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

TL;DR

This study analyzes the relationship between non-interacting CMEs and SEPs during solar cycle 24's ascending phase, revealing that shock waves from fast CMEs primarily accelerate protons, with improved correlation when using instantaneous CME speeds.

Contribution

It introduces a detailed correlation analysis using instantaneous CME speeds and compares results from STEREO and SOHO observations, enhancing understanding of SEP acceleration mechanisms.

Findings

Instantaneous CME speeds correlate better with SEP fluxes.

Protons >10 MeV are mainly accelerated by CME-driven shock waves.

Higher energy protons (>50, >100 MeV) are partly accelerated by flares.

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 (SOHO) 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.