# PSP Bibliography

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## Found 174 entries in the Bibliography.

### Showing entries from 1 through 50

 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 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 The Formation and Lifetime of Outflows in a Solar Active Region Active regions are thought to be one contributor to the slow solar wind. Upflows in EUV coronal spectral lines are routinely observed at their boundaries, and provide the most direct way for upflowing material to escape into the heliosphere. The mechanisms that form and drive these upflows, however, remain to be fully characterized. It is unclear how quickly they form, or how long they exist during their lifetimes. They could be initiated low in the atmosphere during magnetic flux emergence, or as a response to processes occ ... Brooks, David; Harra, Louise; Bale, Stuart; Barczynski, Krzysztof; Mandrini, Cristina; Polito, Vanessa; Warren, Harry; Published by: \apj      Published on: aug YEAR: 2021     DOI: 10.3847/1538-4357/ac0917 First Simultaneous In Situ Measurements of a Coronal Mass Ejection by Parker Solar Probe and STEREO-A We present the first Parker Solar Probe mission (PSP)-observed coronal mass ejection (CME) that hits a second spacecraft before the end of the PSP encounter, providing an excellent opportunity to study short-term CME evolution. The CME was launched from the Sun on 2019 October 10 and was measured in situ at PSP on 2019 October 13 and at STEREO-A on 2019 October 14. The small, but not insignificant, radial (\raisebox-0.5ex\textasciitilde0.15 au) and longitudinal (\raisebox-0.5ex\textasciitilde8\textdegree) separation between ... Winslow, Reka; Lugaz, No\; Scolini, Camilla; Galvin, Antoinette; Published by: \apj      Published on: aug YEAR: 2021     DOI: 10.3847/1538-4357/ac0821 Characteristics of Interplanetary Discontinuities in the Inner Heliosphere Revealed by Parker Solar Probe We present a statistical analysis for the characteristics and spatial evolution of the interplanetary discontinuities (IDs) in the solar wind, from 0.13-0.9 au, by using the Parker Solar Probe measurements on Orbits 4 and 5. We collected 3948 IDs, including 2511 rotational discontinuities (RDs) and 557 tangential discontinuities (TDs), with the remnant unidentified. The statistical results show that (1) the ID occurrence rate decreases from 200 events per day at 0.13 au to 1 event per day at 0.9 au, following a spatial scali ... Liu, Y.~Y.; Fu, H.~S.; Cao, J.~B.; Liu, C.~M.; Wang, Z.; Guo, Z.~Z.; Xu, Y.; Bale, S.~D.; Kasper, J.~C.; Published by: \apj      Published on: aug YEAR: 2021     DOI: 10.3847/1538-4357/ac06a1 Multi-spacecraft study of the solar wind at solar minimum: Dependence on latitude and transient outflows Context. The recent launches of Parker Solar Probe, Solar Orbiter (SO), and BepiColombo, along with several older spacecraft, have provided the opportunity to study the solar wind at multiple latitudes and distances from the Sun simultaneously. \ Aims: We take advantage of this unique spacecraft constellation, along with low solar activity across two solar rotations between May and July 2020, to investigate how the solar wind structure, including the heliospheric current sheet (HCS), varies with latitude. \ Methods: We visua ... Laker, R.; Horbury, T.~S.; Bale, S.~D.; Matteini, L.; Woolley, T.; Woodham, L.~D.; Stawarz, J.~E.; Davies, E.~E.; Eastwood, J.~P.; Owens, M.~J.; Brien, H.; Evans, V.; Angelini, V.; Richter, I.; Heyner, D.; Owen, C.