3He-Rich Solar Energetic Particles in Helical Jets on the Sun

TL;DR

This study reports the observation of intense 3He- and Fe-rich solar energetic particle events associated with helical jets in small active regions, revealing a potential link between jet structure and particle enrichment.

Contribution

First high-resolution imaging of helical jets in small active regions linked to extreme 3He and Fe enrichment in solar energetic particles.

Findings

Helical jets are associated with intense 3He- and Fe-rich events.

Jets originate at coronal hole boundaries from mini-filaments.

Events coincide with non-relativistic electron events and radio bursts.

Abstract

Particle acceleration in stellar flares is ubiquitous in the Universe, however, our Sun is the only astrophysical object where energetic particles and their source flares can both be observed. The acceleration mechanism in solar flares, tremendously enhancing (up to a factor of ten thousand) rare elements like 3He and ultra-heavy nuclei, has been puzzling for almost 50 years. Here we present some of the most intense 3He- and Fe-rich solar energetic particle events ever reported. The events were accompanied by non-relativistic electron events and type III radio bursts. The corresponding high-resolution, extreme-ultraviolet imaging observations have revealed for the first time a helical structure in the source flare with a jet-like shape. The helical jets originated in relatively small, compact active regions, located at the coronal hole boundary. A mini-filament at the base of the jet appears to trigger these events. The events were observed with the two Solar Terrestrial Relations Observatories STEREO on the backside of the Sun, during the period of increased solar activity in 2014. The helical jets may be a distinct feature of these intense events that is related to the production of high 3He and Fe enrichments.