YOKHOH SOFT-X-RAY TELESCOPE IMAGES OF THE DIFFUSE SOLAR CORONA

During the interval 1992 May 3-15, an extended region (out to 1.5 sola r radii) of diffuse, stable corona crossed the northeast limb of the S un. This region underlaid a coronal streamer as revealed by the Mauna Loa Coronagraph of the High Altitude Observatory. During this passage, the soft X-ray telescope on Yohkoh obtained a number of high-quality pairs of images, closely spaced in time, through the two thinnest anal ysis filters. Analysis of these data indicates that (1) the temperatur e increases steadily with height and (2) the variation of temperature with radius is consistent with a conserved inward heat flux. These res ults imply that the magnetic field configuration was substantially ope n out to 1.5 solar radii and that there was no significant coronal hea ting below that height in that region. It appears that this region was being heated by nonthermal energy deposited beyond 1.5 solar radii.