Enhanced He{I} Absorption at the Feet of Solar X-Ray Loops

Abstract

A comparison of He{I} spectroheliograms and Yohkoh soft X-ray images of active regions indicates that He{I} absorption is enhanced at the feet of hot X-ray loops. It is suggested that the conduction of heat from the loops into the transition region at their feet would produce enhanced transition-region emission around 50 eV that would in turn cause enhanced excitation of He{I} leading to the excess He{I} absorption that is observed.