Found 4 results
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Filters: Author is Zank, G. P.  [Clear All Filters]
2020
Authors: Zhao L.-L., Zank G. P., Adhikari L., Hu Q., Kasper J. C., et al.
Title: Identification of Magnetic Flux Ropes from Parker Solar Probe Observations during the First Encounter
Abstract:

The Parker Solar Probe (PSP) observed an interplanetary coronal mass ejection (ICME) event during its first orbit around the Sun, among many other events. This event is analyzed by applying a wavelet analysis technique to obtain the reduced magnetic helicity, cross helicity, and residual energy, the first two of which are magnetohydrodynamics (MHD) invariants. Our results show that the ICME, as a large-scale magnetic flux rope, possesses high magnetic helicity, very low cross helicity, and highly negative residual energy, thus pointing to a magnetic fluctuation dominated structure. Using the same technique, we also search for small-scale coherent magnetic flux rope structures during the period from 2018 October 22 to November 21, which are intrinsic to quasi-two-dimensional MHD turbulen. . .
Date: 02/2020 Publisher: The Astrophysical Journal Supplement Series Pages: 26 DOI: 10.3847/1538-4365/ab4ff1 Available at: https://iopscience.iop.org/article/10.3847/1538-4365/ab4ff1
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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: Adhikari L., Zank G. P., Zhao L.-L., Kasper J. C., Korreck K. E., et al.
Title: Turbulence Transport Modeling and First Orbit Parker Solar Probe ( PSP ) Observations
Abstract:

The Parker Solar Probe (PSP) achieved its first orbit perihelion on 2018 November 6, reaching a heliocentric distance of about 0.165 au (35.55 R). Here, we study the evolution of fully developed turbulence associated with the slow solar wind along the PSP trajectory between 35.55 R and 131.64 R in the outbound direction, comparing observations to a theoretical turbulence transport model. Several turbulent quantities, such as the fluctuating kinetic energy and the corresponding correlation length, the variance of density fluctuations, and the solar wind proton temperature are determined from the PSP Solar Wind Electrons Alphas and Protons (SWEAP) plasma data along its trajectory between 35.55 R and 131.64 R. The evolut. . .
Date: 02/2020 Publisher: The Astrophysical Journal Supplement Series Pages: 38 DOI: 10.3847/1538-4365/ab5852 Available at: https://iopscience.iop.org/article/10.3847/1538-4365/ab5852
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2019
Authors: Adhikari L., Zank G. P., and Zhao L.-L.
Title: Does Turbulence Turn off at the Alfvén Critical Surface?
Abstract:

The Parker Solar Probe (PSP) will eventually reach and cross the Alfvén point or surface as it provides us with direct in situ measurements of the solar atmosphere. The Alfvén surface is the location at which the large-scale bulk solar wind speed ${\boldsymbol{U}}$ and the Alfvén speed ${\boldsymbol{V}}$ A are equal, and thus it separates sub-Aflvénic coronal flow $| {\boldsymbol{U}}| \ll | {{\boldsymbol{V}}}_{{\rm{A}}}| $ from super-Alfv. . .
Date: Jan-05-2019 Publisher: The Astrophysical Journal Pages: 26 DOI: 10.3847/1538-4357/ab141c Available at: https://iopscience.iop.org/article/10.3847/1538-4357/ab141c
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