Likely Common Coronal Source of Solar Wind and 3He-enriched Energetic Particles: Uncoupled Transport from the Low Corona to 0.2 au

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Authors

D G. Mitchell, Johns Hopkins Applied Physics Laboratory
M E. Hill, Johns Hopkins Applied Physics Laboratory
D J. McComas, Princeton University
C M S Cohen, California Institute of Technology
Nathan A. Schwadron, University of New Hampshire, DurhamFollow
P S. Mostafavi, Johns Hopkins Applied Physics Laboratory
W H. Matthaeus, University of Delaware
N E. Raouafi, Johns Hopkins Applied Physics Laboratory
S T. Al-Nussirat, University of California at Berkeley
D E. Larson, University of California at Berkeley
A Rahmati, University of California at Berkeley
J C. Kasper, University of Michigan
P L. Whittlesey, University of California at Berkeley
R Livi, University of California at Berkeley
S D. Bale, University of California at Berkeley
M Pulupa, University of California at Berkeley
J Giacalone, University of Arizona
R L. McNutt, Johns Hopkins Applied Physics Laboratory
E R. Christian, Goddard Space Flight Center
M E. Wiedenbeck, California Institute of Technology
T Sharma, Princeton University

Abstract

Parker Solar Probe (PSP) observations of a small dispersive event on 2022 February 27 and 28 indicate scatter-free propagation as the dominant transport mechanism between the low corona and greater than 35 solar radii. The event occurred during unique orbital conditions that prevailed along specific flux tubes that PSP encountered repeatedly between 25 and 35 Rs during outbound orbit 11. This segment of the PSP orbit exhibits almost stationary angular motion relative to the rotating solar surface, such that in the rotating frame, PSP’s motion is essentially radial. The time dispersion often observed in impulsive solar energetic particle (SEP) events continues in this case down to velocities including the core solar-wind ion velocities. Especially at the onset of this event, the 3He content is much larger than the usual SEP abundances seen in the energy range from ∼100 keV to several MeV for helium. Later in the event, iron is enhanced. The compositional signatures suggest this to be an example of an acceleration mechanism for generating the seed energetic particles required by shock (or compression) acceleration models in SEP events to account for the enrichment of various species above solar abundances in such events. A preliminary search of similar orbital conditions over the PSP mission has not revealed additional such events, although favorable conditions (isolated impulsive acceleration and well-ordered magnetic field connection with minimal magnetic field fluctuation) that would be required are infrequently realized, given the small fraction of the PSP trajectory that meets these observation conditions.

Department

Physics

Publication Date

4-1-2024

Journal Title

The Astrophysical Journal

Publisher

American Astronomical Society

Digital Object Identifier (DOI)

https://dx.doi.org/10.3847/1538-4357/ad2467

Document Type

Article

Recommended Citation

D. G. Mitchell et al 2024 ApJ 965 54

Rights

© 2024. The Author(s).

Comments

This is an open access article published by American Astronomical Society in The Astrophysical Journal in 2024, available online: https://dx.doi.org/10.3847/1538-4357/ad2467