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Energetic Particle Observations from the Parker Solar Probe Using Combined Energy Spectra from the IS⊙IS Instrument Suite

Joyce, C. J. and McComas, D. J. and Christian, E. R. and Schwadron, N. A. and Wiedenbeck, M. E. and McNutt, R. L., Jr. and Cohen, C. M. S. and Leske, R. A. and Mewaldt, R. A. and Stone, E. C. and Labrador, A. W. and Davis, A. J. and Cummings, A. C. and Mitchell, D. G. and Hill, M. E. and Roelof, E. C. and Szalay, J. R. and Rankin, J. S. and Desai, M. I. and Giacalone, J. and Matthaeus, W. H. (2020) Energetic Particle Observations from the Parker Solar Probe Using Combined Energy Spectra from the IS⊙IS Instrument Suite. Astrophysical Journal Supplement Series, 246 (2). Art. No. 41. ISSN 1538-4365. doi:10.3847/1538-4365/ab5948.

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The Integrated Science Investigations of the Sun (IS⊙IS) instrument suite includes two Energetic Particle instruments: EPI-Hi, designed to measure ions from ~1 to 200 MeV nuc⁻¹, and EPI-Lo, designed to measure ions from ~20 to ~15 MeV nuc⁻¹. We present an analysis of eight energetic proton events observed across the energy range of both instruments during Parker Solar Probe's (PSP) first two orbits in order to examine their combined energy spectra. Background corrections are applied to help resolve spectral breaks between the two instruments and are shown to be effective. In doing so we demonstrate that even in the early stages of calibration, IS⊙IS is capable of producing reliable spectral observations across broad energy ranges. In addition to making groundbreaking measurements very near the Sun, IS⊙IS also characterizes energetic particle populations over a range of heliocentric distances inside 1 au. During the first two orbits, IS⊙IS observed energetic particle events from a single corotating interaction region (CIR) at three different distances from the Sun. The events are separated by two Carrington rotations and just 0.11 au in distance; however, the relationship shown between proton intensities and proximity of the spacecraft to the source region shows evidence of the importance of transport effects on observations of energetic particles from CIRs. Future IS⊙IS observations of similar events over larger distances will help disentangle the effects of CIR-related acceleration and transport. We apply similar spectral analyses to the remaining five events, including four that are likely related to stream interaction regions (SIRs) and one solar energetic particle (SEP) event.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper ItemIS⊙IS data and visualization tools ItemNASA Space Physics Data Facility ItemCommunity Coordinated Modeling Center
Joyce, C. J.0000-0002-3841-5020
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
McNutt, R. L., Jr.0000-0002-4722-9166
Cohen, C. M. S.0000-0002-0978-8127
Leske, R. A.0000-0002-0156-2414
Mewaldt, R. A.0000-0003-2178-9111
Stone, E. C.0000-0002-2010-5462
Labrador, A. W.0000-0001-9178-5349
Cummings, A. C.0000-0002-3840-7696
Mitchell, D. G.0000-0003-1960-2119
Hill, M. E.0000-0002-5674-4936
Roelof, E. C.0000-0002-2270-0652
Szalay, J. R.0000-0003-2685-9801
Rankin, J. S.0000-0002-8111-1444
Desai, M. I.0000-0002-7318-6008
Matthaeus, W. H.0000-0001-7224-6024
Additional Information:© 2020. The American Astronomical Society. Received 2019 September 20; revised 2019 November 6; accepted 2019 November 18; published 2020 February 3. Early Results from Parker Solar Probe: Ushering a New Frontier in Space Exploration This work was supported as a part of the Integrated Science Investigations of the Sun on NASA's Parker Solar Probe mission, under contract NNN06AA01C. The IS⊙IS data and visualization tools are available to the community at:; data are also available via the NASA Space Physics Data Facility ( Simulation results have been provided by the Community Coordinated Modeling Center at Goddard Space Flight Center through their public Runs on Request system ( The ENLIL Model was developed by D. Odstrcil at the University of Colorado at Boulder.
Group:Space Radiation Laboratory
Funding AgencyGrant Number
Subject Keywords:Solar energetic particles ; Interplanetary physics ; Corotating streams ; Interplanetary particle acceleration ; Interplanetary shocks
Issue or Number:2
Classification Code:Unified Astronomy Thesaurus concepts: Solar energetic particles (1491); Interplanetary physics (827); Corotating streams (314); Interplanetary particle acceleration (826); Interplanetary shocks (829)
Record Number:CaltechAUTHORS:20200203-092721619
Persistent URL:
Official Citation:C. J. Joyce et al 2020 ApJS 246 41
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:101063
Deposited By: George Porter
Deposited On:03 Feb 2020 22:34
Last Modified:16 Nov 2021 17:58

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