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119 results on '"Phyllis Whittlesey"'

1. Closed magnetic topology in the Venusian magnetotail and ion escape at Venus

Author: Shaosui Xu, David L. Mitchell, Phyllis Whittlesey, Ali Rahmati, Roberto Livi, Davin Larson, Janet G. Luhmann, Jasper S. Halekas, Takuya Hara, James P. McFadden, Marc Pulupa, Stuart D. Bale, Shannon M. Curry, and Moa Persson
Subjects: Science
Abstract: Abstract Venus, lacking an intrinsic global dipole magnetic field, serves as a textbook example of an induced magnetosphere, formed by interplanetary magnetic fields (IMF) enveloping the planet. Yet, various aspects of its magnetospheric dynamics and planetary ion outflows are complex and not well understood. Here we analyze plasma and magnetic field data acquired during the fourth Venus flyby of the Parker Solar Probe (PSP) mission and show evidence for closed topology in the nightside and downstream portion of the Venus magnetosphere (i.e., the magnetotail). The formation of the closed topology involves magnetic reconnection—a process rarely observed at non-magnetized planets. In addition, our study provides an evidence linking the cold Venusian ion flow in the magnetotail directly to magnetic connectivity to the ionosphere, akin to observations at Mars. These findings not only help the understanding of the complex ion flow patterns at Venus but also suggest that magnetic topology is one piece of key information for resolving ion escape mechanisms and thus the atmospheric evolution across various planetary environments and exoplanets.
Published: 2024
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2. Exospheric Solar Wind Model Based on Regularized Kappa Distributions for the Electrons Constrained by Parker Solar Probe Observations

Author: Viviane Pierrard, Maximilien Péters de Bonhome, Jasper Halekas, Charline Audoor, Phyllis Whittlesey, and Roberto Livi
Subjects: solar wind, exospheric models, regularized kappa, Parker Solar Probe, suprathermal electrons, velocity distributions, Physics, QC1-999, Plasma physics. Ionized gases, QC717.6-718.8
Abstract: In the present work, the kinetic exospheric model of the solar wind is improved by considering regularized Kappa distributions that have no diverging moments through consideration of a cut-off at relativistic velocities. The model becomes valid even for kappa indices lower than 2, which is important since low values of kappa are observed in the fast solar wind. The exospheric model shows that the electric potential accelerates the wind to supersonic velocities. The presence of suprathermal Strahl electrons at the exobase can further increase the velocity to higher values, leading to profiles comparable to the observations in the fast and slow wind at all radial distances. The kappa index is not the only parameter that influences the acceleration of the wind: the difference in the altitude of the exobase also makes a significant difference between the fast and slow wind. The exobase is located at lower altitudes in the coronal holes where the density is smaller than in the other regions of the corona, allowing the wind originating from the holes to be accelerated to higher velocities. The new observations of Parker Solar Probe are used to constrain the model. The observations at low radial distances show suprathermal electrons already well present in the Strahl in the antisunward direction and a deficit in the sunward direction, confirming the exospheric feature of almost no incoming particles. For proton distributions, we observe that the proton tail parallel to the magnetic field is already present at 17.2 Rs.
Published: 2023
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3. The multi-point assessment of the kinematics of shocks (MAKOS)

Author: Katherine Goodrich, Ian J. Cohen, Steven Schwartz, Lynn B. Wilson, Drew Turner, Amir Caspi, Keith Smith, Randall Rose, Phyllis Whittlesey, and Ferdinand Plaschke
Subjects: collisionless shock, bow shock, wave-particle interaction, mission concept study, space plasma instrumentation, Astronomy, QB1-991, Geophysics. Cosmic physics, QC801-809
Abstract: Collisionless shock waves are one of the main mechanisms of energy conversion in space plasmas. They can directly or indirectly drive other universal plasma processes such as magnetic reconnection, turbulence, particle acceleration and wave phenomena. Collisionless shocks employ a myriad of kinetic plasma mechanisms to convert the kinetic energy of supersonic flows in space to other forms of energy (e.g., thermal plasma, energetic particles, or electromagnetic energy) in order for the flow to pass an immovable obstacle. The partitioning of energy downstream of collisionless shocks is not well understood, nor are the processes which perform energy conversion. While we, as the heliophysics community, have collected an abundance of observations of the terrestrial bow shock, instrument and mission-level limitations have made it impossible to quantify this partition, to establish the physics within the shock layer responsible for it, and to understand its dependence on upstream conditions. This paper stresses the need for the first ever spacecraft mission specifically designed and dedicated to the observation of both the terrestrial bow shock as well as Interplanetary shocks in the solar wind. Our mission concept, the Multi-point Assessment of the Kinematics of Shocks (MAKOS), will greatly improve on previous observations of the terrestrial bow shock with instrumentation specifically tailored to observe the evolution of the solar wind through the shock.
Published: 2023
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4. Proton- and Alpha-driven Instabilities in an Ion Cyclotron Wave Event

Author: Michael D. McManus, Kristopher G. Klein, Stuart D. Bale, Trevor A. Bowen, Jia Huang, Davin Larson, Roberto Livi, Ali Rahmati, Orlando Romeo, Jaye Verniero, and Phyllis Whittlesey
Subjects: Heliosphere, Fast solar wind, Astrophysics, QB460-466
Abstract: Ion-scale wave events or wave storms in the solar wind are characterized by enhancements in magnetic field fluctuations as well as coherent magnetic field polarization signatures at or around the local ion cyclotron frequencies. In this paper, we study in detail one such wave event from Parker Solar Probe's (PSP) fourth encounter, consisting of an initial period of left-handed (LH) polarization abruptly transitioning to a strong period of right-handed (RH) polarization, accompanied by a clear core beam structure in both the alpha and proton velocity distribution functions. A linear stability analysis shows that the LH-polarized waves are anti-sunward propagating Alfvén/ion cyclotron waves primarily driven by a proton cyclotron instability in the proton core population, and the RH polarized waves are anti-sunward propagating fast magnetosonic/whistler waves driven by a firehose-like instability in the secondary alpha beam population. The abrupt transition from LH to RH is caused by a drop in the proton core temperature anisotropy. We find very good agreement between the frequencies and polarizations of the unstable wave modes as predicted by linear theory and those observed in the magnetic field spectra. Given the ubiquity of ion-scale wave signatures observed by PSP, this work gives insight into which exact instabilities may be active and mediating energy transfer in wave–particle interactions in the inner heliosphere, as well as highlighting the role a secondary alpha population may play as a rarely considered source of free energy available for producing wave activity.
Published: 2024
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5. Interplanetary mesoscale observatory (InterMeso): A mission to untangle dynamic mesoscale structures throughout the heliosphere

Author: Robert C. Allen, Evan J. Smith, Brian J. Anderson, Joseph E. Borovsky, George C. Ho, Lan Jian, Sämuel Krucker, Susan Lepri, Gang Li, Stefano Livi, Noé Lugaz, David M. Malaspina, Bennett A. Maruca, Parisa Mostafavi, Jim M. Raines, Daniel Verscharen, Juliana Vievering, Sarah K. Vines, Phyllis Whittlesey, Lynn B. Wilson III, and Robert F. Wimmer-Schweingruber
Subjects: solar wind, mission concept, mesoscale, particle acceleration, particle transport, Astronomy, QB1-991, Geophysics. Cosmic physics, QC801-809
Abstract: Mesoscale dynamics are a fundamental process in space physics, but fall within an observational gap of current and planned missions. Particularly in the solar wind, measurements at the mesoscales (100s RE to a few degrees heliographic longitude at 1 au) are crucial for understanding the connection between the corona and an observer anywhere within the heliosphere. Mesoscale dynamics may also be key to revealing the currently unresolved physics regulating particle acceleration and transport, magnetic field topology, and the causes of variability in the composition and acceleration of solar wind plasma. Studies using single-point observations do not allow for investigations into mesoscale solar wind dynamics and plasma variability, nor do they allow for the exploration of the sub-structuring of large-scale solar wind structures like coronal mass ejections (CMEs), co-rotating/stream interaction regions (CIR/SIRs), and the heliospheric plasma sheet. To address this fundamental gap in our knowledge of the heliosphere at these scales, the Interplanetary Mesoscale Observatory (InterMeso) concept employs a multi-point approach using four identical spacecraft in Earth-trailing orbits near 1 au. Varying drift speeds of the InterMeso spacecraft enable the mission to span a range of mesoscale separations in the solar wind, achieving significant and innovative science return. Simultaneous, longitudinally-separated measurements of structures co-rotating over the spacecraft also allow for disambiguation of spatiotemporal variability, tracking of the evolution of solar wind structures, and determination of how the transport of energetic particles is impacted by these variabilities.
Published: 2022
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6. Are Switchback Boundaries Observed by Parker Solar Probe Closed?

Author: Nina Bizien, Thierry Dudok de Wit, Clara Froment, Marco Velli, Anthony W. Case, Stuart D. Bale, Justin Kasper, Phyllis Whittlesey, Robert MacDowall, and Davin Larson
Subjects: Solar wind, Interplanetary magnetic fields, Interplanetary discontinuities, Astrophysics, QB460-466
Abstract: Switchbacks are sudden and large deflections in the magnetic field that Parker Solar Probe frequently observes in the inner heliosphere. Their ubiquitous occurrence has prompted numerous studies to determine their nature and origin. Our goal is to describe the boundary of these switchbacks using a series of events detected during the spacecraft’s first encounter with the Sun. Using FIELDS and SWEAP data, we investigate different methods for determining the boundary normal. The observed boundaries are arc-polarized structures with a rotation that is always contained in a plane. Classical minimum variance analysis gives misleading results and overestimates the number of rotational discontinuities. We propose a robust geometric method to identify the nature of these discontinuities, which involves determining whether or not the plane that contains them also includes the origin ( B = 0). Most boundaries appear to have the same characteristics as tangential discontinuities in the context of switchbacks, with little evidence for having rotational discontinuities. We find no effect of the size of the Parker spiral deviation. Furthermore, the thickness of the boundary is within MHD scales. We conclude that most of the switchback boundaries observed by Parker Solar Probe are likely to be closed, in contrast to previous studies. Our results suggest that their erosion may be much slower than expected.
Published: 2023
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7. The Temperature, Electron, and Pressure Characteristics of Switchbacks: Parker Solar Probe Observations

Author: Jia Huang, Justin C. Kasper, Davin E. Larson, Michael D. McManus, Phyllis Whittlesey, Roberto Livi, Ali Rahmati, Orlando Romeo, Mingzhe Liu, Lan K. Jian, Jaye L. Verniero, Marco Velli, Samuel T. Badman, Yeimy J. Rivera, Tatiana Niembro, Kristoff Paulson, Michael Stevens, Anthony W. Case, Trevor A. Bowen, Marc Pulupa, Stuart D. Bale, and Jasper S. Halekas
Subjects: Solar wind, Solar coronal heating, Interplanetary magnetic fields, Space plasmas, Astrophysics, QB460-466
Abstract: Parker Solar Probe observes unexpectedly prevalent switchbacks, which are rapid magnetic field reversals that last from seconds to hours, in the inner heliosphere, posing new challenges to understanding their nature, origin, and evolution. In this work, we investigate the thermal states, electron pitch-angle distributions, and pressure signatures of both inside and outside the switchbacks, separating a switchback into spike, transition region (TR), and quiet period (QP). Based on our analysis, we find that the proton temperature anisotropies in TRs seem to show an intermediate state between spike and QP plasmas. The proton temperatures are more enhanced in the spike than in the TR and QP, but the alpha temperatures and alpha-to-proton temperature ratios show the opposite trend to the proton temperatures, implying that the preferential heating mechanisms of protons and alphas are competing in different regions of switchbacks. Moreover, our results suggest that the electron-integrated intensities are almost the same across the switchbacks, but the electron pitch-angle distributions are more isotropic inside than outside switchbacks, implying switchbacks are intact structures, but strong scattering of electrons happens inside switchbacks. In addition, the examination of pressures reveals that the total pressures are comparable through an individual switchback, confirming switchbacks are pressure-balanced structures. These characteristics could further our understanding of ion heating, electron scattering, and the structure of switchbacks.
Published: 2023
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8. The Solar Probe Cup on the Parker Solar Probe

