# PSP Bibliography

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## Found 216 entries in the Bibliography.

### Showing entries from 1 through 50

 2022 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 Suprathermal Ion Energy Spectra and Anisotropies near the Heliospheric Current Sheet Crossing Observed by the Parker Solar Probe during Encounter 7 We present observations of \ensuremath\gtrsim10-100 keV nucleon$^-1$ suprathermal (ST) H, He, O, and Fe ions associated with crossings of the heliospheric current sheet (HCS) at radial distances of <0.1 au from the Sun. Our key findings are as follows: (1) very few heavy ions are detected during the first full crossing, the heavy-ion intensities are reduced during the second partial crossing and peak just after the second crossing; (2) ion arrival times exhibit no velocity dispersion; (3) He pitch-angle distributions track t ... Desai, M.~I.; Mitchell, D.~G.; McComas, D.~J.; Drake, J.~F.; Phan, T.; Szalay, J.~R.; Roelof, E.~C.; Giacalone, J.; Hill, M.~E.; Christian, E.~R.; Schwadron, N.~A.; McNutt, R.~L.; Wiedenbeck, M.~E.; Joyce, C.; Cohen, C.~M.~S.; Davis, A.~J.; Krimigis, S.~M.; Leske, R.~A.; Matthaeus, W.~H.; Malandraki, O.; Mewaldt, R.~A.; Labrador, A.; Stone, E.~C.; Bale, S.~D.; Verniero, J.; Rahmati, A.; Whittlesey, P.; Livi, R.; Larson, D.; Pulupa, M.; MacDowall, R.~J.; Niehof, J.~T.; Kasper, J.~C.; Horbury, T.~S.; Published by: \apj      Published on: mar YEAR: 2022     DOI: 10.3847/1538-4357/ac4961 Flux rope and dynamics of the heliospheric current sheet. Study of the Parker Solar Probe and Solar Orbiter conjunction of June 2020 Context. Solar Orbiter and Parker Solar Probe jointly observed the solar wind for the first time in June 2020, capturing data from very different solar wind streams: calm, Alfv\ enic wind and also highly dynamic large-scale structures. Context. Our aim is to understand the origin and characteristics of the highly dynamic solar wind observed by the two probes, particularly in the vicinity of the heliospheric current sheet (HCS). \ Methods: We analyzed the plasma data obtained by Parker Solar Probe and Solar Orbiter in situ du ... Réville, V.; Fargette, N.; Rouillard, A.~P.; Lavraud, B.; Velli, M.; Strugarek, A.; Parenti, S.; Brun, A.~S.; Shi, C.; Kouloumvakos, A.; Poirier, N.; Pinto, R.~F.; Louarn, P.; Fedorov, A.; Owen, C.~J.; enot, V.; Horbury, T.~S.; Laker, R.; Brien, H.; Angelini, V.; Fauchon-Jones, E.; Kasper, J.~C.; Published by: \aap      Published on: mar YEAR: 2022     DOI: 10.1051/0004-6361/202142381 Analysis of the Distribution, Rotation and Scale Characteristics of Solar Wind Switchbacks: Comparison between the First and Second Encounters of Parker Solar Probe The S-shaped magnetic structure in the solar wind formed by the twisting of magnetic field lines is called a switchback, whose main characteristics are the reversal of the magnetic field and the significant increase in the solar wind radial velocity. We identify 242 switchbacks during the first two encounters of Parker Solar Probe. Statistics methods are applied to analyze the distribution and the rotation angle and direction of the magnetic field rotation of the switchbacks. The diameter of switchbacks is estimated with a m ... Meng, Ming-Ming; Liu, Ying; Chen, Chong; Wang, Rui; Published by: Research in Astronomy and Astrophysics      Published on: mar YEAR: 2022     DOI: 10.1088/1674-4527/ac49e4 In Situ Measurement of the Energy Fraction in Suprathermal and Energetic Particles at ACE, Wind, and PSP Interplanetary Shocks The acceleration of charged particles by interplanetary shocks (IPs) can drain a nonnegligible fraction of the plasma pressure. In this study, we have selected 17 IPs observed in situ at 1 au by the Advanced Composition Explorer and the Wind spacecraft, and 1 shock at 0.8 au observed by Parker Solar Probe. We