The rare class O main-sequence stars start the end of their lives as the middleweight stars do, bloating, forming energy-producing shells around the core, and fusing heavier and heavier elements together until the core becomes iron. And, once again, when the core attempts to fuse iron into something heavier, it loses its energy support and collapses, crossing the Chandrasekhar Limit and squeezing itself into a ball of neutrons.
There is, however, a theoretical limit on how heavy even a neutron star can become. Past about three solar masses, even neutron degeneracy can't support the core's weight. In fact, no force known can support its weight. The core continues to collapse until it is an infinitely small, infinitely dense point called a singularity. Its gravity will be so strong that neither the material from the original core's outer layers, nor the energy from the core's collapse, nor even a beam of light directed straight outward can escape it. Nothing that comes within the Schwarzchild Radius (3 kilometers times the mass of the singularity in solar masses) can escape it. As far as the outer layers of the star are concerned, the core has merely fizzled out, removing its energy support and letting them fall; these outer layers too will fall within the singularity's gravitational grip never to be seen again. The whole star swallows itself, leaving only its gravity behind; it's now called a black hole.
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Igen, igazad van, a vasmag a neutroncsillag elõtti állapotra jellemzõ.