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| Paper: |
Longitudinal Dependence of SEP Peak Intensities as Evidence of CME-Driven Shock Particle Acceleration |
| Volume: |
484, Outstanding Problems in Heliophysics: From Coronal Heating to the Edge of the Heliosphere |
| Page: |
98 |
| Authors: |
Lario, D.; Roelof, E. C.; Decker, R. B. |
| Abstract: |
Multi-spacecraft observations of solar energetic particle (SEP) events allow us to
estimate the longitudinal distributions of SEP peak intensities.
By fitting a Gaussian functional form to the ensemble of SEP peak intensities
measured by two or more spacecraft as a function of the longitudinal
distance between the associated parent solar flare and the footpoint labels of the magnetic field lines connecting each spacecraft with the Sun,
we found that such distributions are not centered at nominal well-connected flare longitudes
but slightly offset to the west of the associated flare (Lario et al. 2006, 2013).
We offer an interpretation of this result in terms of long-lived particle injection
from shocks driven by the associated coronal mass ejections (CMEs).
By assuming that (i) CME-driven shocks are centered on the longitude of the associated solar flare,
(ii) the injection of shock accelerated particles maximizes at the nose of the shock which propagates radially outward from the Sun,
and (iii) SEP particle injection from the shock starts at a certain distance above the solar surface,
we infer an average radial distance where shocks are located when peak intensities in the prompt component
of the SEP events are observed.
We estimate the heliocentric distance of the CME-driven shock when particle injection from the shock maximizes
and conclude that the injection of ∼20 MeV protons and near-relativistic electrons maximizes well inside ∼0.2 AU. |
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