have calculated the time-dependent partial pressure of suprathermal and energetic particles (smaller and greater than 50 keV for protons and 30 keV for electrons, respectively) in both the upstream and downstream region ... David, Liam; Fraschetti, Federico; Giacalone, Joe; Wimmer-Schweingruber, Robert; Berger, Lars; Lario, David; Published by: \apj      Published on: mar YEAR: 2022     DOI: 10.3847/1538-4357/ac54af 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 Parker Solar Probe detects solar radio bursts related with a behind-the-limb active region Context. The interpretation of solar radio bursts observed by Parker Solar Probe (PSP) in the encounter phase plays a key role in understanding intrinsic properties of the emission mechanism in the solar corona. Lower time-frequency resolution of the PSP receiver can be overcome by simultaneous ground-based observations using more advanced antennas and receivers. \ Aims: In this paper we present such observations for which the active active region 12 765, begetter of type III, J, and U solar bursts, was within sight of groun ... Stanislavsky, Aleksander; Bubnov, Igor; Koval, Artem; Yerin, Serge; Published by: \aap      Published on: jan YEAR: 2022     DOI: 10.1051/0004-6361/202141984 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 Variable Ion Compositions of Solar Energetic Particle Events in the Inner Heliosphere: A Field Line Braiding Model with Compound Injections We propose a model for interpreting highly variable ion composition ratios in solar energetic particle (SEP) events recently observed by the Parker Solar Probe (PSP) at 0.3-0.45 au. We use numerical simulations to calculate SEP propagation in a turbulent interplanetary magnetic field with a Kolmogorov power spectrum from large scales down to the gyration scale of energetic particles. We show that when the source regions of different species are offset by a distance comparable to the size of the source regions, the observed e ... Guo, Fan; Zhao, Lulu; Cohen, Christina; Giacalone, Joe; Leske, R.~A.; Wiedenbeck, M.~E.; Kahler, S.~W.; Li, Xiaocan; Zhang, Qile; Ho, George; Desai, Mihir; Published by: \apj      Published on: jan YEAR: 2022     DOI: 10.3847/1538-4357/ac3233 Widespread 1-2 MeV Energetic Particles Associated with Slow and Narrow Coronal Mass Ejections: Parker Solar Probe and STEREO Measurements Suprathermal ions in the corona are thought to serve as seed particles for large gradual solar energetic particle (SEP) events associated with fast and wide coronal mass ejections (CMEs). A better understanding of the role of suprathermal particles as seed populations for SEP events can be made by using observations close to the Sun. We study a series of SEP events observed by the Integrated Science Investigation of the Sun (IS\ensuremath\odotIS) suite on board the Parker Solar Probe (PSP) from 2020 May 27 to June 2, during ... Zhuang, Bin; Lugaz, No\; Lario, David; Published by: \apj      Published on: jan YEAR: 2022     DOI: 10.3847/1538-4357/ac3af2 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 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 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 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 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 Double-power-law Feature of Energetic Particles Accelerated at Coronal Shocks Recent observations have shown that in many large solar energetic particle (SEP) events the event-integrated differential spectra resemble double power laws. We perform numerical modeling of particle acceleration at coronal shocks propagating through a streamer-like magnetic field by solving the Parker transport equation, including protons and heavier ions. We find that for all ion species the energy spectra integrated over the simulation domain can be described by a double