bluuebunny/crossref_metadata_2025_split huggingface dataset:
Solar Wind Streams and Stream Interaction Regions Observed by the Parker Solar Probe with Corresponding Observations at 1 au
Authors: Allen R. C. , Lario D. , Odstrcil D. , Ho G. C. , Jian L. K. , Cohen C. M. S. , Badman S. T. , Jones S. I. , Arge C. N. , Mays M. L. , Mason G. M. , Bale S. D. , Bonnell J. W. , Case A. W. , Christian E. R. , de Wit T. Dudok , Goetz K. , Harvey P. R. , Henney C. J. , Hill M. E. , Kasper J. C. , Korreck K. E. , Larson D. , Livi R. , MacDowall R. J. , Malaspina D. M. , McComas D. J. , McNutt R. , Mitchell D. G. , Pulupa M. , Raouafi N. , Schwadron N. , Stevens M. L. , Whittlesey P. L. , Wiedenbeck M. 
Published: February 2020

Abstract
Several fast solar wind streams and stream interaction regions (SIRs) were observed by the Parker Solar Probe (PSP) during its first orbit (2018 September–2019 January). During this time, several recurring SIRs were also seen at 1 au at both L1 (Advanced Composition Explorer (ACE) and Wind) and the location of the Solar Terrestrial Relations Observatory-Ahead (STEREO-A). In this paper, we compare four fast streams observed by PSP at different radial distances during its first orbit. For three of these fast stream events, measurements from L1 (ACE and Wind) and STEREO-A indicated that the fast streams were observed by both PSP and at least one of the 1 au monitors. Our associations are supported by simulations made by the ENLIL model driven by GONG-(ADAPT-)WSA, which allows us to contextualize the inner heliospheric conditions during the first orbit of PSP. Additionally, we determine which of these fast streams are associated with an SIR and characterize the SIR properties for these events. From these comparisons, we find that the compression region associated with the fast-speed streams overtaking the preceding solar wind can form at various radial distances from the Sun in the inner heliosphere inside 0.5 au, with the suprathermal ion population (energies between 30 and 586 keV) observed as isolated enhancements suggesting localized acceleration near the SIR stream interface at ∼0.3 au, which is unlike those seen at 1 au, where the suprathermal enhancements extend throughout and behind the SIR. This suprathermal enhancement extends further into the fast stream with increasing distance from the Sun.
Relating Streamer Flows to Density and Magnetic Structures at the Parker Solar Probe
Authors: Rouillard Alexis P. , Kouloumvakos Athanasios , Vourlidas Angelos , Kasper Justin , Bale Stuart , Raouafi Nour-Edine , Lavraud Benoit , Howard Russell A. , Stenborg Guillermo , Stevens Michael , Poirier Nicolas , Davies Jackie A. , Hess Phillip , Higginson Aleida K. , Lavarra Michael , Viall Nicholeen M. , Korreck Kelly , Pinto Rui F. , Griton Léa , Réville Victor , Louarn Philippe , Wu Yihong , Dalmasse Kévin , Génot Vincent , Case Anthony W. , Whittlesey Phyllis , Larson Davin , Halekas Jasper S. , Livi Roberto , Goetz Keith , Harvey Peter R. , MacDowall Robert J. , Malaspina D. , Pulupa M. , Bonnell J. , de Witt T. Dudok , Penou Emmanuel 
Published: February 2020

Abstract
The physical mechanisms that produce the slow solar wind are still highly debated. Parker Solar Probe’s (PSP’s) second solar encounter provided a new opportunity to relate in situ measurements of the nascent slow solar wind with white-light images of streamer flows. We exploit data taken by the Solar and Heliospheric Observatory, the Solar TErrestrial RElations Observatory (STEREO), and the Wide Imager on Solar Probe to reveal for the first time a close link between imaged streamer flows and the high-density plasma measured by the Solar Wind Electrons Alphas and Protons (SWEAP) experiment. We identify different types of slow winds measured by PSP that we relate to the spacecraft’s magnetic connectivity (or not) to streamer flows. SWEAP measured high-density and highly variable plasma when PSP was well connected to streamers but more tenuous wind with much weaker density variations when it exited streamer flows. STEREO imaging of the release and propagation of small transients from the Sun to PSP reveals that the spacecraft was continually impacted by the southern edge of streamer transients. The impact of specific density structures is marked by a higher occurrence of magnetic field reversals measured by the FIELDS magnetometers. Magnetic reversals are associated with much stronger density variations inside than outside streamer flows. We tentatively interpret these findings in terms of magnetic reconnection between open magnetic fields and coronal loops with different properties, providing support for the formation of a subset of the slow wind by magnetic reconnection.
Predicting the Solar Wind at the Parker Solar Probe Using an Empirically Driven MHD Model
Authors: Kim T. K. , Pogorelov N. V. , Arge C. N. , Henney C. J. , Jones-Mecholsky S. I. , Smith W. P. , Bale S. D. , Bonnell J. W. , Dudok de Wit T. , Goetz K. , Harvey P. R. , MacDowall R. J. , Malaspina D. M. , Pulupa M. , Kasper J. C. , Korreck K. E. , Stevens M. , Case A. W. , Whittlesey P. , Livi R. , Larson D. E. , Klein K. G. , Zank G. P. 
Published: February 2020

