(20 points! ) number the steps of stellar evolution in the correct order. step 1 step 2 step 3 step 4 step 5 step 6 stellar core heats as it grows; nuclear fusion begins and a star is born. nebular cloud of gas and dust. nuclear energy runs out; death; possible supernova. cloud collapses under the force of its own gravitational attraction; usually triggered by a supernova. other gas and matter of the nebular cloud begin to rotate around the protostar, forming a flattened, disk. condensed material begins to combine and form a core center. as it warms, a protostar is formed.