Star formation. Image 1 of 6. Computer model of a 1.2-light year diameter sphere of interstellar gas before it collapses under its own gravity, causing star formation. Brighter areas have a greater gas density. The gas ball has a mass 50 times that of the Sun. This model used 100,000 processing hours on a supercomputer at the United Kingdom Astrophysical Fluid Facility (UKAFF) at the University of Leicester, UK. Simulations such as this increase understanding of the chaotic processes of star formation, and the likelihood of the formation of planetary systems around new stars. For a sequence showing star formation over 266,000 years, see images R590/089-094.