Non-interacting coronal mass ejections and solar energetic particles near the quadrature configuration of Solar TErrestrial RElations Observatory

Abstract

We present our results on the correlation of non-interacting coronal mass ejections (CMEs) and solar energetic particles (SEPs). A statistical analysis was conducted on 25 SEP events and the associated CME and flare during the ascending phase of solar cycle 24, i.e., 2009–2013, which marks the quadrature configuration of Solar TErrestrial RElations Observatory (STEREO). The complete kinematics of CMEs is well studied near this configuration of STEREO. In addition, we have made comparison studies of STEREO and SOlar and Heliospheric Observatory results. It is well known that the CME speeds and SEP intensities are closely correlated. We further examine this correlation by employing instantaneous speeds (maximum speed and the CME speed and Mach number at SEP peak flux) to check whether they are a better indicator of SEP fluxes than the average speed. Our preliminary results show a better correlation by this approach. In addition, the correlations show that the fluxes of protons in energy channel >10 MeV are accelerated by shock waves generated by fast CMEs, whereas the particles of >50 MeV and >100 MeV energy bands are mostly accelerated by the same shock waves but partly by the associated flares. In contrast, the X-ray flux of solar flares and SEP peak flux show a poor correlation.

Comment on “Non-interacting coronal mass ejections and solar energetic particles near the quadrature configuration of solar terrestrial relations observatory”: CME shocks are fast magnetosonic shocks and not intermediate Alfvén shocks

“…To obtain the shock magnetosonic Mach number, M ms , the shock speed, V s , should be divided by the upstream magnetosonic wave speed, V ms1 : One should note that the combination of Eqs. ( 3) and ( 4) has no resemblance to the expression used by Ravishankar & Michalek (2020).…”