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

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.

accepted for publication in The Astrophysical Journal

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• 3He-Rich Solar Energetic Particles from Sunspot Jets
• Sixty Years of Element Abundance Measurements in Solar Energetic Particles
• Hydrogen and the Abundances of Elements in Impulsive Solar Energetic-Particle Events
• Temperature in Solar Sources of 3He-rich Solar Energetic Particles and Relation to Ion Abundances
• Hydrogen and the Abundances of Elements in Gradual Solar Energetic-Particle Events
• Distinguishing the Rigidity Dependences of Acceleration and Transport in Solar Energetic Particles
• Fifty Years of 3He-rich Events
• Excess H, Suppressed He, and the Abundances of Elements in Solar Energetic Particles
• Statistical Study and Live Catalogue of Multi-Spacecraft 3He-Rich Time Periods over Solar Cycles 23, 24, and 25
• Solar Energetic Particle Charge States and Abundances with Nonthermal Electrons
• Element Abundances of Solar Energetic Particles and the Photosphere, the Corona, and the Solar Wind
• A Perspective on Solar Energetic Particles