Astronomers Explode Virtual Supernova

DynaSoar writes "Scientists at the University of Chicago's Center for Astrophysical Thermonuclear Flashes have created a simulation of a white dwarf exploding into a type 1a supernova. Using 700 processors and 58,000 hours, they produced a three second movie showing the initial burst that is thought to be the source of much of the iron in the universe. Understanding these supernovas is also important to testing current cosmological theories regarding dark matter and dark energy, as their brightness is used as a measurement of distance, and discrepancies found in the brightness of very distant supernovas consistently seem to indicate a change in the speed of expansion of the universe over time."

58000 hours

[Repton]

So, they started the simulation over six years ago?

Re:58000 hours

[Telvin_3d]

I don't think the point of this story is some big feat of supercomputing. The interesting bit is that they made a really neat simulation and tossed it online. The processing power involved is a point of interest, nothing more.

Re:58000 hours

[einhverfr]

THere are a lot of interesting things about this. Supernovas are believed to be a major (though not the only) source of all elements heavier than iron in the universe.

For a brief overview (based on Fowler's Nobel Prize lecture) on element formation... This is all from memory (and I am not a physicist) so do your own verification. Basically small stars burn Protium (1H). These fuse to product 2He which immediately decays into Deuterium (2H), emiting a positron. This P-P process eventually allows Deuterium to fuse forming the stable 4He.

As the amount of Helium in a star increases, it eventually becomes possible for Helium to fuse. The only problem is that 8Be is unstable and alpha decays almost immediately back into He. However, you get a small amount of 8Be sitting around for a while, and it can fuse with 4He to produce 12C (Carbon-12). From here things get interesting...

For stars with more than about 1.1 times the mass of our sun, The carbon becomes the basis for Helium production, replacing the P-P process. The basic process (called the CNO cycle) involves single captures of protons (2 of which decay into neutrons and positrons) and then the alpha decay back into 12C. In short this allows Carbon to act as a sort of catalyst for Hydrogen fusion. All elements heavier than Carbon are produced using one of a number of processes. These include fast proton capture, slow proton capture, and alpha capture. The problem is that these become endothermic at the point of Iron. So while smaller stars can produce some of the heavier elements, they are limited in the quantities they can produce. Supernovas, however, can rapidly create much larger quantities of heavier elements.

Also note that at a point in the distant past, stars were more massive than they generally are today. This means that at different points in the history of the universe, we saw large amounts of heavier elements generated.

So this is all quite interesting. I am sure at that many hours we are probably talking about a pretty detailed atomic model. The movie probably shows noting near what the simulation shows.