Abstract
Since its launch on 2018 August 12, Parker Solar Probe (PSP) has completed its first and second orbits around the Sun, having reached down to 35.7 solar radii at each perihelion. In anticipation of the exciting new data at such unprecedented distances, we have simulated the global 3D heliosphere using an MHD model coupled with a semi-empirical coronal model using the best available photospheric magnetograms as input. We compare our heliospheric MHD simulation results with in situ measurements along the PSP trajectory from its launch to the completion of the second orbit, with particular emphasis on the solar wind structure around the first two solar encounters. Furthermore, we show our model prediction for the third perihelion, which occurred on 2019 September 1. Comparison of the MHD results with PSP observations provides new insights into solar wind acceleration. Moreover, PSP observations reveal how accurately the Air Force Data Assimilative Photospheric flux Transport-Wang-Sheeley-Arge-based predictions work throughout the inner heliosphere.
Energetic Particle Observations from the Parker Solar Probe Using Combined Energy Spectra from the IS⊙IS Instrument Suite
Authors: Joyce C. J. , McComas D. J. , Christian E. R. , Schwadron N. A. , Wiedenbeck M. E. , McNutt R. L. , Cohen C. M. S. , Leske R. A. , Mewaldt R. A. , Stone E. C. , Labrador A. W. , Davis A. J. , Cummings A. C. , Mitchell D. G. , Hill M. E. , Roelof E. C. , Szalay J. R. , Rankin J. S. , Desai M. I. , Giacalone J. , Matthaeus W. H. 
Published: February 2020

Abstract
The Integrated Science Investigations of the Sun (IS⊙IS) instrument suite includes two Energetic Particle instruments: EPI-Hi, designed to measure ions from ∼1 to 200 MeV nuc−1, and EPI-Lo, designed to measure ions from ∼20 to ∼15 MeV nuc−1. We present an analysis of eight energetic proton events observed across the energy range of both instruments during Parker Solar Probe’s (PSP) first two orbits in order to examine their combined energy spectra. Background corrections are applied to help resolve spectral breaks between the two instruments and are shown to be effective. In doing so we demonstrate that even in the early stages of calibration, IS⊙IS is capable of producing reliable spectral observations across broad energy ranges. In addition to making groundbreaking measurements very near the Sun, IS⊙IS also characterizes energetic particle populations over a range of heliocentric distances inside 1 au. During the first two orbits, IS⊙IS observed energetic particle events from a single corotating interaction region (CIR) at three different distances from the Sun. The events are separated by two Carrington rotations and just 0.11 au in distance; however, the relationship shown between proton intensities and proximity of the spacecraft to the source region shows evidence of the importance of transport effects on observations of energetic particles from CIRs. Future IS⊙IS observations of similar events over larger distances will help disentangle the effects of CIR-related acceleration and transport. We apply similar spectral analyses to the remaining five events, including four that are likely related to stream interaction regions (SIRs) and one solar energetic particle (SEP) event.
3He-rich Solar Energetic Particle Observations at the Parker Solar Probe and near Earth
Authors: Wiedenbeck M. E. , Bučík R. , Mason G. M. , Ho G. C. , Leske R. A. , Cohen C. M. S. , Christian E. R. , Cummings A. C. , Davis A. J. , Desai M. I. , Giacalone J. , Haggerty D. K. , Hill M. E. , Joyce C. J. , Labrador A. W. , Malandraki O. , Matthaeus W. H. , McComas D. J. , McNutt R. L. , Mewaldt R. A. , Mitchell D. G. , Posner A. , Rankin J. S. , Roelof E. C. , Schwadron N. A. , Stone E. C. , Szalay J. R. , Bale S. D. , Case A. W. , Kasper J. C. , Korreck K. E. , Larson D. E. , MacDowall R. J. , Pulupa M. , Stevens M. L. 
Published: February 2020