Author: A. W. Case, Justin C. Kasper, Michael L. Stevens, Kelly E. Korreck, Kristoff Paulson, Peter Daigneau, Dave Caldwell, Mark Freeman, Thayne Henry, Brianna Klingensmith, J. A. Bookbinder, Miles Robinson, Peter Berg, Chris Tiu, K. H. Wright Jr., Matthew J. Reinhart, David Curtis, Michael Ludlam, Davin Larson, Phyllis Whittlesey, Roberto Livi, Kristopher G. Klein, and Mihailo M. Martinović
Subjects: Solar wind, Solar instruments, Space plasmas, Space vehicle instruments, Solar corona, Astrophysics, QB460-466
Abstract: Solar Probe Cup (SPC) is a Faraday cup instrument on board NASA’s Parker Solar Probe ( PSP ) spacecraft designed to make rapid measurements of thermal coronal and solar wind plasma. The spacecraft is in a heliocentric orbit that takes it closer to the Sun than any previous spacecraft, allowing measurements to be made where the coronal and solar wind plasma is being heated and accelerated. The SPC instrument was designed to be pointed directly at the Sun at all times, allowing the solar wind (which is flowing primarily radially away from the Sun) to be measured throughout the orbit. The instrument is capable of measuring solar wind ions with an energy between 100 and 6000 V (protons with speeds from 139 to 1072 km s ^−1 ). It also measures electrons with an energy/charge between 100 and 1500 V. SPC has been designed to have a wide dynamic range that is capable of measuring protons and alpha particles at the closest perihelion (9.86 solar radii from the center of the Sun) and out to 0.25 au. Initial observations from the first orbit of PSP indicate that the instrument is functioning well.
Published: 2020
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9. Density and Velocity Fluctuations of Alpha Particles in Magnetic Switchbacks

Author: Michael D. McManus, Jaye Verniero, Stuart B. Bale, Trevor A. Bowen, Davin E. Larson, Justin C. Kasper, Roberto Livi, Lorenzo Matteini, Ali Rahmati, Orlando Romeo, Phyllis Whittlesey, and Thomas Woolley
Subjects: Solar Physics, Astrophysics
Abstract: Magnetic switchbacks, or sudden reversals in the magnetic field’s radial direction, are one of the more striking observations of the Parker Solar Probe (PSP) in its mission thus far. While their precise production mechanisms are still unknown, the two main theories are via interchange reconnection events and in situ generation. In this work, density and abundance variations of alpha particles are studied inside and outside individual switchbacks. We find no consistent compositional differences in the alpha particle abundance ratio, nαp, inside versus outside switchbacks, nor do we observe any signature when separating the switchbacks according to Vαp/Vpw, the ratio of the alpha–proton differential speed to the wave phase speed (the speed at which the switchback is traveling). We argue that these measurements cannot be used to rule in favor of one production mechanism over the other, due to the distance between PSP and the postulated interchange reconnection events. In addition, we examine the 3D velocity fluctuations of protons and alpha particles within individual switchbacks. While switchbacks are always associated with increases in proton velocity, alpha velocities may be enhanced, unchanged, or decrease. This is due to the interplay between Vpw and Vαp, with the Alfvénic motion of the alpha particles vanishing as the difference |Vpw – Vαp| decreases. We show how the Alfvénic motion of both the alphas and the protons through switchbacks can be understood as an approximately rigid arm rotation about the location of the wave frame, and illustrate that the wave frame can therefore be estimated using particle measurements alone, via sphere fitting.
Published: 2022
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10. A Revised Understanding of the Structure of the Venusian Magnetotail From a High‐Altitude Intercept With a Tail Ray by Parker Solar Probe

Author: Glyn A. Collinson, Robin Ramstad, Rudy Frahm, Lynn Wilson, Shaosui Xu, Phyllis Whittlesey, Stephen H. Brecht, and Stephen Ledvina
Published: 2022
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11. Observations of Quiescent Solar Wind Regions with Near-f ce Wave Activity

Author: Benjamin Short, David M. Malaspina, Jasper Halekas, Orlando Romeo, J. L. Verniero, Adam J. Finley, Justin C. Kasper, Ali Rahmati, Stuart D. Bale, John W. Bonnell, Anthony W. Case, Thierry Dudok de Wit, Keith Goetz, Katherine Goodrich, Peter R. Harvey, Kelly E. Korreck, Davin Larson, Roberto Livi, Robert J. MacDowall, Marc Pulupa, Michael L. Stevens, and Phyllis Whittlesey
Published: 2022
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12. Inhomogeneous Kinetic Alfvén Waves in the Near-Sun Solar Wind

Author: David M. Malaspina, Alexandros Chasapis, Peter Tatum, Chadi Salem, Stuart D. Bale, John W. Bonnell, Thierry Dudok de Wit, Keith Goetz, Marc Pulupa, Jasper Halekas, Phyllis Whittlesey, Roberto Livi, Anthony W. Case, Michael L. Stevens, and Davin Larson
Published: 2022
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13. Source and Propagation of a Streamer Blowout Coronal Mass Ejection Observed by the Parker Solar Probe

Author: Kelly Elizabeth Korreck, Adam Szabo, Teresa Nieves-Chinchilla, Benoit Lavraud, Janet Luhmann, Tatiana Niembro, Aleida Higginson, Nathalia Alzate, Samantha Wallace, Kristoff Paulson, Alexis Rouillard, Athanasios Kouloumvakos, Nicolas Poirier, Justin C Kasper, A W Case, Michael L Stevens, Stuart D Bale, Marc Pulupa, Phyllis Whittlesey, Roberto Livi, Keith Goetz, David Larson, David M Malaspina, Huw Morgan, Ayris A Narock, Nathan A Schwadron, John Bonnell, Peter Harvey, and John Wygant
Subjects: Astrophysics
Abstract: In the ﬁrst orbit of the Parker Solar Probe (PSP), in situ thermal plasma and magnetic ﬁeld measurements were collected as close as 35RSun from the Sun, an environment that had not been previously explored. During the ﬁrst orbit of PSP, the spacecraft ﬂew through a streamer blowout coronal mass ejection (SBO-CME) on 2018 November 11 at 23:50 UT as it exited the science encounter. The SBO-CME on November 11 was directed away from the Earth and was not visible by L1 or Earth-based telescopes due to this geometric conﬁguration. However, PSP and the STEREO-A spacecraft were able to make observations of this slow (v ≈ 380 kms−1) SBO-CME. Using the PSP data, STEREO-A images, and Wang–Sheeley–Arge model, the source region of the CME is found to be a helmet streamer formed between the northern polar coronal hole and a mid-latitude coronal hole. Using the YGUAZU-A model, the propagation of the CME is traced from the source at the Sun to PSP. This model predicts the travel time of the ﬂux rope to the PSP spacecraft as 30 hr, which is within 0.33 hr of the actual measured arrival time. The in situ Solar Wind Electrons Alphas and Protons data were examined to determine that no shock was associated with this SBO-CME. Modeling of the SBO-CME shows that no shock was present at PSP; however, at other positions along the SBO-CME front, a shock could have formed. The geometry of the event requires in situ and remote sensing observations to characterize the SBO-CME and further understand its role in space weather.
Published: 2020
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14. Ambipolar Electric Field and Potential in the Solar Wind Estimated from Electron Velocity Distribution Functions

Author: Laura Berčič, Milan Maksimović, Jasper S. Halekas, Simone Landi, Christopher J. Owen, Daniel Verscharen, Davin Larson, Phyllis Whittlesey, Samuel T. Badman, Stuart. D. Bale, Anthony W. Case, Keith Goetz, Peter R. Harvey, Justin C. Kasper, Kelly E. Korreck, Roberto Livi, Robert J. MacDowall, David M. Malaspina, Marc Pulupa, and Michael L. Stevens
Published: 2021
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15. Broadband Electrostatic Waves near the Lower-hybrid Frequency in the Near-Sun Solar Wind Observed by the Parker Solar Probe

Author: Jinsong Zhao, David M. Malaspina, T. Dudok de Wit, Viviane Pierrard, Yuriy Voitenko, Giovanni Lapenta, Stefaan Poedts, Stuart D. Bale, Justin C. Kasper, Davin Larson, Roberto Livi, Phyllis Whittlesey, and UCL - SST/ELI/ELIC - Earth & Climate
Subjects: Space and Planetary Science, Astronomy and Astrophysics
Abstract: Using Parker Solar Probe observations, this Letter reports for the first time the existence of broadband electrostatic waves below the electron cyclotron frequency in the near-Sun solar wind and even in the extended solar corona. These waves have enhanced power spectral densities of the electric fields near the lower-hybrid frequency f LH, and their peak frequencies can be below or exceed f LH. The perturbed electric fields are distributed between about 0.1 and 50 mV m−1. Accompanying broadband electrostatic waves, strong electrostatic solitary structures can arise, and their peak amplitudes approach nearly 500 mV m−1. Due to the appearance of considerable electric field fluctuations perpendicular to the background magnetic field, the observed waves would propagate obliquely. Moreover, this Letter conjectures the wavenumber and frequency information for the candidate of the wave mode nature being the oblique slow mode wave, the ion Bernstein wave, or the oblique fast-magnetosonic whistler wave. One important consequence of the observed waves is that they may regulate the electron heat flux in the near-Sun solar wind and in the solar corona.
Published: 2022

16. Statistics and Polarization of Type III Radio Bursts Observed in the Inner Heliosphere

Author: Marc Pulupa, Stuart D. Bale, Samuel T. Badman, J. W. Bonnell, Anthony W. Case, Thierry Dudok de Wit, Keith Goetz, Peter R. Harvey, Alexander M. Hegedus, Justin C. Kasper, Kelly E. Korreck, Vladimir Krasnoselskikh, Davin Larson, Alain Lecacheux, Roberto Livi, Robert J. MacDowall, Milan Maksimovic, David M. Malaspina, Juan Carlos Martínez Oliveros, Nicole Meyer-Vernet, Michel Moncuquet, Michael Stevens, and Phyllis Whittlesey
Published: 2020
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17. Plasma Waves near the Electron Cyclotron Frequency in the Near-Sun Solar Wind

Author: David M. Malaspina, Jasper Halekas, Laura Berčič, Davin Larson, Phyllis Whittlesey, Stuart D. Bale, John W. Bonnell, Thierry Dudok de Wit, Robert E. Ergun, Gregory Howes, Keith Goetz, Katherine Goodrich, Peter R. Harvey, Robert J. MacDowall, Marc Pulupa, Anthony W. Case, Justin C. Kasper, Kelly E. Korreck, Roberto Livi, and Michael L. Stevens
Published: 2020
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18. Sharp Alfvénic Impulses in the Near-Sun Solar Wind

