A giant supernova and a tiny gas explosion on Earth may not seem like they have much in common. But according to a new study, they proceed in much the same way.
Not all explosions are the same. Fireworks, for example, are driven by flames moving slower than the speed of sound, known as deflagrations. Under certain conditions, deflagrations can transition into far more powerful detonations, which produce destructive shock waves traveling faster than the speed of sound.
Such detonations can happen in space, for example when a white dwarf star explodes in a kind of supernova called a type 1a supernova (SN1a). But the exact mechanism of these cosmic explosions has remained unclear. That prompted the authors of the new study, published today in Science, to see whether they could tease out the underlying process by studying explosions much closer to home.
The first clip above shows a computer simulation based on the researchers’ theory that when an unconfined gas explosion is subjected to intense turbulence, it generates pressure waves that compress unburned gas in front. That creates a shock wave that grows in strength until triggering a detonation.
To test whether this theory held in the real world, the researchers built a roughly 1-meter-long tube with various compartments that ignited hydrogen gas, subjected it to turbulence, and measured the effects.
Results from explosions in the tube matched the simulations. The scientists then showed their theory could simulate how the same transition from deflagrations to detonations occurs in the kind of explosions found in SN1a, as seen in the second clip.
The authors say their results provide a unified theory of how this transition occurs, whether in a chemical explosion on Earth or a thermonuclear one in space. That could not only expand our understanding of SN1a, but also potentially help predict when detonations might occur in industrial accidents.
Source: Science Mag