power law, and the break energy depends on the ion ... Yu, Feiyu; Kong, Xiangliang; Guo, Fan; Liu, Wenlong; Jiang, Zelong; Chen, Yao; Giacalone, Joe; Published by: \apjl      Published on: feb YEAR: 2022     DOI: 10.3847/2041-8213/ac4cb3 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 Flux Rope Merging and the Structure of Switchbacks in the Solar Wind A major discovery of Parker Solar Probe (PSP) was the presence of large numbers of localized increases in the radial solar wind speed and associated sharp deflections of the magnetic field- switchbacks (SBs). A possible generation mechanism of SBs is through magnetic reconnection between open and closed magnetic flux near the solar surface, termed interchange reconnection, that leads to the ejection of flux ropes (FRs) into the solar wind. Observations also suggest that SBs undergo merging, consistent with an FR picture of t ... Agapitov, O.~V.; Drake, J.~F.; Swisdak, M.; Bale, S.~D.; Horbury, T.~S.; Kasper, J.~C.; MacDowall, R.~J.; Mozer, F.~S.; Phan, T.~D.; Pulupa, M.; Raouafi, N.~E.; Velli, M.; Published by: \apj Published on: feb YEAR: 2022 DOI: 10.3847/1538-4357/ac4016 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 PSP/IS\ensuremath\odotIS Observation of a Solar Energetic Particle Event Associated with a Streamer Blowout Coronal Mass Ejection during Encounter 6 In this paper we examine a low-energy solar energetic particle (SEP) event observed by IS\ensuremath\odotIS s Energetic Particle Instrument-Low (EPI-Lo) inside 0.18 au on 2020 September 30. This small SEP event has a very interesting time profile and ion composition. Our results show that the maximum energy and peak in intensity are observed mainly along the open radial magnetic field. The event shows velocity dispersion, and strong particle anisotropies are observed throughout the event, showing that more particles are stre ... Getachew, T.; McComas, D.~J.; Joyce, C.~J.; Palmerio, E.; Christian, E.~R.; Cohen, C.~M.~S.; Desai, M.~I.; Giacalone, J.; Hill, M.~E.; Matthaeus, W.~H.; McNutt, R.~L.; Mitchell, D.~G.; Mitchell, J.~G.; Rankin, J.~S.; Roelof, E.~C.; Schwadron, N.~A.; Szalay, J.~R.; Zank, G.~P.; Zhao, L.; Lynch, B.~J.; Phan, T.~D.; Bale, S.~D.; Whittlesey, P.~L.; Kasper, J.~C.; Published by: \apj Published on: feb YEAR: 2022 DOI: 10.3847/1538-4357/ac408f 2021 Parker solar probe observations of helical structures as boundaries for energetic particles Energetic particle transport in the interplanetary medium is known to be affected by magnetic structures. It has been demonstrated for solar energetic particles in near-Earth orbit studies, and also for the more energetic cosmic rays. In this paper, we show observational evidence that intensity variations of solar energetic particles can be correlated with the occurrence of helical magnetic flux tubes and their boundaries. The analysis is carried out using data from Parker Solar Probe orbit 5, in the period 2020 May 24 to Ju ... Pecora, F.; Servidio, S.; Greco, A.; Matthaeus, W.~H.; McComas, D.~J.; Giacalone, J.; Joyce, C.~J.; Getachew, T.; Cohen, C.~M.~S.; Leske, R.~A.; Wiedenbeck, M.~E.; McNutt, R.~L.; Hill, M.~E.; Mitchell, D.~G.; Christian, E.~R.; Roelof, E.~C.; Schwadron, N.~A.; Bale, S.~D.; Published by: \mnras Published on: sep YEAR: 2021 DOI: 10.1093/mnras/stab2659 Triggered Ion-acoustic Waves in the Solar Wind For more than 12 hr beginning on 2021 January 18, continuous narrowband electrostatic emissions were observed on the Parker Solar Probe near 20 solar radii. The observed <1000 Hz frequencies were well below the local ion-plasma frequency. Surprisingly, the emissions consisted of electrostatic wave packets with shock- like envelopes, appearing repetitively at a \raisebox-0.5ex\textasciitilde1.5 Hz rate. This repetitiveness correlated and was in phase with low-frequency electromagnetic fluctuations. The emissions were associat ... Mozer, F.