Simulations by researchers show that as the gas cloud collapses, it forms dense filamentary structures that absorb the star's radiation when it passes through them. Stars form when huge clouds of gas collapse. Once the central density and temperature are high enough, hydrogen begins to fuse into helium and the star begins to shine. The most massive stars, though, begin to shine while the clouds are still collapsing. Their ultraviolet light ionizes the surrounding gas, forming a nebula with a temperature of 10,000 degrees Celsius. This suggests that the growth of a massive star should taper off or even cease because the surrounding gas should be blown away by the heating.
The simulations were run on supercomputers at the Texas Advanced Computing Center, funded by the National Science Foundation (NSF), and at the Leibniz and Jxlich Computing Centers in Germany. The research was funded in part by the NSF Astronomy Division (grant AST 08-35734). To learn more about this research, see the American Museum of Natural History news story Simulations Solve a 20-year-old-Riddle About Why Nebulae Around Massive Stars Don't Disappear. (Date of Image: 2010)
Credit: T. Peters et al.