Author: Timothy S. Horbury, Thomas Woolley, Ronan Laker, Lorenzo Matteini, Jonathan Eastwood, Stuart D. Bale, Marco Velli, Benjamin D. G. Chandran, Tai Phan, Nour E. Raouafi, Keith Goetz, Peter R. Harvey, Marc Pulupa, K. G. Klein, Thierry Dudok de Wit, Justin C. Kasper, Kelly E. Korreck, A. W. Case, Michael L. Stevens, Phyllis Whittlesey, Davin Larson, Robert J. MacDowall, David M. Malaspina, and Roberto Livi
Published: 2020
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19. Energetic Particle Increases Associated with Stream Interaction Regions

Author: C. M. S. Cohen, E. R. Christian, A. C. Cummings, A. J. Davis, M. I. Desai, J. Giacalone, M. E. Hill, C. J. Joyce, A. W. Labrador, R. A. Leske, W. H. Matthaeus, D. J. McComas, R. L. McNutt, R. A. Mewaldt, D. G. Mitchell, J. S. Rankin, E. C. Roelof, N. A. Schwadron, E. C. Stone, J. R. Szalay, M. E. Wiedenbeck, R. C. Allen, G. C. Ho, L. K. Jian, D. Lario, D. Odstrcil, S. D. Bale, S. T. Badman, M. Pulupa, R. J. MacDowall, J. C. Kasper, A. W. Case, K. E. Korreck, D. E. Larson, Roberto Livi, M. L. Stevens, and Phyllis Whittlesey
Published: 2020
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20. The Enhancement of Proton Stochastic Heating in the Near-Sun Solar Wind

Author: Mihailo M. Martinović, Kristopher G. Klein, Justin C. Kasper, Anthony W. Case, Kelly E. Korreck, Davin Larson, Roberto Livi, Michael Stevens, Phyllis Whittlesey, Benjamin D. G. Chandran, Ben L. Alterman, Jia Huang, Christopher H. K. Chen, Stuart D. Bale, Marc Pulupa, David M. Malaspina, John W. Bonnell, Peter R. Harvey, Keith Goetz, Thierry Dudok de Wit, and Robert J. MacDowall
Published: 2020
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21. Magnetic Field Kinks and Folds in the Solar Wind

Author: Anna Tenerani, Marco Velli, Lorenzo Matteini, Victor Réville, Chen Shi, Stuart D. Bale, Justin C. Kasper, John W. Bonnell, Anthony W. Case, Thierry Dudok de Wit, Keith Goetz, Peter R. Harvey, Kristopher G. Klein, Kelly Korreck, Davin Larson, Roberto Livi, Robert J. MacDowall, David M. Malaspina, Marc Pulupa, Michael Stevens, and Phyllis Whittlesey
Published: 2020
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22. Linking Small-scale Solar Wind Properties with Large-scale Coronal Source Regions through Joint Parker Solar Probe–Metis/Solar Orbiter Observations

Author: Daniele Telloni, Gary P. Zank, Luca Sorriso-Valvo, Raffaella D’Amicis, Olga Panasenco, Roberto Susino, Roberto Bruno, Denise Perrone, Laxman Adhikari, Haoming Liang, Masaru Nakanotani, Lingling Zhao, Lina Z. Hadid, Beatriz Sánchez-Cano, Daniel Verscharen, Marco Velli, Catia Grimani, Raffaele Marino, Francesco Carbone, Salvatore Mancuso, Ruggero Biondo, Paolo Pagano, Fabio Reale, Stuart D. Bale, Justin C. Kasper, Anthony W. Case, Thierry Dudok de Wit, Keith Goetz, Peter R. Harvey, Kelly E. Korreck, Davin Larson, Roberto Livi, Robert J. MacDowall, David M. Malaspina, Marc Pulupa, Michael L. Stevens, Phyllis Whittlesey, Marco Romoli, Vincenzo Andretta, Vania Da Deppo, Silvano Fineschi, Petr Heinzel, John D. Moses, Giampiero Naletto, Gianalfredo Nicolini, Daniele Spadaro, Marco Stangalini, Luca Teriaca, Gerardo Capobianco, Giuseppe E. Capuano, Chiara Casini, Marta Casti, Paolo Chioetto, Alain J. Corso, Yara De Leo, Michele Fabi, Federica Frassati, Fabio Frassetto, Silvio Giordano, Salvo L. Guglielmino, Giovanna Jerse, Federico Landini, Alessandro Liberatore, Enrico Magli, Giuseppe Massone, Mauro Messerotti, Maurizio Pancrazzi, Maria G. Pelizzo, Paolo Romano, Clementina Sasso, Udo Schühle, Alessandra Slemer, Thomas Straus, Michela Uslenghi, Cosimo A. Volpicelli, Luca Zangrilli, Paola Zuppella, Lucia Abbo, Frédéric Auchère, Regina Aznar Cuadrado, Arkadiusz Berlicki, Angela Ciaravella, Philippe Lamy, Alessandro Lanzafame, Marco Malvezzi, Piergiorgio Nicolosi, Giuseppe Nisticò, Hardi Peter, Sami K. Solanki, Leonard Strachan, Kanaris Tsinganos, Rita Ventura, Jean-Claude Vial, Joachim Woch, Gaetano Zimbardo, Telloni D., Zank G.P., Sorriso-Valvo L., D'amicis R., Panasenco O., Susino R., Bruno R., Perrone D., Adhikari L., Liang H., Nakanotani M., Zhao L., Hadid L.Z., Sanchez-Cano B., Verscharen D., Velli M., Grimani C., Marino R., Carbone F., Mancuso S., Biondo R., Pagano P., Reale F., Bale S.D., Kasper J.C., Case A.W., De Wit T.D., Goetz K., Harvey P.R., Korreck K.E., Larson D., Livi R., Macdowall R.J., Malaspina D.M., Pulupa M., Stevens M.L., Whittlesey P., Romoli M., Andretta V., Deppo V.D., Fineschi S., Heinzel P., Moses J.D., Naletto G., Nicolini G., Spadaro D., Stangalini M., Teriaca L., Capobianco G., Capuano G.E., Casini C., Casti M., Chioetto P., Corso A.J., Leo Y.D., Fabi M., Frassati F., Frassetto F., Giordano S., Guglielmino S.L., Jerse G., Landini F., Liberatore A., Magli E., Massone G., Messerotti M., Pancrazzi M., Pelizzo M.G., Romano P., Sasso C., Schuhle U., Slemer A., Straus T., Uslenghi M., Volpicelli C.A., Zangrilli L., Zuppella P., Abbo L., Auchere F., Cuadrado R.A., Berlicki A., Ciaravella A., Lamy P., Lanzafame A., Malvezzi M., Nicolosi P., Nistico G., Peter H., Solanki S.K., Strachan L., Tsinganos K., Ventura R., Vial J.-C., Woch J., and Zimbardo G.
Subjects: Magnetohydrodynamics (694), Settore FIS/05 - Astronomia E Astrofisica, Astronomi, astrofysik och kosmologi, Space and Planetary Science, Solar corona (1483), Space plasmas (1544), Solar wind (1534), Interplanetary turbulence (830), Astronomy, Astrophysics and Cosmology, Astronomy and Astrophysics, Alfven waves (23), Heliosphere (711)
Abstract: The solar wind measured in situ by Parker Solar Probe in the very inner heliosphere is studied in combination with the remote-sensing observation of the coronal source region provided by the METIS coronagraph aboard Solar Orbiter. The coronal outflows observed near the ecliptic by Metis on 2021 January 17 at 16:30 UT, between 3.5 and 6.3 R ⊙ above the eastern solar limb, can be associated with the streams sampled by PSP at 0.11 and 0.26 au from the Sun, in two time intervals almost 5 days apart. The two plasma flows come from two distinct source regions, characterized by different magnetic field polarity and intensity at the coronal base. It follows that both the global and local properties of the two streams are different. Specifically, the solar wind emanating from the stronger magnetic field region has a lower bulk flux density, as expected, and is in a state of well-developed Alfvénic turbulence, with low intermittency. This is interpreted in terms of slab turbulence in the context of nearly incompressible magnetohydrodynamics. Conversely, the highly intermittent and poorly developed turbulent behavior of the solar wind from the weaker magnetic field region is presumably due to large magnetic deflections most likely attributed to the presence of switchbacks of interchange reconnection origin.
Published: 2022

23. The Solar Probe ANalyzer -Ions on Parker Solar Probe

Author: Katja Klein, J. L. Verniero, M. S. Robinson, Davin Larson, Justin C. Kasper, Amanda Slagle, Kelly E. Korreck, D. W. Curtis, Roberto Livi, R. Abiad, Chris Tiu, Phyllis Whittlesey, George C. Ho, Gregory Dalton, Anthony W. Case, Michael L. Stevens, Mamuda Abatcha, Ali Rahmati, James P. McFadden, Mario Marckwordt, and Jasper Halekas
Subjects: Spectrum analyzer, Materials science, Spacecraft, Physics::Plasma Physics, business.industry, Physics::Space Physics, Astrophysics::Instrumentation and Methods for Astrophysics, Analytical chemistry, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Electrostatic analyzer, business, Ion
Abstract: The Solar Probe ANalyzer for Ions (SPAN-I) onboard NASA's Parker Solar Probe (PSP) spacecraft is an electrostatic analyzer with time-of-flight capabilities that measures the ion composition and thr...
Published: 2021
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24. Observation and Modeling of the Solar Wind Turbulence Evolution in the Sub-Mercury Inner Heliosphere

Author: Daniele Telloni, Laxman Adhikari, Gary P. Zank, Lina Z. Hadid, Beatriz Sánchez-Cano, Luca Sorriso-Valvo, Lingling Zhao, Olga Panasenco, Chen Shi, Marco Velli, Roberto Susino, Daniel Verscharen, Anna Milillo, Tommaso Alberti, Yasuhito Narita, Andrea Verdini, Catia Grimani, Roberto Bruno, Raffaella D’Amicis, Denise Perrone, Raffaele Marino, Francesco Carbone, Francesco Califano, Francesco Malara, Julia E. Stawarz, Ronan Laker, Alessandro Liberatore, Stuart D. Bale, Justin C. Kasper, Daniel Heyner, Thierry Dudok de Wit, Keith Goetz, Peter R. Harvey, Robert J. MacDowall, David M. Malaspina, Marc Pulupa, Anthony W. Case, Kelly E. Korreck, Davin Larson, Roberto Livi, Michael L. Stevens, Phyllis Whittlesey, Hans-Ulrich Auster, and Ingo Richter
Subjects: Fusion, plasma och rymdfysik, Astronomi, astrofysik och kosmologi, Space and Planetary Science, Astronomy, Astrophysics and Cosmology, Astronomy and Astrophysics, Fusion, Plasma and Space Physics
Abstract: This letter exploits the radial alignment between the Parker Solar Probe and BepiColombo in late 2022 February, when both spacecraft were within Mercury’s orbit. This allows the study of the turbulent evolution, namely, the change in spectral and intermittency properties, of the same plasma parcel during its expansion from 0.11 to 0.33 au, a still unexplored region. The observational analysis of the solar wind turbulent features at the two different evolution stages is complemented by a theoretical description based on the turbulence transport model equations for nearly incompressible magnetohydrodynamics. The results provide strong evidence that the solar wind turbulence already undergoes significant evolution at distances less than 0.3 au from the Sun, which can be satisfactorily explained as due to evolving slab fluctuations. This work represents a step forward in understanding the processes that control the transition from weak to strong turbulence in the solar wind and in properly modeling the heliosphere.
Published: 2022
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25. Characteristic Scales of Magnetic Switchback Patches Near the Sun and Their Possible Association With Solar Supergranulation and Granulation