~J.; Louarn, P.; Fedorov, A.; Published by: \aap      Published on: aug YEAR: 2021     DOI: 10.1051/0004-6361/202140679 Evolution of Interplanetary Coronal Mass Ejection Complexity: A Numerical Study through a Swarm of Simulated Spacecraft In-situ measurements carried out by spacecraft in radial alignment are critical to advance our knowledge on the evolutionary behavior of coronal mass ejections (CMEs) and their magnetic structures during propagation through interplanetary space. Yet, the scarcity of radially aligned CME crossings restricts investigations on the evolution of CME magnetic structures to a few case studies, preventing a comprehensive understanding of CME complexity changes during propagation. In this Letter, we perform numerical simulations of C ... Scolini, Camilla; Winslow, Reka; Lugaz, No\; Poedts, Stefaan; Published by: \apjl      Published on: aug YEAR: 2021     DOI: 10.3847/2041-8213/ac0d58 Large Amplitude Switchback Turbulence: Possible Magnetic Velocity Alignment Structures Switchbacks are widely acknowledged phenomena observed by the Parker Solar Probe and appear to occur in patches. Previous studies focused on the fluctuations at the magnetic reversals. However, the nature of the fluctuations inside the switchbacks remains unknown. Here we utilize the magnetic field data and plasma data measured by the Parker Solar Probe in the first four encounters. We investigate the fluctuations in the switchback intervals of 100 s with $B_R 0$ at every instant and compare them to the fluctuations in the n ... Wu, Honghong; Tu, Chuanyi; Wang, Xin; Yang, Liping; Published by: The Astrophysical Journal      Published on: 06/2021 YEAR: 2021     DOI: 10.3847/1538-4357/abec6c Applicability of Taylor s hypothesis during Parker Solar Probe perihelia We investigate the validity of Taylor s hypothesis (TH) in the analysis of velocity and magnetic field fluctuations in Alfvénic solar wind streams measured by Parker Solar Probe (PSP) during the first four encounters. The analysis is based on a recent model of the spacetime correlation of magnetohydrodynamic (MHD) turbulence, which has been validated in high-resolution numerical simulations of strong reduced MHD turbulence. We use PSP velocity and magnetic field measurements from 24 h intervals selected from each of the fir ... Perez, Jean; Bourouaine, Sofiane; Chen, Christopher; Raouafi, Nour; Published by: Astronomy and Astrophysics      Published on: 06/2021 YEAR: 2021     DOI: 10.1051/0004-6361/202039879 The contribution of alpha particles to the solar wind angular momentum flux in the inner heliosphere Context. An accurate assessment of the Sun s angular momentum (AM) loss rate is an independent constraint for models that describe the rotation evolution of Sun-like stars. Aims: In situ measurements of the solar wind taken by Parker Solar Probe (PSP), at radial distances of ~28−55 R⊙, are used to constrain the solar wind AM-loss rate. For the first time with PSP, this includes a measurement of the alpha particle contribution. Methods: The mechanical AM flux in the solar wind protons (core and be ... Finley, A.; McManus, M.; Matt, S.; Kasper, J.; Korreck, K.; Case, A.; Stevens, M.; Whittlesey, P.; Larson, D.; Livi, R.; Bale, S.; de Wit, Dudok; Goetz, K.; Harvey, P.; MacDowall, R.; Malaspina, D.; Pulupa, M.; Published by: Astronomy and Astrophysics      Published on: 06/2021 YEAR: 2021     DOI: 10.1051/0004-6361/202039288 Detection of small magnetic flux ropes from the third and fourth Parker Solar Probe encounters Context. Aims: We systematically search for magnetic flux rope structures in the solar wind to within the closest distance to the Sun of ~0.13 AU, using data from the third and fourth orbits of the Parker Solar Probe. Methods: We extended our previous magnetic helicity-based technique of identifying magnetic flux rope structures. The method was improved upon to incorporate the azimuthal flow, which becomes larger as the spacecraft approaches the Sun. Results: A total of 21 and 34 magnetic flux ropes are ... Zhao, L.; Zank, G.; Hu, Q.; Telloni, D.; Chen, Y.; Adhikari, L.; Nakanotani, M.; Kasper, J.; Huang, J.; Bale, S.; Korreck, K.; Case, A.; Stevens, M.; Bonnell, J.; de Wit, Dudok; Goetz, K.; Harvey, P.; MacDowall, R.; Malaspina, D.; Pulupa, M.; Larson, D.; Livi, R.; Whittlesey, P.; Klein, K.; Raouafi, N.; Published by: Astronomy and Astrophysics      Published on: 06/2021 YEAR: 2021     DOI: 10.1051/0004-6361/202039298 The active region source of a type III radio storm observed by Parker Solar Probe during encounter 2 Context. We investigated the source of a type III radio burst storm during encounter 2 of NASA s Parker Solar Probe (PSP) mission. Aims: It was observed that in encounter 2 of NASA s PSP mission there was a large amount of radio activity and, in particular, a noise storm of frequent, small type III bursts from 31 March to 6 April 2019. Our aim is to investigate the source of these small and frequent bursts. Methods: In order to do this, we analysed data from the Hinode EUV Imaging Spectrometer, PSP FIELDS, and ... Harra, L.; Brooks, D.; Bale, S.; Mandrini, C.; Barczynski, K.; Sharma, R.; Badman, S.; Domínguez, Vargas; Pulupa, M.; Published by: Astronomy and Astrophysics      Published on: 06/2021 YEAR: 2021     DOI: 10.1051/0004-6361/202039514 Periodicities in an active region correlated with Type III radio bursts observed by Parker Solar Probe Context. Periodicities have frequently been reported across many wavelengths in the solar corona. Correlated periods of ~5 min, comparable to solar p-modes, are suggestive of coupling between the photosphere and the corona. Aims: Our study investigates whether there are correlations in the periodic behavior of Type III radio bursts which are indicative of nonthermal electron acceleration processes, and coronal extreme ultraviolet (EUV) emission used to assess heating and cooling in an active region when there are no l ... Cattell, Cynthia; Glesener, Lindsay; Leiran, Benjamin; Dombeck, John; Goetz, Keith; Oliveros, Juan; Badman, Samuel; Pulupa, Marc; Bale, Stuart; Published by: Astronomy and Astrophysics      Published on: 06/2021 YEAR: 2021     DOI: 10.1051/0004-6361/202039510 Direct evidence for magnetic reconnection at the boundaries of magnetic switchbacks with Parker Solar Probe Context. The first encounters of Parker Solar Probe (PSP) with the Sun revealed the presence of ubiquitous localised magnetic deflections in the inner heliosphere; these structures, often called switchbacks, are particularly striking in solar wind streams originating from coronal holes. Aims: We report the direct piece of evidence for magnetic reconnection occurring at the boundaries of three switchbacks crossed by PSP at a distance of 45 to 48 solar radii to the Sun during its first encounter. Methods: We anal ... Froment, C.; Krasnoselskikh, V.; de Wit, Dudok; Agapitov, O.; Fargette, N.; Lavraud, B.; Larosa, A.; Kretzschmar, M.; Jagarlamudi, V.; Velli, M.; Malaspina, D.; Whittlesey, P.; Bale, S.; Case, A.; Goetz, K.; Kasper, J.; Korreck, K.; Larson, D.; MacDowall, R.; Mozer, F.; Pulupa, M.; Revillet, C.; Stevens, M.; Published by: Astronomy and Astrophysics      Published on: 06/2021 YEAR: 2021     DOI: 10.1051/0004-6361/202039806 Switchbacks: statistical properties and deviations from Alfvénicity Context. Parker Solar Probe s first solar encounter has revealed the presence of sudden magnetic field deflections in the slow Alfvénic solar wind. These structures, which are often called switchbacks, are associated with proton velocity enhancements. Aims: We study their statistical properties with a special focus on their boundaries. Methods: Using data from SWEAP and FIELDS, we investigate particle and wavefield properties. The magnetic boundaries are analyzed with the minimum variance technique. Res ... Larosa, A.; Krasnoselskikh, V.; de