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Solar Energetic Particles Produced by a Slow Coronal Mass Ejection at ∼0.25 au

Giacalone, J. and Mitchell, D. G. and Allen, R. C. and Hill, M. E. and McNutt, R. L., Jr. and Szalay, J. R. and Desai, M. I. and Rouillard, A. P. and Kouloumvakos, A. and McComas, D. J. and Christian, E. R. and Schwadron, N. A. and Wiedenbeck, M. E. and Bale, S. and Brown, L. E. and Case, A. and Chen, X. and Cohen, C. M. S. and Joyce, C. and Kasper, J. C. and Klein, K. G. and Korreck, K. and Larson, D. E. and Livi, R. and Leske, R. A. and MacDowall, R. J. and Matthaeus, W. H. and Mewaldt, R. A. and Nieves-Chinchilla, T. and Pulupa, M. and Roelof, E. C. and Stevens, M. L. and Szabo, A. and Whittlesey, P. L. (2020) Solar Energetic Particles Produced by a Slow Coronal Mass Ejection at ∼0.25 au. Astrophysical Journal Supplement Series, 246 (2). Art. No. 29. ISSN 1538-4365. https://resolver.caltech.edu/CaltechAUTHORS:20200203-092721189

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Abstract

We present an analysis of Parker Solar Probe (PSP) IS⊙IS observations of ~30–300 keV n⁻¹ ions on 2018 November 11 when PSP was about 0.25 au from the Sun. Five hours before the onset of a solar energetic particle (SEP) event, a coronal mass ejection (CME) was observed by STEREO-A/COR2, which crossed PSP about a day later. No shock was observed locally at PSP, but the CME may have driven a weak shock earlier. The SEP event was dispersive, with higher energy ions arriving before the lower energy ones. Timing suggests the particles originated at the CME when it was at ~7.4R_⊙. SEP intensities increased gradually from their onset over a few hours, reaching a peak, and then decreased gradually before the CME arrived at PSP. The event was weak, having a very soft energy spectrum (−4 to −5 spectral index). The earliest arriving particles were anisotropic, moving outward from the Sun, but later, the distribution was observed to be more isotropic. We present numerical solutions of the Parker transport equation for the transport of 30–300 keV n⁻¹ ions assuming a source comoving with the CME. Our model agrees well with the observations. The SEP event is consistent with ion acceleration at a weak shock driven briefly by the CME close to the Sun, which later dissipated before arriving at PSP, followed by the transport of ions in the interplanetary magnetic field.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.3847/1538-4365/ab5221DOIArticle
ORCID:
AuthorORCID
Mitchell, D. G.0000-0003-1960-2119
Allen, R. C.0000-0003-2079-5683
Hill, M. E.0000-0002-5674-4936
Szalay, J. R.0000-0003-2685-9801
Desai, M. I.0000-0002-7318-6008
McComas, D. J.0000-0001-6160-1158
Christian, E. R.0000-0003-2134-3937
Schwadron, N. A.0000-0002-3737-9283
Wiedenbeck, M. E.0000-0002-2825-3128
Bale, S.0000-0002-1989-3596
Case, A.0000-0002-3520-4041
Cohen, C. M. S.0000-0002-0978-8127
Joyce, C.0000-0002-3841-5020
Kasper, J. C.0000-0002-7077-930X
Korreck, K.0000-0001-6095-2490
Leske, R. A.0000-0002-0156-2414
MacDowall, R. J.0000-0003-3112-4201
Matthaeus, W. H.0000-0001-7224-6024
Mewaldt, R. A.0000-0003-2178-9111
Nieves-Chinchilla, T.0000-0003-0565-4890
Pulupa, M.0000-0002-1573-7457
Stevens, M. L.0000-0002-7728-0085
Szabo, A.0000-0003-3255-9071
Additional Information:© 2020. The American Astronomical Society. Received 2019 September 12; revised 2019 October 24; accepted 2019 October 27; published 2020 February 3. Early Results from Parker Solar Probe: Ushering a New Frontier in Space Exploration 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 (LWS) program (contract NNN06AA01C). Support from the LWS management and technical team has played a critical role in the success of the Parker Solar Probe mission.​ J.G. acknowledges useful conversations about the Parker transport equation with J. Kota and F. Fraschetti. A.K. and A.P.R. acknowledge financial support from the ANR project COROSHOCK ANR-17-CE31-0006-01 and from the ERC project SLOW_SOURCE—DLV-819189. We thank Jon Linker and Pete Riley of Predictive Sciences for providing the background solar wind model exploited in this study. The STA/C2 images, which were analyzed for results presented in this paper, were obtained from the STEREO science center.
Group:Space Radiation Laboratory
Funders:
Funding AgencyGrant Number
NASANNN06AA01C
Agence Nationale pour la Recherche (ANR)ANR-17-CE31-0006-01
European Research Council (ERC)819189
Subject Keywords:Solar energetic particles ; Interplanetary particle acceleration ; Interplanetary shocks
Issue or Number:2
Classification Code:Unified Astronomy Thesaurus concepts: Solar energetic particles (1491); Interplanetary particle acceleration (826); Interplanetary shocks (829)
Record Number:CaltechAUTHORS:20200203-092721189
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20200203-092721189
Official Citation:J. Giacalone et al 2020 ApJS 246 29
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:101059
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:03 Feb 2020 19:25
Last Modified:03 Feb 2020 19:25

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