Found 116 results
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2020
Authors: Nieves-Chinchilla Teresa, Szabo Adam, Korreck Kelly E., Alzate Nathalia, Balmaceda Laura A., et al.
Title: Analysis of the Internal Structure of the Streamer Blowout Observed by the Parker Solar Probe During the First Solar Encounter
Abstract:

In this paper, we present an analysis of the internal structure of a coronal mass ejection (CME) detected by in situ instruments on board the Parker Solar Probe (PSP) spacecraft during its first solar encounter. On 2018 November 11 at 23:53 UT, the FIELDS magnetometer measured an increase in strength of the magnetic field as well as a coherent change in the field direction. The SWEAP instrument simultaneously detected a low proton temperature and signatures of bidirectionality in the electron pitch angle distribution (PAD). These signatures are indicative of a CME embedded in the slow solar wind. Operating in conjunction with PSP was the STEREO A spacecraft, which enabled the remote observation of a streamer blowout by the SECCHI suite of instruments. The source at the Sun of the slow a. . .
Date: 02/2020 Publisher: The Astrophysical Journal Supplement Series Pages: 63 DOI: 10.3847/1538-4365/ab61f5 Available at: https://iopscience.iop.org/article/10.3847/1538-4365/ab61f5
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Authors: Maksimovic M., Bale S. D., Berčič L., Bonnell J. W., Case A. W., et al.
Title: Anticorrelation between the Bulk Speed and the Electron Temperature in the Pristine Solar Wind: First Results from the Parker Solar Probe and Comparison with Helios
Abstract:

We discuss the solar wind electron temperatures Te as measured in the nascent solar wind by Parker Solar Probe during its first perihelion pass. The measurements have been obtained by fitting the high-frequency part of quasi-thermal noise spectra recorded by the Radio Frequency Spectrometer. In addition we compare these measurements with those obtained by the electrostatic analyzer discussed in Halekas et al. These first electron observations show an anticorrelation between Te and the wind bulk speed V: this anticorrelation is most likely the remnant of the well-known mapping observed at 1 au and beyond between the fast wind and its coronal hole sources, where electrons are observed to be cooler than in the quiet corona. We also revisit Helios electron temperature . . .
Date: 02/2020 Publisher: The Astrophysical Journal Supplement Series Pages: 62 DOI: 10.3847/1538-4365/ab61fc Available at: https://iopscience.iop.org/article/10.3847/1538-4365/ab61fch
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Authors: Chhiber Rohit, Goldstein M L., Maruca B. A., Chasapis A., Matthaeus W. H., et al.
Title: Clustering of Intermittent Magnetic and Flow Structures near Parker Solar Probe ’s First Perihelion—A Partial-variance-of-increments Analysis
Abstract:

During the Parker Solar Probe’s (PSP) first perihelion pass, the spacecraft reached within a heliocentric distance of ̃37 R and observed numerous magnetic and flow structures characterized by sharp gradients. To better understand these intermittent structures in the young solar wind, an important property to examine is their degree of correlation in time and space. To this end, we use the well-tested partial variance of increments (PVI) technique to identify intermittent events in FIELDS and SWEAP observations of magnetic and proton-velocity fields (respectively) during PSP’s first solar encounter, when the spacecraft was within 0.25 au from the Sun. We then examine distributions of waiting times (WT) between events with varying separation and PVI thresholds. We find . . .
Date: 02/2020 Publisher: The Astrophysical Journal Supplement Series Pages: 31 DOI: 10.3847/1538-4365/ab53d2 Available at: https://iopscience.iop.org/article/10.3847/1538-4365/ab53d2
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Authors: Bowen Trevor A., Mallet Alfred, Bale Stuart D., Bonnell J. W., Case Anthony W., et al.
Title: Constraining Ion-Scale Heating and Spectral Energy Transfer in Observations of Plasma Turbulence
Abstract:

We perform a statistical study of the turbulent power spectrum at inertial and kinetic scales observed during the first perihelion encounter of the Parker Solar Probe. We find that often there is an extremely steep scaling range of the power spectrum just above the ion-kinetic scales, similar to prior observations at 1 A.U., with a power-law index of around -4 . Based on our measurements, we demonstrate that either a significant (>50 %) fraction of the total turbulent energy flux is dissipated in this range of scales, or the characteristic nonlinear interaction time of the turbulence decreases dramatically from the expectation based solely on the dispersive nature of nonlinearly interacting kinetic Alfvén waves.