Author: Victor Réville, Matthieu Berthomier, Kelly E. Korreck, Phyllis Whittlesey, Jasper Halekas, Justin C. Kasper, Davin Larson, N. Fargette, Clara Froment, Stuart D. Bale, Philippe Louarn, Benoit Lavraud, Thierry Dudok de Wit, David M. Malaspina, Tai Phan, Anthony W. Case, Marc Pulupa, Alexis P. Rouillard, Michael L. Stevens, Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National d’Études Spatiales [Paris] (CNES)
Subjects: Physics, [PHYS.ASTR.IM]Physics [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], 010504 meteorology & atmospheric sciences, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Solar physics, [PHYS.ASTR.SR]Physics [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], 01 natural sciences, [PHYS.PHYS.PHYS-SPACE-PH]Physics [physics]/Physics [physics]/Space Physics [physics.space-ph], Solar wind, Granulation, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, [PHYS.PHYS.PHYS-PLASM-PH]Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph], 0103 physical sciences, Physics::Space Physics, Astrophysics::Solar and Stellar Astrophysics, Supergranulation, Astrophysics::Earth and Planetary Astrophysics, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), [PHYS.PHYS.PHYS-DATA-AN]Physics [physics]/Physics [physics]/Data Analysis, Statistics and Probability [physics.data-an], 0105 earth and related environmental sciences
Abstract: 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 reconnection processes, or result from the evolution of turbulence or velocity shears in the expanding solar wind. In this work, we investigate the temporal and spatial characteristic scales of magnetic switchback patches. We define switchbacks as a deviation from the nominal Parker spiral direction and detect them automatically for PSP encounters 1, 2, 4 and 5. We focus in particular on a 5.1-day interval dominated by switchbacks during E5. We perform a wavelet transform of the solid angle between the magnetic field and the Parker spiral and find periodic spatial modulations with two distinct wavelengths, respectively consistent with solar granulation and supergranulation scales. In addition we find that switchback occurrence and spectral properties seem to depend on the source region of the solar wind rather than on the radial distance of PSP. These results suggest that switchbacks are formed in the low corona and modulated by the solar surface convection pattern., Comment: 12 pages, 7 figures
Published: 2021
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26. Correcting Parker Solar Probe Electron Measurements for Spacecraft Magnetic and Electric Fields

Author: Phyllis Whittlesey, D. McGinnis, Davin Larson, Justin C. Kasper, and Jasper Halekas
Subjects: Physics, Geophysics, Spacecraft, Space and Planetary Science, business.industry, Electric field, Electron, business, Computational physics
Published: 2019
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27. The Electron Structure of the Solar Wind

Author: Joseph E. Borovsky, Jasper Halekas, and Phyllis Whittlesey
Subjects: 010504 meteorology & atmospheric sciences, Astrophysics::High Energy Astrophysical Phenomena, magnetic structure, Astronomy, Geophysics. Cosmic physics, Population, QB1-991, interplanetary potential, 01 natural sciences, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, education, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Physics, education.field_of_study, Number density, Flux tube, QC801-809, heliosphere, Astronomy and Astrophysics, Corona, Magnetic flux, Computational physics, Solar wind, solar wind, Physics::Space Physics, Astrophysics::Earth and Planetary Astrophysics, Interplanetary spaceflight, corona, Heliosphere
Abstract: Time-series measurements of the number density ncore and temperature Tcore of the core-electron population of the solar wind are examined at 1 AU and at 0.13 AU using measurements from the WIND and Parker Solar Probe spacecraft, respectively. A statistical analysis of the ncore and Tcore measurements at 1 AU finds that the core-electron spatial structure of the solar wind is related to the magnetic-flux-tube structure of the solar wind; this electron structure is characterized by jumps in the values of ncore and Tcore when passing from one magnetic flux tube into the next. The same types of flux-tube jumps are seen for Tcore at 0.13 AU. Some models of the interplanetary electrical potential of the heliosphere predict that Tcore is a direct measure of the local electrical potential in the heliosphere. If so, then jumps seen in Tcore represent jumps in the electrical potential from flux tube to flux tube. This may imply that the interplanetary electrical potential (and its effect on the radial evolution away from the Sun of solar-wind ions and electrons) independently operates in each flux tube of the heliosphere.
Published: 2021
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28. Alfvénic versus non-Alfvénic turbulence in the inner heliosphere as observed by Parker Solar Probe

Author: Victor Réville, Phyllis Whittlesey, Anthony W. Case, Robert J. MacDowall, Olga Panasenco, Davin Larson, Peter Harvey, Justin C. Kasper, Kelly E. Korreck, Keith Goetz, Michael L. Stevens, Michel Moncuquet, Marco Velli, David M. Malaspina, Stuart D. Bale, Milan Maksimovic, Roberto Livi, Marc Pulupa, Thierry Dudok de Wit, Chen Shi, J. W. Bonnell, J. L. Verniero, Anna Tenerani, Department of Earth, Planetary and Space Sciences [Los Angeles] (EPSS), University of California [Los Angeles] (UCLA), University of California (UC)-University of California (UC), Institut de recherche en astrophysique et planétologie (IRAP), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), University of California-University of California, Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)
Subjects: Physics, 010504 meteorology & atmospheric sciences, Magnetic energy, Turbulence, Coronal hole, Astronomy and Astrophysics, Context (language use), Astrophysics, 01 natural sciences, Wind speed, Solar wind, Astrophysics - Solar and Stellar Astrophysics, Physics - Space Physics, 13. Climate action, Space and Planetary Science, [SDU]Sciences of the Universe [physics], 0103 physical sciences, Physics::Space Physics, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Magnetohydrodynamics, 010303 astronomy & astrophysics, Heliosphere, 0105 earth and related environmental sciences
Abstract: Context. Parker Solar Probe (PSP) measures the magnetic field and plasma parameters of the solar wind at unprecedentedly close distances to the Sun. These data provide great opportunities to study the early-stage evolution of magnetohydrodynamic (MHD) turbulence in the solar wind. Aims. In this study, we make use of the PSP data to explore the nature of solar wind turbulence focusing on the Alfvénic character and power spectra of the fluctuations and their dependence on the distance and context (i.e., large-scale solar wind properties), aiming to understand the role that different effects such as source properties, solar wind expansion, and stream interaction might play in determining the turbulent state. Methods. We carried out a statistical survey of the data from the first five orbits of PSP with a focus on how the fluctuation properties at the large MHD scales vary with different solar wind streams and the distance from the Sun. A more in-depth analysis from several selected periods is also presented. Results. Our results show that as fluctuations are transported outward by the solar wind, the magnetic field spectrum steepens while the shape of the velocity spectrum remains unchanged. The steepening process is controlled by the “age” of the turbulence, which is determined by the wind speed together with the radial distance. Statistically, faster solar wind has higher “Alfvénicity,” with a more dominant outward propagating wave component and more balanced magnetic and kinetic energies. The outward wave dominance gradually weakens with radial distance, while the excess of magnetic energy is found to be stronger as we move closer toward the Sun. We show that the turbulence properties can significantly vary from stream to stream even if these streams are of a similar speed, indicating very different origins of these streams. Especially, the slow wind that originates near the polar coronal holes has much lower Alfvénicity compared with the slow wind that originates from the active regions and pseudostreamers. We show that structures such as heliospheric current sheets and velocity shears can play an important role in modifying the properties of the turbulence.
Published: 2021
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29. Whistler wave occurrence and the interaction with strahl electrons during the first encounter of Parker Solar Probe

Author: Jasper Halekas, Michel Moncuquet, Justin C. Kasper, Vladimir Krasnoselskikh, Michael L. Stevens, Oleksiy Agapitov, A. Larosa, Stuart D. Bale, Kelly E. Korreck, L. Bercic, T. Dudok de Wit, Marc Pulupa, Matthieu Kretzschmar, Anthony W. Case, Clara Froment, Phyllis Whittlesey, Davin Larson, David M. Malaspina, V. K. Jagarlamudi, Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Istituto di Astrofisica Spaziale e Fisica cosmica - Roma (IASF-Roma), Istituto Nazionale di Astrofisica (INAF), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Università degli Studi di Firenze = University of Florence [Firenze] (UNIFI), Space Sciences Laboratory [Berkeley] (SSL), University of California [Berkeley], University of California-University of California, Department of Physics and Astronomy [Iowa City], University of Iowa [Iowa City], University of Colorado [Boulder], University of California, Imperial College London, Queen Mary University of London (QMUL), Smithsonian Astrophysical Observatory, Smithsonian Institution, University of Michigan [Ann Arbor], University of Michigan System, Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National d’Études Spatiales [Paris] (CNES)
Subjects: 010504 meteorology & atmospheric sciences, Whistler, FOS: Physical sciences, Electron, magnetic fields, 01 natural sciences, Electromagnetic radiation, Physics - Space Physics, 0103 physical sciences, waves, Sun: heliosphere, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Physics, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], scattering, Astronomy and Astrophysics, plasmas, Space Physics (physics.space-ph), [PHYS.PHYS.PHYS-SPACE-PH]Physics [physics]/Physics [physics]/Space Physics [physics.space-ph], Computational physics, Magnetic field, Strahl, Solar wind, Amplitude, 13. Climate action, Space and Planetary Science, Physics::Space Physics, Electron temperature
Abstract: We studied the properties and occurrence of narrow band whistler waves and their interaction with strahl electrons observed between 0.17 and 0.26 au during the first encounter of Parker Solar Probe. We observe that occurrence of whistler waves is low, nearly 1.5% and less than 0.5% in the analyzed peak and average BPF data respectively. Whistlers occur highly intermittently and 80% of the whistlers appear continuously for less than 3 s. Occurrence rate of whistler waves was found to be anti-correlated with the solar wind bulk velocity. The study of the duration of the whistler intervals revealed an anti-correlation between the duration and the solar wind velocity, as well as between the duration and the normalized amplitude of magnetic field variations. The pitch-angle widths (PAWs) of the field-aligned electron population referred to as the strahl are broader by at least 12 degrees during the presence of large amplitude narrow band whistler waves. This observation points towards a EM wave electron interaction, resulting in pitch-angle scattering. PAW of strahl electrons corresponding to the short duration whistlers are higher compared to the long duration whistlers. Parallel cuts through the strahl electron velocity distribution function (VDF) observed during the whistler intervals appear to depart from the Maxwellian shape typically found in the near-Sun strahl VDFs (Bercic et al. 2020). The relative decrease of parallel electron temperature and the increase of PAW for the electrons in strahl energy range suggests that the interaction with whistler waves results in a transfer of electron momentum from the parallel to the perpendicular direction., Comment: Accepted for publication in Astronomy & Astrophysics PSP special issue on January 12, 2021
Published: 2021
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30. Evolution of Solar Wind Turbulence from 0.1 to 1 au during the First Parker Solar Probe-Solar Orbiter Radial Alignment

