Statistical relationship between filaments and solar energetic particle fluxes (above 10 MeV) has not been previously reported. We investigate the association rate using the largest reported event sample, based on observations by the Atmospheric Imaging Assembly (AIA) aboard the Solar Dynamics Observatory (SDO), EUVI (Extreme Ultraviolet Imager) onboard STEREO (Solar TErrestrial RElations Observatory) A & B and Hα data archive from Big Bear Solar Observatory or Kanzelhöhe Observatory. We inspected 156 proton events in the time period between 2010 and 2016 since the most detailed observations of prominences with SDO started.
Figure 1. The association rate between SEPs and filaments (pie chart on the left) & SEP-related filaments link with active regions (bar plot on the right).
Figure 2. Heliographic locations of the origin of SEP events. Cases observed before and after the maximum of solar cycle 24 (SC24) are noted with different symbols.
From our list, 143/156 SEP events were accompanied by prominences (92%), while in the remaining 13/156 cases (8%) could not be associated with any filaments (Figure 1). The association rate between SEP-related filaments and active regions (ARs) is 88%. Only 17 (about 12%) of the 143 SEP-related prominences are not connected with ARs.
SEP events tend to appear in an area ±300 around the solar equator, preferring latitudes around ±150 (Figure 2). The maximum of solar cycle 24 (as defined by sunspot number) reached in April 2014 coincides well with the maximum of registered proton events.
Figure 3. Distribution of SEP fluxes in time according to the solar hemisphere they originate from.
SEPs appear mostly in northern hemisphere before the maximum of solar cycle 24 and prefer southern hemisphere after the solar maximum (Figure 3 left plot). Moreover, we obtain that nearly 68% (103/152) of the proton sample originate from the western heliolongitudes, whereas the remaining 32% (49/152) are from the eastern (Figure 3 right plot). These percentages confirm the well-known observation for the preferential western origin of in situ observed particles.
Publications
Tsvetan Tsvetkov, Rositsa Miteva, Nikola Petrov. On the relationship between filaments and solar energetic particles, (2018) JASTP, Vol.179, Pages 1‑10 [DOI:10.1016/j.jastp.2018.06.005]