~S.; Vasko, I.~Y.; Verniero, J.~L.; Published by: \apjl Published on: sep YEAR: 2021 DOI: 10.3847/2041-8213/ac2259 On the Origin of Switchbacks Observed in the Solar Wind The origin of switchbacks in the solar wind is discussed in two classes of theory that differ in the location of the source being either near the transition region near the Sun or in the solar wind itself. The two classes of theory differ in their predictions of the switchback rate (the number of switchbacks observed per hour) as a function of distance from the Sun. To distinguish between these theories, one-hour averages of Parker Solar Probe data were averaged over five orbits to find the following: (1) The hourly averaged ... Mozer, F.~S.; Bale, S.~D.; Bonnell, J.~W.; Drake, J.~F.; Hanson, E.~L.~M.; Mozer, M.~C.; Published by: \apj Published on: sep YEAR: 2021 DOI: 10.3847/1538-4357/ac110d On the Role of Solar Wind Expansion as a Source of Whistler Waves: Scattering of Suprathermal Electrons and Heat Flux Regulation in the Inner Heliosphere The role of solar wind expansion in generating whistler waves is investigated using the EB-iPic3D code, which models solar wind expansion self-consistently within a fully kinetic semi-implicit approach. The simulation is initialized with an electron velocity distribution function modeled after observations of the Parker Solar Probe during its first perihelion at 0.166 au, consisting of a dense core and an antisunward strahl. This distribution function is initially stable with respect to kinetic instabilities. Expansion drive ... Micera, A.; Zhukov, A.~N.; opez, R.~A.; Boella, E.; Tenerani, A.; Velli, M.; Lapenta, G.; Innocenti, M.~E.; Published by: \apj Published on: sep YEAR: 2021 DOI: 10.3847/1538-4357/ac1067 The Evolution of Compressible Solar Wind Turbulence in the Inner Heliosphere: PSP, THEMIS, and MAVEN Observations The first computations of the compressible energy transfer rate from \raisebox-0.5ex\textasciitilde0.2 up to \raisebox-0.5ex\textasciitilde1.7 au is obtained using Parker Solar Probe (PSP), Time History of Events and Macroscale Interactions during Substorms (THEMIS), and Mars Atmosphere and Volatile EvolutioN (MAVEN) observations. Using a recently derived exact relation for isothermal magnetohydrodynamics turbulence, the compressible energy cascade rate, \ensuremath\varepsilon$_C$, is computed for hundred of events at differ ... es, Andr\; Sahraoui, F.; Hadid, L.~Z.; Huang, S.~Y.; Romanelli, N.; Galtier, S.; DiBraccio, G.; Halekas, J.; Published by: \apj Published on: sep YEAR: 2021 DOI: 10.3847/1538-4357/ac0af5 Solar wind rotation rate and shear at coronal hole boundaries. Possible consequences for magnetic field inversions Context. In situ measurements by several spacecraft have revealed that the solar wind is frequently perturbed by transient structures that have been interpreted as magnetic folds, jets, waves, and flux ropes that propagate rapidly away from the Sun over a large range of heliocentric distances. Parker Solar Probe (PSP), in particular, has detected very frequent rotations of the magnetic field vector at small heliocentric radial distances, accompanied by surprisingly large solar wind rotation rates. The physical origin of such ... Pinto, R.~F.; Poirier, N.; Rouillard, A.~P.; Kouloumvakos, A.; Griton, L.; Fargette, N.; Kieokaew, R.; Lavraud, B.; Brun, A.