Issue |
A&A
Volume 614, June 2018
|
|
---|---|---|
Article Number | A61 | |
Number of page(s) | 7 | |
Section | The Sun | |
DOI | https://doi.org/10.1051/0004-6361/201732041 | |
Published online | 13 June 2018 |
Strong non-radial propagation of energetic electrons in solar corona
1
Institut für Experimentelle und Angewandte Physik, Universität Kiel,
24118
Kiel,
Germany
e-mail: klassen@physik.uni-kiel.de
2
SRG, Universidad de Alcalá, Dpto. de Física y Matemáticas,
28871
Alcalá de Henares,
Spain
3
Institute of Physics/Kanzelhöhe Observatory, University of Graz,
8010
Graz,
Austria
Received:
4
October
2017
Accepted:
20
February
2018
Analyzing the sequence of solar energetic electron events measured at both STEREO-A (STA) and STEREO-B (STB) spacecraft during 17–21 July 2014, when their orbital separation was 34°, we found evidence of a strong non-radial electron propagation in the solar corona below the solar wind source surface. The impulsive electron events were associated with recurrent flare and jet (hereafter flare/jet) activity at the border of an isolated coronal hole situated close to the solar equator. We have focused our study on the solar energetic particle (SEP) event on 17 July 2014, during which both spacecraft detected a similar impulsive and anisotropic energetic electron event suggesting optimal connection of both spacecraft to the parent particle source, despite the large angular separation between the parent flare and the nominal magnetic footpoints on the source surface of STA and STB of 68° and 90°, respectively. Combining the remote-sensing extreme ultraviolet (EUV) observations, in-situ plasma, magnetic field, and energetic particle data we investigated and discuss here the origin and the propagation trajectory of energetic electrons in the solar corona. We find that the energetic electrons in the energy range of 55–195 keV together with the associated EUV jet were injected from the flare site toward the spacecraft’s magnetic footpoints and propagate along a strongly non-radial and inclined magnetic field below the source surface. From stereoscopic (EUV) observations we estimated the inclination angle of the jet trajectory and the respective magnetic field of 63° ± 11° relative to the radial direction. We show how the flare accelerated electrons reach very distant longitudes in the heliosphere, when the spacecraft are nominally not connected to the particle source. This example illustrates how ballistic backmapping can occasionally fail to characterize the magnetic connectivity during SEP events. This finding also provides an additional mechanism (one among others), which may explain the origin of widespread SEP events.
Key words: Sun: flares / Sun: particle emission / Sun: magnetic fields
© ESO 2018
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.