A2 Gravitational Collapse

Topic

The central element of this model is the iron core of a massive star at the final moment of its life.

In stars ranging from approximately eight to twenty-five solar masses, nuclear fusion builds up—layer by layer—an iron core that can no longer yield energy through fusion; once the core's mass exceeds the limit that degeneracy pressure can support, it collapses in a fraction of a second, and the resulting rebound generates a shock wave that ejects the star's outer layers in a supernova explosion.

Meanwhile, the core itself transforms into a neutron star if its mass remains below the Oppenheimer-Volkoff limit, or continues collapsing into a black hole if that mass exceeds the limit.

Almost all the energy released during this collapse escapes as neutrinos, with only a small fraction converting into the visible light observed as the supernova explosion.

This gravitational collapse pathway—distinct from the thermonuclear channel described in a separate model—is responsible for producing, via rapid neutron capture, the majority of the universe's heaviest elements; it also yields the compact objects that later undergo the mergers described in another model. Thus, from the iron core that initiates this process to the compact objects that conclude it—spanning the split-second collapse and the Oppenheimer-Volkoff limit that determines whether a neutron star or black hole forms—gravitational core collapse ensures that a massive star's violent death simultaneously seeds the universe with its heaviest elements and creates the very objects that will later merge with one another.

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