Why do fast and wide CMEs not always produce observable solar energetic particles?
Abstract
Statistical studies have found a close association between large solar energetic particle (SEP) events and fast and wide coronal mass ejections (CMEs). However, not all fast and wide CMEs have an associated SEP event. The lack of an intense solar flare during the parent solar eruption (Marque et al., 2006) or the slow evolution of the CME speed at the origin of the solar eruption (Gopalswamy et al., 2017) have been pointed out as possible factors that play a role in the absence of high-energy particles. The observation by a given spacecraft of the putative SEPs accelerated during these fast CMEs may also depend on whether the spacecraft establishes magnetic connection with the source of the SEPs and/or on how these SEPs propagate through the interplanetary medium. From the list of CMEs in the CDAW LASCO catalog during January 2009 - September 2014, we have selected fast (plane-of-sky speeds >1000 km/s) and wide (angular width >120 deg) CMEs and determined whether >25 MeV protons were detected by STEREO-A, STEREO-B or SOHO. Among the 123 selected CMEs, only eleven CMEs did not produce a >25 MeV proton intensity increase at any of the three spacecraft. By characterizing the shocks driven by these CMEs, the magnetic connection established between the traveling shock and each one of the three spacecraft, and the radio emission observed during these events, we analyze the factors responsible for the absence of observed >25 MeV proton increases in these events.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMSH21B..02L
- Keywords:
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- 7514 Energetic particles;
- SOLAR PHYSICS;
- ASTROPHYSICS;
- AND ASTRONOMY;
- 7519 Flares;
- SOLAR PHYSICS;
- ASTROPHYSICS;
- AND ASTRONOMY;
- 7845 Particle acceleration;
- SPACE PLASMA PHYSICS;
- 7859 Transport processes;
- SPACE PLASMA PHYSICS