The Missing Cool Corona in the Flat Magnetic Field around Solar Active Regions

SDO/AIA images the full solar disk in several EUV bands that are each sensitive to coronal plasma emissions of one or more specific temperatures. We observe when isolated active regions (ARs) on disk, full-disk some channels show outskirts AR as a dark moat surrounding AR. Here we present seven examples, selected from time periods there was only single disk. Visually, be most prominent AIA 171 Angstrom band, which has sensitivity emission at log10 T = 5.8. By examining 1D line-of-sight measure temperature distribution found six channels, find intensity depressed over range ~ 5.7 - 6.2 for cases. argue exists because pressure strong magnetic field splays out presses down underlying loops, flattening those loops -- along with lowest AR's own low altitude. Those would normally emit bulk emission, restricted heights above surface too have Angstrom-emitting plasmas sustained them, according Antiochos & Noci (1986), while hotter EUV-emitting overlying higher-altitude long AR-rooted loops. This potentially explains low-coronal-temperature moats ARs.