In the latter moments of 2023 July 17, the solar active region (AR) 13363, near the southwestern face of the Sun, was undergoing considerable evolution, which resulted in a significant solar energetic particle (SEP) event measured by Parker Solar Probe’s Integrated Science Investigation of the Sun (IS⊙IS) and near-Earth spacecraft. Remote observations from GOES and CHASE captured two M5.0+ solar flares that peaked at 23:34 and 00:06 UT from the source region. In tandem, STEREO COR2 first recorded a small, narrow coronal mass ejection (CME) emerging at 22:54 UT and then saw a major halo CME emerge at 23:43 UT with a bright, rapidly expanding core and CME-driven magnetic shock with an estimated speed of ∼1400 km s−1. Parker Solar Probe was positioned at 0.65 au, near-perfectly on the nominal Parker spiral magnetic field line, which connected Earth and the AR for a 537 km s−1 ambient solar wind speed at L1. This fortuitous alignment provided the opportunity to examine how the SEP velocity dispersion, energy spectra, elemental composition, and fluence varied from 0.65 to 1 au along a shared magnetic connection to the Sun. We find a strong radial gradient, which is best characterized for H and He as r−4.0, and most surprisingly, is stronger for O and Fe, which is better described by r−5.7.
Radial Dependence of Ion Fluences in the 2023 July 17 Solar Energetic Particle Event from Parker Solar Probe to STEREO and ACE
Creators
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Muro, G. D.1
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Cohen, C. M. S.1
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Xu, Z.1
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Leske, R. A.1
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Christian, E. R.2
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Cummings, A. C.1
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De Nolfo, G.2
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Desai, M. I.3, 4
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Fraschetti, F.5, 6
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Giacalone, J.5
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Labrador, A.1
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McComas, D. J.7
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Mitchell, J. G.2
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Mitchell, D. G.8
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Rankin, J.7
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Schwadron, N. A.9
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Shen, M.7
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Wiedenbeck, M. E.10
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Bale, S. D.11
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Romeo, O.11
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Vourlidas, A.8
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1.
California Institute of Technology
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2.
Goddard Space Flight Center
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3.
Southwest Research Institute
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4.
The University of Texas at San Antonio
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5.
University of Arizona
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6.
Harvard-Smithsonian Center for Astrophysics
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7.
Princeton University
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8.
Johns Hopkins University Applied Physics Laboratory
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9.
University of New Hampshire
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10.
Jet Propulsion Lab
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11.
University of California, Berkeley
Abstract
Copyright and License
© 2025. 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.
Acknowledgement
We acknowledge the contributions of the Parker Solar Probe, STEREO, and ACE mission teams in collecting and providing data for this study. Parker Solar Probe was designed, built, and is now operated by the Johns Hopkins Applied Physics Laboratory as part of NASA’s Living with a Star program, contract No. NNN06AA01C. Support from the LWS management and technical team has played a critical role in the success of the Parker Solar Probe mission. We thank the scientists and engineers whose technical contributions prelaunch have made the IS⊙IS instruments such a success. A.V. was supported by NASA grant No. 80NSSC22K0970. As always, we thank the Sun for providing the energy and particles necessary for this inquiry.
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Additional details
Related works
- Is new version of
- Discussion Paper: arXiv:2502.17806 (arXiv)
Funding
- National Aeronautics and Space Administration
- NNN06AA01C
- National Aeronautics and Space Administration
- 80NSSC22K0970
Dates
- Accepted
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2025-01-22
- Available
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2025-02-21Published