Nonuniform Heating of Coronal Loop Footpoints and Formation of Loop Threads Associated with Up‐ and Downflows in the Solar Chromosphere

Recent TRACE observations of active loops in the EUV showed that there is a class of EUV loops that consists of near-isothermal loop threads with substantially smaller temperature gradients than are predicted by the uniform loop heating model. These results support coronal heating mechanisms operating in or near the chromosphere and transition region. We propose a new local heating model of loop footpoints in the chromosphere in which there occurs nonuniform heating near the interaction regions of several loops, and the loop interaction results in the formation of loop threads associated with up- and downflows.