3He-rich Solar Energetic Particles from Sunspot Jets

3He-rich solar energetic particles (SEPs) present one of the most extreme fractionation examples in astrophysics where abundances of 3He and ultra-heavy elements are enhanced by factors up to ten thousand above their ambient coronal composition. Solar sources of suprathermal (< 1 MeV/nucleon) 3He-rich SEPs have been commonly associated with jets originating in small, compact active regions at the periphery of near-equatorial coronal holes. Sources of relatively rare, high-energy (> 10 MeV/nucleon) 3He-rich SEPs remain unexplored. Here we present the two most intense high-energy 3He-rich (3He/4He > 1) SEP events of the current solar cycle 24 measured on board the Advanced Composition Explorer (at 10.5 MeV/nucleon) and the Solar and Heliospheric Observatory (at 5-25 MeV/nucleon). Although 3He shows the highest intensities, Z > 6 ions are below the detection threshold at these high energies. The events are accompanied by type III radio bursts, but no type II emission as typically seen for low-energy 3He-rich SEPs. The corresponding solar sources were analyzed using high-resolution, extreme-ultraviolet imaging and photospheric magnetic field observations on board the Solar Dynamics Observatory. We report that solar sources of these events are associated with jets originating at the boundary of large sunspots with complex Beta-Gamma-Delta magnetic configuration. We discuss whether the examined extreme events require a re-acceleration in shocks, as considered in previous studies, or details of the source active regions are important to produce 3He to high energies.