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Press Release 06-023
Sound Waves Rock a Star to Death

New model explains sound before sight

Reverberating sound waves are about to tear this simulated star apart.

Reverberating sound waves are about to tear this simulated star apart.
Credit and Larger Version

February 7, 2006

In most explosions, there's the flash and then the "bang." But in the exploding stars known as supernovae, it may be just the opposite. In fact, according to new computer simulations carried out by University of Arizona astronomer Adam Burrows and his colleagues, the bang actually makes the flash.

Or to put it another way, says Burrows, "it's the sound waves that actually cause the star to explode."

This conclusion sounds paradoxical, says Burrows. But if borne out, it would solve a long-standing puzzle.

Astronomers know that a supernova explosion can occur only in a very massive star--say, 10 to 25 times the mass of our own Sun. And they know the initial release of energy is confined to the very deepest core of the star. The puzzle is how the energy gets out. Previous simulations suggested the layers of gas surrounding the core were just too dense for the energy to escape. The simulated blast wave would stall and die before it reached the star's surface, as if it were muffled by a blanket, and observers on the outside would see nothing at all.

But, those earlier simulations had always used highly simplified models of supernovae outbursts, because that was the only way to cope with the complex calculations. Many, for example, assumed the explosions were completely spherical and symmetric.

Now, however, Burrows and his colleagues have developed computer models that allow them to simulate a more natural flow of material and radiation, especially in the central regions of the star. They found that the initial energy release at the core pulsates the surrounding layers of gas--with a typical frequency around middle C. Within a fraction of a second, moreover, the pulsations grow so violent they tear the star apart, blowing its outer layers into space.

Burrows has posted images and videos of the simulations online. He and his colleagues were funded by the National Science Foundation, the Department of Energy, and the Joint Institute for Nuclear Astrophysics. They will be publishing their research in the Astrophysical Journal.

For more details, see the University of Arizona news release.

-NSF-

Media Contacts
M. Mitchell Waldrop, NSF, (703) 292-7752, mwaldrop@nsf.gov
Lori Stiles, University of Arizona, (520) 621-1877, lstiles@u.arizona.edu

Program Contacts
Michael Briley, NSF, (703) 292-4901, mbriley@nsf.gov

Principal Investigators
Adam Burrows, University of Arizona, (520) 621-1795, burrows@zenith.as.arizona.edu

Related Websites
University of Arizona news release: http://uanews.org/spots/12170.html
Adam Burrows' movies and images page: http://zenith.as.arizona.edu/~burrows/briley/

The National Science Foundation (NSF) is an independent federal agency that supports fundamental research and education across all fields of science and engineering. In fiscal year (FY) 2014, its budget is $7.2 billion. NSF funds reach all 50 states through grants to nearly 2,000 colleges, universities and other institutions. Each year, NSF receives about 50,000 competitive requests for funding, and makes about 11,500 new funding awards. NSF also awards about $593 million in professional and service contracts yearly.

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