Comparative morphology of EIT/SOHO images and He II excitation

Abstract

Morphological differences between coronal images on the one hand, and a He i image on the other, are used to demonstrate the independence of He ii excitation from coronal radiation. The distribution of magnetic flux is found to be more important for He ii excitation. Collisional excitation by non-thermal electrons produced in nano-flare events is proposed as the mechanism for He ii excitation.