Date: 07/2020 Publisher: Physical Review Letters DOI: 10.1103/PhysRevLett.125.025102 Available at: https://link.aps.org/doi/10.1103/PhysRevLett.125.025102
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Authors: Berčič Laura, Larson Davin, Whittlesey Phyllis, Maksimovic Milan, Badman Samuel T., et al.
Title: Coronal Electron Temperature Inferred from the Strahl Electrons in the Inner Heliosphere: Parker Solar Probe and Helios Observations
Abstract:

The shape of the electron velocity distribution function plays an important role in the dynamics of the solar wind acceleration. Electrons are normally modeled with three components, the core, the halo, and the strahl. We investigate how well the fast strahl electrons in the inner heliosphere preserve the information about the coronal electron temperature at their origin. We analyzed the data obtained by two missions, Helios, spanning the distances between 65 and 215 RS, and Parker Solar Probe (PSP), reaching down to 35 RS during its first two orbits around the Sun. The electron strahl was characterized with two parameters: pitch-angle width (PAW) and the strahl parallel temperature (Ts||). PSP observations confirm the already reported dependence of stra. . .
Date: 04/2020 Publisher: The Astrophysical Journal Pages: 88 DOI: 10.3847/1538-4357/ab7b7a Available at: https://iopscience.iop.org/article/10.3847/1538-4357/ab7b7a
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Authors: Sterling Alphonse C., and Moore Ronald L.
Title: Coronal-jet-producing Minifilament Eruptions as a Possible Source of Parker Solar Probe Switchbacks
Abstract:

The Parker Solar Probe (PSP) has observed copious rapid magnetic field direction changes in the near-Sun solar wind. These features have been called "switchbacks," and their origin is a mystery. But their widespread nature suggests that they may be generated by a frequently occurring process in the Sun’s atmosphere. We examine the possibility that the switchbacks originate from coronal jets. Recent work suggests that many coronal jets result when photospheric magnetic flux cancels, and forms a small-scale "minifilament" flux rope that erupts and reconnects with coronal field. We argue that the reconnected erupting-minifilament flux rope can manifest as an outward propagating Alfvénic fluctuation that steepens into an increasingly compact disturbance as it moves through the solar wind. . .
Date: 06/2020 Publisher: The Astrophysical Journal Pages: L18 DOI: 10.3847/2041-8213/ab96be Available at: https://iopscience.iop.org/article/10.3847/2041-8213/ab96behttps://iopscience.iop.org/article/10.3847/2041-8213/ab96be/
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Authors: McManus Michael D., Bowen Trevor A., Mallet Alfred, Chen Christopher H. K., Chandran Benjamin D. G., et al.
Title: Cross Helicity Reversals in Magnetic Switchbacks
Abstract:

We consider 2D joint distributions of normalized residual energy, σr(s, t), and cross helicity, σc(s, t), during one day of Parker Solar Probe’s (PSP’s) first encounter as a function of wavelet scale s. The broad features of the distributions are similar to previous observations made by Helios in slow solar wind, namely well-correlated and fairly Alfvénic wind, except for a population with negative cross helicity that is seen at shorter wavelet scales. We show that this population is due to the presence of magnetic switchbacks, or brief periods where the magnetic field polarity reverses. Such switchbacks have been observed before, both in Helios data and in Ulysses data in the polar solar wind. Their abundance and short timescales as seen by PSP in its first. . .
Date: 02/2020 Publisher: The Astrophysical Journal Supplement Series Pages: 67 DOI: 10.3847/1538-4365/ab6dce Available at: https://iopscience.iop.org/article/10.3847/1538-4365
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Authors: Krupar Vratislav, Szabo Adam, Maksimovic Milan, Kruparova Oksana, Kontar Eduard P., et al.
Title: Density Fluctuations in the Solar Wind Based on Type III Radio Bursts Observed by Parker Solar Probe
Abstract:

Radio waves are strongly scattered in the solar wind, so that their apparent sources seem to be considerably larger and shifted than the actual ones. Since the scattering depends on the spectrum of density turbulence, a better understanding of the radio wave propagation provides indirect information on the relative density fluctuations, ϵ=⟨δn⟩/⟨n⟩ ϵ=⟨δn⟩/⟨n⟩ , at the effective turbulence scale length. Here, we analyzed 30 type III bursts detected by Parker Solar Probe (PSP). For the first time, we retrieved type III burst decay times, τ d  τd , between 1 and 10 MHz thanks to an unparalleled temporal resolution of PSP. We observed a significant deviation in a power-law slope for frequencies above 1 MHz. . .
Date: 02/2020 Publisher: The Astrophysical Journal Supplement Series Pages: 57 DOI: 10.3847/1538-4365/ab65bd Available at: https://iopscience.iop.org/article/10.3847/1538-4365/ab65bd
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Authors: Poirier Nicolas, Kouloumvakos Athanasios, Rouillard Alexis P., Pinto Rui F., Vourlidas Angelos, et al.
Title: Detailed Imaging of Coronal Rays with the Parker Solar Probe
Abstract:

The Wide-field Imager for Solar PRobe (WISPR) obtained the first high-resolution images of coronal rays at heights below 15 R when the Parker Solar Probe (PSP) was located inside 0.25 au during the first encounter. We exploit these remarkable images to reveal the structure of coronal rays at scales that are not easily discernible in images taken from near 1 au. To analyze and interpret WISPR observations, which evolve rapidly both radially and longitudinally, we construct a latitude versus time map using the full WISPR data set from the first encounter. From the exploitation of this map and also from sequential WISPR images. we show the presence of multiple substructures inside streamers and pseudostreamers. WISPR unveils the fine-scale structure of the densest part of str. . .
Date: 02/2020 Publisher: The Astrophysical Journal Supplement Series Pages: 60 DOI: 10.3847/1538-4365/ab6324 Available at: https://iopscience.iop.org/article/10.3847/1538-4365/ab6324
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Authors: Lapenta Giovanni, Zhukov Andrei, and van Driel-Gesztelyi Lidia
Title: Editorial: Solar Wind at the Dawn of the Parker Solar Probe and Solar Orbiter Era
Abstract:

Solar Wind 15 brought together almost 250 experts from all continents of the world to discuss the current trends and future perspectives of the research on the Sun and its solar wind. The present article collection recaptures some of the highlights of their contributions.


Date: 07/2020 Publisher: Solar Physics DOI: 10.1007/s11207-020-01670-8 Available at: http://link.springer.com/10.1007/s11207-020-01670-8http://link.springer.com/content/pdf/10.1007/s11207-020-01670-8.pdf
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Authors: Bowen Trevor A., Bale Stuart D., Bonnell J. W., Larson Davin, Mallet Alfred, et al.
Title: The Electromagnetic Signature of Outward Propagating Ion-scale Waves
Abstract:

First results from the Parker Solar Probe (PSP) mission have revealed ubiquitous coherent ion-scale waves in the inner heliosphere, which are signatures of kinetic wave-particle interactions and fluid instabilities. However, initial studies of the circularly polarized ion-scale waves observed by PSP have only thoroughly analyzed magnetic field signatures, precluding a determination of solar wind frame propagation direction and intrinsic wave polarization. A comprehensive determination of wave properties requires measurements of both electric and magnetic fields. Here, we use full capabilities of the PSP/FIELDS instrument suite to measure both the electric and magnetic components of circularly polarized waves. Comparing spacecraft frame magnetic field measurements with the Doppler-shifte. . .
Date: 08/2020 Publisher: The Astrophysical Journal Pages: 74 DOI: 10.3847/1538-4357/ab9f37 Available at: https://iopscience.iop.org/article/10.3847/1538-4357/ab9f37https://iopscience.iop.org/article/10.3847/1538-4357/ab9f37/
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Authors: Halekas J. S., Whittlesey P., Larson D. E., McGinnis D., Maksimovic M., et al.
Title: Electrons in the Young Solar Wind: First Results from the Parker Solar Probe
Abstract:

The Solar Wind Electrons Alphas and Protons experiment on the Parker Solar Probe (PSP) mission measures the three-dimensional electron velocity distribution function. We derive the parameters of the core, halo, and strahl populations utilizing a combination of fitting to model distributions and numerical integration for ̃100,000 electron distributions measured near the Sun on the first two PSP orbits, which reached heliocentric distances as small as ̃0.17 au. As expected, the electron core density and temperature increase with decreasing heliocentric distance, while the ratio of electron thermal pressure to magnetic pressure (βe) decreases. These quantities have radial scaling consistent with previous observations farther from the Sun, with superposed variations associated. . .
Date: 02/2020 Publisher: The Astrophysical Journal Supplement Series Pages: 22 DOI: 10.3847/1538-4365/ab4cec Available at: https://iopscience.iop.org/article/10.3847/1538-4365/ab4cec
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Authors: Cohen C. M. S., Christian E. R., Cummings A. C., Davis A. J., Desai M. I., et al.
Title: Energetic Particle Increases Associated with Stream Interaction Regions
Abstract:

The Parker Solar Probe was launched on 2018 August 12 and completed its second orbit on 2019 June 19 with perihelion of 35.7 solar radii. During this time, the Energetic Particle Instrument-Hi (EPI-Hi, one of the two energetic particle instruments comprising the Integrated Science Investigation of the Sun, IS☉IS) measured seven proton intensity increases associated with stream interaction regions (SIRs), two of which appear to be occurring in the same region corotating with the Sun. The events are relatively weak, with observed proton spectra extending to only a few MeV and lasting for a few days. The proton spectra are best characterized by power laws with indices ranging from -4.3 to -6.5, generally softer than events associated with SIRs observed at 1 au and beyond. Helium spectra . . .
Date: 02/2020 Publisher: The Astrophysical Journal Supplement Series Pages: 20 DOI: 10.3847/1538-4365/ab4c38 Available at: https://iopscience.iop.org/article/10.3847/1538-4365/ab4c38
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Authors: Joyce C. J., McComas D. J., Christian E. R., Schwadron N. A., Wiedenbeck M. E., et al.
Title: Energetic Particle Observations from the Parker Solar Probe Using Combined Energy Spectra from the IS⊙IS Instrument Suite
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 gro. . .
Date: 02/2020 Publisher: The Astrophysical Journal Supplement Series Pages: 41 DOI: 10.3847/1538-4365/ab5948 Available at: https://iopscience.iop.org/article/10.3847/1538-4365/ab5948
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Authors: Bandyopadhyay Riddhi, Goldstein M. L., Maruca B. A., Matthaeus W. H., Parashar T. N., et al.
Title: Enhanced Energy Transfer Rate in Solar Wind Turbulence Observed near the Sun from Parker Solar Probe
Abstract:

Direct evidence of an inertial-range turbulent energy cascade has been provided by spacecraft observations in heliospheric plasmas. In the solar wind, the average value of the derived heating rate near 1 au is \~10 3 Jkg -1 s -1  \~103Jkg-1s-1 , an amount sufficient to account for observed departures from adiabatic expansion. Parker Solar Probe, even during its first solar encounter, offers the first opportunity to compute, in a similar fashion, a fluid-scale energy decay rate, much closer to the solar corona than any prior in situ observations. Using the Politano-Pouquet third-order law and the von Kármán decay law, we estimate the fluid-range energy transfer rate in the inner heliosphere, at heliocentric distance R ranging from 54 R (. . .
Date: 02/2020 Publisher: The Astrophysical Journal Supplement Series Pages: 48 DOI: 10.3847/1538-4365/ab5dae Available at: https://iopscience.iop.org/article/10.3847/1538-4365/ab5dae
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Authors: Martinović Mihailo M., Klein Kristopher G., Kasper Justin C., Case Anthony W., Korreck Kelly E., et al.
Title: The Enhancement of Proton Stochastic Heating in the Near-Sun Solar Wind
Abstract:

Stochastic heating (SH) is a nonlinear heating mechanism driven by the violation of magnetic moment invariance due to large-amplitude turbulent fluctuations producing diffusion of ions toward higher kinetic energies in the direction perpendicular to the magnetic field. It is frequently invoked as a mechanism responsible for the heating of ions in the solar wind. Here, we quantify for the first time the proton SH rate Q at radial distances from the Sun as close as 0.16 au, using measurements from the first two Parker Solar Probe encounters. Our results for both the amplitude and radial trend of the heating rate, Q ∝ r-2.5, agree with previous results based on the Helios data set at heliocentric distances from 0.3 to 0.9 au. Also in agreement with . . .
Date: 02/2020 Publisher: The Astrophysical Journal Supplement Series Pages: 30 DOI: 10.3847/1538-4365/ab527f Available at: https://iopscience.iop.org/article/10.3847/1538-4365/ab527f
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Authors: Chen C. H. K., Bale S. D., Bonnell J. W., Borovikov D., Bowen T. A., et al.
Title: The Evolution and Role of Solar Wind Turbulence in the Inner Heliosphere
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 R ⊙  R⊙ ). 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 . . .
Date: 02/2020 Publisher: The Astrophysical Journal Supplement Series Pages: 53 DOI: 10.3847/1538-4365/ab60a3 Available at: https://iopscience.iop.org/article/10.3847/1538-4365/ab60a3
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Authors: Page Brent, Bale Stuart D., Bonnell J. W., Goetz Keith, Goodrich Katherine, et al.
Title: Examining Dust Directionality with the Parker Solar Probe FIELDS Instrument
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 inciden. . .
Date: 02/2020 Publisher: The Astrophysical Journal Supplement Series Pages: 51 DOI: 10.3847/1538-4365/ab5f6a Available at: https://iopscience.iop.org/article/10.3847/1538-4365/ab5f6a
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Authors: Panasenco Olga, Velli Marco, D’Amicis Raffaella, Shi Chen, Réville Victor, et al.
Title: Exploring Solar Wind Origins and Connecting Plasma Flows from the Parker Solar Probe to 1 au: Nonspherical Source Surface and Alfvénic Fluctuations
Abstract:

The magnetic field measurements of the FIELDS instrument on the Parker Solar Probe (PSP) have shown intensities, throughout its first solar encounter, that require a very low source surface (SS) height ( R SS ⩽1.8R ⊙  RSS⩽1.8R⊙ ) to be reconciled with magnetic field measurements at the Sun via potential field extrapolation (PFSS). However, during PSP’s second encounter, the situation went back to a more classic SS height ( R SS ⩽2.5R ⊙  RSS⩽2.5R⊙ ). Here we use high-resolution observations of the photospheric magnetic field (Solar Dynamics Observatory/Helioseismic and Magnetic Imager) to calculate neutral lines and boundaries of the open field regions for SS heights from 1.2 to 2.5 R<. . .
Date: 02/2020 Publisher: The Astrophysical Journal Supplement Series Pages: 54 DOI: 10.3847/1538-4365/ab61f4 Available at: https://iopscience.iop.org/article/10.3847/1538-4365/ab61f4
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Authors: Parker Eugene N.
Title: Exploring the innermost solar atmosphere
Abstract:

The Parker Solar Probe spacecraft completed the first two of its 24 scheduled orbits around the Sun on 18 June 2019, making history by flying halfway between Mercury and the Sun.


Date: 01/2020 Publisher: Nature Astronomy Pages: 19 - 20 DOI: 10.1038/s41550-019-0985-7 Available at: http://www.nature.com/articles/s41550-019-0985-7
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Authors: Moncuquet Michel, Meyer-Vernet Nicole, Issautier Karine, Pulupa Marc, Bonnell J. W., et al.
Title: First In Situ Measurements of Electron Density and Temperature from Quasi-thermal Noise Spectroscopy with Parker Solar Probe /FIELDS
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 pertur. . .
Date: 02/2020 Publisher: The Astrophysical Journal Supplement Series Pages: 44 DOI: 10.3847/1538-4365/ab5a84 Available at: https://iopscience.iop.org/article/10.3847/1538-4365/ab5a84
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Authors: Fisk L. A., and Kasper J. C.
Title: Global Circulation of the Open Magnetic Flux of the Sun
Abstract:

The global circulation of the open magnetic flux of the Sun, the component of the solar magnetic field that opens into the heliosphere, and the consequences of the global circulation were proposed by Fisk and coworkers in the early 2000s. The Parker Solar Probe, on its initial encounters with the Sun, has provided direct confirmation of both the global circulation and the physical mechanism by which the circulation occurs, transport by interchange reconnection between open magnetic flux and large coronal loops. The implications of this confirmation of the global circulation of open magnetic flux and the importance of interchange reconnection is discussed.