Wit, Dudok; Agapitov, O.; Froment, C.; Jagarlamudi, V.; Velli, M.; Bale, S.; Case, A.; Goetz, K.; Harvey, P.; Kasper, J.; Korreck, K.; Larson, D.; MacDowall, R.; Malaspina, D.; Pulupa, M.; Revillet, C.; Stevens, M.; Published by: Astronomy and Astrophysics      Published on: 06/2021 YEAR: 2021     DOI: 10.1051/0004-6361/202039442 Stellar versus Galactic: the intensity of cosmic rays at the evolving Earth and young exoplanets around Sun-like stars Energetic particles, such as stellar cosmic rays, produced at a heightened rate by active stars (like the young Sun) may have been important for the origin of life on Earth and other exoplanets. Here, we compare, as a function of stellar rotation rate (Ω), contributions from two distinct populations of energetic particles: stellar cosmic rays accelerated by impulsive flare events and Galactic cosmic rays. We use a 1.5D stellar wind model combined with a spatially 1D cosmic ray transport model. We formulate the evolution of ... Rodgers-Lee, D.; Taylor, A.; Vidotto, A.; Downes, T.; Published by: Monthly Notices of the Royal Astronomical Society      Published on: 06/2021 YEAR: 2021     DOI: 10.1093/mnras/stab935 Turbulent Proton Heating Rate in the Solar Wind from 545 R Various remote sensing observations have been used so far to probe the turbulent properties of the solar wind. Using the recently reported density modulation indices that are derived using angular broadening observations of Crab Nebula during 19522013, we measured the solar wind proton heating using the kinetic Alfvn wave dispersion equation. The estimated heating rates vary from 1.58 1014 to 1.01 108 erg cm3 s1 in the heliocentric distance range of 545 R. Further, we found that he ... Raja, Sasikumar; Subramanian, Prasad; Ingale, Madhusudan; Ramesh, R.; Maksimovic, Milan; Published by: The Astrophysical Journal      Published on: 06/2021 YEAR: 2021     DOI: 10.3847/1538-4357/abfcd1 Could Switchbacks Originate in the Lower Solar Atmosphere? II. Propagation of Switchbacks in the Solar Corona The magnetic switchbacks observed recently by the Parker Solar Probe have raised the question about their nature and origin. One of the competing theories of their origin is the interchange reconnection in the solar corona. In this scenario, switchbacks are generated at the reconnection site between open and closed magnetic fields, and are either advected by an upflow or propagate as waves into the solar wind. In this paper we test the wave hypothesis, numerically modeling the propagation of a switchback, modeled as an embed ... Magyar, Norbert; Utz, Dominik; Erdélyi, Robertus; Nakariakov, Valery; Published by: The Astrophysical Journal      Published on: 06/2021 YEAR: 2021     DOI: 10.3847/1538-4357/abfa98 Using Parker Solar Probe observations during the first four perihelia to constrain global magnetohydrodynamic models Context. Parker Solar Probe (PSP) is providing an unprecedented view of the Sun s corona as it progressively dips closer into the solar atmosphere with each solar encounter. Each set of observations provides a unique opportunity to test and constrain global models of the solar corona and inner heliosphere and, in turn, use the model results to provide a global context for interpreting such observations. Aims: In this study, we develop a set of global magnetohydrodynamic (MHD) model solutions of varying degrees of soph ... Riley, Pete; Lionello, Roberto; Caplan, Ronald; Downs, Cooper; Linker, Jon; Badman, Samuel; Stevens, Michael; Published by: Astronomy and Astrophysics      Published on: 06/2021 YEAR: 2021     DOI: 10.1051/0004-6361/202039815 Correlation of the Sunspot Number and the Waiting-time Distribution of Solar Flares, Coronal Mass Ejections, and Solar Wind Switchback Events Observed with the Parker Solar Probe Waiting-time distributions of solar flares and coronal mass ejections (CMEs) exhibit power-law-like