The steps of stellar evolution:
– Nebula – an immense cloud of gas and dust in interstellar space.
– Protostar – early form of a star; lies between the collapsing of dust and beginning of nuclear fusion.
– Clouds and matters begin to rotate around the protostar. They surround protostar like a rotating disk.
– The core continues to heat and when it is hot enough, nuclear fusion begins.
– The star can go through many stages and die in different ways. One of these ways is being a supernova.
– Supernova – a gigantic explosion in which a massive star collapses and throws its outer layers into space.
Step 1 – 4. Nebular cloud of gas and dust.
Step 2. – 2. Cloud collapses under the force of its own gravitational attraction; usually triggered by a supernova.
Step 3. – 6. Condensed material begins to combine and form a core center, as it warms, a  protostar is formed.
Step 4. – 3. Other gas and matter of the nebular cloud begin to rotate around the protostar, forming a flattened disk.
Step 5. – 5. Stellar core heats as it grows; nuclear fusion begins and a star is born.
Step 6. – 1.Nuclear energy runs out; death: possible supernova.