PRESENTATION OUTLINE
An enormous cloud of dust and gas is pulled together by gravity.
The molecular cloud collapses under its own self-gravity due to turbulent conditions.
The material at the center of the cloud heats up as it collapses.
The hot core of the cloud is known as a protostar. A protostar is still gathering mass from its parent cloud.
The protostar phase can last between 100,000 and 10 million years. The next stage in stellar evolution begins when the star stops acquring mass.
The star is now a pre-main sequence star. It becomes optically visible after blowing away the remaining dust and gas from the protostar stage.
Pre-main sequence stars are fueled by gravitational contraction. Very massive stars skip this stage and go straight to the main-sequence, which starts when the core of the star is hot enough for hydrogen fusion.
When hydrogen fusion begins in the core, the star is now a main sequence star. It will remain here for 90% of it's life.
