Stars begin their lives burning hydrogen, a simple and light atom. After they exhaust the available supply of hydrogen, they burn increasingly heavier elements. When a star finally meets its fate in a Type II supernova, its core is composed entirely of iron and is no longer capable of resisting the tremendous gravitational forces pressuring it from outside. The iron atoms get squashed together until the force of gravity exceeds the repulsive forces between the nuclei, causing the temperature to rise to more than 10 billion degrees. The formerly gigantic star's core collapses to a diameter of 100 kilometers and radiates energy, heating the surrounding gas. Through convection, this heat ends up causing a catastrophic explosion: a supernova.
Older computer models have furnished researchers with fundamental data regarding how and why supernovae explode with such intense energy, including the role of convection in the process. Primitive models, however, neglected key variables such as star rotation, which precluded exact depiction of these spectacular events. The new research begins to alleviate this problem. Using one of the world's fastest computers outfitted with a host of sophisticated software, Michael Warren and Chris Fryer of Los Alamos National Laboratory and their colleagues created the first three-dimensional computer simulations of a dying star's last moments (see image). From the point of core collapse to the fierce supernova explosion--events only milliseconds apartthe new model allows researchers to answer important questions in more detail than ever before. "Modeling the collapse of a massive star represents one of the greatest challenges in computational physics," Warren remarks. "All four fundamental forces of nature are at play, giving us a cosmic laboratory with conditions unlike anywhere else in the Universe."