Abstract
The Integrated Science Investigation of the Sun (IS⊙IS) instrument suite on the Parker Solar Probe (PSP) spacecraft is making in situ observations of energetic ions and electrons closer to the Sun than any previous mission. Using data collected during its first two orbits, which reached perihelion distances of 0.17 au, we have searched for

-rich solar energetic particle (SEP) events under very quiet solar minimum conditions. On 2019-110–111 (April 20–21),

-rich SEPs were observed at energies near 1 MeV nucleon–1 in association with energetic protons, heavy ions, and electrons. This activity was also detected by the Ultra-Low-Energy Isotope Spectrometer and the Electron, Proton, and Alpha Monitor instruments on the Advanced Composition Explorer (ACE) spacecraft located near Earth, 0.99 au from the Sun. At that time, PSP and ACE were both magnetically connected to locations near the west limb of the Sun. Remote sensing measurements showed the presence of type III radio bursts and also helical jets from this region of the Sun. This combination of observations is commonly associated with

-rich SEP acceleration on the Sun. AR 12738, which was located at Carrington coordinates from which numerous X-ray flares were observed over a period of more than 6 months, was identified as the source of the

-rich events. This region was also the source of several other SEP events detected at PSP or ACE. Aside from the period in 2019 April, IS⊙IS did not observe any other

-rich SEPs during orbits 1 and 2.
First In Situ Measurements of Electron Density and Temperature from Quasi-thermal Noise Spectroscopy with Parker Solar Probe/FIELDS
Authors: Moncuquet Michel , Meyer-Vernet Nicole , Issautier Karine , Pulupa Marc , Bonnell J. W. , Bale Stuart D. , de Wit Thierry Dudok , Goetz Keith , Griton Léa , Harvey Peter R. , MacDowall Robert J. , Maksimovic Milan , Malaspina David M. 
Published: February 2020

Abstract
Heat transport in the solar corona and wind is still a major unsolved astrophysical problem. Because of the key role played by electrons, the electron density and temperature(s) are important prerequisites for understanding these plasmas. We present such in situ measurements along the two first solar encounters of the Parker Solar Probe, between 0.5 and 0.17 au from the Sun, revealing different states of the emerging solar wind near the solar activity minimum. These preliminary results are obtained from a simplified analysis of the plasma quasi-thermal noise (QTN) spectrum measured by the Radio Frequency Spectrometer (FIELDS). The local electron density is deduced from the tracking of the plasma line, which enables accurate measurements, independent of calibrations and spacecraft perturbations, whereas the temperatures of the thermal and suprathermal components of the velocity distribution, as well as the average kinetic temperature, are deduced from the shape of the plasma line. The temperature of the weakly collisional thermal population, similar for both encounters, decreases with the distance as R
−0.74, which is much slower than adiabatic. In contrast, the temperature of the nearly collisionless suprathermal population exhibits a virtually flat radial variation. The 7 s resolution of the density measurements enables us to deduce the low-frequency spectrum of compressive fluctuations around perihelion, varying as f
−1.4. This is the first time that QTN spectroscopy is implemented with an electric antenna length not exceeding the plasma Debye length. As PSP will approach the Sun, the decrease in the Debye length is expected to considerably improve the accuracy of the temperature measurements.
Sharp Alfvénic Impulses in the Near-Sun Solar Wind
Authors: Horbury Timothy S. , Woolley Thomas , Laker Ronan , Matteini Lorenzo , Eastwood Jonathan , Bale Stuart D. , Velli Marco , Chandran Benjamin D. G. , Phan Tai , Raouafi Nour E. , Goetz Keith , Harvey Peter R. , Pulupa Marc , Klein K. G. , Dudok de Wit Thierry , Kasper Justin C. , Korreck Kelly E. , Case A. W. , Stevens Michael L. , Whittlesey Phyllis , Larson Davin , MacDowall Robert J. , Malaspina David M. , Livi Roberto 
Published: February 2020

