A large cloud of gas (hydrogen) and dust a nebula begins to collapse
The collapsing cloud begins to spin
The spinning collapsing cloud flattens into a rotating disk
Material in the disk begins to accumulate in the center
As the material coalesces in center, it becomes dense, compresses, and heats up.
More and more material coalesces to form a protostar.
The protostar continuse to accomulate material from the surronding disk and grow.
Eventually, the protostar becomes massive enough, dense enough and hot enough to cause the process of nuclear fusion to begin.
Nuclear Fussion isotops of hydrogen atoms (deuterium, tritium) combine to form helium atoms, energy, and subatomic particles.
Once nuclear fusion begins the protostar's “ignition” to nuclear fusion creates a solar wind that drives remaining gas and dust to the outer parts of the disk.
Then the young star stops accumulating material.
