Protostar, illustration. A protostar is a star in the process of formation. They are created when a globule, a dusty and gaseous nebula, condenses under gravity. The globule acts as a cocoon. Because of this, protostars are generally invisible to the universe at large, except at infrared wavelengths. Protostars may be flattened out by rapid rotation, and are probably surrounded by a vast disc of gas and dust, around which planets will one day form.