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

• Published in: The Astrophysical journal Vol. 852; no. 2; p. 76
• Main Authors: Bučík, Radoslav, Innes, Davina E., Mason, Glenn M., Wiedenbeck, Mark E., Gómez-Herrero, Raúl, Nitta, Nariaki V.
• Format: Journal Article
• Language: English
• Published: 10.01.2018
• ISSN: 0004-637X; 1538-4357
• DOI: 10.3847/1538-4357/aa9d8f

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 10,000) rare elements like 3 He and ultra-heavy nuclei, has been puzzling for almost 50 years. Here we present some of the most intense 3 He- and Fe-rich solar energetic particle events ever reported. The events were accompanied by nonrelativistic 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 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 3 He and Fe enrichments.