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Comparison of the Coronal Mass Ejection Shock Acceleration of Three Widespread SEP Events During Solar Cycle 24
External Online Source: doi:10.1002/2017JA024218
Author and Affiliation:
Xie, H.(Catholic Univ. of America, Dept. of Physics, Washington, DC, United States)
Makela, P.(Catholic Univ. of America, Dept. of Physics, Washington, DC, United States)
St. Cyr, O. C.(NASA Goddard Space Flight Center, Greenbelt, MD, United States)
Gopalswamy, N.(NASA Goddard Space Flight Center, Greenbelt, MD, United States)
Abstract: We studied three solar energetic particle (SEP) events observed on 14 August 2010, 3 November 2011, and 5 March 2013 by Solar Terrestrial Relations Observatory (STEREO) A, B, and near-Earth (L1) spacecraft with a longitudinal distribution of particles greater than 90 degrees. Using a forward modeling method combined with extreme ultraviolet and white-light images, we determined the angular extent of the shock, the time and location (cobpoint) of the shock intersection with the magnetic field line connecting to each spacecraft, and compute the shock speed at the cobpoint of each spacecraft. We then examine whether the observations of SEPs at each spacecraft were accelerated and injected by the spatially extended shocks or whether another mechanism such as cross-field transport is required for an alternative explanation. Our analyses results indicate that the SEPs observed at the three spacecraft on 3 November, STEREO B (STB) and L1 on 14 August, and the 5 March SEP event at STEREO A (STA) can be explained by the direct shock acceleration. This is consistent with the observed significant anisotropies, short time delays between particle release times and magnetic connection times, and sharp rises in the SEP time profiles. Cross-field diffusion is the likely cause for the 14 August SEP event observed by STA and the 5 March SEPs observed by STB and L1 spacecraft, as particle observations featured weak electron anisotropies and slow rising intensity profiles. Otherwise, the wide longitudinal spread of these SEP increases would require an existence of a circumsolar shock, which may not be a correct assumption in the corona and heliosphere.
Publication Date: Jul 25, 2017
Document ID:
20180000632
(Acquired Feb 13, 2018)
Subject Category: SOLAR PHYSICS
Report/Patent Number: GSFC-E-DAA-TN50953
Document Type: Journal Article
Publication Information: Journal of Geophysical Research: Space Physics; p. 7021–7041; (ISSN 2169-9380; e-ISSN 2169-9402); Volume 122; Issue 7
Publisher Information: AGU Publications
Contract/Grant/Task Num: NNG11PL10A
Financial Sponsor: NASA Goddard Space Flight Center; Greenbelt, MD, United States
Organization Source: NASA Goddard Space Flight Center; Greenbelt, MD, United States
Description: 21p; In English
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: Copyright
NASA Terms: CORONAL MASS EJECTION; ENERGETIC PARTICLES; SOLAR STORMS; SOLAR CORPUSCULAR RADIATION; SOLAR CYCLES; INTERPLANETARY SHOCK WAVES; MAGNETIC FIELD CONFIGURATIONS; EXPANSION; SOLAR ELECTRONS; MAGNETOSPHERIC ELECTRON DENSITY; SOLAR PROTONS; MAGNETOSPHERIC PROTON DENSITY; PARTICLE DIFFUSION; CROSSED FIELDS; SOLAR ACTIVITY EFFECTS; TIME LAG; ULTRAVIOLET RADIATION; POSITION (LOCATION); SOLAR WIND; ANISOTROPY
Availability Source: Other Sources
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