During the not-actually-adiabatic “adiabatic phase” of these objects, the expression for their temperature contains a factor written E51 (“E-sub-51”) and is proportional to time to the negative 6/5ths. A transition during the evolution of these structures occurs when the sweep-up mass exceeds the ejecta mass. These objects can be dated by measuring the decay of titanium-44 in them. These objects are believed to be the primary source of “below-the-knee” cosmic rays. These objects are morphologically classified as shell-type, mixed morphology-type, or (*) plerions, the last of which consists of one of these objects excited by the winds of a central pulsar. (-5[1])One of these objects is the brightest extrasolar radio source in the night sky; that object is Cas A. A pulsar is located at the center of one of these objects that forms the Crab Nebula. For 10 points, name these clouds of heated interstellar gas left behind by massive stellar explosions. ■END■ (10[1]0[1])