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2020
Authors: Florido-Llinas M., Nieves-Chinchilla T., and Linton M. G.
Title: Analysis of the Helical Kink Stability of Differently Twisted Magnetic Flux Ropes
Abstract:

Magnetic flux ropes (MFRs) are usually considered to be the magnetic structure that dominates the transport of helicity from the Sun into the heliosphere. They entrain a confined plasma within a helically organized magnetic structure and are able to cause geomagnetic activity. The formation, evolution, and twist distribution of MFRs are issues subject to strong debate. Although different twist profiles have been suggested so far, none of them has been thoroughly explored yet. The aim of this work is to present a theoretical study of the conditions under which MFRs with different twist profiles are kink stable and thereby shed some light on the aforementioned aspects. The magnetic field is modeled according to the circular-cylindrical analytical flux rope model in Nieves-Chinchilla et al. . .
Date: 09/2020 Publisher: Solar Physics DOI: 10.1007/s11207-020-01687-z Available at: http://link.springer.com/10.1007/s11207-020-01687-zhttp://link.springer.com/content/pdf/10.1007/s11207-020-01687-z.pdf
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Authors: Nieves-Chinchilla Teresa, Szabo Adam, Korreck Kelly E., Alzate Nathalia, Balmaceda Laura A., et al.
Title: Analysis of the Internal Structure of the Streamer Blowout Observed by the Parker Solar Probe During the First Solar Encounter
Abstract:

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

We discuss the solar wind electron temperatures Te as measured in the nascent solar wind by Parker Solar Probe during its first perihelion pass. The measurements have been obtained by fitting the high-frequency part of quasi-thermal noise spectra recorded by the Radio Frequency Spectrometer. In addition we compare these measurements with those obtained by the electrostatic analyzer discussed in Halekas et al. These first electron observations show an anticorrelation between Te and the wind bulk speed V: this anticorrelation is most likely the remnant of the well-known mapping observed at 1 au and beyond between the fast wind and its coronal hole sources, where electrons are observed to be cooler than in the quiet corona. We also revisit Helios electron temperature . . .
Date: 02/2020 Publisher: The Astrophysical Journal Supplement Series Pages: 62 DOI: 10.3847/1538-4365/ab61fc Available at: https://iopscience.iop.org/article/10.3847/1538-4365/ab61fch
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2017
Authors: Kong Xiangliang, Guo Fan, Giacalone Joe, Li Hui, and Chen Yao
Title: The Acceleration of High-energy Protons at Coronal Shocks: The Effect of Large-scale Streamer-like Magnetic Field Structures
Abstract:

Recent observations have shown that coronal shocks driven by coronal mass ejections can develop and accelerate particles within several solar radii in large solar energetic particle (SEP) events. Motivated by this, we present an SEP acceleration study that including the process in which a fast shock propagates through a streamer-like magnetic field with both closed and open field lines in the low corona region. The acceleration of protons is modeled by numerically solving the Parker transport equation with spatial diffusion both along and across the magnetic field. We show that particles can be sufficiently accelerated to up to several hundred MeV within 2-3 solar radii. When the shock propagates through a streamer-like magnetic field, particles are more efficiently accelerated compared. . .
Date: 12/2017 Publisher: The Astrophysical Journal Pages: 38 DOI: 10.3847/1538-4357/aa97d7 Available at: http://stacks.iop.org/0004-637X/851/i=1/a=38?key=crossref.2009ec10fbd1f6f8cd1462070076984f
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2014
Authors: Goelzer Molly L., Schwadron Nathan A., and Smith Charles W.
Title: An analysis of Alfvén radius based on sunspot number from 1749 to today
Abstract:

The Solar Probe Plus mission now under construction will provide the first in situ measurements from inside the orbit of Mercury. The most critical part of that mission will be measurements from inside the Alfvén radius where the Alfvén speed exceeds the wind speed and the physics of the solar wind changes fundamentally due, in part, to the multidirectionality of wave propagation. In this region waves from both sunward and antisunward of the observation point can effect the local dynamics including the turbulent evolution, heating, and acceleration of the plasma. While the location of this point can change with solar wind conditions, we ask the question of whether there is a systematic dependence on the solar cycle that moves the average Alfvén radius to different locations depending. . .
Date: 01/2014 Publisher: Journal of Geophysical Research: Space Physics Pages: 115 - 120 DOI: 10.1002/2013JA019420 Available at: http://doi.wiley.com/10.1002/2013JA019420http://onlinelibrary.wiley.com/wol1/doi/10.1002/2013JA019420/fullpdf
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2013
Authors: Bastian T. S.
Title: AIP Conference ProceedingsA view from the ground: Next generation instrumentation for solar and heliospheric physics
Abstract:

The solar and space physics community has recently completed its second decadal survey under the auspices of the National Research Council. An integrated strategy for ground and space based studies of the Sun and space physics has been recommended, with specific recommendations made regarding new instrumentation, programs, and facilities. The ground based component of these recommendations is briefly reviewed here: the Advanced Technology Solar Telescope (ATST), the Frequency Agile Solar Radiotelescope (FASR), and the Coronal Solar Magnetism Observatory (COSMO). Although not considered as part of the decadal portfolio, but of which the community should nevertheless be aware, are the Atacama Large Millimeter/submillimeter Array (ALMA) and the Jansky Very Large Array (VLA). Several additi. . .
Date: 07/2013 Publisher: AIP DOI: 10.1063/1.4811080 Available at: http://aip.scitation.org/doi/abs/10.1063/1.4811080
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Authors: Case A. W., Kasper J. C., Daigneau P. S., Caldwell D., Freeman M., et al.
Title: AIP Conference ProceedingsDesigning a sun-pointing Faraday cup for solar probe plus
Abstract:

The NASA Solar Probe Plus (SPP) mission will be the first spacecraft to pass through the sub-Alfvénic solar corona. The objectives of the mission are to trace the flow of energy that heats and accelerates the solar corona and solar wind, to determine the structure and dynamics of the plasma and magnetic fields at the sources of the solar wind, and to explore mechanisms that accelerate and transport energetic particles. The Solar Wind Electrons, Alphas, and Protons (SWEAP) Investigation instrument suite on SPP will measure the bulk solar wind conditions in the inner heliosphere. SWEAP consists of the Solar Probe Cup (SPC), a sun-pointing Faraday Cup, and the Solar Probe ANalyzers (SPAN), a set of 3 electrostatic analyzers that will reside in the penumbra of SPP’s thermal protection sy. . .
Date: Publisher: AIP DOI: 10.1063/1.4811083 Available at: http://scitation.aip.org/content/aip/proceeding/aipcp/10.1063/1.4811083
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Authors: Wicks Robert T., Matteini Lorenzo, Horbury Timothy S., Hellinger Petr, and Roberts Aaron
Title: AIP Conference ProceedingsTemperature anisotropy instabilities; combining plasma and magnetic field data at different distances from the Sun
Abstract:

We present a new data analysis method enabling the observation of magnetic field fluctuations associated with temperature anisotropy instabilities using the Ulysses spacecraft. The movement of the spacecraft away from the Sun causes the observed plasma conditions, turbulent fluctuation amplitude, magnetic field strength and important physical scales to change. We normalize wavelet power spectra of the magnetic field using local values for the proton gyroscale and large scale magnetic field fluctuation amplitude to remove the effects of varying heliocentric distance. We recover the enhancement of magnetic fluctuations where temperature anisotropy instability growth rates are large, as seen by previous studies in the ecliptic at 1 AU. This method can be applied to any spacecraft data that. . .
Date: 07/2013 Publisher: AIP DOI: 10.1063/1.4811048 Available at: http://aip.scitation.org/doi/abs/10.1063/1.4811048
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