distribution functions with slopes in the range of ατ ≍ 1.4-3.2, as observed in annual data sets during four solar cycles (1974-2012). We find a close correlation between the waiting-time power-law slope ατ and the sunspot number (SN), i.e., ατ = 1.38 + 0.01 × SN. The waiting-time distribution can be fitted with a Pareto-type function of the form N(τ) = N0 $(\tau _0+\tau )^ ... Aschwanden, Markus; de Wit, Thierry; Published by: The Astrophysical Journal Published on: 05/2021 YEAR: 2021 DOI: 10.3847/1538-4357/abef69 Multiscale Solar Wind Turbulence Properties inside and near Switchbacks Measured by the Parker Solar Probe The Parker Solar Probe (PSP) routinely observes magnetic field deflections in the solar wind at distances less than 0.3 au from the Sun. These deflections are related to structures commonly called "switchbacks" (SBs), whose origins and characteristic properties are currently debated. Here, we use a database of visually selected SB intervals—and regions of solar wind plasma measured just before and after each SB—to examine plasma parameters, turbulent spectra from inertial to dissipation scales, and intermittency ... Martinovic, Mihailo; Klein, Kristopher; Huang, Jia; Chandran, Benjamin; Kasper, Justin; Lichko, Emily; Bowen, Trevor; Chen, Christopher; Matteini, Lorenzo; Stevens, Michael; Case, Anthony; Bale, Stuart; Published by: The Astrophysical Journal Published on: 05/2021 YEAR: 2021 DOI: 10.3847/1538-4357/abebe5 An approximate analytic solution to the coupled problems of coronal heating and solar-wind acceleration Between the base of the solar corona at$r=r_\textrm b$and the Alfvén critical point at$r=r_\textrm A$, where$r$is heliocentric distance, the solar-wind density decreases by a factor$ \mathop > \limits_∼ 10^5$, but the plasma temperature varies by a factor of only a few. In this paper, I show that such quasi-isothermal evolution out to$r=r_\textrm A$is a generic property of outflows powered by reflection-driven Alfvén-wave (AW) turbulence, in which outward-propagating AWs partially reflect, and counter-propagating ... Chandran, Benjamin; Published by: Journal of Plasma Physics Published on: 05/2021 YEAR: 2021 DOI: 10.1017/S0022377821000052 A New View of the Solar Interface Region from the Interface Region Imaging Spectrograph (IRIS) The Interface Region Imaging Spectrograph (IRIS) has been obtaining near- and far-ultraviolet images and spectra of the solar atmosphere since July 2013. IRIS is the highest resolution observatory to provide seamless coverage of spectra and images from the photosphere into the low corona. The unique combination of near- and far-ultraviolet spectra and images at sub-arcsecond resolution and high cadence allows the tracing of mass and energy through the critical interface between the surface and the corona or solar wind. IRIS ... De Pontieu, Bart; Polito, Vanessa; Hansteen, Viggo; Testa, Paola; Reeves, Katharine; Antolin, Patrick; Nóbrega-Siverio, Daniel; Kowalski, Adam; Martinez-Sykora, Juan; Carlsson, Mats; McIntosh, Scott; Liu, Wei; Daw, Adrian; Kankelborg, Charles; Published by: Solar Physics Published on: 05/2021 YEAR: 2021 DOI: 10.1007/s11207-021-01826-0 On the violation of the zeroth law of turbulence in space plasmas The zeroth law of turbulence states that, for fixed energy input into large-scale motions, the statistical steady state of a turbulent system is independent of microphysical dissipation properties. This behaviour, which is fundamental to nearly all fluid-like systems from industrial processes to galaxies, occurs because nonlinear processes generate smaller and smaller scales in the flow, until the dissipation - no matter how small - can thermalise the energy input. Using direct numerical simulations and theoretical arguments ... Meyrand, R.; Squire, J.; Schekochihin, A.; Dorland, W.; Published