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Variable Ion Compositions of Solar Energetic Particle Events in the Inner Heliosphere: A Field Line Braiding Model with Compound Injections

Guo, Fan and Zhao, Lulu and Cohen, Christina M. S. and Giacalone, Joe and Leske, R. A. and Wiedenbeck, M. E. and Kahler, S. W. and Li, Xiaocan and Zhang, Qile and Ho, George C. and Desai, Mihir I. (2022) Variable Ion Compositions of Solar Energetic Particle Events in the Inner Heliosphere: A Field Line Braiding Model with Compound Injections. Astrophysical Journal, 924 (1). Art. No. 22. ISSN 0004-637X. doi:10.3847/1538-4357/ac3233.

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We propose a model for interpreting highly variable ion composition ratios in solar energetic particle (SEP) events recently observed by the Parker Solar Probe (PSP) at 0.3–0.45 au. We use numerical simulations to calculate SEP propagation in a turbulent interplanetary magnetic field with a Kolmogorov power spectrum from large scales down to the gyration scale of energetic particles. We show that when the source regions of different species are offset by a distance comparable to the size of the source regions, the observed energetic particle composition He/H can be strongly variable over more than two orders of magnitude, even if the source ratio is at the nominal value. Assuming a ³He/⁴He source ratio of 10% in impulsive ³He-rich events and the same spatial offset of the source regions, the ³He/⁴He ratio at observation sites also vary considerably. The variability of the ion composition ratios depends on the radial distance, which can be tested by observations made at different radial locations. We discuss the implications of these results on the variability of ion composition of impulsive events and on further PSP and Solar Orbiter observations close to the Sun.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Guo, Fan0000-0003-4315-3755
Zhao, Lulu0000-0003-3936-5288
Cohen, Christina M. S.0000-0002-0978-8127
Giacalone, Joe0000-0002-0850-4233
Leske, R. A.0000-0002-0156-2414
Wiedenbeck, M. E.0000-0002-2825-3128
Kahler, S. W.0000-0002-0470-7236
Li, Xiaocan0000-0001-5278-8029
Zhang, Qile0000-0002-9504-641X
Ho, George C.0000-0003-1093-2066
Desai, Mihir I.0000-0002-7318-6008
Additional Information:© 2022. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Received 2021 July 25; revised 2021 October 9; accepted 2021 October 20; published 2022 January 6. We acknowledge the constructive comments from the reviewer of this paper, which significantly helped improve the clarity of the paper. We thank members of SolFER collaboration for helpful feedback. SolFER is a multi-institutional collaboration for understanding the release of magnetic field energy and associated particle acceleration in flares in the solar corona. F.G., C.M.S.C., M.W., and Q.Z. acknowledge SolFER DRIVE center program with grant number 80NSSC20K0627 and 80HQTR20T0040. F.G. and L.Z. acknowledge support from NASA PSP GI Program 80HQTR21T0117. F.G. and J.G. acknowledge support in part from NASA LWS Program grant 80HQTR21T0005. L.Z. is supported in part by NASA SOLSTICE DRIVE Science Center grant 80NSSC20K0600 and NASA LWS grant 80NSSC21K0417. The work by X.L. and F.G. is funded in part by NASA grant 80NSSC21K1313 and 80HQTR21T0087. The work of C.M.S.C., J.G., R.A.L., M.E.W., and M.D. was supported in part by NASA's Parker Solar Probe Mission under contract NNN06AA01C. J.G. also acknowledges NASA under grant 80NSSC20K1283, and NSF/AGS under grant1931252. Q.Z. also acknowledges support from NASA grant 80HQTR21T0103. F.G. is also supported by DOE through the LDRD program at LANL and office of Fusion Energy Sciences.
Group:Space Radiation Laboratory
Funding AgencyGrant Number
Los Alamos National LaboratoryUNSPECIFIED
Subject Keywords:Solar energetic particles
Issue or Number:1
Classification Code:Unified Astronomy Thesaurus concepts: Solar energetic particles (1491)
Record Number:CaltechAUTHORS:20220119-572574000
Persistent URL:
Official Citation:Fan Guo et al 2022 ApJ 924 22
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:112990
Deposited By: George Porter
Deposited On:19 Jan 2022 22:53
Last Modified:19 Jan 2022 22:53

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