TEMPERATURE STRUCTURE OF THE SOLAR CORONA - COMPARISON OF THE NIXT AND YOHKOH X-RAY IMAGES

Solar soft X-ray images taken simultaneously by the Yohkoh and the Nor mal Incidence X-ray Telescope (NIXT) reveal significantly different co ronal structures. Coronal loops are more clearly seen in the Yohkoh im ages, and the isolated island-like structures seen in the NIXT image h ave been found to correspond to the footpoints of the Yohkoh loops. Th e difference is due to the difference in the temperature response of t he telescopes: NIXT is sensitive to temperatures ranging from 0.9 to 3 MK, while Yohkoh is more sensitive to temperatures above 2.5 MK. The morphological differences reflect the multi-temperature (1-5 MK) natur e of the solar coronal plasmas.