In April and July 2014, the Sun emitted three jets of energetic particles into space, that were quite exceptional: the particle flows contained such high amounts of iron and helium-3, a rare variety of helium, as have been observed only few times before. Since these extraordinary events occurred on the backside of our star, they were not discovered immediately. A group of researchers headed by the Max Planck Institute for Solar System Research (MPS) and the Institute for Astrophysics of the University of Göttingen (Germany) present a comprehensive analysis now in the Astrophysical Journal. It is based on data from the twin space probes STEREO A and STEREO B, which – at that time still both operating – were in a favorable observation position behind the Sun at the crucial time. For the first time, the study shows a correlation between helium-3 and iron-rich particle flows and helical eruptions of ultraviolet radiation in the Sun’s atmosphere. These could provide the necessary energy to accelerate the particles into space.

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