Author: Stuart D. Bale, Michael L. Stevens, Phyllis Whittlesey, Peter R. Harvey, Christopher J. Owen, Philippe Louarn, Stefano Livi, Francesco Carbone, Ester Antonucci, Rossana De Marco, L. D. Woodham, Helen O'Brien, V. Angelini, Marco Romoli, Lingling Zhao, Marc Pulupa, Robert J. MacDowall, Thierry Dudok de Wit, Anthony W. Case, Olga Panasenco, Davin Larson, Vincent Evans, Chen Shi, Laxman Adhikari, R. Laker, Luca Sorriso-Valvo, Raffaella D'Amicis, Roberto Livi, Daniele Telloni, Denise Perrone, Anna Tenerani, Konrad Steinvall, David M. Malaspina, Masaru Nakanotani, Vamsee Krishna Jagarlamudi, Keith Goetz, Kelly E. Korreck, Justin C. Kasper, Marco Velli, Roberto Bruno, Haoming Liang, Timothy S. Horbury, Raffaele Marino, Gary P. Zank, Imperial College London, Department of Physics [Imperial College London], Laboratoire de Mecanique des Fluides et d'Acoustique (LMFA), École Centrale de Lyon (ECL), Université de Lyon-Université de Lyon-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Space Sciences Laboratory [Berkeley] (SSL), University of California [Berkeley], University of California-University of California, Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National d’Études Spatiales [Paris] (CNES), Université de Lyon, and Centre National de la Recherche Scientifique (CNRS)
Subjects: [PHYS.ASTR.IM]Physics [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], HIGH-SPEED STREAMS, WAVES, Astronomy & Astrophysics, FREQUENCY, 01 natural sciences, law.invention, Orbiter, [SPI]Engineering Sciences [physics], [PHYS.PHYS.PHYS-PLASM-PH]Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph], law, 0103 physical sciences, 0201 Astronomical and Space Sciences, Astrophysics::Solar and Stellar Astrophysics, SPACE, 010306 general physics, 010303 astronomy & astrophysics, ComputingMilieux_MISCELLANEOUS, Physics, [PHYS]Physics [physics], ANISOTROPY, Science & Technology, Spacecraft, Turbulence, business.industry, Astronomy and Astrophysics, Plasma, EMPIRICAL MODE DECOMPOSITION, FLUCTUATIONS, [PHYS.ASTR.SR]Physics [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], [PHYS.PHYS.PHYS-SPACE-PH]Physics [physics]/Physics [physics]/Space Physics [physics.space-ph], Computational physics, Magnetic field, Solar wind, Space and Planetary Science, [SDU]Sciences of the Universe [physics], ORIGINS, Physics::Space Physics, Physical Sciences, Solar Wind, INTERMITTENCY, Astrophysics::Earth and Planetary Astrophysics, SCALES, Magnetohydrodynamics, business, [PHYS.PHYS.PHYS-DATA-AN]Physics [physics]/Physics [physics]/Data Analysis, Statistics and Probability [physics.data-an], Heliosphere
Abstract: The first radial alignment between Parker Solar Probe and Solar Orbiter spacecraft is used to investigate the evolution of solar wind turbulence in the inner heliosphere. Assuming ballistic propagation, two 1.5 hr intervals are tentatively identified as providing measurements of the same plasma parcels traveling from 0.1 to 1 au. Using magnetic field measurements from both spacecraft, the properties of turbulence in the two intervals are assessed. Magnetic spectral density, flatness, and high-order moment scaling laws are calculated. The Hilbert–Huang transform is additionally used to mitigate short sample and poor stationarity effects. Results show that the plasma evolves from a highly Alfvénic, less-developed turbulence state near the Sun, to fully developed and intermittent turbulence at 1 au. These observations provide strong evidence for the radial evolution of solar wind turbulence.
Published: 2021
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31. Evidence of Subproton‐Scale Magnetic Holes in the Venusian Magnetosheath

Author: Robert J. MacDowall, F. S. Mozer, Peter Harvey, Jasper Halekas, Justin C. Kasper, Trevor A. Bowen, John W. Bonnell, Davin Larson, Shannon Curry, M. McManus, Roberto Livi, Thierry Dudok de Wit, Keith Goetz, Katherine Goodrich, Anthony W. Case, Phyllis Whittlesey, Marc Pulupa, Stuart D. Bale, David M. Malaspina, Michael L. Stevens, Space Sciences Laboratory [Berkeley] (SSL), University of California [Berkeley], University of California-University of California, Department of Astrophysical and Planetary Sciences [Boulder], University of Colorado [Boulder], Harvard-Smithsonian Center for Astrophysics (CfA), Smithsonian Institution-Harvard University [Cambridge], Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National d’Études Spatiales [Paris] (CNES)
Subjects: Physics, 010504 meteorology & atmospheric sciences, Gyroradius, Astrophysics::High Energy Astrophysical Phenomena, Magnetosphere, Plasma, 010502 geochemistry & geophysics, Bow shocks in astrophysics, 01 natural sciences, Computational physics, Magnetic field, Geophysics, Magnetosheath, [SDU]Sciences of the Universe [physics], Electric field, Physics::Space Physics, General Earth and Planetary Sciences, Astrophysical plasma, 0105 earth and related environmental sciences
Abstract: International audience; Depressions in magnetic field strength, commonly referred to as magnetic holes, are observed ubiquitously in space plasmas. Subproton-scale magnetic holes with spatial scales smaller than or on the order of a proton gyroradius, are likely supported by electron current vortices, rotating perpendicular to the ambient magnetic field. While there are numerous accounts of subproton-scale magnetic holes within the Earth’s magnetosphere, there are few, if any, reported observations in other space plasma environments. We present the first evidence of subproton-scale magnetic holes in the Venusian magnetosheath. During Parker Solar Probe’s first Venus Gravity Assist, the spacecraft crossed the planet’s bow shock and subsequently observed the Venusian magnetosheath. The FIELDS instrument suite onboard the spacecraft achieved magnetic and electric field measurements of magnetic hole structures. The electric fields associated with magnetic depressions are consistent with electron current vortices with amplitudes on the order of 1µA/m2.
Published: 2021
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32. Plasma Waves Near the Electron Cyclotron Frequency in the Near Sun Solar Wind: Wave Mode Identification and Driving Instabilities

Author: Katherine Goodrich, Keith Goetz, Davin Larson, Robert E. Ergun, Phyllis Whittlesey, Stuart D. Bale, Peter Harvey, Marc Pulupa, Lynn B. Wilson, Jasper Halekas, Michael L. Stevens, Anthony W. Case, David M. Malaspina, John W. Bonnell, Thierry Dudok de Wit, and Robert J. MacDowall
Subjects: Physics, Solar wind, Identification (information), law, Physics::Space Physics, Wave mode, Cyclotron, Astrophysics::Solar and Stellar Astrophysics, Plasma, Electron, Computational physics, law.invention
Abstract: Recent studies of the solar wind sunward of 0.25 AU using the Parker Solar Probe spacecraft reveal that that solar wind can be bimodal, alternating between near quiescent regions with low turbulent fluctuation amplitudes and Parker-like magnetic field direction and regions of highly turbulent plasma and magnetic field fluctuations associated with ‘switchbacks’ of the radial magnetic field. The quiescent solar wind regions are highly unstable to the formation of plasma waves near the electron cyclotron frequency (fce), possibly driven by strahl electrons, which carry the solar wind heat flux, and may provide one of the most direct particle diagnostics of the solar corona at the source of the solar wind. These waves are most intense near ~0.7 fce and ~fce. The near-fce waves are found to become more intense and more frequent closer to the Sun, and statistical evidence indicates that their occurrence rate is related to the sunward drift of the core electron population. In this study, we examine high time resolution burst captures of these waves, demonstrating that each wave burst contains several distinct wave types, including electron Bernstein waves and extremely narrow band waves that are highly sensitive to the magnetic field orientation. Using properties of these waves we provide evidence to support the identification of their likely plasma wave modes and the instabilities responsible for generating these waves. By understanding the driving instabilities responsible for these waves, we infer their ability to modify electron distribution functions in the quiescent near-Sun solar wind.
Published: 2021
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33. Kinetic‐Scale Turbulence in the Venusian Magnetosheath

Author: T. Dudok de Wit, Phyllis Whittlesey, Keith Goetz, Robert J. MacDowall, J. R. Gruesbeck, Peter Harvey, N. E. Raouafi, Justin C. Kasper, Davin Larson, Alexandros Chasapis, Jasper Halekas, Marc Pulupa, Michael L. Stevens, Shannon Curry, M. McManus, Kelly E. Korreck, John W. Bonnell, David M. Malaspina, Katherine Goodrich, Riddhi Bandyopadhyay, Roberto Livi, Stuart D. Bale, Alfred Mallet, Anthony W. Case, Gregory G. Howes, Christopher H. K. Chen, B. Page, and Trevor A. Bowen
Subjects: Physics, Geophysics, Magnetosheath, Scale (ratio), biology, Turbulence, General Earth and Planetary Sciences, Venus, Plasma, Kinetic energy, biology.organism_classification, Instability
Published: 2021
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34. Electrostatic Waves with Rapid Frequency Shifts in the Solar Wind from PSP observations

Author: Peter Harvey, Phyllis Whittlesey, Jasper Halekas, Davin Larson, Thierry Dudok de Wit, J. L. Verniero, Katherine Goodrich, David M. Malaspina, Justin C. Kasper, Stuart D. Bale, John W. Bonnell, Alexandros Chasapis, Lily Kromyda, Daniel Vech, Kelly E. Korreck, Keith Goetz, Roberto Livi, Robert E. Ergun, Anthony W. Case, Michael L. Stevens, Robert J. MacDowall, and Marc Pulupa
Subjects: On board, Physics, Solar wind, Whistler, Physics::Plasma Physics, Waves in plasmas, Physics::Space Physics, Plasma, Electron, Electrostatics, Electromagnetic radiation, Computational physics
Abstract: During its first five orbits, the FIELDS plasma wave investigation on board Parker Solar Probe (PSP) has observed a multitude of plasma waves, including electrostatic whistler and electron Bernstein waves (Malaspina et al. 2020), sunward propagating whistlers (Agapitov et al. 2020), ion-scale electromagnetic waves (Verniero et al. 2020, Bowen et al. 2020) and Alfven, slow and fast mode waves (Chaston et al. 2020).
Published: 2021
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35. Direct evidence for magnetic reconnection at the boundaries of magnetic switchbacks with Parker Solar Probe

