High spatial resolution observations of a hot region in a solar flare withthe transition region and coronal explorer

The Transition Region and Coronal Explorer (TRACE) provides some of the hig hest spatial resolution images ever taken of hot solar flare plasma. The TR ACE 195 Angstrom channel is particularly sensitive to high-temperature Rare plasma because of the presence of the Fe XXIV lambda 192 resonance line in this bandpass. The TRACE 171 Angstrom channel observes emission From therm al bremsstrahlung during a flare. Since this emission is generally weak, it is usually not possible to derive electron temperatures for flare plasma f rom TRACE observations. In this Letter, we present analysis of the 2000 Mar ch 24 X1.8 limb flare that produced high count rates in both the TRACE 195 and 171 Angstrom channels. We find evidence for a small, high-temperature r egion near the top of the Rare arcade. This hot region appears to lie at th e base of the cusp-shaped structure that extends above the arcade. The TRAC E observations are consistent with a strong enrichment of Fe over its photo spheric value in the hot region that suggests in situ heating of this plasm a. We also find that multithermal simulations of Rare evolution reproduce t he observations much better than an isothermal model does.