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Neat supernova mechanism for more powerful explosions


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Many SFN posters must be familiar with the usual models of stellar explosion---this "pair instability" mechanism is different, and far more powerful.


If anyone is interested in a simple explanation of how these hyper-powerful explosions work, here's the SciAm article



Here is the technical article:


from a team led by Avishay Gal-Yam.


Usual supernovae result in two ways: One way is from a binary star where one partner is burnt-out and modest-size (like around 1.4 solar mass). The small burnt-out partner explodes when the large active partner dumps mass on it and it reaches a critical mass.


The other way is from from core-collapse. That's the scenario everybody knows (it would be in Wikipedia). A large star in the range 10-100 solar fuses all the elements up to iron and develops an iron core. Since iron can't generate energy by fusing, the star has a dead iron core, which (as it cools and loses pressure) becomes subject to sudden violent collapse. Read Wikipedia to see how the core-collapse (to neutron matter or even to a black hole) by sudden release of gravitational energy can lead to explosion. Some of the infall matter bounces.


What I want to discuss is a different kind of core-collapse, when the core is oxygen, that can happen in stars of some 140+ solar mass.

Say it burns to where there is a 50 solar mass core of oxygen.


Ordinarily the oxygen core would keep on fusing and releasing energy as photons and exerting pressure outwards to support the rest of the star. It would be generating so it would not collapse. The iron core only collapses because it is dead and has no energy to support the weight.

But something tricky happens that DEFLATES the photon pressure from the oxygen core.

It produces photons but they are so energetic that PAIRS of photons collide and produce electron-antielectron pairs. The formation of these matter-antimatter pairs EATS UP some of the photons being produced by the core. Outward pressure is canceled. And the oxygen core starts to collapse. This accelerates the process of soaking up photons and forming matter-antimatter pairs. So if the star is massive enough, like 140 solar, there can be a sudden and near total collapse. Then the matter-antimatter annihilates and blows away all the outer layer material with a huge release of pure energy---very little if anything left behind.

Edited by Martin
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