Stars form deep within dense clouds of cold molecular gas and dust. The clouds become gravitationally unstable and collapse rapidly to smaller sizes and higher densities. Rotation causes the infalling gas to form a flattened disk around each growing protostar. Most of the gas and dust in this protostellar disk are able to flow onto the central protostar, adding to the potential star’s mass.
Why didn’t Jupiter become a star?
Gerald Reed, Leavenworth, Kansas