Abstract
Whilst the bulk of the electrons accelerated in solar eruptions precipitate into the chromosphere, a fraction of them either escape into the heliosphere or stay trapped in the corona. We present three studies, based on Solar Orbiter observations, that explore the latter two scenarios.
(1) Escaping electrons: solar energetic electrons (SEEs). The Comprehensive Solar Energetic Electron event Catalogue (CoSEE-Cat) links 303 SEE events measured in situ by Solar Orbiter (2020–2022) to their X-ray, radio and EUV counterparts and to their magnetic connectivity. We find that the apparent delay of the electron release time grows with heliocentric distance, a signature of interplanetary transport rather than delayed injection.
(2) Where they escape from: coronal jets. Revisiting the CoSEE-Cat events with SDO/AIA imaging, we find that jets are the dominant source: they are the counterpart of two thirds of the events whose source region is visible from Earth, and as many as 90% of the jet-associated events are impulsive. Jet-associated reconnection gives the SEEs access to interplanetary space. Measured from the jet onset, the release delays are consistent with those found for the wider CoSEE-Cat sample.
(3) When they cannot escape: failed filament eruptions. In several failed eruptions, where the field stays closed, STIX detects non-thermal hard X-rays from the confined filament itself. With densities of 10¹⁰–10¹¹ cm⁻³, the filament can act as a thick target: the trapped electrons lose all their energy in the filament material and heat it directly.