Search Publications
Proposed Resolution to the Solar Open Magnetic Flux Problem
Antiochos, Spiro K.; Wallace, Samantha; Henney, Carl J. +2 more
The solar magnetic fields emerging from the photosphere into the chromosphere and corona are comprised of a combination of closed (field lines with both ends rooted at the Sun) and open (field lines with only one end at the Sun) fields. Since the early 2000s, the magnitude of total unsigned open magnetic flux estimated by coronal models has been i…
New Horizons Venetia Burney Student Dust Counter Observes Higher than Expected Fluxes Approaching 60 au
Singer, Kelsi N.; Stern, S. Alan; Verbiscer, Anne +8 more
The NASA New Horizons Venetia Burney Student Dust Counter (SDC) measures dust particle impacts along the spacecraft's flight path for grains with mass ≥10‑12 g, mapping out their spatial density distribution. We present the latest SDC dust density, size distribution, and flux measurements through 55 au and compare them to numerical mode…
Comparative Analysis of Type III Radio Bursts and Solar Flares: Spatial Localization and Correlation with Solar Flare Intensity
Maksimovic, Milan; Szabo, Adam; Bale, Stuart D. +8 more
We present a comprehensive study of type III radio bursts and their association with solar flares of magnitude M1.0 and larger, as observed by four widely separated spacecraft (Parker Solar Probe, Solar Orbiter, STEREO-A, and Wind). Our main focus is the introduction and validation of two methods for localizing radio bursts using the available mul…
Parallel Diffusion Coefficient of Energetic Charged Particles in the Inner Heliosphere from the Turbulent Magnetic Fields Measured by Parker Solar Probe
Klein, Kristopher G.; Chen, Xiaohang; Giacalone, Joe +1 more
Diffusion coefficients of energetic charged particles in turbulent magnetic fields are a fundamental aspect of diffusive transport theory but remain incompletely understood. In this work, we use quasi-linear theory to evaluate the spatial variation of the parallel diffusion coefficient κ ∥ from the measured magnetic turbulence power spe…
Radial Distribution of Electron Quasi-thermal Noise in the Outer Heliosphere
Chen, Ling; Li, Yi-Lun; Wu De, Jin
Voyager 1 and 2 are only the two spacecraft that have arrived and passed through the heliospheric boundaries. Based on the plasma data from the Voyager 2 spacecraft, the electron quasi-thermal noise (QTN) is investigated by using of the electron population model consisting of a core with Maxwellian distribution and a halo with kappa distribution. …
Solar Wind Density and Core Temperature Derived from the PSP Quasi-thermal Noise Measurements
Liu, Mingzhe; Liu, Kaijun; Pierrard, Viviane +6 more
Quasi-thermal noise (QTN) spectroscopy is a valuable method to deduce important parameters in space plasma, such as plasma density and temperature, especially when direct particle measurements are not available. The present study develops a new fitting method to fit the QTN spectra observed by the Parker Solar Probe (PSP) with a comprehensive theo…
A Numerical Study of the Effects of a Corotating Interaction Region on Cosmic-Ray Transport. II. Features of Cosmic-Ray Composition and Rigidity
Luo, Xi; Shen, Fang; Zhang, Ming +1 more
We continue the numerical modeling of a corotating interaction region (CIR) and the effects it has on solar-rotational recurrent variations of galactic cosmic rays (GCRs). A magnetohydrodynamic model is adapted to simulate the background solar wind plasma with a CIR structure in the inner heliosphere, which is incorporated into a comprehensive Par…
Cosmic-Ray Transport in the Presence of a Fisk-type Heliospheric Magnetic Field: Investigating the Influence of Drift
Engelbrecht, N. E.; Steyn, P. J.; Troskie, J. S.
Drifts due to the gradients in, and curvatures of, the heliospheric magnetic field (HMF) play a significant role in the transport of galactic cosmic rays (GCRs) in the heliosphere. Although this has been well studied for the Parker HMF, the influence of Fisk-type fields, with their unique geometry, has hitherto received less attention. Here, drift…
Origins of Very Low Helium Abundance Streams Detected in the Solar Wind Plasma
Yashiro, Seiji; Gopalswamy, N.; Srivastava, Nandita +4 more
The abundance of helium (A He) in the solar wind exhibits variations typically in the range from 2% to 5% with respect to solar cycle activity and solar wind velocity. However, there are instances where the observed A He is exceptionally low (<1%). These low-A He occurrences are detected both near the Sun and at…
Modeling of the Polytropic Index and Temperature Anisotropy in the Solar Wind
Engelbrecht, N. E.; Strauss, R. D.; Desta, Ephrem Tesfaye
The polytropic index is a fundamental physical parameter related to the thermodynamic processes present in space and astrophysical plasmas. This paper investigates the theoretical relationship between the polytropic index and the temperature anisotropy for flow parameters relevant to space plasmas. The derivation is based on the Chew–Goldberger–Lo…