Found 188 results
Author Title [ Type(Desc)] Year
Journal Article
Authors: Isenberg Philip A., and Vasquez Bernard J.
Title: KINETIC EVOLUTION OF CORONAL HOLE PROTONS BY IMBALANCED ION-CYCLOTRON WAVES: IMPLICATIONS FOR MEASUREMENTS BY SOLAR PROBE PLUS
Abstract:

We extend the kinetic guiding-center model of collisionless coronal hole protons presented in Isenberg & Vasquez to consider driving by imbalanced spectra of obliquely propagating ion-cyclotron waves. These waves are assumed to be a small by-product of the imbalanced turbulent cascade to high perpendicular wavenumber, and their total intensity is taken to be 1% of the total fluctuation energy. We also extend the kinetic solutions for the proton distribution function in the resulting fast solar wind to heliocentric distances of 20 solar radii, which will be attainable by the Solar Probe Plus spacecraft. We consider three ratios of outward-propagating to inward-propagating resonant intensities: 1, 4, and 9. The self-consistent bulk flow speed reaches fast solar wind values in all case. . .
Date: 08/2015 Publisher: The Astrophysical Journal Pages: 119 DOI: 10.1088/0004-637X/808/2/119 Available at: http://stacks.iop.org/0004-637X/808/i=2/a=119?key=crossref.961efccaa84816c8b4c9e041f523e07f
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Authors: Vech Daniel, Kasper Justin C., Klein Kristopher G., Huang Jia, Stevens Michael L., et al.
Title: Kinetic-scale Spectral Features of Cross Helicity and Residual Energy in the Inner Heliosphere
Abstract:

In this work, we present the first results from the flux angle (FA) operation mode of the Faraday Cup instrument on board the Parker Solar Probe (PSP). The FA mode allows rapid measurements of phase space density fluctuations close to the peak of the proton velocity distribution function with a cadence of 293 Hz. This approach provides an invaluable tool for understanding kinetic-scale turbulence in the solar wind and solar corona. We describe a technique to convert the phase space density fluctuations into vector velocity components and compute several turbulence parameters, such as spectral index, residual energy, and cross helicity during two intervals when the FA mode was used in PSP's first encounter at 0.174 au distance from the Sun.


Date: 02/2020 Publisher: The Astrophysical Journal Supplement Series Pages: 52 DOI: 10.3847/1538-4365/ab60a2 Available at: https://iopscience.iop.org/article/10.3847/1538-4365/ab60a2
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Authors: Reid Hamish A. S., and Kontar Eduard P.
Title: Langmuir wave electric fields induced by electron beams in the heliosphere
Abstract:

Solar electron beams responsible for type III radio emission generate Langmuir waves as they propagate out from the Sun. The Langmuir waves are observed via in situ electric field measurements. These Langmuir waves are not smoothly distributed but occur in discrete clumps, commonly attributed to the turbulent nature of the solar wind electron density. Exactly how the density turbulence modulates the Langmuir wave electric fields is understood only qualitatively. Using weak turbulence simulations, we investigate how solar wind density turbulence changes the probability distribution functions, mean value and variance of the beam-driven electric field distributions. Simulations show rather complicated forms of the distribution that are dependent upon how the electric fields are sampled. Ge. . .
Date: 02/2017 Publisher: Astronomy & Astrophysics Pages: A44 DOI: 10.1051/0004-6361/201629697 Available at: http://www.aanda.org/10.1051/0004-6361/201629697http://www.aanda.org/10.1051/0004-6361/201629697/pdf
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Authors: Scudder J. D.
Title: The Long-standing Closure Crisis in Coronal Plasmas
Abstract:

Coronal and solar wind physics have long used plasma fluid models to motivate physical explanations of observations; the hypothesized model is introduced into a fluid simulation to see if observations are reproduced. This procedure is called Verification of Mechanism (VoM) modeling; it is contingent on the self consistency of the closure that made the simulation possible. Inner corona VoMs typically assume weak gradient Spitzer─Braginskii closures. Four prominent coronal VoMs in place for decades are shown to contradict their closure hypotheses, demonstrably shaping coronal and solar wind research. These findings have been possible since 1953. This unchallenged evolution is worth understanding, so that similarly flawed VoMs do not continue to mislead new research. As a first step in t. . .
Date: 11/2019 Publisher: The Astrophysical Journal Pages: 148 DOI: 10.3847/1538-4357/ab48e0 Available at: https://iopscience.iop.org/article/10.3847/1538-4357/ab48e0
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Authors: ZALDIVAR J
Title: Long-term simulation of main biogeochemical events in a coastal lagoon: Sacca Di Goro (Northern Adriatic Coast, Italy)
Abstract:

A biogeochemical model for the Sacca di Goro Lagoon has been developed and partially validated with field data from 1989 to 1998. The model considers the nutrient cycles in the water column as well as in the sediments. Furthermore, phytoplankton, zooplankton, and Ulva sp. dynamics, as well as shellfish farming, are taken into account. Due to the recent anoxic crises in the lagoon, the dynamic of oxygen has also been simulated. The actual version of the model is a 0D with input fluxes from the watershed and exchange with the Northern Adriatic Sea. Nutrients from the watershed, wet and dry deposition, temperature, light intensity, wind speed and shellfish production are considered as forcing functions. The results show that the model is able to capture the essential dynamics of the lagoon. . .
Date: 11/2003 Publisher: Continental Shelf Research Pages: 1847 - 1875 DOI: 10.1016/j.csr.2003.01.001 Available at: http://linkinghub.elsevier.com/retrieve/pii/S027843430300150Xhttp://api.elsevier.com/content/article/PII:S0278-4343(03)00150-X?httpAccept=text/xmlhttp://api.elsevier.com/content/article/PII:S0278-4343(03)00150-X?httpAccept=text/plain
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Authors: Badman Samuel T., Bale Stuart D., Oliveros Juan C. Martín, Panasenco Olga, Velli Marco, et al.
Title: Magnetic Connectivity of the Ecliptic Plane within 0.5 au: Potential Field Source Surface Modeling of the First Parker Solar Probe Encounter
Abstract:

We compare magnetic field measurements taken by the FIELDS instrument on board Parker Solar Probe (PSP) during its first solar encounter to predictions obtained by potential field source surface (PFSS) modeling. Ballistic propagation is used to connect the spacecraft to the source surface. Despite the simplicity of the model, our results show striking agreement with PSP's first observations of the heliospheric magnetic field from ̃0.5 au (107.5 R) down to 0.16 au (35.7 R). Further, we show the robustness of the agreement is improved both by allowing the photospheric input to the model to vary in time, and by advecting the field from PSP down to the PFSS model domain using in situ PSP/Solar Wind Electrons Alphas and Protons measurements of the solar wind spee. . .
Date: 02/2020 Publisher: The Astrophysical Journal Supplement Series Pages: 23 DOI: 10.3847/1538-4365/ab4da7 Available at: https://iopscience.iop.org/article/10.3847/1538-4365/ab4da7
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Authors: Tenerani Anna, Velli Marco, Matteini Lorenzo, Réville Victor, Shi Chen, et al.
Title: Magnetic Field Kinks and Folds in the Solar Wind
Abstract:

Parker Solar Probe (PSP) observations during its first encounter at 35.7 R have shown the presence of magnetic field lines that are strongly perturbed to the point that they produce local inversions of the radial magnetic field, known as switchbacks. Their counterparts in the solar wind velocity field are local enhancements in the radial speed, or jets, displaying (in all components) the velocity─magnetic field correlation typical of large amplitude Alfvén waves propagating away from the Sun. Switchbacks and radial jets have previously been observed over a wide range of heliocentric distances by Helios, Wind, and Ulysses, although they were prevalent in significantly faster streams than seen at PSP. Here we study via numerical magnetohydrodynamics simulations the evolut. . .
Date: 02/2020 Publisher: The Astrophysical Journal Supplement Series Pages: 32 DOI: 10.3847/1538-4365/ab53e1 Available at: https://iopscience.iop.org/article/10.3847/1538-4365/ab53e1
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Authors: Bourdin Philippe, Singh Nishant K., and Brandenburg Axel
Title: Magnetic Helicity Reversal in the Corona at Small Plasma Beta
Abstract:

Solar and stellar dynamos shed small-scale and large-scale magnetic helicity of opposite signs. However, solar wind observations and simulations have shown that some distance above the dynamo both the small-scale and large-scale magnetic helicities have reversed signs. With realistic simulations of the solar corona above an active region now being available, we have access to the magnetic field and current density along coronal loops. We show that a sign reversal in the horizontal averages of the magnetic helicity occurs when the local maximum of the plasma beta drops below unity and the field becomes nearly fully force free. Hence, this reversal is expected to occur well within the solar corona and would not directly be accessible to in situ measurements with the Parker Solar Probe or . . .
Date: 12/2018 Publisher: The Astrophysical Journal Pages: 2 DOI: 10.3847/1538-4357/aae97a Available at: http://stacks.iop.org/0004-637X/869/i=1/a=2?key=crossref.90fa7f41d90e2c8b57f8248c0437cc6b
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Authors: Rasca A. P., Oran R., and ányi M.
Title: Mass loading of the solar wind by a sungrazing comet
Abstract:

Collisionless mass loading was suggested by Biermann et al. (1967) for describing interactions between the solar wind and cometary atmospheres. Recent observations have led to an increased interest in coronal mass loading due to sungrazing comets and collisional debris of sunward migrating interplanetary dust particles. In a previous paper, we presented a 3-D MHD model of the solar corona based on the Block-Adaptive-Tree-Solarwind-Roe-Upwind-Scheme code which includes the interaction of dust with the solar wind. We have shown the impact on the solar wind from abrupt mass loading in the coronal region. We apply the model to a sungrazing cometary source, using ejected dust dynamics to generate tail-shaped mass-loading regions. Results help predict the effects on the solar wind acceleratio. . .
Date: 08/2014 Publisher: Geophysical Research Letters Pages: 5376 - 5381 DOI: 10.1002/2014GL060990 Available at: http://doi.wiley.com/10.1002/2014GL060990http://onlinelibrary.wiley.com/wol1/doi/10.1002/2014GL060990/fullpdfhttps
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Authors: Parashar T. N., Goldstein M. L., Maruca B. A., Matthaeus W. H., Ruffolo D., et al.
Title: Measures of Scale-dependent Alfvénicity in the First PSP Solar Encounter
Abstract:

The solar wind shows periods of highly Alfvénic activity, where velocity fluctuations and magnetic fluctuations are aligned or antialigned with each other. It is generally agreed that solar wind plasma velocity and magnetic field fluctuations observed by the Parker Solar Probe (PSP) during the first encounter are mostly highly Alfvénic. However, quantitative measures of Alfvénicity are needed to understand how the characterization of these fluctuations compares with standard measures from prior missions in the inner and outer heliosphere, in fast wind and slow wind, and at high and low latitudes. To investigate this issue, we employ several measures to quantify the extent of Alfvénicity—the Alfvén ratio rA, the normalized cross helicity σc, the normalized r. . .
Date: 02/2020 Publisher: The Astrophysical Journal Supplement Series Pages: 58 DOI: 10.3847/1538-4365/ab64e6 Available at: https://iopscience.iop.org/article/10.3847/1538-4365/ab64e6
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Authors: Klein K. G., and Howes G. G.
Title: MEASURING COLLISIONLESS DAMPING IN HELIOSPHERIC PLASMAS USING FIELD–PARTICLE CORRELATIONS
Abstract:

An innovative field-particle correlation technique is proposed that uses single-point measurements of the electromagnetic fields and particle velocity distribution functions to investigate the net transfer of energy from fields to particles associated with the collisionless damping of turbulent fluctuations in weakly collisional plasmas, such as the solar wind. In addition to providing a direct estimate of the local rate of energy transfer between fields and particles, it provides vital new information about the distribution of that energy transfer in velocity space. This velocity-space signature can potentially be used to identify the dominant collisionless mechanism responsible for the damping of turbulent fluctuations in the solar wind. The application of this novel field-particle co. . .
Date: 08/2016 Publisher: The Astrophysical Journal Pages: L30 DOI: 10.3847/2041-8205/826/2/L30 Available at: http://stacks.iop.org/2041-8205/826/i=2/a=L30?key=crossref.1f33350dac6f20e78faa0a9e9d852985http://stacks.iop.org/2041-8205/826/i=2/a=L30/pdfhttp://stacks.iop.org/2041-8205/826/i=2/a=L30?key=crossref.1f33350dac6f20e78faa0a9e9d852985
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Authors: Hu Junxiang, Li Gang, Fu Shuai, Zank Gary, and Ao Xianzhi
Title: Modeling a Single SEP Event from Multiple Vantage Points Using the iPATH Model
Abstract:

Using the recently extended 2D improved Particle Acceleration and Transport in the Heliosphere (iPATH) model, we model an example gradual solar energetic particle event as observed at multiple locations. Protons and ions that are energized via the diffusive shock acceleration mechanism are followed at a 2D coronal mass ejection-driven shock where the shock geometry varies across the shock front. The subsequent transport of energetic particles, including cross-field diffusion, is modeled by a Monte Carlo code that is based on a stochastic differential equation method. Time intensity profiles and particle spectra at multiple locations and different radial distances, separated in longitudes, are presented. The results shown here are relevant to the upcoming Parker Solar Probe mission.

. . .
Date: 02/2018 Publisher: The Astrophysical Journal Pages: L19 DOI: 10.3847/2041-8213/aaabc1 Available at: http://stacks.iop.org/2041-8205/854/i=2/a=L19?key=crossref.3db06d37bee0fc065cdec82f4faaf3b7
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Authors: Plus M
Title: Modelling of oxygen and nitrogen cycling as a function of macrophyte community in the Thau lagoon
Abstract:

A three-dimensional model coupling physical and biological processes for the whole Thau lagoon (Mediterranean coast of France) was developed in order to assess the relationships between macrophytes and the oxygen and nitrogen cycles. Ten species have been inserted as forcing variables in the model. Plankton dynamics, shellfish cultivation impact and mineralization of organic matter are also considered, as well as nutrient and oxygen exchanges between the sediment and the water column. Simulations with and without the macrophytes have shown that the system can be characterized as having a highly structured pattern involving lagoon nitrogen and oxygen cycles. This pattern is created by the combined influence of macrophytes, watershed and oyster farming. The model has been also used to ass. . .
Date: 11/2003 Publisher: Continental Shelf Research Pages: 1877 - 1898 DOI: 10.1016/j.csr.2003.03.001 Available at: https://linkinghub.elsevier.com/retrieve/pii/S0278434303001511https://api.elsevier.com/content/article/PII:S0278-4343(03)00151-1?httpAccept=text/xmlhttps://api.elsevier.com/content/article/PII:S0278-4343(03)00151-1?httpAccept=text/plain
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Authors: Kombiadou Katerina, Ganthy Florian, Verney Romaric, Plus Martin, and Sottolichio Aldo
Title: Modelling the effects of Zostera noltei meadows on sediment dynamics: application to the Arcachon lagoon
Abstract:

A three-dimensional model has been modified to describe the complex interactions between hydrodynamics, sediment dynamics and biological parameters in the presence of Zostera noltei. The model treats seagrass leafs as flexible blades that bend under hydrodynamic forcing and alter the local momentum and turbulence fluxes and, therefore, the benthic shear conditions; these changes cause related changes to the mass balance at the boundary of the bed, in turn affecting the suspended matter in the column and ultimately primary productivity and the growth of the dwarf-grass. Modelling parameters related to the impact of Z. noltei to the local flow and to erosion and deposition rates were calibrated using flume experimental measurements; results from the calibration of the model are presented . . .
Date: 10/2014 Publisher: Ocean Dynamics Pages: 1499 - 1516 DOI: 10.1007/s10236-014-0754-1 Available at: http://link.springer.com/10.1007/s10236-014-0754-1http://link.springer.com/content/pdf/10.1007/s10236-014-0754-1
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Authors: Klein Kristopher G., Perez Jean C., Verscharen Daniel, Mallet Alfred, and Chandran Benjamin D. G.
Title: A MODIFIED VERSION OF TAYLOR’S HYPOTHESIS FOR SOLAR PROBE PLUS OBSERVATIONS
Abstract:

The Solar Probe Plus (SPP) spacecraft will explore the near-Sun environment, reaching heliocentric distances less than 10 {{R}}. Near Earth, spacecraft measurements of fluctuating velocities and magnetic fields taken in the time domain are translated into information about the spatial structure of the solar wind via Taylor’s “frozen turbulence” hypothesis. Near the perihelion of SPP, however, the solar-wind speed is comparable to the Alfvén speed, and Taylor’s hypothesis in its usual form does not apply. In this paper, we show that under certain assumptions, a modified version of Taylor’s hypothesis can be recovered in the near-Sun region. We consider only the transverse, non-compressive component of the fluctuations at length scales exceeding the proton gyrora. . .
Date: 03/2015 Publisher: The Astrophysical Journal Pages: L18 DOI: 10.1088/2041-8205/801/1/L18 Available at: http://stacks.iop.org/2041-8205/801/i=1/a=L18?key=crossref.c92a2bde23ce9cdd58185dec581d5a09
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Authors: Wood Brian E., Hess Phillip, Howard Russell A., Stenborg Guillermo, and Wang Yi-Ming
Title: Morphological Reconstruction of a Small Transient Observed by Parker Solar Probe on 2018 November 5
Abstract:

On 2018 November 5, about 24 hr before the first close perihelion passage of Parker Solar Probe (PSP), a coronal mass ejection (CME) entered the field of view of the inner detector of the Wide-field Imager for Solar PRobe (WISPR) instrument on board PSP, with the northward component of its trajectory carrying the leading edge of the CME off the top edge of the detector about four hours after its first appearance. We connect this event to a very small jetlike transient observed from 1 au by coronagraphs on both the SOlar and Heliospheric Observatory (SOHO) and the A component of the Solar TErrestrial RElations Observatory mission (STEREO-A). This allows us to make the first three-dimensional reconstruction of a CME structure considering both observations made very close to the Sun and im. . .
Date: 02/2020 Publisher: The Astrophysical Journal Supplement Series Pages: 28 DOI: 10.3847/1538-4365/ab5219 Available at: https://iopscience.iop.org/article/10.3847/1538-4365/ab5219
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Authors: Chang Qing, Xu Xiaojun, Xu Qi, Zhong Jun, Xu Jiaying, et al.
Title: Multiple-point Modeling the Parker Spiral Configuration of the Solar Wind Magnetic Field at the Solar Maximum of Solar Cycle 24
Abstract:

By assuming that the solar wind flow is spherically symmetric and that the flow speed becomes constant beyond some critical distance r = R 0 (neglecting solar gravitation and acceleration by high coronal temperature), the large-scale solar wind magnetic field lines are distorted into a Parker spiral configuration, which is usually simplified to an Archimedes spiral. Using magnetic field observations near Mercury, Venus, and Earth during solar maximum of Solar Cycle 24, we statistically surveyed the Parker spiral angles and obtained the empirical equations of the Archimedes and Parker spirals by fitting the multiple-point results. We found that the solar wind magnetic field configurations are slightly different during different years. Archimedes and Parker spiral configuration. . .
Date: 10/2019 Publisher: The Astrophysical Journal Pages: 102 DOI: 10.3847/1538-4357/ab412a Available at: https://iopscience.iop.org/article/10.3847/1538-4357/ab412
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Authors: Hill M. E., Mitchell D. G., Andrews G. B., Cooper S. A., Gurnee R. S., et al.
Title: The Mushroom: A half-sky energetic ion and electron detector
Abstract:

We present a time-of-flight mass spectrometer design for the measurement of ions in the 30 keV to 10 MeV range for protons (up to 40 MeV and 150 MeV for He and heavy ions, respectively) and 30 keV to 1 MeV range for electrons, covering half of the sky with 80 apertures. The instrument, known as the "Mushroom," owing to its shape, solves the field of view problem for magnetospheric and heliospheric missions that employ three-axis stabilized spacecraft, yet still require extended angular coverage; the Mushroom is also compatible with a spinning spacecraft. The most important new feature of the Mushroom is the method through which uncomplicated electrostatic optics and clean position sensing combine to permit many apertures to fit into a compact, low-mass sensor head (or wedge), several of. . .
Date: 02/2017 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2016JA022614 Available at: https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1002/2016JA022614
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Authors: Banks Michael
Title: NASA launches Parker Solar Probe mission to 'touch' the Sun
Abstract:

NASA has launched a mission to study the Sun’s atmosphere and solar wind that will come far closer to our star than any other craft before.


Date: 09/2018 Publisher: Physics World Pages: 7 - 7 DOI: 10.1088/2058-7058/31/9/11 Available at: http://stacks.iop.org/2058-7058/31/i=9/a=11?key=crossref.74cb5927650dbdc73ec7a9da93480898
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Authors: Szalay J. R., Pokorný P., Bale S. D., Christian E. R., Goetz K., et al.
Title: The Near-Sun Dust Environment: Initial Observations from Parker Solar Probe
Abstract:

The Parker Solar Probe (PSP) spacecraft has flown into the densest, previously unexplored, innermost region of our solar system's zodiacal cloud. While PSP does not have a dedicated dust detector, multiple instruments on the spacecraft are sensitive to the effects of meteoroid bombardment. Here, we discuss measurements taken during PSP's second orbit and compare them to models of the zodiacal cloud's dust distribution. Comparing the radial impact rate trends and the timing and location of a dust impact to an energetic particle detector, we find the impactor population to be consistent with dust grains on hyperbolic orbits escaping the solar system. Assuming PSP's impact environment is dominated by hyperbolic impactors, the total quantity of dust ejected from our solar system is estimate. . .
Date: 02/2020 Publisher: The Astrophysical Journal Supplement Series Pages: 27 DOI: 10.3847/1538-4365/ab50c1 Available at: https://iopscience.iop.org/article/10.3847/1538-4365/ab50c1
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Authors: Howard R. A., Vourlidas A., Bothmer V., Colaninno R. C., DeForest C. E., et al.
Title: Near-Sun observations of an F-corona decrease and K-corona fine structure
Abstract:

Remote observations of the solar photospheric light scattered by electrons (the K-corona) and dust (the F-corona or zodiacal light) have been made from the ground during eclipses and from space at distances as small as 0.3 astronomical units to the Sun. Previous observations of dust scattering have not confirmed the existence of the theoretically predicted dust-free zone near the Sun. The transient nature of the corona has been well characterized for large events, but questions still remain (for example, about the initiation of the corona and the production of solar energetic particles) and for small events even its structure is uncertain. Here we report imaging of the solar corona during the first two perihelion passes (0.16-0.25 astronomical units) of the Parker Solar Probe spacecraft. . .
Date: 12/2019 Publisher: Nature Pages: 232 - 236 DOI: 10.1038/s41586-019-1807-x Available at: http://www.nature.com/articles/s41586-019-1807-x
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Authors: Lawrence David J., Feldman William C., Gold Robert E., Goldsten John O., and McNutt Ralph L.
Title: The neutron, gamma-ray, X-ray spectrometer (NGXS): A compact instrument for making combined measurements of neutrons, gamma-rays, and X-rays
Abstract:

The Neutron, Gamma ray, and X-ray Spectrometer (NGXS) is a compact instrument designed to detect neutrons, gamma-rays, and hard X-rays. The original goal of NGXS was to detect and characterize neutrons, gamma-rays, and X-rays from the Sun as part of the Solar Probe Plus mission in order to provide direct insight into particle acceleration, magnetic reconnection, and cross-field transport processes that take place near the Sun. Based on high-energy neutron detections from prompt solar flares, it is estimated that the NGXS would detect neutrons from 15 to 24 impulsive flares. The NGXS sensitivity to 2.2 MeV gamma rays would enable a detection of ̃50-60 impulsive flares. The NGXS is estimated to measure ̃120 counts/s for a GOES C1-type flare at 0.1 AU, which allows for a large dynamic ra. . .
Date: 01/2014 Publisher: Acta Astronautica Pages: 524 - 529 DOI: 10.1016/j.actaastro.2012.06.017 Available at: https://linkinghub.elsevier.com/retrieve/pii/S009457651200255Xhttps://api.elsevier.com/content/article/PII:S009457651200255X?httpAccept=text/xmlhttps://api.elsevier.com/content/article/PII:S009457651200255X?httpAccept=text/plain
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Authors: Stansby David, Salem Chadi, Matteini Lorenzo, and Horbury Timothy
Title: A New Inner Heliosphere Proton Parameter Dataset from the Helios Mission
Abstract:

In the near future, Parker Solar Probe and Solar Orbiter will provide the first comprehensive in-situ measurements of the solar wind in the inner heliosphere since the Helios mission in the 1970s. We describe a reprocessing of the original Helios ion distribution functions to provide reliable and reproducible data to characterise the proton core population of the solar wind in the inner heliosphere. A systematic fitting of bi-Maxwellian distribution functions was performed to the raw Helios ion distribution function data to extract the proton core number density, velocity, and temperatures parallel and perpendicular to the magnetic field. We present radial trends of these derived proton parameters, forming a benchmark to which new measurements in the inner heliosphere will be compared. . . .
Date: 11/2018 Publisher: Solar Physics DOI: 10.1007/s11207-018-1377-3 Available at: http://link.springer.com/10.1007/s11207-018-1377-3http://link.springer.com/content/pdf/10.1007/s11207-018-1377-3.pdfhttp://link.springer.com/article/10.1007/s11207-018-1377-3/fulltext.htmlhttp://link.springer.com/content/pdf/10.1007/s11207-018-1377-3.pdf
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Title: News at a glance
Abstract:

In science news around the world, the U.S. National Institutes of Health (NIH) responds to a report on "foreign influences," Australia slashes its future research funding, Mars's methane mystery deepens, and the Paris agreement on climate change survives a contentious rulemaking session in Poland. Also, astronomers discover the solar system's farthest-known planet, NIH comes under fire for clinical trial reporting results, the late Paul Allen bequests a new immunology research institute, and NASA's Parker Solar Probe makes its first dip into the sun's atmosphere. Plus, a new study suggests tourists and scientists are making Antarctica's birds sick, and an interview with a Harvard University historian helps explain India's monsoon—one of Asia's most important weather patterns.


Date: 12/2018 Publisher: Science Pages: 1334 - 1336 DOI: 10.1126/science.362.6421.1334 Available at: http://www.sciencemag.org/lookup/doi/10.1126/science.362.6421.1334https://syndication.highwire.org/content/doi/10.1126/science.362.6421.1334
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Authors: Roberts Aaron, Karimabadi Homa, Sipes Tamara, Ko Yuan-Kuen, and Lepri Susan
Title: Objectively Determining States of the Solar Wind Using Machine Learning
Abstract:

Conclusively determining the states of the solar wind will aid in tracing the origins of those states to the Sun, and in the process help to find the wind's origin and acceleration mechanism(s). Prior studies have characterized the various states of the wind, making lists that are only partially based on objective criteria; different approaches obtain substantially different results. To uncover the unbiased states of the solar wind, we use "k-means clustering"—an unsupervised machine learning method—including constructed multipoint variables. The method allows exploration of different descriptive state variables and numbers of fundamental states (clusters). We show that the clusters reveal structures similar to those found by more ad hoc means, including coronal hole wind, interplan. . .
Date: 02/2020 Publisher: The Astrophysical Journal Pages: 153 DOI: 10.3847/1538-4357/ab5a7a Available at: https://iopscience.iop.org/article/10.3847/1538-4357/ab5a7a
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