by: Journal of Plasma Physics Published on: 05/2021 YEAR: 2021 DOI: 10.1017/S0022377821000489 How Alfvén waves energize the solar wind: heat versus work A growing body of evidence suggests that the solar wind is powered to a large extent by an Alfvén-wave (AW) energy flux. AWs energize the solar wind via two mechanisms: heating and work. We use high-resolution direct numerical simulations of reflection-driven AW turbulence (RDAWT) in a fast-solar-wind stream emanating from a coronal hole to investigate both mechanisms. In particular, we compute the fraction of the AW power at the coronal base ($P_\textrm AWb$) that is transferred to solar-wind particles via heating between ... Perez, Jean; Chandran, Benjamin; Klein, Kristopher; Martinovic, Mihailo; Published by: Journal of Plasma Physics Published on: 04/2021 YEAR: 2021 DOI: 10.1017/S0022377821000167 Subproton-scale Intermittency in Near-Sun Solar Wind Turbulence Observed by the Parker Solar Probe High time-resolution solar wind magnetic field data are employed to study statistics describing intermittency near the first perihelion (∼35.6 R⊙) of the Parker Solar Probe mission. A merged data set employing two instruments on the FIELDS suite enables broadband estimation of higher-order moments of magnetic field increments, with five orders established with reliable accuracy. The duration, cadence, and low noise level of the data permit evaluation of scale dependence of the observed intermittency from the i ... Chhiber, Rohit; Matthaeus, William; Bowen, Trevor; Bale, Stuart; Published by: The Astrophysical Journal Published on: 04/2021 YEAR: 2021 DOI: 10.3847/2041-8213/abf04e Parker Solar Probe Evidence for Scattering of Electrons in the Young Solar Wind by Narrowband Whistler-mode Waves Observations of plasma waves by the Fields Suite and of electrons by the Solar Wind Electrons Alphas and Protons Investigation on the Parker Solar Probe provide strong evidence for pitch angle scattering of strahl-energy electrons by narrowband whistler-mode waves at radial distances less than ∼0.3 au. We present two example intervals of a few hours each that include eight waveform captures with whistler-mode waves and 26 representative electron distributions that are examined in detail. Two were narrow, seventeen were cle ... Cattell, C.; Breneman, A.; Dombeck, J.; Short, B.; Wygant, J.; Halekas, J.; Case, Tony; Kasper, J.; Larson, D.; Stevens, Mike; Whittesley, P.; Bale, S.; de Wit, Dudok; Goodrich, K.; MacDowall, R.; Moncuquet, M.; Malaspina, D.; Pulupa, M.; Published by: The Astrophysical Journal Published on: 04/2021 YEAR: 2021 DOI: 10.3847/2041-8213/abefdd Could Switchbacks Originate in the Lower Solar Atmosphere? I. Formation Mechanisms of Switchbacks The recent rediscovery of magnetic field switchbacks or deflections embedded in the solar wind flow by the Parker Solar Probe mission lead to a huge interest in the modeling of the formation mechanisms and origin of these switchbacks. Several scenarios for their generation were put forth, ranging from lower solar atmospheric origins by reconnection, to being a manifestation of turbulence in the solar wind, and so on. Here we study some potential formation mechanisms of magnetic switchbacks in the lower solar atmosphere, usin ... Magyar, Norbert; Utz, Dominik; Erdélyi, Robertus; Nakariakov, Valery; Published by: The Astrophysical Journal Published on: 04/2021 YEAR: 2021 DOI: 10.3847/1538-4357/abec49 Evolving solar wind flow properties of magnetic inversions observed by Helios Macneil, Allan; Owens, Mathew; Wicks, Robert; Lockwood, Mike; Published by: \mnras Published on: 03/2021 YEAR: 2021 DOI: 10.1093/mnras/staa3983 Switchbacks Explained: Super-Parker Fields—The Other Side of the Sub-Parker Spiral We provide a simple geometric explanation for the source of switchbacks and