Abstract
Measurements of the near-Sun solar wind by the Parker Solar Probe have revealed the presence of large numbers of discrete Alfvénic impulses with an anti-sunward sense of propagation. These are similar to those previously observed near 1 au, in high speed streams over the Sun’s poles and at 60 solar radii. At 35 solar radii, however, they are typically shorter and sharper than seen elsewhere. In addition, these spikes occur in “patches” and there are also clear periods within the same stream when they do not occur; the timescale of these patches might be related to the rate at which the spacecraft magnetic footpoint tracks across the coronal hole from which the plasma originated. While the velocity fluctuations associated with these spikes are typically under 100 km s−1, due to the rather low Alfvén speeds in the streams observed by the spacecraft to date, these are still associated with large angular deflections of the magnetic field—and these deflections are not isotropic. These deflections do not appear to be related to the recently reported large-scale, pro-rotation solar wind flow. Estimates of the size and shape of the spikes reveal high aspect ratio flow-aligned structures with a transverse scale of ≈104 km. These events might be signatures of near-Sun impulsive reconnection events.
Observations of Heating along Intermittent Structures in the Inner Heliosphere from PSP Data
Authors: Qudsi R. A. , Maruca B. A. , Matthaeus W. H. , Parashar T. N. , Bandyopadhyay Riddhi , Chhiber R. , Chasapis A. , Goldstein Melvyn L. , Bale S. D. , Bonnell J. W. , Dudok de Wit T. , Goetz K. , Harvey P. R. , MacDowall R. J. , Malaspina D. , Pulupa M. , Kasper J. C. , Korreck K. E. , Case A. W. , Stevens M. , Whittlesey P. , Larson D. , Livi R. , Velli M. , Raouafi N. 
Published: February 2020

Abstract
The solar wind proton temperature at 1 au has been found to be correlated with small-scale intermittent magnetic structures, i.e., regions with enhanced temperature are associated with coherent structures, such as current sheets. Using Parker Solar Probe data from the first encounter, we study this association using measurements of the radial proton temperature, employing the partial variance of increments (PVI) technique to identify intermittent magnetic structures. We observe that the probability density functions of high PVI events have higher median temperatures than those with lower PVI. The regions in space where PVI peaks were also locations that had enhanced temperatures when compared with similar regions, suggesting a heating mechanism in the young solar wind that is associated with intermittency developed by a nonlinear turbulent cascade in the immediate vicinity.
Statistics and Polarization of Type III Radio Bursts Observed in the Inner Heliosphere
Authors: Pulupa Marc , Bale Stuart D. , Badman Samuel T. , Bonnell J. W. , Case Anthony W. , de Wit Thierry Dudok , Goetz Keith , Harvey Peter R. , Hegedus Alexander M. , Kasper Justin C. , Korreck Kelly E. , Krasnoselskikh Vladimir , Larson Davin , Lecacheux Alain , Livi Roberto , MacDowall Robert J. , Maksimovic Milan , Malaspina David M. , Martínez Oliveros Juan Carlos , Meyer-Vernet Nicole , Moncuquet Michel , Stevens Michael , Whittlesey Phyllis 
Published: February 2020

Abstract
We present initial results from the Radio Frequency Spectrometer, the high-frequency component of the FIELDS experiment on the Parker Solar Probe (PSP). During the first PSP solar encounter (2018 November), only a few small radio bursts were observed. During the second encounter (2019 April), copious type III radio bursts occurred, including intervals of radio storms where bursts occurred continuously. In this paper, we present initial observations of the characteristics of type III radio bursts in the inner heliosphere, calculating occurrence rates, amplitude distributions, and spectral properties of the observed bursts. We also report observations of several bursts during the second encounter that display circular polarization in the right-hand-polarized sense, with a degree of polarization of 0.15–0.38 in the range from 8 to 12 MHz. The degree of polarization can be explained either by depolarization of initially 100% polarized o-mode emission or by direct generation of emission in the o-mode and x-mode simultaneously. Direct in situ observations in future PSP encounters could provide data that can distinguish these mechanisms.
Time Domain Structures and Dust in the Solar Vicinity: Parker Solar Probe Observations
Authors: Mozer F. S. , Agapitov O. V. , Bale S. D. , Bonnell J. W. , Goetz K. , Goodrich K. A. , Gore R. , Harvey P. R. , Kellogg P. J. , Malaspina D. , Pulupa M. , Schumm G. 
Published: February 2020

