The Formation of Stars
By Corey, Rohan, Blair, Austin, Chase
Step 1: initial collapse of an interstellar cloud
If the cloud can cool sufficiently, gravity will always cause a contraction and subsequent collapse. Many star-forming clouds appear to have collapsed spontaneously in this way. The process starts slowly, but can become more violent as the first stars form.
Step 2: the cloud fragments into clumps
A typical interstellar cloud is supported against collapse by internal turbulent motions.
Once such a cloud is "tipped over the edge" and starts to collapse, it reaches a state where gravity can pull the gas together to form dense "cores".
These cores continue to collapse, often fragmenting further, until they form star - sized clumps.
Step 3: The clumps collapse into a star
Once the force of gravity becomes larger than the pressure supporting the clumps, their collapse happens very fast.
Eventually the gas gets sufficiently compressed that it is dense and hot enough that the pressure balances the gravitational force, and the collapse stops. This situation is similar to the hydorstatic equilibrium we discussed for the sun. We call these objects "protostars."