EGU21-12154, updated on 09 Jan 2024
EGU General Assembly 2021
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.

Three-dimensional reconstruction of an expanding shock associated with a Solar particle event

Federica Frassati1, Monica Laurenza2, Alessandro Bemporad1, Matthew J. West3,4, Salvatore Mancuso1, Roberto Susino1, Tommaso Alberti2, and Paolo Romano5
Federica Frassati et al.
  • 1INAF - Osservatorio Astrofisico di Torino, via Osservatorio 20, Pino Torinese (TO), Italy (
  • 2IAPS – Istituto di Astrofisica e Planetologia Spaziali, via del Fosso del Cavaliere 100, Roma, Italy
  • 3ROB - Royal Observatory of Belgium, Ringlaan -3- Av. Circulaire, 1180 Brussels, Belgium
  • 4SRI - Southwest Research Institute, 1050 Walnut Street, Suite 300, Boulder, CO 80302, USA
  • 5INAF - Osservatorio Astrofisico di Catania, Via S.Sofia 78, 95123 Catania (CT) ITALY

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.

How to cite: Frassati, F., Laurenza, M., Bemporad, A., West, M. J., Mancuso, S., Susino, R., Alberti, T., and Romano, P.: Three-dimensional reconstruction of an expanding shock associated with a Solar particle event, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-12154,, 2021.

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