Star birth. Conceptual artwork of star birth in a gaseous cloud (nebula), showing two hands touch- ing. The image of the hands is based upon Michelangelo's Creation of Adam painting in the Sistine Chapel, Rome, Italy. Star formation begins when a dense part of a nebula begins to pull more material towards it by gravitational attraction. As material falls towards the dense region (the protostar) it converts its gravitational potential energy into heat. The protostar eventually becomes so hot that the atomic nuclei in its core begin to bind together when they collide, a process known as fusion. This releases large amounts of energy, and a star is born.