In one type of supernova, an explosion begins as a bubble of flames buried deep inside a dense star called a white dwarf. Because the flame bubble is lighter than its surroundings, it is highly buoyant, so it rises to the surface in a plume, topped with an accelerating smoke ring. In the video above, you can see a similar process happening in the self-sustaining reaction of iodate and arsenous acid contained in a jar 9cm in diameter.
"The solution is stable until it is triggered" says Stephen Morris of the University of Toronto. "We do this triggering at the bottom of a small tube that you can see in the bottom of the video. This is something like a fuse. The reaction proceeds as a front up the tube until it enters the much larger main vessel. Then it billows out as a plume. All over the surface of the plume, at a thin front, like a flame front, the reaction is happening. All the fluid motion is generated by the reaction itself."
In this reaction, some of the products serve as catalysts for the reaction itself. The catalyst diffuses a short distance and sets off the nearby unreacted solution, producing more catalyst. A moving front develops, leaving more buoyant fluid in its wake, which rises to continue the reaction. The whole process takes about 10 minutes form start to finish, and is sped up in the video.
In a real supernova, the fluid dynamics are much more turbulent and energetic. "Fundamentally the driving forces and the effect of gravity (buoyancy) is similar" says Morris.
Journal reference: Physical Review E, DOI:10.1103/PhysRevE.82.066307
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