Search Publications
Alpha-Proton Differential Flow of the Young Solar Wind: Parker Solar Probe Observations
Bale, S. D.; Allen, R. C.; Raouafi, N. E. +5 more
The velocity of alpha particles relative to protons can vary depending on the solar wind type and distance from the Sun. Measurements from the previous spacecraft provided the alpha-proton differential velocities down to 0.3 au. The Parker Solar Probe (PSP) now enables insights into differential flows of the newly accelerated solar wind closer to …
Mixing Interstellar Clouds Surrounding the Sun
Zank, Gary P.; Redfield, Seth; Winslow, Réka M. +9 more
On its journey through the Galaxy, the Sun passes through diverse regions of the interstellar medium. High-resolution spectroscopic measurements of interstellar absorption lines in spectra of nearby stars show absorption components from more than a dozen warm partially ionized clouds within 15 pc of the Sun. The two nearest clouds-the Local Inters…
Multi-spacecraft Observations of the Evolution of Interplanetary Coronal Mass Ejections between 0.3 and 2.2 au: Conjunctions with the Juno Spacecraft
Lugaz, Noé; Scolini, Camilla; Winslow, Réka M. +4 more
We present a catalog of 35 interplanetary coronal mass ejections (ICMEs) observed by the Juno spacecraft and at least one other spacecraft during its cruise phase to Jupiter. We identify events observed by MESSENGER, Venus Express, Wind, and STEREO with magnetic features that can be matched unambiguously with those observed by Juno. A multi-spacec…
Anomalous Cosmic-Ray Oxygen Observations into 0.1 au
McComas, D. J.; Christian, E. R.; Leske, R. A. +10 more
The Integrated Science Investigation of the Sun instrument suite onboard NASA's Parker Solar Probe mission continues to measure solar energetic particles and cosmic rays closer to the Sun than ever before. Here, we present the first observations of cosmic rays into 0.1 au (21.5 solar radii), focusing specifically on oxygen from ~2018.7 to ~2021.2.…
Geminga SNR: Possible Candidate of the Local Cosmic-Ray Factory
Yuan, Qiang; Liu, Wei; Bi, Xiao-Jun +5 more
The precise measurements of energy spectra and anisotropy could help us uncover the local cosmic-ray accelerators. Our recent works have shown that spectral hardening above 200 GeV in the energy spectra and transition of large-scale anisotropy at ~100 TeV are of local source origin. Less than 100 TeV, both spectral hardening and anisotropy explici…
Charge State Calculation for Global Solar Wind Modeling
Landi, E.; van der Holst, B.; Szente, J.
The charge state composition of the solar wind carries information about the electron temperature, density, and velocity of plasma in the solar corona that cannot always be measured with remote sensing techniques, due to limitations in instrumental sensitivity and field of view as well as line-of-sight integration issues. However, in situ measurem…
Heliospheric Compression Due to Recent Nearby Supernova Explosions
Fields, Brian D.; Miller, Jesse A.
The widespread detection of 60Fe in geological and lunar archives provides compelling evidence for recent nearby supernova explosions within ~100 pc at 3 and 7 Myr ago. The blasts from these explosions had a profound effect on the heliosphere. We perform new calculations to study the compression of the heliosphere due to a supernova bla…
Galactic Cosmic-Ray Propagation in the Inner Heliosphere: Improved Force-field Model
Peter, Annika H. G.; Beacom, John F.; Li, Jung-Tsung
A key goal of heliophysics is to understand how cosmic rays propagate in the solar system's complex, dynamic environment. One observable is solar modulation, i.e., how the flux and spectrum of cosmic rays change as they propagate inward. We construct an improved force-field model, taking advantage of new measurements of magnetic power spectral den…
The Fractality and Size Distributions of Astrophysical Self-Organized Criticality Systems
Aschwanden, Markus J.
The statistics of nonlinear processes in avalanching systems, based on the self-organized criticality (SOC) concept of Bak et al. (1988), predicts power-law-like size (or occurrence frequency) distribution functions. Following up on previous work, we define a standard SOC model in terms of six assumptions: (i) area fractality, (ii) volume fractali…
The Yaglom Scaling of the Third-order Structure Functions in the Inner Heliosphere Observed by Helios 1 and 2
He, Jiansen; Wang, Xin; Tu, Chuanyi +2 more
The third-order scaling law, Yaglom law, of Elsässer fluctuations in the solar wind is believed to reflect the inertial range energy cascade of the MHD turbulence and provides an approach to evaluate the cascade rate. However, the occurrence ratio with the Yaglom scaling law, the fraction of the intervals where the Yaglom linear scaling is observe…