Found 17 results
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2020
Authors: Verniero J. L., Larson D. E., Livi R., Rahmati A., McManus M. D., et al.
Title: Parker Solar Probe Observations of Proton Beams Simultaneous with Ion-scale Waves
Abstract:

Parker Solar Probe (PSP), NASA’s latest and closest mission to the Sun, is on a journey to investigate fundamental enigmas of the inner heliosphere. This paper reports initial observations made by the Solar Probe Analyzer for Ions (SPAN-I), one of the instruments in the Solar Wind Electrons Alphas and Protons instrument suite. We address the presence of secondary proton beams in concert with ion-scale waves observed by FIELDS, the electromagnetic fields instrument suite. We show two events from PSP’s second orbit that demonstrate signatures consistent with wave-particle interactions. We showcase 3D velocity distribution functions (VDFs) measured by SPAN-I during times of strong wave power at ion scales. From an initial instability analysis, we infer that the VDFs departed far enough. . .
Date: 05/2020 Publisher: The Astrophysical Journal Supplement Series Pages: 5 DOI: 10.3847/1538-4365/ab86af Available at: https://iopscience.iop.org/article/10.3847/1538-4365/ab86afhttps
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Authors: Yang Zhongwei, Liu Ying D., Matsukiyo Shuichi, Lu Quanming, Guo Fan, et al.
Title: PIC Simulations of Microinstabilities and Waves at Near-Sun Solar Wind Perpendicular Shocks: Predictions for Parker Solar Probe and Solar Orbiter
Abstract:

Microinstabilities and waves excited at moderate-Mach-number perpendicular shocks in the near-Sun solar wind are investigated by full particle-in-cell simulations. By analyzing the dispersion relation of fluctuating field components directly issued from the shock simulation, we obtain key findings concerning wave excitations at the shock front: (1) at the leading edge of the foot, two types of electrostatic (ES) waves are observed. The relative drift of the reflected ions versus the electrons triggers an electron cyclotron drift instability (ECDI) that excites the first ES wave. Because the bulk velocity of gyro-reflected ions shifts to the direction of the shock front, the resulting ES wave propagates oblique to the shock normal. Immediately, a fraction of incident electrons are accele. . .
Date: 09/2020 Publisher: The Astrophysical Journal Pages: L24 DOI: 10.3847/2041-8213/abaf59 Available at: https://iopscience.iop.org/article/10.3847/2041-8213/abaf59https://iopscience.iop.org/article/10.3847/2041-8213/abaf59/pdf
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Authors: Meyer-Vernet Nicole, and Moncuquet Michel
Title: Plasma Waves in Space: The Importance of Properly Accounting for the Measuring Device
Abstract:

Electric fields are generally measured or calculated using two intuitive assumptions: (1) the electric field equals the voltage divided by the antenna length when the antenna is electromagnetically short (2) the antenna responds best to electric field along its length. Both assumptions are often incorrect for electrostatic fields because they scale as the Debye length or as the electron gyroradius, which may be smaller than the antenna length. Taking into account this little-known fact enables us to complete or correct several recent papers on plasma spontaneous fluctuations in various solar system environments.


Date: 03/2020 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2019JA027723 Available at: https://onlinelibrary.wiley.com/doi/abs/10.1029/2019JA027723
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Authors: Malaspina David M., Halekas Jasper, Berčič Laura, Larson Davin, Whittlesey Phyllis, et al.
Title: Plasma Waves near the Electron Cyclotron Frequency in the Near-Sun Solar Wind
Abstract:

Data from the first two orbits of the Sun by Parker Solar Probe reveal that the solar wind sunward of 50 solar radii is replete with plasma waves and instabilities. One of the most prominent plasma wave power enhancements in this region appears near the electron cyclotron frequency (fce). Most of this wave power is concentrated in electric field fluctuations near 0.7 fce and fce, with strong harmonics of both frequencies extending above fce. At least two distinct, often concurrent, wave modes are observed, preliminarily identified as electrostatic whistler-mode waves and electron Bernstein waves. Wave intervals range in duration from a few seconds to hours. Both the amplitudes and number of detections of these near-fce waves increas. . .
Date: 02/2020 Publisher: The Astrophysical Journal Supplement Series Pages: 21 DOI: 10.3847/1538-4365/ab4c3b Available at: https://iopscience.iop.org/article/10.3847/1538-4365/ab4c3b
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Authors: Nicolaou Georgios, Livadiotis George, Wicks Robert T., Verscharen Daniel, and Maruca Bennett A.
Title: Polytropic Behavior of Solar Wind Protons Observed by Parker Solar Probe
Abstract:

A polytropic process describes the transition of a fluid from one state to another through a specific relationship between the fluid density and temperature. The value of the polytropic index that governs this relationship determines the heat transfer and the effective degrees of freedom during a specific process. In this study, we analyze solar wind proton plasma measurements, obtained by the Faraday cup instrument on board the Parker Solar Probe. We examine the large-scale variations of the proton plasma density and temperature within the inner heliosphere explored by the spacecraft. We then address the polytropic behavior in the density and temperature fluctuations in short time intervals, which we analyze in order to derive the effective polytropic index of . . .
Date: 09/2020 Publisher: The Astrophysical Journal Pages: 26 DOI: 10.3847/1538-4357/abaaae Available at: https://iopscience.iop.org/article/10.3847/1538-4357/abaaaehttps://iopscience.iop.org/article/10.3847/1538-4357/abaaae/pdf
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Authors: Kim T. K., Pogorelov N. V., Arge C. N., Henney C. J., Jones-Mecholsky S. I., et al.
Title: Predicting the Solar Wind at the Parker Solar Probe Using an Empirically Driven MHD Model
Abstract:

Since its launch on 2018 August 12, Parker Solar Probe (PSP) has completed its first and second orbits around the Sun, having reached down to 35.7 solar radii at each perihelion. In anticipation of the exciting new data at such unprecedented distances, we have simulated the global 3D heliosphere using an MHD model coupled with a semi-empirical coronal model using the best available photospheric magnetograms as input. We compare our heliospheric MHD simulation results with in situ measurements along the PSP trajectory from its launch to the completion of the second orbit, with particular emphasis on the solar wind structure around the first two solar encounters. Furthermore, we show our model prediction for the third perihelion, which occurred on 2019 September 1. Comparison of the MHD r. . .
Date: 02/2020 Publisher: The Astrophysical Journal Supplement Series Pages: 40 DOI: 10.3847/1538-4365/ab58c9 Available at: https://iopscience.iop.org/article/10.3847/1538-4365/ab58c9
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Authors: Hibberd Adam, Hein Andreas M., and Eubanks Marshall
Title: Project Lyra: Catching 1I/‘Oumuamua – Mission opportunities after 2024
Abstract:

In October 2017, the first interstellar object within our solar system was discovered. Today designated 1I/’Oumuamua, it shows characteristics that have never before been observed in a celestial body. Due to these characteristics, an in-situ investigation of 1I would be of extraordinary scientific value. Previous studies have demonstrated that a mission to 1I/’Oumuamua is feasible using current and near-term technologies, however, with an anticipated launch date of 2020-2021. This is too soon to be realistic. This paper aims at addressing the question of the feasibility of a mission to 1I/’Oumuamua in 2024 and beyond. Using the OITS trajectory simulation tool, various scenarios are analyzed, including a powered Jupiter flyby and Solar Oberth maneuver, a Jupiter powered flyby, and . . .
Date: 05/2020 Publisher: Acta Astronautica Pages: 136 - 144 DOI: 10.1016/j.actaastro.2020.01.018 Available at: https://linkinghub.elsevier.com/retrieve/pii/S0094576520300291
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Authors: Desai M. I., Mitchell D. G., Szalay J. R., Roelof E. C., Giacalone J., et al.
Title: Properties of Suprathermal-through-energetic He Ions Associated with Stream Interaction Regions Observed over the Parker Solar Probe ’s First Two Orbits
Abstract:

The Integrated Science Investigation of the Sun (IS☉IS) suite on board NASA's Parker Solar Probe (PSP) observed six distinct enhancements in the intensities of suprathermal-through-energetic (∼0.03─3 MeV nucleon−1) He ions associated with corotating or stream interaction regions (CIR or SIR) during its first two orbits. Our results from a survey of the time histories of the He intensities, spectral slopes, and anisotropies and the event-averaged energy spectra during these events show the following: (1) In the two strongest enhancements, seen at 0.35 and 0.85 au, the higher-energy ions arrive and maximize later than those at lower energies. In the event seen at 0.35 au, the He ions arrive when PSP was away from the SIR trailing edge and entered the rarefaction region . . .
Date: 02/2020 Publisher: The Astrophysical Journal Supplement Series Pages: 56 DOI: 10.3847/1538-4365/ab65ef Available at: https://iopscience.iop.org/article/10.3847/1538-4365/ab65efhttps://iopscience.iop.org/article/10.3847/1538-4365/ab65ef/
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2019
Authors: Riley Pete, Downs Cooper, Linker Jon A., Mikic Zoran, Lionello Roberto, et al.
Title: Predicting the Structure of the Solar Corona and Inner Heliosphere during Parker Solar Probe ’s First Perihelion Pass
Abstract:

NASA’s Parker Solar Probe (PSP) spacecraft reached its first perihelion of 35.7 solar radii on 2018 November 5. To aid in mission planning, and in anticipation of the unprecedented measurements to be returned, in late October, we developed a three-dimensional magnetohydrodynamic (MHD) solution for the solar corona and inner heliosphere, driven by the then available observations of the Sun’s photospheric magnetic field. Our model incorporates a wave-turbulence-driven model to heat the corona. Here, we present our predictions for the structure of the solar corona and the likely in situ measurements that PSP will be returning over the next few months. We infer that, in the days prior to first encounter, PSP was immersed in wind emanating from a well-established, positive-polarity north. . .
Date: 04/2019 Publisher: The Astrophysical Journal Pages: L15 DOI: 10.3847/2041-8213/ab0ec3 Available at: http://stacks.iop.org/2041-8205/874/i=2/a=L15?key=crossref.94a3f13ef95cab063c2cc60115d0f410http://stacks.iop.org/2041-8205/874/i=2/a=L15/pd
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Authors: McComas D. J., Christian E. R., Cohen C. M. S., Cummings A. C., Davis A. J., et al.
Title: Probing the energetic particle environment near the Sun
Abstract:

NASA’s Parker Solar Probe mission recently plunged through the inner heliosphere of the Sun to its perihelia, about 24 million kilometres from the Sun. Previous studies farther from the Sun (performed mostly at a distance of 1 astronomical unit) indicate that solar energetic particles are accelerated from a few kiloelectronvolts up to near-relativistic energies via at least two processes: "impulsive" events, which are usually associated with magnetic reconnection in solar flares and are typically enriched in electrons, helium-3 and heavier ions, and "gradual" events, which are typically associated with large coronal-mass-ejection-driven shocks and compressions moving through the corona and inner solar wind and are the dominant source of protons with energies between 1 and 10 megaelect. . .
Date: 12/2019 Publisher: Nature Pages: 223 - 227 DOI: 10.1038/s41586-019-1811-1 Available at: http://www.nature.com/articles/s41586-019-1811-1
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Authors: Hein Andreas M., Perakis Nikolaos, Eubanks Marshall, Hibberd Adam, Crowl Adam, et al.
Title: Project Lyra: Sending a spacecraft to 1I/’Oumuamua (former A/2017 U1), the interstellar asteroid
Abstract:

The first definitely interstellar object 1I/’Oumuamua (previously A/2017 U1) observed in our solar system provides the opportunity to directly study material from an other star system. Can such objects be intercepted? The challenge of reaching the object within a reasonable timeframe is formidable due to its high heliocentric hyperbolic excess velocity of about 26 km/s; much faster than any vehicle yet launched. This paper presents a high-level analysis of potential near-term options for a mission to 1I/’Oumuamua and potential similar objects. Reaching 1I/’Oumuamua via a spacecraft launched in a reasonable timeframe of 5-10 years (launch in 2022-2027) requires an Earth departure hyperbolic excess velocity between 33 and 76 km/s for mission durations between 30 and 5 years, respect. . .
Date: 08/2019 Publisher: Acta Astronautica Pages: 552 - 561 DOI: 10.1016/j.actaastro.2018.12.042 Available at: https://linkinghub.elsevier.com/retrieve/pii/S0094576518317004
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2018
Authors: Réville Victor, Tenerani Anna, and Velli Marco
Title: Parametric Decay and the Origin of the Low-frequency Alfvénic Spectrum of the Solar Wind
Abstract:

The fast solar wind shows a wide spectrum of transverse magnetic and velocity field perturbations. These perturbations are strongly correlated in the sense of Alfvén waves propagating mostly outward, from the Sun to the interplanetary medium. They are likely to be fundamental to the acceleration and the heating of the solar wind. However, the precise origin of the broadband spectrum is unknown to date. Typical periods of chromospheric Alfvén waves are limited to a few minutes, and any longer period perturbations should be strongly reflected at the transition region. In this work, we show that minute long Alfvénic fluctuations are unstable to the parametric instability. Parametric instability enables an inverse energy cascade by exciting several-hour-long periods of Alfvénic fluctuat. . .
Date: 10/2018 Publisher: The Astrophysical Journal Pages: 38 DOI: 10.3847/1538-4357/aadb8f Available at: http://stacks.iop.org/0004-637X/866/i=1/a=38?key=crossref.877507b60fca8d8ddb73692a546936b0
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Authors: Chandran Benjamin D. G.
Title: Parametric instability, inverse cascade and the range of solar-wind turbulence
Abstract:

In this paper, weak-turbulence theory is used to investigate the nonlinear evolution of the parametric instability in three-dimensional low-β plasmas at wavelengths much greater than the ion inertial length under the assumption that slow magnetosonic waves are strongly damped. It is shown analytically that the parametric instability leads to an inverse cascade of Alfvén wave quanta, and several exact solutions to the wave kinetic equations are presented. The main results of the paper concern the parametric decay of Alfvén waves that initially satisfy e+ >> e-, where e+ and e- are the frequency (f) spectra of Alfvén waves propagating in opposite directions along the magnetic field lines. If e+ initially has a peak frequency fDate: 02/2018 Publisher: Journal of Plasma Physics DOI: 10.1017/S0022377818000016 Available at: https://www.cambridge.org/core/product/identifier/S0022377818000016/type/journal_article
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Authors: Milligan Ryan O., and Ireland Jack
Title: On the Performance of Multi-Instrument Solar Flare Observations During Solar Cycle 24
Abstract:

The current fleet of space-based solar observatories offers us a wealth of opportunities to study solar flares over a range of wavelengths. Significant advances in our understanding of flare physics often come from coordinated observations between multiple instruments. Consequently, considerable efforts have been, and continue to be, made to coordinate observations among instruments ( e.g. through the Max Millennium Program of Solar Flare Research). However, there has been no study to date that quantifies how many flares have been observed by combinations of various instruments. Here we describe a technique that retrospectively searches archival databases for flares jointly observed by the Ramaty High Energy Solar Spectroscopic Imager (RHESSI), Solar Dynamics Observatory (SDO)/ EUV Vari. . .
Date: 02/2018 Publisher: Solar Physics DOI: 10.1007/s11207-017-1233-x Available at: http://link.springer.com/10.1007/s11207-017-1233-xhttp://link.springer.com/content/pdf/10.1007/s11207-017-1233-x.pdfhttp://link.springer.com/article/10.1007/s11207-017-1233-x/fulltext.htmlhttp://link.springer.com/content/pdf/10.1007/s11207-017-1233-x.pdf
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Authors: Xiong Ming, Davies Jackie A., Feng Xueshang, Li Bo, Yang Liping, et al.
Title: Prospective White-light Imaging and In Situ Measurements of Quiescent Large-scale Solar-wind Streams from the Parker Solar Probe and Solar Orbiter
Abstract:

Deep-space exploration of the inner heliosphere is in an unprecedented golden age, with the recent and forthcoming launches of the Parker Solar Probe (PSP) and Solar Orbiter (SolO) missions, respectively. In order to both predict and understand the prospective observations by PSP and SolO, we perform forward MHD modeling of the 3D inner heliosphere at solar minimum, and synthesize the white-light (WL) emission that would result from Thomson scattering of sunlight from the coronal and heliospheric plasmas. Both solar rotation and spacecraft trajectory should be considered when reconstructing quiescent large-scale solar-wind streams from PSP and SolO WL observations. When transformed from a static coordinate system into a corotating one, the elliptical orbit of PSP becomes a multiwinding . . .
Date: 12/2018 Publisher: The Astrophysical Journal Pages: 137 DOI: 10.3847/1538-4357/aae978 Available at: http://stacks.iop.org/0004-637X/868/i=2/a=137?key=crossref.fe473eb9a278d1ea105f9203808e2eab
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2016
Authors: Clemens Adam, and Burgess David
Title: Pickup ion processes associated with spacecraft thrusters: Implications for solar probe plus
Abstract:

Chemical thrusters are widely used in spacecraft for attitude control and orbital manoeuvres. They create an exhaust plume of neutral gas which produces ions via photoionization and charge exchange. Measurements of local plasma properties will be affected by perturbations caused by the coupling between the newborn ions and the plasma. A model of neutral expansion has been used in conjunction with a fully three-dimensional hybrid code to study the evolution and ionization over time of the neutral cloud produced by the firing of a mono-propellant hydrazine thruster as well as the interactions of the resulting ion cloud with the ambient solar wind. Results are presented which show that the plasma in the region near to the spacecraft will be perturbed for an extended period of time with the. . .
Date: 03/2016 Publisher: Physics of Plasmas Pages: 032901 DOI: 10.1063/1.4942938 Available at: http://aip.scitation.org/doi/10.1063/1.4942938http://aip.scitation.org/doi/pdf/10.1063/1.4942938
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Authors: Cranmer Steven R.
Title: Predictions for Dusty Mass Loss from Asteroids During Close Encounters with Solar Probe Plus
Abstract:

The Solar Probe Plus ( SPP) mission will explore the Sun’s corona and innermost solar wind starting in 2018. The spacecraft will also come close to a number of Mercury-crossing asteroids with perihelia less than 0.3 AU. At small heliocentric distances, these objects may begin to lose mass, thus becoming "active asteroids" with comet-like comae or tails. This paper assembles a database of 97 known Mercury-crossing asteroids that may be encountered by SPP, and it presents estimates of their time-dependent visible-light fluxes and mass loss rates. Assuming a similar efficiency of sky background subtraction as was achieved by STEREO , we find that approximately 80 % of these asteroids are bright enough to be observed by the Wide-field Imager for SPP (WISPR). A model of gas/dust mass loss . . .
Date: 11/2016 Publisher: Earth, Moon, and Planets Pages: 51 - 79 DOI: 10.1007/s11038-016-9490-5 Available at: http://link.springer.com/10.1007/s11038-016-9490-5http://link.springer.com/content/pdf/10.1007/s11038-016-9490-5.pdfhttp://link.springer.com/content/pdf/10.1007/s11038-016-9490-5.pdfhttp://link.springer.com/article/10.1007/s11038-016-9490-5/fulltext.html
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