~S.; Published by: \aap Published on: sep YEAR: 2021 DOI: 10.1051/0004-6361/202040180 Characteristic Scales of Magnetic Switchback Patches Near the Sun and Their Possible Association With Solar Supergranulation and Granulation Parker Solar Probe (PSP) data recorded within a heliocentric radial distance of 0.3 au have revealed a magnetic field dominated by Alfv\ enic structures that undergo large local variations or even reversals of the radial magnetic field. They are called magnetic switchbacks, they are consistent with folds in magnetic field lines within a same magnetic sector and are associated with velocity spikes during an otherwise calmer background. They are thought to originate either in the low solar atmosphere through magnetic reconnect ... Fargette, Na; Lavraud, Benoit; Rouillard, Alexis; eville, Victor; de Wit, Thierry; Froment, Clara; Halekas, Jasper; Phan, Tai; Malaspina, David; Bale, Stuart; Kasper, Justin; Louarn, Philippe; Case, Anthony; Korreck, Kelly; Larson, Davin; Pulupa, Marc; Stevens, Michael; Whittlesey, Phyllis; Berthomier, Matthieu; Published by: \apj Published on: oct YEAR: 2021 DOI: 10.3847/1538-4357/ac1112 Effect of Dust Rotational Disruption by Radiative Torques and Implications for the F-corona Decrease Revealed by the Parker Solar Probe The first-year results from the Parker Solar Probe (PSP) reveal a Hoang, Thiem; Lazarian, Alex; Lee, Hyeseung; Cho, Kyungsuk; Gu, Pin-Gao; Ng, Chi-Hang; Published by: \apj Published on: oct YEAR: 2021 DOI: 10.3847/1538-4357/ac126e Exploring the Solar Wind from Its Source on the Corona into the Inner Heliosphere during the First Solar Orbiter-Parker Solar Probe Quadrature This Letter addresses the first Solar Orbiter (SO)-Parker Solar Probe (PSP) quadrature, occurring on 2021 January 18 to investigate the evolution of solar wind from the extended corona to the inner heliosphere. Assuming ballistic propagation, the same plasma volume observed remotely in the corona at altitudes between 3.5 and 6.3 solar radii above the solar limb with the Metis coronagraph on SO can be tracked to PSP, orbiting at 0.1 au, thus allowing the local properties of the solar wind to be linked to the coronal source re ... Telloni, Daniele; Andretta, Vincenzo; Antonucci, Ester; Bemporad, Alessandro; Capuano, Giuseppe; Fineschi, Silvano; Giordano, Silvio; Habbal, Shadia; Perrone, Denise; Pinto, Rui; Sorriso-Valvo, Luca; Spadaro, Daniele; Susino, Roberto; Woodham, Lloyd; Zank, Gary; Romoli, Marco; Bale, Stuart; Kasper, Justin; Auchère, Fr\; Bruno, Roberto; Capobianco, Gerardo; Case, Anthony; Casini, Chiara; Casti, Marta; Chioetto, Paolo; Corso, Alain; Da Deppo, Vania; De Leo, Yara; de Wit, Thierry; Frassati, Federica; Frassetto, Fabio; Goetz, Keith; Guglielmino, Salvo; Harvey, Peter; Heinzel, Petr; Jerse, Giovanna; Korreck, Kelly; Landini, Federico; Larson, Davin; Liberatore, Alessandro; Livi, Roberto; MacDowall, Robert; Magli, Enrico; Malaspina, David; Massone, Giuseppe; Messerotti, Mauro; Moses, John; Naletto, Giampiero; Nicolini, Gianalfredo; o, Giuseppe; Panasenco, Olga; Pancrazzi, Maurizio; Pelizzo, Maria; Pulupa, Marc; Reale, Fabio; Romano, Paolo; Sasso, Clementina; Schühle, Udo; Stangalini, Marco; Stevens, Michael; Strachan, Leonard; Straus, Thomas; Teriaca, Luca; Uslenghi, Michela; Velli, Marco; Verscharen, Daniel; Volpicelli, Cosimo; Whittlesey, Phyllis; Zangrilli, Luca; Zimbardo, Gaetano; Zuppella, Paola; Published by: \apjl Published on: oct YEAR: 2021 DOI: 10.3847/2041-8213/ac282f Predicting the Magnetic Fields of a Stealth CME Detected by Parker Solar Probe at 0.5 au Stealth coronal mass ejections (CMEs) are eruptions from the Sun that are not associated with appreciable low-coronal signatures. Because they often cannot be linked to a well-defined source region on the Sun, analysis of their initial magnetic configuration and eruption dynamics is particularly problematic. In this article, we address this issue by undertaking the first attempt at predicting the magnetic fields of a stealth CME that erupted in 2020 June from the Earth-facing Sun. We estimate its source region with the aid o ... Palmerio, Erika; Kay, Christina; Al-Haddad, Nada; Lynch, Benjamin; Yu, Wenyuan; Stevens, Michael; Pal, Sanchita; Lee, Christina; Published by: \apj Published on: oct YEAR: 2021 DOI: 10.3847/1538-4357/ac25f4 