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Switchbacks are Aflv\'enic fluctuations in the solar wind, which exhibit large rotations in the magnetic field direction. Observations from Parker Solar Probe's (PSP's) first two solar encounters have formed the basis for many of the…

Space Physics · Physics 2022-09-14 R. Laker , T. S. Horbury , L. Matteini , S. D. Bale , J. E. Stawarz , L. D. Woodham , T. Woolley

Recent observations from Parker Solar Probe have revealed that the solar wind has a highly variable structure. How this complex behaviour is formed in the solar corona is not yet known, since it requires omnipresent fluctuations, which…

For the past 30+ years, the magnetic expansion factor ($f_s$) has been used in empirical relationships to predict solar wind speed ($v_{obs}$) at 1 AU, based on an inverse relationship between these two quantities. Coronal unipolar…

Solar and Stellar Astrophysics · Physics 2020-08-03 Samantha Wallace , Charles N. Arge , Nicholeen M. Viall , Ylva Pihlstrom

We present a scalable machine learning framework for analyzing Parker Solar Probe (PSP) solar wind data using distributed processing and the quantum-inspired Kernel Density Matrices (KDM) method. The PSP dataset (2018--2024) exceeds 150 GB,…

During Parker Solar Probe (Parker) Encounter 15 (E15), we observe an 18-hour period of near subsonic ($\mathrm{M_S \sim}$ 1) and sub-Alfv\'enic (SA), $\mathrm{M_A}$ <<< 1, slow speed solar wind from 22 to 15.6 R$_\odot$. As the most extreme…

The study concerns the streamer belt observed at high spectral resolution during the minimum of solar cycle 22 with the Ultraviolet Coronagraph Spectrometer (UVCS) onboard SOHO. On the basis of a spectroscopic analysis of the O VI doublet,…

Solar and Stellar Astrophysics · Physics 2011-03-09 Lucia Abbo , Ester Antonucci , Zoran Mikić , Jon A. Linker , Pete Riley , Roberto Lionello

Drawing connections between heliospheric spacecraft and solar wind sources is a vital step in understanding the evolution of the solar corona into the solar wind and contextualizing \textit{in situ} timeseries. Furthermore, making advanced…

We provide a simple geometric explanation for the source of switchbacks and associated large and one-sided transverse flows in the solar wind observed by Parker Solar Probe. The more radial, Sub-Parker Spiral structure of the heliospheric…

Solar and Stellar Astrophysics · Physics 2021-03-17 N. A. Schwadron , D. J. McComas

The WISPR imager on Parker Solar Probe provides a unique view the young solar wind, flying through solar wind structures at high speed. It is of interest to use WISPR image sequences to measure the velocity of both large features (such as…

Solar and Stellar Astrophysics · Physics 2025-02-05 Samuel J. Van Kooten , Craig E. Deforest , Guillermo Stenborg , Kenny N. Kenny

Magnetic flux rope, formed by the helical magnetic field lines, can sometimes remain its shape while carrying significant plasma flow that is aligned with the local magnetic field. We report the existence of such structures and static flux…

Solar and Stellar Astrophysics · Physics 2021-06-30 Yu Chen , Qiang Hu , Lingling Zhao , Justin C. Kasper , Jia Huang

From the the solar photosphere to the outer heliosphere, the Sun's plasma properties are fluctuating with a broad range of temporal and spatial scales. In fact, a turbulent cascade of energy from large to small scales is a frequently…

Solar and Stellar Astrophysics · Physics 2018-08-30 Steven R. Cranmer

Recent in situ observations from Parker Solar Probe (PSP) near perihelia reveal ion beams, temperature anisotropies, and kinetic wave activity. These features are likely linked to solar wind heating and acceleration. During PSP Encounter 17…

We systematically search for magnetic flux rope structures in the solar wind to within the closest distance to the Sun of 0.13 AU, using data from the third and fourth orbits of the Parker Solar Probe. We extend our previous magnetic…

Observations of plasma waves by the Fields Suite and of electrons by the Solar Wind Electrons Alphas and Protons Investigation (SWEAP) on Parker Solar Probe provide strong evidence for pitch angle scattering of strahl-energy electrons by…

The solar corona and young solar wind may be characterized by critical surfaces -- the sonic, Alfv\'en, and first plasma-$\beta$ unity surfaces -- that demarcate regions where the solar wind flow undergoes certain crucial transformations.…

Solar and Stellar Astrophysics · Physics 2019-03-20 Rohit Chhiber , Arcadi V. Usmanov , William H. Matthaeus , Melvyn L. Goldstein

During the solar minimum STEREO observations show that the three-dimensional structure of the solar corona can be described well by a tilted bi-polar magnetic configuration. The slow solar wind is modeled using three-fluid model that…

Solar and Stellar Astrophysics · Physics 2010-04-28 Leon Ofman , Maxim Kramar

Solar Energetic Particle (SEP) events are critical for understanding particle acceleration and transport in the heliosphere. While most SEP events involve outward streaming particles along open magnetic field lines, bidirectional events…

The last 60 years of space exploration have shown that the interplanetary medium is continually perturbed by a myriad of different solar winds and storms that transport solar material across the whole heliosphere. If there is a consensus on…

Solar and Stellar Astrophysics · Physics 2022-08-25 Nicolas Poirier , Alexis Rouillard , Pierre-Louis Blelly

The effect of solar rotation on the proton-alpha differential flow speed, $v_{\alpha p}$, and consequently on the angular momentum transport in the solar wind, is explored. It is found that the force introduced by the azimuthal components…

Astrophysics · Physics 2011-02-11 Bo Li , Shadia Rifai Habbal , Xing Li

Small-scale magnetic flux ropes (SFRs), in the solar wind, have been studied for decades. Statistical analysis utilizing various in situ spacecraft measurements is the main observational approach which helps investigate the generation and…

Space Physics · Physics 2020-05-13 Yu Chen , Qiang Hu