On the identification of the solar sources of 3He-rich solar energetic events

Solar energetic particle (SEP) events with compositional anomalies such as the highly elevated ³He/⁴He ratio have been known for more than half a century, but their origin is still not well-understood.  This is largely because of the difficulty of identifying their solar sources. In solar cycle 23, thanks to the availability of high-resolution coronal images from SOHO and other missions, coronal jets were found to be the typical solar manifestation of ³He-rich SEP events observed by ACE and Wind. They were often temporally correlated with type III radio bursts and electron events, which often gave the onset times with less uncertainties than the velocity dispersions of the ³He-rich SEP events themselves.  The widely used technique has been to search for jets and related phenomena around the times of the type III bursts that occur in the interval that is estimated from ion data.  However, data from Solar Orbiter in the present solar cycle have revealed ³He-rich SEP events whose solar sources are unidentifiable with this technique because unique jets are not found at the times of the type III bursts. In some cases, it is even hard to find a type III burst. In this work, we further investigate some of these difficult cases including the late October 2022 period, trying to find some clues in high-resolution and differently scaled EUV intensity and difference images. Other possibilities will also be pursued, including subtle changes in global magnetic field configurations (that may be related to observed dropouts) and acceleration above the low corona, etc.  We also discuss how these events may change our views of the solar sources of ³He-rich SEP events that are based on previous results.