Author: Vladimir Krasnoselskikh, Marco Velli, Robert J. MacDowall, Phyllis Whittlesey, Anthony W. Case, Davin Larson, T. Dudok de Wit, Keith Goetz, Marc Pulupa, Benoit Lavraud, Justin C. Kasper, David M. Malaspina, Vamsee Krishna Jagarlamudi, Kelly E. Korreck, N. Fargette, Clara Froment, Oleksiy Agapitov, A. Larosa, Stuart D. Bale, F. S. Mozer, C. Revillet, Michael L. Stevens, Matthieu Kretzschmar, Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Space Sciences Laboratory [Berkeley] (SSL), University of California [Berkeley] (UC Berkeley), University of California (UC)-University of California (UC), Institut de recherche en astrophysique et planétologie (IRAP), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), University of Colorado [Boulder], Smithsonian Astrophysical Observatory, Smithsonian Institution, School of Physics and Astronomy [Minneapolis], University of Minnesota [Twin Cities] (UMN), University of Minnesota System-University of Minnesota System, Department of Climate and Space Sciences and Engineering (CLaSP), University of Michigan [Ann Arbor], University of Michigan System-University of Michigan System, GSFC Solar System Exploration Division, NASA Goddard Space Flight Center (GSFC), IACR Brooms Barn, Partenaires INRAE, University of California [Berkeley], University of California-University of California, Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)
Subjects: Field (physics), FOS: Physical sciences, Context (language use), Solar radius, Astrophysics, magnetic fields, 01 natural sciences, Current sheet, Physics - Space Physics, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Sun: heliosphere, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Physics, 010308 nuclear & particles physics, Astronomy and Astrophysics, Magnetic reconnection, Space Physics (physics.space-ph), Magnetic field, Solar wind, Astrophysics - Solar and Stellar Astrophysics, solar wind, Space and Planetary Science, magnetic reconnection, Physics::Space Physics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Heliosphere
Abstract: Parker Solar Probe's first encounters 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. We report the direct evidence for magnetic reconnection occuring at the boundaries of three switchbacks crossed by Parker Solar Probe (PSP) at a distance of 45 to 48 solar radii of the Sun during its first encounter. We analyse the magnetic field and plasma parameters from the FIELDS and SWEAP instruments. The three structures analysed all show typical signatures of magnetic reconnection. The ion velocity and magnetic field are first correlated and then anti-correlated at the inbound and outbound edges of the bifurcated current sheets with a central ion flow jet. Most of the reconnection events have a strong guide field and moderate magnetic shear but one current sheet shows indications of quasi anti-parallel reconnection in conjunction with a magnetic field magnitude decrease by $90\%$. Given the wealth of intense current sheets observed by PSP, reconnection at switchbacks boundaries appears to be rare. However, as the switchback boundaries accomodate currents one can conjecture that the geometry of these boundaries offers favourable conditions for magnetic reconnection to occur. Such a mechanism would thus contribute in reconfiguring the magnetic field of the switchbacks, affecting the dynamics of the solar wind and eventually contributing to the blending of the structures with the regular wind as they propagate away from the Sun., Comment: 11 pages, 7 figures, 2 tables, accepted for publication in A&A, PSP special issue (v2: typos correction)
Published: 2021
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36. Ambipolar electric field and potential in the solar wind estimated from electron velocity distribution functions

Author: Jasper Halekas, Robert J. MacDowall, Roberto Livi, Anthony W. Case, Keith Goetz, David M. Malaspina, Samuel T. Badman, Phyllis Whittlesey, Christopher J. Owen, Laura Bercic, Peter R. Harvey, Stuart D. Bale, Justin C. Kasper, Daniel Verscharen, Simone Landi, Milan Maksimovic, Davin Larson, Michael L. Stevens, Kelly E. Korreck, and Marc Pulupa
Subjects: Physics, Ambipolar diffusion, FOS: Physical sciences, Astronomy and Astrophysics, Electron, Power law, Physics - Plasma Physics, Space Physics (physics.space-ph), Plasma Physics (physics.plasm-ph), Solar wind, Strahl, Distribution function, Astrophysics - Solar and Stellar Astrophysics, Physics - Space Physics, Space and Planetary Science, Quantum electrodynamics, Electric field, Physics::Space Physics, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Energy (signal processing), Solar and Stellar Astrophysics (astro-ph.SR)
Abstract: The solar wind escapes from the solar corona and is accelerated, over a short distance, to its terminal velocity. The energy balance associated with this acceleration remains poorly understood. To quantify the global electrostatic contribution to the solar wind dynamics, we empirically estimate the ambipolar electric field ($\mathrm{E}_\parallel$) and potential ($\Phi_\mathrm{r,\infty}$). We analyse electron velocity distribution functions (VDFs) measured in the near-Sun solar wind, between 20.3\,$R_S$ and 85.3\,$R_S$, by the Parker Solar Probe. We test the predictions of two different solar wind models. Close to the Sun, the VDFs exhibit a suprathermal electron deficit in the sunward, magnetic field aligned part of phase space. We argue that the sunward deficit is a remnant of the electron cutoff predicted by collisionless exospheric models (Lemaire & Sherer 1970, 1971, Jockers 1970). This cutoff energy is directly linked to $\Phi_\mathrm{r,\infty}$. Competing effects of $\mathrm{E}_\parallel$ and Coulomb collisions in the solar wind are addressed by the Steady Electron Runaway Model (SERM) (Scudder 2019). In this model, electron phase space is separated into collisionally overdamped and underdamped regions. We assume that this boundary velocity at small pitch angles coincides with the strahl break-point energy, which allows us to calculate $\mathrm{E}_\parallel$. The obtained $\Phi_\mathrm{r,\infty}$ and $\mathrm{E}_\parallel$ agree well with theoretical expectations. They decrease with radial distance as power law functions with indices $\alpha_\Phi = -0.66$ and $\alpha_\mathrm{E} = -1.69$. We finally estimate the velocity gained by protons from electrostatic acceleration, which equals to 77\% calculated from the exospheric models, and to 44\% from the SERM model.
Published: 2021
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37. Whistler Waves at Venus's Quasi-Parallel Bow Shock

Author: Brent Page, Trevor A Bowen, Stuart D. Bale, John W. Bonnell, Anthony William Case, Thierry Dudok de Wit, Keith Goetz, Katherine Amanda Goodrich, Jasper S. Halekas, Peter R Harvey, Justin C. Kasper, Davin E. Larson, Robert John MacDowall, David M. Malaspina, Mitsuo Oka, Marc Pulupa, and Phyllis Whittlesey
Published: 2020
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38. Kinetic-Scale Turbulence in the Venusian Magnetosheath

Author: Trevor A Bowen, Stuart D. Bale, Riddhi Bandyopadhyay, John W. Bonnell, Anthony William Case, Alexandros Chasapis, Christopher Chen, Shannon M. Curry, Thierry Dudok de Wit, Keith Goetz, Katherine Amanda Goodrich, Jacob R. Gruesbeck, Jasper S. Halekas, Peter R Harvey, Gregory Gershom Howes, Justin C. Kasper, Kelly Korreck, Davin E. Larson, Roberto Livi, Robert John MacDowall, David M. Malaspina, Alfred Mallet, Michael D McManus, Brent Page, Marc Pulupa, Nour-Eddine Raouafi, Michael Louis Stevens, and Phyllis Whittlesey
Published: 2020
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39. Electron heat flux in the near-Sun environment

Author: Benjamin D. G. Chandran, Kelly E. Korreck, Milan Maksimovic, Phyllis Whittlesey, Jasper Halekas, Justin C. Kasper, Lorenzo Matteini, M. Berthomier, D. McGinnis, Katja Klein, Robert J. MacDowall, Davin Larson, Roberto Livi, Anthony W. Case, David M. Malaspina, Stuart D. Bale, Marc Pulupa, Michael L. Stevens, Department of Physics and Astronomy [Iowa City], University of Iowa [Iowa City], Space Sciences Laboratory [Berkeley] (SSL), University of California [Berkeley], University of California-University of California, Department of Physics and Astronomy, University of Iowa, Laboratoire de Physique des Plasmas (LPP), Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École polytechnique (X)-Sorbonne Université (SU)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Smithsonian Astrophysical Observatory, Smithsonian Institution, University of New Hampshire (UNH), Department of Climate and Space Sciences and Engineering (CLaSP), University of Michigan [Ann Arbor], and University of Michigan System-University of Michigan System
Subjects: 010504 meteorology & atmospheric sciences, Whistler, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Electron, Astrophysics, 01 natural sciences, Physics - Space Physics, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), 0105 earth and related environmental sciences, Physics, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], Astronomy and Astrophysics, Plasma, Thermal conduction, Space Physics (physics.space-ph), Physics - Plasma Physics, Computational physics, Plasma Physics (physics.plasm-ph), Solar wind, Heat flux, Astrophysics - Solar and Stellar Astrophysics, 13. Climate action, Space and Planetary Science, Beta (plasma physics), Physics::Space Physics, Heliospheric current sheet, Astrophysics::Earth and Planetary Astrophysics
Abstract: Aims. We survey the electron heat flux observed by the Parker Solar Probe (PSP) in the near-Sun environment at heliocentric distances of 0.125–0.25 AU. Methods. We utilized measurements from the Solar Wind Electrons Alphas and Protons and FIELDS experiments to compute the solar wind electron heat flux and its components and to place these in context. Results. The PSP observations reveal a number of trends in the electron heat flux signatures near the Sun. The magnitude of the heat flux is anticorrelated with solar wind speed, likely as a result of the lower saturation heat flux in the higher-speed wind. When divided by the saturation heat flux, the resulting normalized net heat flux is anticorrelated with plasma beta on all PSP orbits, which is consistent with the operation of collisionless heat flux regulation mechanisms. The net heat flux also decreases in very high beta regions in the vicinity of the heliospheric current sheet, but in most cases of this type the omnidirectional suprathermal electron flux remains at a comparable level or even increases, seemingly inconsistent with disconnection from the Sun. The measured heat flux values appear inconsistent with regulation primarily by collisional mechanisms near the Sun. Instead, the observed heat flux dependence on plasma beta and the distribution of suprathermal electron parameters are both consistent with theoretical instability thresholds associated with oblique whistler and magnetosonic modes.
Published: 2020
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40. ESCAPADE: Coordinated multipoint measurements of Mars' unique hybrid magnetosphere

Author: Christopher M. Fowler, Yuki Harada, Shannon Curry, David Brain, Janet G. Luhmann, Paul Withers, Yingjuan Ma, Matthieu Berthomier, Ronan Modolo, Aroh Barjatya, Edward Thiemann, Shaosui Xu, Christopher T. Russell, Davin Larson, Robert Lillis, Phyllis Whittlesey, Roberto Livi, Space Sciences Laboratory [Berkeley] (SSL), University of California [Berkeley], University of California-University of California, Institute of Geophysics and Planetary Physics [Los Angeles] (IGPP), University of California [Los Angeles] (UCLA), Embry-Riddle Aeronautical University, University of California, Laboratory for Atmospheric and Space Physics [Boulder] (LASP), University of Colorado [Boulder], Department of Astronomy [Boston], Boston University [Boston] (BU), HELIOS - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Laboratoire de Physique des Plasmas (LPP), Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École polytechnique (X)-Sorbonne Université (SU)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)
Subjects: Physics, Solar System, Ion thruster, Spacecraft, business.industry, Astronomy, Magnetosphere, Mars Exploration Program, Proton (rocket family), Solar wind, [SDU]Sciences of the Universe [physics], Physics::Space Physics, Van Allen Probes, Astrophysics::Earth and Planetary Astrophysics, business
Abstract: Multi-spacecraft missions after 2000 (Cluster II, THEMIS, Van Allen Probes, and MMS) have revolutionized our understanding of the causes, patterns and variability of a wide array of plasma phenomena in the terrestrial magnetospheric environment. ESCAPADE is a twin-spacecraft Mars mission concept that will similarly revolutionize our understanding of how solar wind momentum and energy flows throughout Mars’ magnetosphere to drive ion and sputtering escape, two processes which have helped shape Mars’ climate evolution over solar system history. ESCAPADE will measure magnetic field strength and topology, ion plasma distributions (separated into light and heavy masses), as well as suprathermal electron flows and thermal electron and ion densities, from coordinated elliptical, 200 km x ~7000 km orbits. ESCAPADE are small spacecraft ( ESCAPADE is due to complete its preliminary design review in August 2020, thereafter moving toward build, test, integration and launch two years later. We will report on science goals and objectives, mission design challenges, and provide a status update.
Published: 2020
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41. The solar wind angular momentum flux as observed by Parker solar probe

