The material falls inward, forming a dense rotating disk with a hot core called a protostar. Conservation of angular momentum means the collapsing cloud spins faster as it shrinks, just like a figure skater pulling in their arms.

The protostar is not yet a star. It glows from the heat of gravitational compression, not nuclear fusion. It takes roughly 100,000 years for a Sun-like protostar to gather most of its mass, pulling in gas from the surrounding cloud all the while.