associated large and one-sided transverse flows in the solar wind observed by the Parker Solar Probe (PSP). The more radial, sub-Parker spiral structure of the heliospheric magnetic field observed previously by Ulysses, ACE, and STEREO is created within rarefaction regions where footpoint motion from the source of fast into slow wind at the Sun creates a magnetic fieldline connection across solar wind speed shear. Conversely, when footpoints move fro ... Schwadron, N.; McComas, D.; Published by: The Astrophysical Journal Published on: 03/2021 YEAR: 2021 DOI: 10.3847/1538-4357/abd4e6 The Encounter of the Parker Solar Probe and a Comet-like Object Near the Sun: Model Predictions and Measurements The Parker Solar Probe (PSP) aims to explore the nascent solar wind close to the Sun. Meanwhile, PSP is also expected to encounter small objects like comets and asteroids. In this work, we survey the ephemerides to find the chance of a recent encounter and then model the interaction between released dusty plasmas and solar wind plasmas. On 2019 September 2, a comet-like object, the 322P/Solar and Heliosphere Observatory, just passed its perihelion flying to a heliocentric distance of 0.12 au and swept by PSP at a relative di ... He, Jiansen; Cui, Bo; Yang, Liping; Hou, Chuanpeng; Zhang, Lei; Ip, Wing-Huen; Jia, Ying-Dong; Dong, Chuanfei; Duan, Die; Zong, Qiugang; Bale, Stuart; Pulupa, Marc; Bonnell, John; de Wit, Thierry; Goetz, Keith; Harvey, Peter; MacDowall, Robert; Malaspina, David; Published by: The Astrophysical Journal Published on: 03/2021 YEAR: 2021 DOI: 10.3847/1538-4357/abdf4a Source-dependent Properties of Two Slow Solar Wind States Two states of the slow solar wind are identified from in situ measurements by the Parker Solar Probe (PSP) inside 50 solar radii from the Sun. At such distances the wind measured by PSP has not yet undergone significant transformation related to the expansion and propagation of the wind. We focus in this study on the properties of the quiet solar wind with no magnetic switchbacks. The two states differ by their plasma beta, flux, and magnetic pressure. PSP s magnetic connectivity established with potential field source surfa ... Griton, Lea; Rouillard, Alexis; Poirier, Nicolas; Issautier, Karine; Moncuquet, Michel; Pinto, Rui; Published by: The Astrophysical Journal Published on: 03/2021 YEAR: 2021 DOI: 10.3847/1538-4357/abe309 Upflows in the Upper Solar Atmosphere Spectroscopic observations at extreme- and far-ultraviolet wavelengths have revealed systematic upflows in the solar transition region and corona. These upflows are best seen in the network structures of the quiet Sun and coronal holes, boundaries of active regions, and dimming regions associated with coronal mass ejections. They have been intensively studied in the past two decades because they are likely to be closely related to the formation of the solar wind and heating of the upper solar atmosphere. We present an overvi ... Tian, Hui; Harra, Louise; Baker, Deborah; Brooks, David; Xia, Lidong; Published by: Solar Physics Published on: 03/2021 YEAR: 2021 DOI: 10.1007/s11207-021-01792-7 Inferred Linear Stability of Parker Solar Probe Observations Using One- and Two-component Proton Distributions The hot and diffuse nature of the Sun s extended atmosphere allows it to persist in non-equilibrium states for long enough that wave-particle instabilities can arise and modify the evolution of the expanding solar wind. Determining which instabilities arise, and how significant a role they play in governing the dynamics of the solar wind, has been a decades-long process involving in situ observations at a variety of radial distances. With new measurements from the Parker Solar Probe (PSP), we can study what wave modes are dr ... Klein, K.; Verniero, J.; Alterman, B.; Bale, S.; Case, A.; Kasper, J.; Korreck, K.; Larson, D.; Lichko, E.; Livi, R.; McManus, M.; Martinovic, M.; Rahmati, A.; Stevens, M.; Whittlesey, P.; Published by: The Astrophysical Journal Published on: 03/2021 YEAR: 2021 DOI: 10.3847/1538-4357/abd7a0 The Ion Transition Range of Solar Wind Turbulence in the Inner Heliosphere: Parker Solar Probe Observations The scaling of the turbulent spectra provides a key measurement that allows us to discriminate between different theoretical predictions of turbulence. In the solar wind, this has driven a large number of studies dedicated to this issue using in situ data from various orbiting spacecraft. While a semblance of consensus exists regarding the scaling in the magnetohydrodynamic (MHD) and dispersive ranges, the precise scaling in the transition range and the actual physical mechanisms that control it remain open questions. Using ... Huang, S; Sahraoui, F.; Andrés, N.; Hadid, L.; Yuan, Z.; He, J.; Zhao, J.; Galtier, S.; Zhang, J.; Deng, X.; Jiang, K.; Yu, L.; Xu, S.; Xiong, Q; Wei, Y; de Wit, Dudok; Bale, S.; Kasper, J.; Published by: The Astrophysical Journal Published on: 03/2021 YEAR: 2021 DOI: 10.3847/2041-8213/abdaaf A Self-consistent Simulation of Proton Acceleration and Transport Near a High-speed Solar Wind Stream Wijsen, Nicolas; Samara, Evangelia; Aran, Angels; Lario, David; Pomoell, Jens; Poedts, Stefaan; Published by: \apjl Published on: 02/2021 YEAR: 2021 DOI: 10.3847/2041-8213/abe1cb Characteristics of Magnetic Holes in the Solar Wind Revealed by Parker Solar Probe Yu, L.; Huang, S.~Y.; Yuan, Z.~G.; Jiang, K.; Xiong, Q.~Y.; Xu, S.~B.; Wei, Y.~Y.; Zhang, J.; Zhang, Z.~H.; Published by: \apj Published on: 02/2021 YEAR: 2021 DOI: 10.3847/1538-4357/abb9a8 Harmonic Radio Emission in Randomly Inhomogeneous Plasma In the present paper, we describe a theoretical model of the generation of harmonic emissions of type III solar radio bursts. The goal of our study is to fully take into account the most efficient physical processes involved in the generation of harmonic electromagnetic emission via nonlinear coupling of Langmuir waves in randomly inhomogeneous plasma of solar wind ($l+l^\prime \to t\$ ). We revisit the conventional mechanism of coalescence of primarily generated and back-scattered Langmuir waves in quasihomogeneous plasma. ... Tkachenko, Anna; Krasnoselskikh, Vladimir; Voshchepynets, Andrii; Published by: The Astrophysical Journal      Published on: 02/2021 YEAR: 2021     DOI: 10.3847/1538-4357/abd2bd Random Walk and Trapping of Interplanetary Magnetic Field Lines: Global Simulation, Magnetic Connectivity, and Implications for Solar Energetic Particles The random walk of magnetic field lines is an important ingredient in understanding how the connectivity of the magnetic field affects the spatial transport and diffusion of charged particles. As solar energetic particles propagate away from near-solar sources, they interact with the fluctuating magnetic field, which modifies their distributions. We develop a formalism in which the differential equation describing the field line random walk contains both effects due to localized magnetic displacements and a non-stochastic co ... Chhiber, Rohit; Ruffolo, David; Matthaeus, William; Usmanov, Arcadi; Tooprakai, Paisan; Chuychai, Piyanate; Goldstein, Melvyn; Published by: The Astrophysical Journal      Published on: 02/2021 YEAR: 2021     DOI: 10.3847/1538-4357/abd7f0 Properties of Type III and Type IIIb Bursts in the Frequency Band of 8 - 80 MHz During PSP Perihelion at the Beginning of April 2019 Melnik, V.~N.; Brazhenko, A.~I.; Konovalenko, A.~A.; Frantsuzenko, A.~V.; Yerin, S.~M.; Dorovskyy, V.~V.; Bubnov, I.~M.; Published by: \solphys      Published on: 01/2021 YEAR: 2021     DOI: 10.1007/s11207-020-01754-5

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