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Scientists Add New Dimension to Supernovae Simulations

supernova model



MICHAEL S. WARREN/Los Alamos National Laboratory
Briefly exceeding the power of 100 billion stars, a supernova explosion ironically signifies the death of a massive celestial sun. But because these immense blasts are typically situated in galaxies far, far away, studying their intricate workings is problematical: scientists can't go to the experiment so they instead must bring the experiment to them. Since 1966, researchers have developed increasingly more realistic computer simulations of these dazzling events. First one-dimensional, then two, the models have gradually revealed key details behind supernova activity. New research takes this work one step further. Scientists unveiled the first three-dimensional models ever created that depict star collapse and the subsequent tremendous explosion yesterday at the Astronomical Society Meeting in Albuquerque, NM.

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 apart—the 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."

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