single-view Observations of Cometary Plasma Tails to Infer Solar Wind Speed A comet plasma tail is a product of the interaction between the solar wind and the comet s coma, and has long been studied as a natural probe of the solar wind condition. We previously developed a method to derive the solar wind speed from dual-view observations of comet plasma tails. Here we improve the method to use single-view observations by assuming a radially propagating solar wind and apply it to two comets, C/2011 W3 (Lovejoy) and C/2012 S1 (ISON) observed by coronagraphs on board the Solar and Heliospheric Observato ... Cheng, Long; Wang, Yuming; Li, Xiaolei; Published by: \apj Published on: apr YEAR: 2022 DOI: 10.3847/1538-4357/ac5410 Solar Wind Model Supported by Parker Solar Probe Observations During Faint Venusian Auroral Emission The encounter of the Parker Solar Probe (PSP) with Venus during the Venus Gravity Assist 3 on 2020 July 11 provided a unique opportunity to gather in situ solar wind data in the Venusian environment while also being able to observe Venus from ground- based facilities on Earth. The Wang-Sheeley-Arge (WSA) model was used to make accurate predictions of solar wind velocity and interplanetary magnetic field polarity at Earth and STEREO-A, as compared to in situ data at each spacecraft. The same model was then used to predict sol ... Kovac, Sarah; Gray, Candace; Arge, Nick; Chanover, Nancy; Churchill, Christopher; Szabo, Adam; Hill, Matthew; McAteer, James; Published by: \apj Published on: apr YEAR: 2022 DOI: 10.3847/1538-4357/ac58f4 Markovian Features of the Solar Wind at Subproton Scales The interplanetary magnetic field carried out from the Sun by the solar wind displays fluctuations over a wide range of scales. While at large scales, say at frequencies lower than 0.1-1 Hz, fluctuations display the universal character of fully developed turbulence with a well-defined Kolmogorov-like inertial range, the physical and dynamical properties of the small-scale regime as well as their connection with the large-scale ones are still a debated topic. In this work we investigate the near-Sun magnetic field fluctuation ... Benella, Simone; Stumpo, Mirko; Consolini, Giuseppe; Alberti, Tommaso; Carbone, Vincenzo; Laurenza, Monica; Published by: \apjl Published on: apr YEAR: 2022 DOI: 10.3847/2041-8213/ac6107 Anisotropy of Magnetic Field Spectra at Kinetic Scales of Solar Wind Turbulence as Revealed by the Parker Solar Probe in the Inner Heliosphere Using the Parker Solar Probe data taken in the inner heliosphere, we investigate the power and spatial anisotropy of magnetic field spectra at kinetic scales (i.e., around sub-ion scales) in solar wind turbulence in the inner heliosphere. We find that strong anisotropy of the magnetic spectra occurs at kinetic scales with the strongest power in the perpendicular direction with respect to the local magnetic field (forming an angle \ensuremath\theta$_B$with the mean flow velocity). The spectral index of the magnetic spectra ... Huang, S.~Y.; Xu, S.~B.; Zhang, J.; Sahraoui, F.; es, Andr\; He, J.~S.; Yuan, Z.~G.; Deng, X.~H.; Jiang, K.; Wei, Y.~Y.; Xiong, Q.~Y.; Wang, Z.; Yu, L.; Lin, R.~T.; Published by: \apjl Published on: apr YEAR: 2022 DOI: 10.3847/2041-8213/ac5f02 Kinetic-scale Current Sheets in Near-Sun Solar Wind: Properties, Scale-dependent Features and Reconnection Onset We present statistical analysis of 11,200 proton kinetic-scale current sheets (CS) observed by the Parker Solar Probe during 10 days around the first perihelion. The CS thickness {\ensuremath{\lambda}} is in the range from a few to 200 km with the typical value around 30 km, while current densities are in the range from 0.1 to 10 {\ensuremath{\mu}}A m$^{-2}$with the typical value around 0.7 {\ensuremath{\mu}}A m$^{-2}$. These CSs are resolved thanks to magnetic field measurements at 73-290 samples s$^{-1}\$ resolution. In te ... Lotekar, A.~B.; Vasko, I.~Y.; Phan, T.; Bale, S.~D.; Bowen, T.~A.; Halekas, J.; Artemyev, A.~V.; Khotyaintsev, Yu.; Mozer, F.~S.; Published by: \apj      Published on: apr YEAR: 2022     DOI: 10.3847/1538-4357/ac5bd9

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