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3D simulations show asymmetric supernovae
DR EMILY BALDWIN
ASTRONOMY NOW
Posted: 17 September 2010


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New 3D simulations of supernova explosions take astronomers a step closer to understanding the most powerful events in the Universe.

Supernova explosions are the cataclysmic end point of stars. As the star exhausts its supply of hydrogen and helium fuel it begins to fuse progressively heavier elements in its core, becoming denser and denser until it begins to implode. At a critical point, a shockwave of energy is released and the star explodes out into space.


The new 3D simulations are based on the collapse of an asymmetric and unstable star.

Supernovae explosions and their remnants have been observed for thousands of years, but the step-by-step process by which this occurs is poorly understood, largely because it is impossible to observe what is going on inside the central core of the star. Scientists strive to understand how the star becomes instantly unstable. “We don’t know what the mechanism of explosion is,” says Burrows. “As a theorist who wants to get to root causes, this is a natural problem to explore.”

New computer simulations created led by Burrows at Princeton University may provide new insight into this process. The simulations are based on the idea that the collapsing star is not sphere-like, like many models assume, but distinctly asymmetric and influenced by instabilities in the volatile mix surrounding its core.

“I think this is a big jump in our understanding of how these things can explode,” he says. “In principle, if you could go inside the supernovae to their centres, this is what you might see.”


Click here for movie of the asymmetric supernova explosion created by Adam Burrows and colleagues.

To visualize the explosion, the team combined expertise from astrophysics, applied mathematics and computer science. They assigned values for the energetic behaviour of stars based on equations used by geophysicists for climate modeling and weather forecasting, and also took into account factors that change with time, such as fluid density, temperature, pressure, gravitational acceleration and velocity.

“It may well prove to be the case that the fundamental impediment to progress in supernova theory over the last few decades has not been lack of physical detail, but lack of access to codes and computers with which to properly simulate the collapse phenomenon in 3-D,” conclude the team. “This could explain the agonizingly slow march since the 1960s toward demonstrating a robust mechanism of explosion.”

The next step is to connect the simulations to real observations. “Visualization is crucial,” adds Burrows. “Otherwise, all you have is merely a jumble of numbers. Visualization via stills and movies conjures the entire phenomenon and brings home what has happened. It also allows one to diagnose the dynamics, so that the event is not only visualized, but understood.”

The simulations are described in detail in the 1 September issue of the Astrophysical Journal.

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