Evolution of Switchbacks in the Inner Heliosphere We analyze magnetic field data from the first six encounters of Parker Solar Probe, three Helios fast streams and two Ulysses south polar passes covering heliocentric distances 0.1 \ensuremath\lesssim R \ensuremath\lesssim 3 au. We use this data set to statistically determine the evolution of switchbacks of different periods and amplitudes with distance from the Sun. We compare the radial evolution of magnetic field variances with that of the mean square amplitudes of switchbacks, and quantify the radial evolution of the cum ... Tenerani, Anna; Sioulas, Nikos; Matteini, Lorenzo; Panasenco, Olga; Shi, Chen; Velli, Marco; Published by: \apjl Published on: oct YEAR: 2021 DOI: 10.3847/2041-8213/ac2606 Ambipolar Electric Field and Potential in the Solar Wind Estimated from Electron Velocity Distribution Functions The solar wind escapes from the solar corona and is accelerated, over a short distance, to its terminal velocity. The energy balance associated with this acceleration remains poorly understood. To quantify the global electrostatic contribution to the solar wind dynamics, we empirically estimate the ambipolar electric field (E$_\ensuremath\parallel$) and potential (\ensuremath\Phi$_r,\ensuremath\infty$). We analyze electron velocity distribution functions (VDFs) measured in the near-Sun solar wind between 20.3 R$_S$and 85.3 ... Ber\vci\vc, Laura; c, Milan; Halekas, Jasper; Landi, Simone; Owen, Christopher; Verscharen, Daniel; Larson, Davin; Whittlesey, Phyllis; Badman, Samuel; Bale, Stuart.; Case, Anthony; Goetz, Keith; Harvey, Peter; Kasper, Justin; Korreck, Kelly; Livi, Roberto; MacDowall, Robert; Malaspina, David; Pulupa, Marc; Stevens, Michael; Published by: \apj Published on: nov YEAR: 2021 DOI: 10.3847/1538-4357/ac1f1c Measurement of the open magnetic flux in the inner heliosphere down to 0.13 AU Context. Robustly interpreting sets of in situ spacecraft data of the heliospheric magnetic field (HMF) for the purpose of probing the total unsigned magnetic flux in the heliosphere is critical for constraining global coronal models as well as understanding the large scale structure of the heliosphere itself. The heliospheric flux (\ensuremath\Phi$_H) is expected to be a spatially conserved quantity with a possible secular dependence on the solar cycle and equal to the measured radial component of the HMF weighted by the s ... Badman, Samuel; Bale, Stuart; Rouillard, Alexis; Bowen, Trevor; Bonnell, John; Goetz, Keith; Harvey, Peter; MacDowall, Robert; Malaspina, David; Pulupa, Marc; Published by: \aap Published on: jun YEAR: 2021 DOI: 10.1051/0004-6361/202039407 Small-scale Magnetic Flux Ropes with Field-aligned Flows via the PSP In Situ Observations Magnetic flux rope, formed by the helical magnetic field lines, can sometimes maintain its shape while carrying significant plasma flow that is aligned with the local magnetic field. We report the existence of such structures and static flux ropes by applying the Grad-Shafranov-based algorithm to the Parker Solar Probe in situ measurements in the first five encounters. These structures are detected at heliocentric distances, ranging from 0.13 to 0.66 au, in a 4-month time period. We find that flux ropes with field-aligned fl ... Chen, Yu; Hu, Qiang; Zhao, Lingling; Kasper, Justin; Huang, Jia; Published by: \apj Published on: jun YEAR: 2021 DOI: 10.3847/1538-4357/abfd30 Anisotropy of Solar Wind Turbulence in the Inner Heliosphere at Kinetic Scales: PSP Observations The anisotropy of solar wind turbulence is a critical issue in understanding the physics of energy transfer between scales and energy conversion between fields and particles in the heliosphere. Using the measurement of Parker Solar Probe (PSP), we present an observation of the anisotropy at kinetic scales in the slow, Alfv\ enic, solar wind in the inner heliosphere. The magnetic compressibility behaves as expected for kinetic Alfv\ enic turbulence below the ion scale. A steepened transition range is found between the inertia ... Duan, Die; He, Jiansen; Bowen, Trevor; Woodham, Lloyd; Wang, Tieyan; Chen, Christopher; Mallet, Alfred; Bale, Stuart; Published by: \apjl Published on: jul YEAR: 2021 DOI: 10.3847/2041-8213/ac07ac Turbulent Generation of Magnetic Switchbacks in the Alfv\ enic Solar Wind One of the most important early results from the Parker Solar Probe (PSP) is the ubiquitous presence of magnetic switchbacks, whose origin is under debate. Using a three-dimensional direct numerical simulation of the equations of compressible magnetohydrodynamics from the corona to 40 solar radii, we investigate whether magnetic switchbacks emerge from granulation-driven Alfv\ en waves and turbulence in the solar wind. The simulated solar wind is an Alfv\ enic slow-solar- wind stream with a radial profile consistent with var ... Shoda, Munehito; Chandran, Benjamin; Cranmer, Steven; Published by: \apj Published on: jul YEAR: 2021 DOI: 10.3847/1538-4357/abfdbc Analysis of Magnetohydrodynamic Perturbations in the Radial-field Solar Wind from Parker Solar Probe Observations We report analysis of sub-Alfv\ enic magnetohydrodynamic (MHD) perturbations in the low-\ensuremath\beta radial-field solar wind employing the Parker Solar Probe spacecraft data from 2018 October 31 to November 12. We calculate wavevectors using the singular value decomposition method and separate MHD perturbations into three eigenmodes (Alfv\ en, fast, and slow modes) to explore the properties of sub-Alfv\ enic perturbations and the role of compressible perturbations in solar wind heating. The MHD perturbations show a high ... Zhao, S.~Q.; Yan, Huirong; Liu, Terry; Liu, Mingzhe; Shi, Mijie; Published by: \apj Published on: dec YEAR: 2021 DOI: 10.3847/1538-4357/ac2ffe A Solar Source of Alfv\ enic Magnetic Field Switchbacks: In Situ Remnants of Magnetic Funnels on Supergranulation Scales 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) fluctuations occur over a range of timescales and in patches separated by intervals of quiet, radial magnetic field. We use measurements from PSP to demonstrate that patches of switchbacks are localized within the extensions of plasma structures originating at the base of the corona. These ... Bale, S.~D.; Horbury, T.~S.; Velli, M.; Desai, M.~I.; Halekas, J.~S.; McManus, M.~D.; Panasenco, O.; Badman, S.~T.; Bowen, T.~A.; Chandran, B.~D.~G.; Drake, J.~F.; Kasper, J.~C.; Laker, R.; Mallet, A.; Matteini, L.; Phan, T.~D.; Raouafi, N.~E.; Squire, J.; Woodham, L.~D.; Woolley, T.; Published by: \apj Published on: dec YEAR: 2021 DOI: 10.3847/1538-4357/ac2d8c Domains of Magnetic Pressure Balance in Parker Solar Probe Observations of the Solar Wind The Parker Solar Probe (PSP) spacecraft is performing the first in situ exploration of the solar wind within 0.2 au of the Sun. Initial observations confirmed the Alfv\ enic nature of aligned fluctuations of the magnetic field B and velocity V in solar wind plasma close to the Sun, in domains of nearly constant magnetic field magnitude \ensuremath\mid B \ensuremath\mid, i.e., approximate magnetic pressure balance. Such domains are interrupted by particularly strong fluctuations, including but not limited to radial field (pol ... Ruffolo, David; Ngampoopun, Nawin; Bhora, Yash; Thepthong, Panisara; Pongkitiwanichakul, Peera; Matthaeus, William; Chhiber, Rohit; Published by: \apj Published on: dec YEAR: 2021 DOI: 10.3847/1538-4357/ac2ee3 Large-scale Structure and Turbulence Transport in the Inner Solar Wind: Comparison of Parker Solar Probe s First Five Orbits with a Global 3D Reynolds-averaged MHD Model Simulation results from a global magnetohydrodynamic model of the solar corona