Association of 3He-Rich Solar Energetic Particles with Large-Scale Coronal Waves

TL;DR

This study links 3He-rich solar energetic particle events to large-scale EUV coronal waves, suggesting these waves influence particle injection into space, based on observations from STEREO and ACE during solar minimum.

Contribution

It is the first comprehensive analysis showing that about half of 3He-rich SEP events are associated with large-scale EUV coronal waves, highlighting their potential role in particle acceleration.

Findings

Approximately 50% of 3He-rich SEP events are associated with EUV coronal waves.

EUV waves may influence the injection of 3He-rich SEPs into interplanetary space.

First direct observation of 3He-rich flares from STEREO-A.

Abstract

Small 3He-rich solar energetic particle (SEP) events have been commonly associated with extreme-ultraviolet (EUV) jets and narrow coronal mass ejections (CMEs) which are believed to be the signatures of magnetic reconnection involving field lines open to interplanetary space. The elemental and isotopic fractionation in these events are thought to be caused by processes confined to the flare sites. In this study we identify 32 3He-rich SEP events observed by the Advanced Composition Explorer near the Earth during the solar minimum period 2007-2010 and examine their solar sources with the high resolution Solar Terrestrial Relations Observatory (STEREO) EUV images. Leading the Earth, STEREO-A provided for the first time a direct view on 3He-rich flares, which are generally located on the Sun's western hemisphere. Surprisingly, we find that about half of the 3He-rich SEP events in this survey are associated with large-scale EUV coronal waves. An examination of the wave front propagation, the source-flare distribution and the coronal magnetic field connections suggests that the EUV waves may affect the injection of 3He-rich SEPs into interplanetary space.