Spectroscopic evidence for helicity in explosive events

We suspect that these small volumes could be spicule-like structures and try to find evidence for this. We show observations of helical motion in macrospicules and argue that these features - if scaled down to a radius comparable to the slit size of a spectrometer - should have a spectroscopic signature similar to that observed in explosive events, which is admittedly not easily detectable by imagers. Despite of this difficulty, evidence of helicity in spicules has been reported in the literature.

This led us to the new insight that the same narrow spinning structures may be the drivers in both cases, structures that imagers observe as spicules and that in spectrometers cross the slit and are seen as explosive events. Results. We arrive at a concept that supports the idea that explosive events and spicules are different manifestations of the same helicity-driven scenario.

In contrast to the conventional view of explosive events as linear bidirectional jets that are triggered by a reconnection event in the transition region, this new interpretation is compatible with the observational results. Consequently, in this case a photospheric or subphotospheric trigger has to be assumed. Conclusions.

We suggest that explosive events/spicules are to be compared to the unwinding of a loaded torsional spring.