and solar wind are compared with Parker Solar Probe (PSP) observations during its first five orbits. The fully three- dimensional model is based on Reynolds-averaged mean-flow equations coupled with turbulence-transport equations. The model includes the effects of electron heat conduction, Coulomb collisions, turbulent Reynolds stresses, and heating of protons and electrons via a turbulent cascade. Turbulence-transport equations for average turbul ... Chhiber, Rohit; Usmanov, Arcadi; Matthaeus, William; Goldstein, Melvyn; Published by: \apj Published on: dec YEAR: 2021 DOI: 10.3847/1538-4357/ac1ac7 Internal Structure of the 2019 April 2 CME We present the first analysis of internal coronal mass ejection (CME) structure observed very close to the Sun by the Wide-field Imager for Solar PRobe (WISPR) instrument on board the Parker Solar Probe (PSP). The transient studied here is a CME observed during PSP s second perihelion passage on 2019 April 2, when PSP was only 40 R_\ensuremath\odot\$ from the Sun. The CME was also well observed from 1 au by the STEREO-A spacecraft, which tracks the event all the way from the Sun to 1 au. However, PSP/WISPR observes internal ... Wood, Brian; Braga, Carlos; Vourlidas, Angelos; Published by: \apj      Published on: dec YEAR: 2021     DOI: 10.3847/1538-4357/ac2aab Signatures of Type III Solar Radio Bursts from Nanoflares: Modeling There is a wide consensus that the ubiquitous presence of magnetic reconnection events and the associated impulsive heating (nanoflares) are strong candidates for solving the solar coronal heating problem. Whether nanoflares accelerate particles to high energies like full-sized flares is unknown. We investigate this question by studying the type III radio bursts that the nanoflares may produce on closed loops. The characteristic frequency drifts that type III bursts exhibit can be detected using a novel application of the ti ... Chhabra, Sherry; Klimchuk, James; Gary, Dale; Published by: \apj      Published on: dec YEAR: 2021     DOI: 10.3847/1538-4357/ac2364 Simulations of radio-wave anisotropic scattering to interpret type III radio burst data from Solar Orbiter, Parker Solar Probe, STEREO, and Wind \ Aims: We use multi-spacecraft observations of individual type III radio bursts to calculate the directivity of the radio emission. We compare these data to the results of ray-tracing simulations of the radio-wave propagation and probe the plasma properties of the inner heliosphere. \ Methods: We used ray-tracing simulations of radio-wave propagation with anisotropic scattering on density inhomogeneities to study the directivity of radio emissions. Simultaneous observations of type III radio bursts by four widely separated ... Musset, S.; Maksimovic, M.; Kontar, E.; Krupar, V.; Chrysaphi, N.; Bonnin, X.; Vecchio, A.; Cecconi, B.; Zaslavsky, A.; Issautier, K.; Bale, S.~D.; Pulupa, M.; Published by: \aap      Published on: dec YEAR: 2021     DOI: 10.1051/0004-6361/202140998 Probing Upflowing Regions in the Quiet Sun and Coronal Holes Recent observations from Parker Solar Probe have revealed that the solar wind has a highly variable structure. How this complex behaviour is formed in the solar corona is not yet known, since it requires omnipresent fluctuations, which constantly emit material to feed the wind. In this article we analyse 14 upflow regions in the solar corona to find potential sources for plasma flow. The upflow regions are derived from spectroscopic data from the EUV Imaging Spectrometer (EIS) on board Hinode determining their Doppler veloci ... Schwanitz, Conrad; Harra, Louise; Raouafi, Nour; Sterling, Alphonse; Vacas, Alejandro; Iniesta, Jose; arez, David; Hara, Hirohisa; Published by: \solphys      Published on: dec YEAR: 2021     DOI: 10.1007/s11207-021-01915-0

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