Presentation #409.06 in the session General Topics IV: Non-solar.
Impulsive solar energetic particle (SEP) events are distinguished from shock-accelerated gradual SEP events especially in terms of their abundance enriched in 3He and heavy ions. Historically, they have been known to be associated with type III radio bursts and energetic electrons. Today the standard procedure to isolate the source regions of impulsive SEP events is to find a transient solar activity around the time of a type III burst or a related electron event that is observed within a reasonable interval preceding the SEP onset. The solar source of impulsive SEP events is often generalized as coronal jets based on solar cycle 23 events observed by the Solar and Heliospheric Observatory. Many of the impulsive SEP events during solar cycle 24 were associated with a jet, but sometimes with an eruption wider than typical jets and even with an EUV wave. This study is aimed to investigate whether a coronal jet or even a type III burst needs to be always present when we isolate the source regions of impulsive SEP events. We critically analyze high-cadence coronal images from SDO/AIA in comparison with radio dynamic spectra from STEREO/WAVES during late May 2021, when a series of impulsive SEP events were observed by the Energetic Particle Detector suite on board Solar Orbiter. It was almost certain that these SEP events came from active region (AR) 12824, which abounded in not only coronal jets but also more spatially extended eruptions and EUV waves. We evaluate the possible origin of these impulsive SEP events in phenomena other than jets. We also discuss which jets might have contributed to the impulsive SEP events and whether recurrent jets with or without an associated type III burst might have been more important. Lastly, possible effects of compromised cadence are discussed on the detection of short-lived jets and other phenomena that were associated with impulsive SEP events in previous studies.