Observations of a Coronal Shock Wave and the Production of Solar Energetic Particles

Journal Article · Mon May 01 04:00:00 EDT 2017 · Astrophysical Journal

DOI:https://doi.org/10.3847/1538-4357/AA6BA2· OSTI ID:22872746

Xu, Z. G.; Li, C.

We present a study that clarifies the acceleration source/mechanism of the solar energetic particle (SEP) event on 2011 August 9. Based on the assumption of scatter-free propagation of charged particles along the interplanetary magnetic field, the solar particle release times of the electrons and protons are derived and both found to be in the decay phase of the flare emission. Furthermore, we compare the peak-flux spectra of the in situ particles and the remote-sensing hard X-ray photons and find a weak correlation between them. In particular, we note that an extreme ultraviolet shock wave, presumed to be a signature of coronal mass ejection (CME) shock front on the solar surface, and an associated type II radio burst were observed alongside this event. Under the framework of diffusive shock acceleration, the derived shock compression ratio can accelerate particles with a theoretical spectral index γ=2.14{sub −0.02}{sup +0.01}, which is comparable to the observational index of ∼2.0. Our results appear to support the notion that the coronal shock wave was most likely responsible for the SEP event. Specifically, we find that the electrons were released in a low coronal site at ∼0.58 solar radii, and protons were released when the CME-driven shock propagated to ∼1.38 solar radii. The multi-spacecraft observations, in addition, reveal the connection between the acceleration of shock waves and the release of SEPs.

• OSTI ID: 22872746
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 840; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
CHARGED PARTICLES
COMPARATIVE EVALUATIONS
COMPRESSION RATIO
DECAY
ELECTRONS
EMISSION
EXTREME ULTRAVIOLET RADIATION
HARD X RADIATION
INTERPLANETARY MAGNETIC FIELDS
MASS
PHOTONS
PROTONS
SHOCK WAVES
SOLAR CORONA
SOLAR PARTICLES
SPACE VEHICLES
SPECTRA
SUN
SURFACES