Author: Roberto Livi, Kelly E. Korreck, Mathew J. Owens, Adam J. Finley, Victor Réville, Justin C. Kasper, Davin Larson, Anthony W. Case, Phyllis Whittlesey, Rui F. Pinto, Sean P. Matt, Michael L. Stevens, Institut de recherche en astrophysique et planétologie (IRAP), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)
Subjects: Rotation period, Angular momentum, 010504 meteorology & atmospheric sciences, Solar wind, Astrophysics::High Energy Astrophysical Phenomena, Stellar physics, FOS: Physical sciences, Astrophysics, Rotation, 01 natural sciences, Stellar evolution, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Solar rotation, Stellar rotation, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), 0105 earth and related environmental sciences, Physics, Solar physics, Earth and Planetary Astrophysics (astro-ph.EP), Astronomy and Astrophysics, Astrophysics - Solar and Stellar Astrophysics, 13. Climate action, Space and Planetary Science, [SDU]Sciences of the Universe [physics], Physics::Space Physics, Solar evolution, Astrophysics::Earth and Planetary Astrophysics, Heliosphere, Astrophysics - Earth and Planetary Astrophysics
Abstract: The long-term evolution of the Sun's rotation period cannot be directly observed, and is instead inferred from trends in the measured rotation periods of other Sun-like stars. Assuming the Sun spins-down as it ages, following rotation rate $\propto$ age$^{-1/2}$, requires the current solar angular momentum-loss rate to be around $6\times 10^{30}$erg. Magnetohydrodynamic models, and previous observations of the solar wind (from the Helios and Wind spacecraft), generally predict a values closer to $1\times 10^{30}$erg or $3\times 10^{30}$erg, respectively. Recently, the Parker Solar Probe (PSP) observed tangential solar wind speeds as high as $\sim50$km/s in a localized region of the inner heliosphere. If such rotational flows were prevalent throughout the corona, it would imply that the solar wind angular momentum-loss rate is an order of magnitude larger than all of those previous estimations. In this letter, we evaluate the angular momentum flux in the solar wind, using data from the first two orbits of PSP. The solar wind is observed to contain both large positive (as seen during perihelion), and negative angular momentum fluxes. We analyse two solar wind streams that were repeatedly traversed by PSP; the first is a slow wind stream whose average angular momentum flux fluctuates between positive to negative, and the second is an intermediate speed stream containing a positive angular momentum flux (more consistent with a constant flow of angular momentum). When the data from PSP is evaluated holistically, the average equatorial angular momentum flux implies a global angular momentum-loss rate of around $2.6-4.2\times 10^{30}$ erg (which is more consistent with observations from previous spacecraft)., Comment: 11 pages + 6 figures, accepted for publication to ApJL
Published: 2020
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42. Evidence of Sub-proton-scale Magnetic Holes in the Venusian Magnetosheath

Author: Katherine Amanda Goodrich, John W. Bonnell, Shannon M. Curry, Roberto Livi, Phyllis Whittlesey, Forrest Mozer, Marc Pulupa, David M. Malaspina, Stuart d Bale, Trevor A Bowen, Anthony William Case, Thierry Dudok de Wit, Keith Goetz, Peter R Harvey, Jasper S. Halekas, Justin C. Kasper, Davin E. Larson, Robert John MacDowall, Michael D McManus, and Michael Louis Stevens
Published: 2020
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43. Plasma Double Layers at the Boundary between Venus and the Solar Wind

Author: David M. Malaspina, Katherine Amanda Goodrich, Roberto Livi, Jasper S. Halekas, Michael D McManus, Shannon M. Curry, Stuart D. Bale, John W. Bonnell, Thierry Dudok de Wit, Keith Goetz, Peter R Harvey, Robert John MacDowall, Marc Pulupa, Anthony William Case, Justin Kasper, Kelly Korreck, Davin E. Larson, and Phyllis Whittlesey
Published: 2020
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44. Constraining Ion-Scale Heating and Spectral Energy Transfer in Observations of Plasma Turbulence

Author: Phyllis Whittlesey, Stuart D. Bale, Roberto Livi, Benjamin D. G. Chandran, Thierry Dudok de Wit, Kelly E. Korreck, Trevor A. Bowen, Jasper Halekas, Anthony W. Case, Christopher H. K. Chen, Robert J. MacDowall, Michael L. Stevens, David M. Malaspina, Alfred Mallet, M. McManus, Peter R. Harvey, Justin C. Kasper, Keith Goetz, Marc Pulupa, John W. Bonnell, Die Duan, Alexandros Chasapis, Davin Larson, Space Sciences Laboratory [Berkeley] (SSL), University of California [Berkeley], University of California-University of California, Smithsonian Astrophysical Observatory, Smithsonian Institution, University of New Hampshire (UNH), Laboratory for Atmospheric and Space Physics [Boulder] (LASP), University of Colorado [Boulder], Queen Mary University of London (QMUL), Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National d’Études Spatiales [Paris] (CNES), GSFC Solar System Exploration Division, and NASA Goddard Space Flight Center (GSFC)
Subjects: Physics, Range (particle radiation), Turbulence, General Physics and Astronomy, Spectral density, Energy flux, Kinetic energy, 7. Clean energy, 01 natural sciences, Ion, Computational physics, Nonlinear system, 13. Climate action, [SDU]Sciences of the Universe [physics], 0103 physical sciences, Physics::Space Physics, 010306 general physics, Scaling
Abstract: International audience; 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.
Published: 2020
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45. The Heliospheric Current Sheet and Plasma Sheet during Parker Solar Probe's First Orbit

Author: Jasper Halekas, N.-E. Raouafi, T. Dudok de Wit, Roberto Livi, Peter Harvey, A. Kouloumvakos, Robert J. MacDowall, Victor Réville, Benoit Lavraud, Milan Maksimovic, Michael Lavarra, Marc Pulupa, Teresa Nieves-Chinchilla, T. D. Phan, Léa Griton, Phyllis Whittlesey, Adam Szabo, Rui F. Pinto, A. P. Rouillard, N. Fargette, John W. Bonnell, Kelly E. Korreck, Nicolas Poirier, Jia Huang, R. Kieokaew, M. Berthomier, Sergio Toledo-Redondo, Anthony W. Case, Katja Klein, David M. Malaspina, Stuart D. Bale, Justin C. Kasper, Davin Larson, Philippe Louarn, Michael L. Stevens, Nicholeen M. Viall, Keith Goetz, Jonathan Eastwood, Vincent Génot, Centre d'étude spatiale des rayonnements (CESR), Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées, Commissariat à l'énergie atomique et aux énergies alternatives (CEA), GSFC Laboratory for Extraterrestrial Physics, NASA Goddard Space Flight Center (GSFC), School of Physics and Astronomy [Southampton], University of Southampton, Centre de physique moléculaire optique et hertzienne (CPMOH), Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1, Harvard-Smithsonian Center for Astrophysics (CfA), Harvard University [Cambridge]-Smithsonian Institution, University of California [Berkeley], University of California, Space Sciences Laboratory [Berkeley] (SSL), University of California-University of California, Institut de recherche en astrophysique et planétologie (IRAP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), School of Physics and Astronomy [Minneapolis], University of Minnesota [Twin Cities] (UMN), University of Minnesota System-University of Minnesota System, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Department of Physics and Astronomy [Iowa City], University of Iowa [Iowa City], Groupement de Recherche et d'Etudes en Gestion à HEC (GREGH), Ecole des Hautes Etudes Commerciales (HEC Paris)-Centre National de la Recherche Scientifique (CNRS), Consiglio Nazionale delle Ricerche (CNR), Centre de Recherche en Transplantation et Immunologie (U1064 Inserm - CRTI), Institut National de la Santé et de la Recherche Médicale (INSERM)-Université de Nantes - UFR de Médecine et des Techniques Médicales (UFR MEDECINE), Université de Nantes (UN)-Université de Nantes (UN), Naval Research Laboratory (NRL), European Space Agency (ESA), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Université Sciences et Technologies - Bordeaux 1 (UB)-Centre National de la Recherche Scientifique (CNRS), Harvard University-Smithsonian Institution, University of California [Berkeley] (UC Berkeley), University of California (UC), University of California (UC)-University of California (UC), Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), Agence Spatiale Européenne = European Space Agency (ESA), and Science and Technology Facilities Council (STFC)
Subjects: 010504 meteorology & atmospheric sciences, INTERPLANETARY MAGNETIC-FIELD, Astrophysics, Astronomy & Astrophysics, 01 natural sciences, Plasma jets, Heliosphere, RECONNECTION, 0201 Astronomical and Space Sciences, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Pitch angle, Interplanetary magnetic field, 010303 astronomy & astrophysics, Solar coronal streamers, 0105 earth and related environmental sciences, Physics, DENSITY STRUCTURES, Science & Technology, ORIGIN, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], SUN, Plasma sheet, Astronomy and Astrophysics, Magnetic reconnection, WIND, Helmet streamer, Solar magnetic reconnection, Strahl, Space and Planetary Science, Physical Sciences, Physics::Space Physics, Space plasmas, Slow solar wind, Heliospheric current sheet, Solar coronal transients
Abstract: International audience; 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 magnetic reconnection, (4) there often exists a layer of disconnected magnetic field just outside the high-density regions, in agreement with a reconnected topology, (5) while a few cases consist of short-lived density and velocity changes, compatible with short-duration reconnection exhausts, most events are much longer and show the presence of flux ropes interleaved with higher-β regions. These findings are consistent with the transient release of density blobs and flux ropes through sequential magnetic reconnection at the tip of the helmet streamer. The data also demonstrate that, at least during PSP's first orbit, the only structure that may be defined as the HPS is the density structure that results from magnetic reconnection, and its by-products, likely released near the tip of the helmet streamer.
Published: 2020
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46. ESCAPADE: coordinated multipoint measurements of Mars' near-space plasma environment

Author: Shaosui Xu, Yuki Harada, Shannon Curry, Aroh Barjatya, David Brain, Roberto Livi, Paul Withers, Robert Lillis, Ronan Modolo, Davin Larson, Christopher M. Fowler, Janet G. Luhmann, Edward Thiemann, Christopher T. Russell, and Phyllis Whittlesey
Subjects: Physics, Mars Exploration Program, Plasma, Astrobiology, Near space
Abstract: Multi-spacecraft missions after 2000 (Cluster II, THEMIS, Van Allen Probes, and MMS) have revolutionized our understanding of the causes, patterns and variability of a wide array of plasma phenomena in the terrestrial magnetospheric environment. ESCAPADE is a twin-spacecraft Mars mission concept that will similarly revolutionize our understanding of how solar wind momentum and energy flows throughout Mars’ magnetosphere to drive ion and sputtering escape, two processes which have helped shape Mars’ climate evolution over solar system history. ESCAPADE will measure magnetic field strength and topology, ion plasma distributions (separated into light and heavy masses), as well as suprathermal electron flows and thermal electron and ion densities, from elliptical, 200 km x 7000 km orbits. ESCAPADE are small spacecraft (ESCAPADE has been selected for Phase A and B study by NASA as one of three finalists in the SIMPLEX-II program. We will report on science goals, engineering and mission design challenges, and provide a status update.
Published: 2020
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47. Coronal Electron Temperature inferred from the Strahl Electrons in the Inner Heliosphere: Parker Solar Probe and Helios observations

