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Seed Population Preconditioning and Acceleration Observed by the Parker Solar Probe

Schwadron, N. A. and Bale, S. and Bonnell, J. and Case, A. and Christian, E. R. and Cohen, C. M. S. and Cummings, A. C. and Davis, A. J. and Dudok de Wit, T. and de Wet, W. and Desai, M. I. and Joyce, C. J. and Goetz, K. and Giacalone, J. and Goerby, M. and Harvey, P. and Heber, B. and Hill, M. E. and Karavolos, M. and Kasper, J. C. and Korreck, K. and Larson, D. and Livi, R. and Leske, R. A. and Malandraki, O. and MacDowall, R. and Malaspina, D. and Matthaeus, W. H. and McComas, D. J. and McNutt, R. L., Jr. and Mewaldt, R. A. and Mitchell, D. G. and Mays, L. and Niehof, J. T. and Odstrcil, D. and Pulupa, M. and Poduval, B. and Rankin, J. S. and Roelof, E. C. and Stevens, M. and Stone, E. C. and Szalay, J. R. and Wiedenbeck, M. E. and Winslow, R. and Whittlesey, P. (2020) Seed Population Preconditioning and Acceleration Observed by the Parker Solar Probe. Astrophysical Journal Supplement Series, 246 (2). Art. No. 33. ISSN 1538-4365.

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A series of solar energetic particle (SEP) events was observed by the Integrated Science Investigation of the Sun (IS⊙IS) on the Parker Solar Probe (PSP) during the period from 2019 April 18 through 24. The PSP spacecraft was located near 0.48 au from the Sun on Parker spiral field lines that projected out to 1 au within ~25° of the near-Earth spacecraft. These SEP events, though small compared to historically large SEP events, were among the largest observed thus far in the PSP mission and provide critical information about the space environment inside 1 au during SEP events. During this period, the Sun released multiple coronal mass ejections (CMEs). One of these CMEs observed was initiated on 2019 April 20 at 01:25 UTC, and the interplanetary CME (ICME) propagated out and passed over the PSP spacecraft. Observations by the Electromagnetic Fields Investigation show that the magnetic field structure was mostly radial throughout the passage of the compression region and the plasma that followed, indicating that PSP did not directly observe a flux rope internal to the ICME, consistent with the location of PSP on the ICME flank. Analysis using relativistic electrons observed near Earth by the Electron, Proton and Alpha Monitor on the Advanced Composition Explorer demonstrates the presence of electron seed populations (40–300 keV) during the events observed. The energy spectrum of the IS⊙IS-observed proton seed population below 1 MeV is close to the limit of possible stationary-state plasma distributions out of equilibrium. IS⊙IS observations reveal the enhancement of seed populations during the passage of the ICME, which likely indicates a key part of the preacceleration process that occurs close to the Sun.

Item Type:Article
Related URLs:
URLURL TypeDescription ItemISʘIS data and visualization tools ItemNASA Space Physics Data Facility
Schwadron, N. A.0000-0002-3737-9283
Bale, S.0000-0002-1989-3596
Case, A.0000-0002-3520-4041
Christian, E. R.0000-0003-2134-3937
Cohen, C. M. S.0000-0002-0978-8127
Cummings, A. C.0000-0002-3840-7696
Dudok de Wit, T.0000-0002-4401-0943
Desai, M. I.0000-0002-7318-6008
Joyce, C. J.0000-0002-3841-5020
Heber, B.0000-0003-0960-5658
Hill, M. E.0000-0002-5674-4936
Kasper, J. C.0000-0002-7077-930X
Korreck, K.0000-0001-6095-2490
Leske, R. A.0000-0002-0156-2414
MacDowall, R.0000-0003-3112-4201
Malaspina, D.0000-0003-1191-1558
Matthaeus, W. H.0000-0001-7224-6024
McComas, D. J.0000-0001-6160-1158
Mewaldt, R. A.0000-0003-2178-9111
Mitchell, D. G.0000-0003-1960-2119
Pulupa, M.0000-0002-1573-7457
Rankin, J. S.0000-0002-8111-1444
Stevens, M.0000-0002-7728-0085
Stone, E. C.0000-0002-2010-5462
Szalay, J. R.0000-0003-2685-9801
Wiedenbeck, M. E.0000-0002-2825-3128
Additional Information:© 2020. The American Astronomical Society. Received 2019 September 13; revised 2019 November 4; accepted 2019 November 5; published 2020 February 3. Early Results from Parker Solar Probe: Ushering a New Frontier in Space Exploration We are deeply indebted to everyone who helped make the Parker Solar Probe (PSP) mission possible. We thank all of the outstanding scientists, engineers, technicians, and administrative support people across all of the IS⊙IS, FIELDS, and SWEAP institutions that produced and supported the IS⊙IS, FIELDS, and SWEAP instrument suites, support its operations and the scientific analysis of its data. This work was supported as a part of the PSP mission under contract NNN06AA01C. The ISʘIS data and visualization tools are available to the community at:; data are also available via the NASA Space Physics Data Facility ( Parker Solar Probe was designed, built, and is now operatedby the Johns Hopkins Applied Physics Laboratory aspart 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. We thank and acknowledge Dr. X.P. Zhao for providing the CSSS model.
Group:Space Radiation Laboratory
Funding AgencyGrant Number
Subject Keywords:Solar wind ; Solar energetic particles ; Solar coronal mass ejections
Issue or Number:2
Classification Code:Unified Astronomy Thesaurus concepts: Solar wind (1534); Solar energetic particles (1491); Solar coronal mass ejections (310)
Record Number:CaltechAUTHORS:20200203-092721301
Persistent URL:
Official Citation:N. A. Schwadron et al 2020 ApJS 246 33
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:101060
Deposited By: George Porter
Deposited On:03 Feb 2020 21:28
Last Modified:03 Feb 2020 21:28

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