Date: 05/2020 Publisher: The Astrophysical Journal Pages: L4 DOI: 10.3847/2041-8213/ab8acd Available at: https://iopscience.iop.org/article/10.3847/2041-8213/ab8acd
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Authors: Lavraud B., Fargette N., Réville V., Szabo A., Huang J., et al.
Title: The Heliospheric Current Sheet and Plasma Sheet during Parker Solar Probe’s First Orbit
Abstract:

We present heliospheric current sheet (HCS) and plasma sheet (HPS) observations during Parker Solar Probe’s (PSP) first orbit around the Sun. We focus on the eight intervals that display a true sector boundary (TSB; based on suprathermal electron pitch angle distributions) with one or several associated current sheets. The analysis shows that (1) the main density enhancements in the vicinity of the TSB and HCS are typically associated with electron strahl dropouts, implying magnetic disconnection from the Sun, (2) the density enhancements are just about twice that in the surrounding regions, suggesting mixing of plasmas from each side of the HCS, (3) the velocity changes at the main boundaries are either correlated or anticorrelated with magnetic field changes, consistent with magneti. . .
Date: 05/2020 Publisher: The Astrophysical Journal Pages: L19 DOI: 10.3847/2041-8213/ab8d2d Available at: https://iopscience.iop.org/article/10.3847/2041-8213/ab8d2d
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Authors: Szabo Adam, Larson Davin, Whittlesey Phyllis, Stevens Michael L., Lavraud Benoit, et al.
Title: The Heliospheric Current Sheet in the Inner Heliosphere Observed by the Parker Solar Probe
Abstract:

The Parker Solar Probe (PSP) completed its first solar encounter in 2018 November, bringing it closer to the Sun than any previous mission. This allowed in situ investigation of the heliospheric current sheet (HCS) inside the orbit of Venus. The Parker observations reveal a well defined magnetic sector structure placing the spacecraft in a negative polarity region for most of the encounter. The observed current sheet crossings are compared to the predictions of both potential field source surface and magnetohydrodynamic models. All the model predictions are in good qualitative agreement with the observed crossings of the HCS. The models also generally agree that the HCS was nearly parallel with the solar equator during the inbound leg of the encounter and more significantly inclined dur. . .
Date: 02/2020 Publisher: The Astrophysical Journal Supplement Series Pages: 47 DOI: 10.3847/1538-4365/ab5dac Available at: https://iopscience.iop.org/article/10.3847/1538-4365/ab5dach
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Authors: Zhao L.-L., Zank G. P., Adhikari L., Hu Q., Kasper J. C., et al.
Title: Identification of Magnetic Flux Ropes from Parker Solar Probe Observations during the First Encounter
Abstract:

The Parker Solar Probe (PSP) observed an interplanetary coronal mass ejection (ICME) event during its first orbit around the Sun, among many other events. This event is analyzed by applying a wavelet analysis technique to obtain the reduced magnetic helicity, cross helicity, and residual energy, the first two of which are magnetohydrodynamics (MHD) invariants. Our results show that the ICME, as a large-scale magnetic flux rope, possesses high magnetic helicity, very low cross helicity, and highly negative residual energy, thus pointing to a magnetic fluctuation dominated structure. Using the same technique, we also search for small-scale coherent magnetic flux rope structures during the period from 2018 October 22 to November 21, which are intrinsic to quasi-two-dimensional MHD turbulen. . .
Date: 02/2020 Publisher: The Astrophysical Journal Supplement Series Pages: 26 DOI: 10.3847/1538-4365/ab4ff1 Available at: https://iopscience.iop.org/article/10.3847/1538-4365/ab4ff1
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