Energetic Particle Increases Associated with Stream Interaction Regions
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Author
Cohen, C. M. S.Christian, E. R.
Cummings, A. C.
Davis, A. J.
Desai, M. I.
Giacalone, J.
Hill, M. E.
Joyce, C. J.
Labrador, A. W.
Leske, R. A.
Matthaeus, W. H.
McComas, D. J.
McNutt, R. L., Jr.
Mewaldt, R. A.
Mitchell, D. G.
Rankin, J. S.
Roelof, E. C.
Schwadron, N. A.
Stone, E. C.
Szalay, J. R.
Wiedenbeck, M. E.
Allen, R. C.
Ho, G. C.
Jian, L. K.
Lario, D.
Odstrcil, D.
Bale, S. D.

Badman, S. T.
Pulupa, M.
MacDowall, R. J.
Kasper, J. C.
Case, A. W.
Korreck, K. E.
Larson, D. E.
Livi, Roberto
Stevens, M. L.
Whittlesey, Phyllis
Affiliation
Univ ArizonaIssue Date
2020-02-03
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Cohen, C. M. S., Christian, E. R., Cummings, A. C., Davis, A. J., Desai, M. I., Giacalone, J., ... & Whittlesey, P. (2020). Energetic Particle Increases Associated with Stream Interaction Regions. The Astrophysical Journal Supplement Series, 246(2), 20.Rights
© 2020. The American Astronomical Society. All rights reserved.Collection Information
This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at repository@u.library.arizona.edu.Abstract
The Parker Solar Probe was launched on 2018 August 12 and completed its second orbit on 2019 June 19 with perihelion of 35.7 solar radii. During this time, the Energetic Particle Instrument-Hi (EPI-Hi, one of the two energetic particle instruments comprising the Integrated Science Investigation of the Sun, IS circle dot IS) measured seven proton intensity increases associated with stream interaction regions (SIRs), two of which appear to be occurring in the same region corotating with the Sun. The events are relatively weak, with observed proton spectra extending to only a few MeV and lasting for a few days. The proton spectra are best characterized by power laws with indices ranging from -4.3 to -6.5, generally softer than events associated with SIRs observed at 1 au and beyond. Helium spectra were also obtained with similar indices, allowing He/H abundance ratios to be calculated for each event. We find values of 0.016-0.031, which are consistent with ratios obtained previously for corotating interaction region events with fast solar wind <= 600 km s(-1). Using the observed solar wind data combined with solar wind simulations, we study the solar wind structures associated with these events and identify additional spacecraft near 1 au appropriately positioned to observe the same structures after some corotation. Examination of the energetic particle observations from these spacecraft yields two events that may correspond to the energetic particle increases seen by EPI-Hi earlier.ISSN
0067-0049EISSN
1538-4365Version
Final published versionSponsors
National Aeronautics and Space Administrationae974a485f413a2113503eed53cd6c53
10.3847/1538-4365/ab4c38