Extreme Kinematics of the 2017 September 10 Solar Eruption and the Spectral Characteristics of the Associated Energetic Particles

We report on the 2017 September 10 ground-level enhancement (GLE) event associated with a coronal mass ejection whose initial acceleration (∼9.1 km s−2) and initial speed (∼4300 km s−1) were among the highest observed in the Solar and Heliospheric Observatory era. The GLE event was of low intensity...

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Bibliographic Details
Published in:Astrophysical journal. Letters 2018-08, Vol.863 (2), p.L39
Main Authors: Gopalswamy, N., Yashiro, S., Mäkelä, P., Xie, H., Akiyama, S., Monstein, C.
Format: Article
Language:English
Subjects:
Acceleration
Coronal mass ejection
Energetic particles
Fluence
Kinematics
Longitude
Magnetic fields
Magnetic properties
SOHO Mission
Sun: coronal mass ejections (CMEs)
Sun: particle emission
Sun: radio radiation
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Summary:We report on the 2017 September 10 ground-level enhancement (GLE) event associated with a coronal mass ejection whose initial acceleration (∼9.1 km s−2) and initial speed (∼4300 km s−1) were among the highest observed in the Solar and Heliospheric Observatory era. The GLE event was of low intensity (∼4.4% above background) and softer-than-average fluence spectrum. We suggest that poor connectivity (longitudinal and latitudinal) of the source to Earth compounded by the weaker ambient magnetic field contributed to these GLE properties. Events with similar high initial speed either lacked GLE association or had softer fluence spectra. The shock-formation height inferred from the metric type II burst was ∼1.4 Rs, consistent with other GLE events. The shock height at solar particle release (SPR) was ∼4.4 0.38 Rs, consistent with the parabolic relationship between the shock height at SPR and source longitude. At SPR, the eastern flank of the shock was observed in EUV projected on the disk near the longitudes magnetically connected to Earth: W60 to W45.
ISSN:2041-8205
2041-8213
DOI:10.3847/2041-8213/aad86c