Abstract
On 2019 April 5, while the Parker Solar Probe was at its 35 solar radius perihelion, the data set collected at 293 samples/s contained more than 10,000 examples of spiky electric-field-like structures with durations less than 200 milliseconds and amplitudes greater than 10 mV m−1. The vast majority of these events were caused by plasma turbulence. Defining dust events as those with similar, narrowly peaked, positive, and single-ended signatures resulted in finding 135 clear dust events, which, after correcting for the low detection efficiently, resulted in an estimate consistent with the 1000 dust events expected from other techniques. Defining time domain structures (TDS) as those with opposite polarity signals in the opposite antennas resulted in finding 238 clear TDS events which, after correcting for the detection efficiency, resulted in an estimated 500–1000 TDS events on this day. The TDS electric fields were bipolar, as expected for electron holes. Several events were found at times when the magnetic field was in the plane of the two measured components of the electric field such that the component of the electric field parallel to the magnetic field was measured. One example of significant parallel electric fields shows the negative potential that classified them as electron holes. Because the TDS observation rate was not uniform with time, it is likely that there were local regions below the spacecraft with field-aligned currents that generated the TDS.
Examining Dust Directionality with the Parker Solar Probe FIELDS Instrument
Authors: Page Brent , Bale Stuart D. , Bonnell J. W. , Goetz Keith , Goodrich Katherine , Harvey Peter R. , Larsen Rhiannon , MacDowall Robert J. , Malaspina David M. , Pokorný Petr , Pulupa Marc , Szalay Jamey R. 
Published: February 2020

Abstract

Parker Solar Probe’s (PSP’s) FIELDS instrument provides a measure of the dust impact rate on the spacecraft with a full-coverage summary of the voltages recorded by the spacecraft’s antennas. From consecutively sampled periods throughout PSP’s orbit, FIELDS stores the maximum amplitude measured by each active antenna. The occurrence of a dust impact during a given period can be identified by these amplitudes exceeding a few tens of millivolts, and a dust grain’s impact location can be approximated using the differential amplitudes between antennas. The impact locations indicated in the data are inspected for compatibility with the incident directions of prograde, retrograde, and β-meteoroid orbits in the ecliptic. Important features in the data are consistent with the incidence of β-meteoroids, but others are better explained by the incidence of grains on prograde or retrograde orbits.
Kinetic-scale Spectral Features of Cross Helicity and Residual Energy in the Inner Heliosphere
Authors: Vech Daniel , Kasper Justin C. , Klein Kristopher G. , Huang Jia , Stevens Michael L. , Chen Christopher H. K. , Case Anthony W. , Korreck Kelly , Bale Stuart D. , Bowen Trevor A. , Whittlesey Phyllis L. , Livi Roberto , Larson Davin E. , Malaspina David , Pulupa Marc , Bonnell John , Harvey Peter , Goetz Keith , Dudok de Wit Thierry , MacDowall Robert 
Published: February 2020

Abstract
In this work, we present the first results from the flux angle (FA) operation mode of the Faraday Cup instrument on board the Parker Solar Probe (PSP). The FA mode allows rapid measurements of phase space density fluctuations close to the peak of the proton velocity distribution function with a cadence of 293 Hz. This approach provides an invaluable tool for understanding kinetic-scale turbulence in the solar wind and solar corona. We describe a technique to convert the phase space density fluctuations into vector velocity components and compute several turbulence parameters, such as spectral index, residual energy, and cross helicity during two intervals when the FA mode was used in PSP’s first encounter at 0.174 au distance from the Sun.
The Evolution and Role of Solar Wind Turbulence in the Inner Heliosphere
Authors: Chen C. H. K. , Bale S. D. , Bonnell J. W. , Borovikov D. , Bowen T. A. , Burgess D. , Case A. W. , Chandran B. D. G. , de Wit T. Dudok , Goetz K. , Harvey P. R. , Kasper J. C. , Klein K. G. , Korreck K. E. , Larson D. , Livi R. , MacDowall R. J. , Malaspina D. M. , Mallet A. , McManus M. D. , Moncuquet M. , Pulupa M. , Stevens M. L. , Whittlesey P. 
Published: February 2020

Abstract
The first two orbits of the Parker Solar Probe spacecraft have enabled the first in situ measurements of the solar wind down to a heliocentric distance of 0.17 au (or 36

). Here, we present an analysis of this data to study solar wind turbulence at 0.17 au and its evolution out to 1 au. While many features remain similar, key differences at 0.17 au include increased turbulence energy levels by more than an order of magnitude, a magnetic field spectral index of −3/2 matching that of the velocity and both Elsasser fields, a lower magnetic compressibility consistent with a smaller slow-mode kinetic energy fraction, and a much smaller outer scale that has had time for substantial nonlinear processing. There is also an overall increase in the dominance of outward-propagating Alfvénic fluctuations compared to inward-propagating ones, and the radial variation of the inward component is consistent with its generation by reflection from the large-scale gradient in Alfvén speed. The energy flux in this turbulence at 0.17 au was found to be ∼10% of that in the bulk solar wind kinetic energy, becoming ∼40% when extrapolated to the Alfvén point, and both the fraction and rate of increase of this flux toward the Sun are consistent with turbulence-driven models in which the solar wind is powered by this flux.