Search Publications
Particle Acceleration at 5 au Associated with Turbulence and Small-scale Magnetic Flux Ropes
Chen, Y.; Zank, G. P.; Zhao, L. -L. +4 more
An observational analysis of an atypical energetic particle event near 5 au measured by the Ulysses spacecraft is presented. A previous study has attributed the unusual enhancement of energetic proton flux to the presence of small-scale dynamic magnetic islands or flux ropes. Here, we find that the generation of these magnetic islands may be relat…
Validation of the Alfvén Wave Solar Atmosphere Model (AWSoM) with Observations from the Low Corona to 1 au
van der Holst, Bart; Lamy, Philippe; Vásquez, Alberto M. +9 more
We perform a validation study of the latest version of the Alfvén Wave Solar atmosphere Model (AWSoM) within the Space Weather Modeling Framework. To do so, we compare the simulation results of the model with a comprehensive suite of observations for Carrington rotations representative of the solar minimum conditions extending from the solar coron…
Slowing of the Solar Wind in the Outer Heliosphere
Stern, S. Alan; Weaver, Harold A.; Young, Leslie A. +15 more
This study provides a deeper understanding of how the solar wind evolves with increasing distance from the Sun as it encounters an increasing amount of interstellar material. This work extends our prior work by (1) extending the solar wind proton data radial profiles for New Horizons (NH) out to nearly 43 au, (2) quantifying the observed amount of…
Time variation of Jupiter's internal magnetic field consistent with zonal wind advection
Bolton, S. J.; Connerney, J. E. P.; Cao, H. +3 more
Determination of the time dependency (secular variation) of a planet's magnetic field provides a window into understanding the dynamo responsible for generating its field. However, of the six Solar System planets with active dynamos, secular variation has been firmly established only for Earth. Here, we compare magnetic field observations of Jupit…
Solar wind charge exchange: an astrophysical nuisance
Kuntz, K. D.
Solar wind charge-exchange (SWCX) emission is present in every X-ray observation of an astrophysical object. The emission is problematic when one cannot remove the foreground by the simultaneous measurement of a nearby field. SWCX emission is a serious impediment to the study of the diffuse hot ISM, including the galactic halo, as its contribution…
ACR Proton Acceleration Associated with Reconnection Processes beyond the Heliospheric Termination Shock
Chen, Y.; Burlaga, L. F.; Zank, G. P. +6 more
One of the curious observations from the Voyagers is that the intensity of anomalous cosmic rays (ACRs) did not peak at the heliospheric termination shock (HTS) but instead a short distance (within ∼1 au) downstream of the HTS. One possible explanation is that the interaction of the wavy heliospheric current sheet with the HTS enhances magnetic re…
Magnetic Turbulence Spectra and Intermittency in the Heliosheath and in the Local Interstellar Medium
Pogorelov, Nikolai V.; Fraternale, Federico; Richardson, John D. +1 more
The understanding of inertial-scale dynamics in the heliosheath is not yet thorough. Magnetic field fluctuations across the inner heliosheath (IHS) and the local interstellar medium (LISM) are here considered to provide accurate and highly resolved statistics over different plasma conditions between 88 and 136 au. By using the unique in situ 48 s …
Interstellar Neutral Gas Species and Their Pickup Ions inside the Heliospheric Termination Shock. Ionization Rates for H, O, Ne, and He
Tokumaru, Munetoshi; Bzowski, Maciej; Sokół, Justyna M.
Solar ionizing factors are responsible for modulation of interstellar neutral gas and its derivative populations inside the heliosphere. We provide an overview of the current state of knowledge about them for heliospheric particles inside the termination shock. We discuss charge exchange with solar wind particles, photoionization, and electron imp…
Can an Unobserved Concentration of Magnetic Flux Above the Poles of the Sun Resolve the Open Flux Problem?
Downs, Cooper; Riley, Pete; Linker, Jon A. +3 more
Global models of the extended solar corona, driven by observed photospheric magnetic fields, generally cannot reproduce the amplitude of the measured interplanetary magnetic field at 1 au (or elsewhere in the heliosphere), often underestimating it by a factor of two or more. Some modelers have attempted to resolve this “open flux” problem by adjus…
Current Sheets, Magnetic Islands, and Associated Particle Acceleration in the Solar Wind as Observed by Ulysses near the Ecliptic Plane
Zank, Gary P.; Bruno, Roberto; Li, Gang +16 more
Recent studies of particle acceleration in the heliosphere have revealed a new mechanism that can locally energize particles up to several MeV nucleon-1. Stream-stream interactions, as well as the heliospheric current sheet (CS)—stream interactions, lead to formation of large magnetic cavities, bordered by strong CSs, which in turn prod…