Author: John W. Bonnell, Peter R. Harvey, Robert J. MacDowall, Keith Goetz, Milan Maksimovic, Anthony W. Case, Lorenzo Matteini, Stuart D. Bale, Justin C. Kasper, Kelly E. Korreck, Marc Pulupa, Samuel T. Badman, Davin Larson, Roberto Livi, David M. Malaspina, Phyllis Whittlesey, Thierry Dudok de Wit, Laura Bercic, Simone Landi, Michael L. Stevens, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Università degli Studi di Firenze = University of Florence [Firenze] (UNIFI), University of California [Berkeley], University of California, INAF - Osservatorio Astrofisico di Arcetri (OAA), Istituto Nazionale di Astrofisica (INAF), Imperial College London, Queen Mary University of London (QMUL), Smithsonian Astrophysical Observatory, Smithsonian Institution, Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), University of Michigan [Ann Arbor], University of Michigan System, GSFC Solar System Exploration Division, NASA Goddard Space Flight Center (GSFC), and University of Colorado [Boulder]
Subjects: 010504 meteorology & atmospheric sciences, Solar wind, Solar corona, Electron, Astrophysics, 01 natural sciences, ENERGY, Physics - Space Physics, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, Solar physics, 0306 Physical Chemistry (incl. Structural), Physics, Strahl, Astrophysics - Solar and Stellar Astrophysics, Beta (plasma physics), Physical Sciences, HALO, 0202 Atomic, Molecular, Nuclear, Particle and Plasma Physics, Physics::Space Physics, Electron temperature, Space plasmas, RADIAL EVOLUTION, Solar atmosphere, FOS: Physical sciences, Astronomy & Astrophysics, PROTONS, 0201 Astronomical and Space Sciences, 0103 physical sciences, DISTRIBUTIONS, Solar and Stellar Astrophysics (astro-ph.SR), 0105 earth and related environmental sciences, Science & Technology, Astronomy and Astrophysics, Plasma, WIND, VELOCITY, Space Physics (physics.space-ph), MODEL, SLOW, Distribution function, [SDU]Sciences of the Universe [physics], 13. Climate action, Space and Planetary Science, HEAT-FLUX, Astronomy data analysis, Space vehicle instruments, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Heliosphere
Abstract: The shape of the electron velocity distribution function plays an important role in the dynamics of the solar wind acceleration. Electrons are normally modelled 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 analysed the data obtained by two missions, Helios spanning the distances between 65 and 215 R$_S$, and Parker Solar Probe (PSP) reaching down to 35 R$_S$ during its first two orbits around the Sun. The electron strahl was characterised with two parameters, pitch-angle width (PAW), and the strahl parallel temperature (T$_{s\parallel}$). PSP observations confirm the already reported dependence of strahl PAW on core parallel plasma beta ($\beta_{ec\parallel}$)\citep{Bercic2019}. Most of the strahl measured by PSP appear narrow with PAW reaching down to 30$^o$. The portion of the strahl velocity distribution function aligned with the magnetic field is for the measured energy range well described by a Maxwellian distribution function. T$_{s\parallel}$ was found to be anti-correlated with the solar wind velocity, and independent of radial distance. These observations imply that T$_{s\parallel}$ carries the information about the coronal electron temperature. The obtained values are in agreement with coronal temperatures measured using spectroscopy (David et al. 2998), and the inferred solar wind source regions during the first orbit of PSP agree with the predictions using a PFSS model (Bale et al. 2019, Badman et al. 2019).
Published: 2020
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48. 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

Author: Davin Larson, T. Dudok de Wit, Justin C. Kasper, Phyllis Whittlesey, V. Krishna Jagarlamudi, Chadi Salem, Michael L. Stevens, Michel Moncuquet, Anthony W. Case, Jasper Halekas, A. Lecacheux, L. Bercic, Marc Pulupa, Stuart D. Bale, N. Lahmiti, Peter Harvey, Nicole Meyer-Vernet, Roberto Livi, David M. Malaspina, Robert J. MacDowall, Štěpán Štverák, John W. Bonnell, Milan Maksimovic, Keith Goetz, Kelly E. Korreck, Mihailo M. Martinović, K. Issautier, Marco Velli, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), University of California [Berkeley], University of California, Imperial College London, Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES)
Subjects: Physics, 010504 meteorology & atmospheric sciences, Astrophysics::High Energy Astrophysical Phenomena, Astronomy and Astrophysics, HeliOS, 7. Clean energy, 01 natural sciences, Computational physics, Solar wind, 13. Climate action, Space and Planetary Science, [SDU]Sciences of the Universe [physics], 0103 physical sciences, Physics::Space Physics, Electron temperature, Astrophysics::Solar and Stellar Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], 010303 astronomy & astrophysics, 0105 earth and related environmental sciences
Abstract: International audience; We discuss the solar wind electron temperatures T-e 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 quasithermal 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 T-e and the wind bulk speed V: this anticorrelation is most likely the remnant of the wellknown 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 measurements and show, for the first time, that an in situ (T-e, V) anticorrelation is well observed at 0.3 au but disappears as the wind expands, evolves, and mixes with different electron temperature gradients for different wind speeds.
Published: 2020
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49. Electrons in the Young Solar Wind: First Results from the Parker Solar Probe

Author: David M. Malaspina, Jasper Halekas, Michael L. Stevens, Katja Klein, Phyllis Whittlesey, Anthony W. Case, Milan Maksimovic, Robert J. MacDowall, Stuart D. Bale, D. McGinnis, Davin Larson, Marc Pulupa, Peter Harvey, Justin C. Kasper, Keith Goetz, M. Berthomier, Kelly E. Korreck, Department of Physics and Astronomy, University of Iowa, University of Iowa [Iowa City], Space Sciences Laboratory, University of California, Berkeley, CA94720-7450, USA (SSL), Space Sciences Laboratory, University of California, Berkeley, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Laboratoire de Physique des Plasmas (LPP), Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École polytechnique (X)-Sorbonne Université (SU)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)
Subjects: 010504 meteorology & atmospheric sciences, FOS: Physical sciences, Electron, Astrophysics, 7. Clean energy, 01 natural sciences, Wind speed, Physics - Space Physics, 0103 physical sciences, Thermal, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), 0105 earth and related environmental sciences, Physics, [PHYS]Physics [physics], [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], Astronomy and Astrophysics, Space Physics (physics.space-ph), Strahl, Solar wind, Astrophysics - Solar and Stellar Astrophysics, 13. Climate action, Space and Planetary Science, Beta (plasma physics), Physics::Space Physics, Electron temperature, Halo, Astrophysics::Earth and Planetary Astrophysics
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 $\sim 100,000$ electron distributions measured near the Sun on the first two PSP orbits, which reached heliocentric distances as small as $\sim 0.17$ AU. As expected, the electron core density and temperature increase with decreasing heliocentric distance, while the ratio of electron thermal pressure to magnetic pressure ($\beta_e$) decreases. These quantities have radial scaling consistent with previous observations farther from the Sun, with superposed variations associated with different solar wind streams. The density in the strahl also increases; however, the density of the halo plateaus and even decreases at perihelion, leading to a large strahl/halo ratio near the Sun. As at greater heliocentric distances, the core has a sunward drift relative to the proton frame, which balances the current carried by the strahl, satisfying the zero-current condition necessary to maintain quasi-neutrality. Many characteristics of the electron distributions near perihelion have trends with solar wind flow speed, $\beta_e$, and/or collisional age. Near the Sun, some trends not clearly seen at 1 AU become apparent, including anti-correlations between wind speed and both electron temperature and heat flux. These trends help us understand the mechanisms that shape the solar wind electron distributions at an early stage of their evolution.
Published: 2020
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50. Seed Population Preconditioning and Acceleration Observed by the Parker Solar Probe

Author: R. A. Leske, David M. Malaspina, Leila Mays, Mark E. Wiedenbeck, Matthew E. Hill, Michael L. Stevens, B. Poduval, M. I. Desai, William H. Matthaeus, W. C. de Wet, Bernd Heber, Christina Cohen, E. R. Christian, Ralph L. McNutt, Roberto Livi, Phyllis Whittlesey, Dusan Odstrcil, Robert J. MacDowall, John W. Bonnell, Davin Larson, Donald G. Mitchell, Marc Pulupa, Edmond C. Roelof, Justin C. Kasper, Andrew Davis, Stuart D. Bale, J. R. Szalay, R. A. Mewaldt, A. C. Cummings, J. S. Rankin, Reka M. Winslow, D. J. McComas, Anthony W. Case, E. C. Stone, K. E. Korreck, Peter Harvey, T. Dudok de Wit, Olga Malandraki, M. Karavolos, J. T. Niehof, M. Gorby, Joe Giacalone, Colin J. Joyce, Nathan A. Schwadron, K. Goetz, Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES)
Subjects: Proton, 010504 meteorology & atmospheric sciences, Field line, Population, Flux, FOS: Physical sciences, Astrophysics, 01 natural sciences, Physics - Space Physics, 0103 physical sciences, Coronal mass ejection, Astrophysics::Solar and Stellar Astrophysics, education, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), 0105 earth and related environmental sciences, Physics, education.field_of_study, Solar energetic particles, Astronomy and Astrophysics, Space Physics (physics.space-ph), Solar wind, Astrophysics - Solar and Stellar Astrophysics, 13. Climate action, Space and Planetary Science, [SDU]Sciences of the Universe [physics], Physics::Space Physics, Heliospheric current sheet, Astrophysics::Earth and Planetary Astrophysics, Interplanetary spaceflight, Space environment
Abstract: A series of solar energetic particle (SEP) events were observed at Parker Solar Probe (PSP) by the Integrated Science Investigation of the Sun (IS☉IS) during the period from April 18, 2019 through April 24, 2019. The PSP spacecraft was located near 0.48 au from the Sun on Parker spiral field lines that projected out to 1 au within ∼25° of near Earth spacecraft. These SEP events, though small compared to historically large SEP events, were amongst the largest observed thus far in the PSP mission and provide critical information about the space environment inside 1 au during SEP events. During this period the Sun released multiple coronal mass ejections (CMEs). One of these CMEs observed was initiated on April 20, 2019 at 01:25 UTC, and the interplanetary CME (ICME) propagated out and passed over the PSP spacecraft. Observations by the Electromagnetic Fields Investigation (FIELDS) show that the magnetic field structure was mostly radial throughout the passage of the compression region and the plasma that followed, indicating that PSP did not directly observe a flux rope internal to the ICME, consistent with the location of PSP on the flank of the ICME. Analysis using relativistic electrons observed near Earth by the Electron, Proton and Alpha Monitor (EPAM) on the Advanced Composition Explorer (ACE) demonstrates the presence of flare-accelerated seed populations during the events observed. The energy spectrum of the IS☉IS observed seed population below 1 MeV is consistent with the superposition of acceleration processes near the limit of plasma stability. IS☉IS observations reveal the compression and acceleration of seed populations during the passage of the ICME, which is likely a key part of the pre-acceleration process that occurs close to the Sun and pre-conditions the energetic particle acceleration process.
Published: 2020
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