TY - JOUR
T1 - Unusual enhancement of ~ 30 MeV proton flux in an ICME sheath region
AU - Oka, Mitsuo
AU - Obara, Takahiro
AU - Nitta, Nariaki V.
AU - Yashiro, Seiji
AU - Shiota, Daikou
AU - Ichimoto, Kiyoshi
N1 - Funding Information:
This work was supported by JSPS Grants-in-Aid for Scientific Research (15H05812, 15K21709, 15H05814). M.O. was supported by NASA grants 80NSSC18K1002, 80NSSC18K1373, and 80NSSC20K0627 at UC Berkeley. N.V.N. was supported by NASA grant 80NSSC18K1126.
Funding Information:
This work was initiated and partly carried out at Coordinated Data Analysis Workshops on Solar Energetic Particles (CDAW/SEP) which were held in 2018 and 2019 at Nagoya University, Japan, in the framework of Project for Solar-Terrestrial Environment Prediction (PSTEP). We thank D. Reames for his guidance on usage of the Wind EPACT data. We thank all members of the ACE, Wind, SOHO, ARTEMIS, and GOES projects.
Publisher Copyright:
© 2021, The Author(s).
PY - 2021/12
Y1 - 2021/12
N2 - In gradual Solar Energetic Particle (SEP) events, shock waves driven by coronal mass ejections (CMEs) play a major role in accelerating particles, and the energetic particle flux enhances substantially when the shock front passes by the observer. Such enhancements are historically referred to as Energetic Storm Particle (ESP) events, but it remains unclear why ESP time profiles vary significantly from event to event. In some cases, energetic protons are not even clearly associated with shocks. Here, we report an unusual, short-duration proton event detected on 5 June 2011 in the compressed sheath region bounded by an interplanetary shock and the leading edge of the interplanetary CME (or ICME) that was driving the shock. While < 10 MeV protons were detected already at the shock front, the higher-energy (> 30 MeV) protons were detected about four hours after the shock arrival, apparently correlated with a turbulent magnetic cavity embedded in the ICME sheath region.[Figure not available: see fulltext.]
AB - In gradual Solar Energetic Particle (SEP) events, shock waves driven by coronal mass ejections (CMEs) play a major role in accelerating particles, and the energetic particle flux enhances substantially when the shock front passes by the observer. Such enhancements are historically referred to as Energetic Storm Particle (ESP) events, but it remains unclear why ESP time profiles vary significantly from event to event. In some cases, energetic protons are not even clearly associated with shocks. Here, we report an unusual, short-duration proton event detected on 5 June 2011 in the compressed sheath region bounded by an interplanetary shock and the leading edge of the interplanetary CME (or ICME) that was driving the shock. While < 10 MeV protons were detected already at the shock front, the higher-energy (> 30 MeV) protons were detected about four hours after the shock arrival, apparently correlated with a turbulent magnetic cavity embedded in the ICME sheath region.[Figure not available: see fulltext.]
KW - Coronal mass ejections
KW - Interplanetary shocks
KW - Particle acceleration
KW - Solar energetic particles
KW - Turbulence
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U2 - 10.1186/s40623-021-01362-y
DO - 10.1186/s40623-021-01362-y
M3 - Article
AN - SCOPUS:85100180161
SN - 1343-8832
VL - 73
JO - Earth, Planets and Space
JF - Earth, Planets and Space
IS - 1
M1 - 31
ER -