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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: 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: 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.125.025102http://harvest.aps.org/v2/journals/articles/10.1103/PhysRevLett.125.025102/fulltexthttps://link.aps.org/article/10.1103/PhysRevLett.125.025102
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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.125.025102http://harvest.aps.org/v2/journals/articles/10.1103/PhysRevLett.125.025102/fulltexthttps://link.aps.org/article/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 str. . .
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: 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: 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 enc. . .
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: 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: 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: 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 RDate: 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: 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 wit. . .
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: 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: 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: 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 incidence of β-m. . .
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 RDate: 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: 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: 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: 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: 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: 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: Malaspina David M., Szalay Jamey R., Pokorný Petr, Page Brent, Bale Stuart D., et al.
Title: In Situ Observations of Interplanetary Dust Variability in the Inner Heliosphere
Abstract:

This work examines the variation of interplanetary dust count rates and directionality during the first three solar encounters made by the Parker Solar Probe spacecraft, covering distances between 0.65 au (∼140 solar radii, RS) and 0.16 au (∼35 RS). Dust detections are made by the FIELDS instrument via plasma clouds, produced by impact ionization of dust grains on spacecraft surfaces and resultant spacecraft potential perturbations. Dust count rates and inferred densities are found to vary by ∼50% between the three solar encounters (∼5 months per orbit), with most of the variation concentrated below 0.23 au (∼50RS). Dust count rates and directionality, as well as the encounter-to-encounter variability in both quantities are found to be consiste. . .
Date: 04/2020 Publisher: The Astrophysical Journal Pages: 115 DOI: 10.3847/1538-4357/ab799b Available at: https://iopscience.iop.org/article/10.3847/1538-4357/ab799b
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Authors: Malaspina David M., Szalay Jamey R., Pokorný Petr, Page Brent, Bale Stuart D., et al.
Title: In Situ Observations of Interplanetary Dust Variability in the Inner Heliosphere
Abstract:

This work examines the variation of interplanetary dust count rates and directionality during the first three solar encounters made by the Parker Solar Probe spacecraft, covering distances between 0.65 au (\~140 solar radii, RS) and 0.16 au (\~35 RS). Dust detections are made by the FIELDS instrument via plasma clouds, produced by impact ionization of dust grains on spacecraft surfaces and resultant spacecraft potential perturbations. Dust count rates and inferred densities are found to vary by \~50% between the three solar encounters (\~5 months per orbit), with most of the variation concentrated below 0.23 au (\~50RS). Dust count rates and directionality, as well as the encounter-to-encounter variability in both quantities are found to be consistent wi. . .
Date: 04/2020 Publisher: The Astrophysical Journal Pages: 115 DOI: 10.3847/1538-4357/ab799b Available at: https://iopscience.iop.org/article/10.3847/1538-4357/ab799b
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Authors: Bowen Trevor A., Mallet Alfred, Huang Jia, Klein Kristopher G., Malaspina David M., et al.
Title: Ion-scale Electromagnetic Waves in the Inner Heliosphere
Abstract:

Understanding the physical processes in the solar wind and corona that actively contribute to heating, acceleration, and dissipation is a primary objective of NASA's Parker Solar Probe (PSP) mission. Observations of circularly polarized electromagnetic waves at ion scales suggest that cyclotron resonance and wave─particle interactions are dynamically relevant in the inner heliosphere. A wavelet-based statistical study of circularly polarized events in the first perihelion encounter of PSP demonstrates that transverse electromagnetic waves at ion resonant scales are observed in 30─50% of radial field intervals. Average wave amplitudes of approximately 4 nT are measured, while the mean duration of wave events is on the order of 20 s; however, long-duration wave events can exist withou. . .
Date: 02/2020 Publisher: The Astrophysical Journal Supplement Series Pages: 66 DOI: 10.3847/1538-4365/ab6c65 Available at: https://iopscience.iop.org/article/10.3847/1538-4365/
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