Three-dimensional reconstruction of an expanding shock associated with a Solar particle event
Abstract
On 2013 June 21st an eruption occurred in the active region NOAA 1177 (14S73E), giving rise to a M2.9 class flare starting at 02:30 UT, a fast partial halo coronal mass ejection (CME), and a type II radio burst. The concomitant emission of solar energetic particles (SEPs) produced a significant increase in the proton fluxes measured by LET and HET aboard STEREO-B. By using stereoscopic observations in extreme ultra violet (EUV) and white light (WL) spectral intervals, we performed a 3D reconstruction of the expanding front by processing SDO/AIA, STEREO/EUVI, COR1 and COR2, and SOHO/LASCO data assuming a spheroidal model. By using the 3D reconstruction, we estimated the temporal evolution of θBn, i.e., the angle between the normal to the expanding front and the coronal magnetic field computed by the Potential-Field Source-Surface (PFSS) approximation, within 2.5 Rʘ. The front of the CMEwas found to be quasi-parallel to the magnetic field almost everywhere. Above 2.5 Rʘ, where the front was identified as a shock, we projected the 3D expanding surface reconstructed for different times on the ecliptic plane and we calculated the θBn between the normal to the front and Parker spiral arms. In this case the shock was almost perpendicular to the magnetic field (quasi-parallel shock). During the expansion the region located between the nose and the eastern flank of the shock was magnetically connected with ST-B in agreement with the significant SEP flux measured on-board this spacecraft. While the shock was only marginally connected with ST-A and GOES-15. The SEP release time was estimated to be 10 minutes after the Type II onset, when the shock front was already above 2.5 Rʘ with a quasi-parallel configuration. Our results are discussed in the framework of the shock acceleration scenario, even if quasi-parallel shocks are expected to have a reduced acceleration efficiency.
- Publication:
-
EGU General Assembly Conference Abstracts
- Pub Date:
- April 2021
- DOI:
- 10.5194/egusphere-egu21-12154
- Bibcode:
- 2021EGUGA..2312154F