Iron
Iron spells death, and death deliverance. The iron core grows like a cancer in the heart of the star, damping nuclear reactions in all that it touches, until the star becomes fatally imbalanced and falls victim to a general collapse. If the mass of the core is a tenth to two or three times that of the sun — here we draw on research by Gamow, Baade, Robert Oppenheimer, Fritz Zwicky, and others — the core rapidly crystallizes into a steely sphere, a "neutron star." Smooth as a ball bearing and smaller than a city but as massive as the sun, a neutron star spins rapidly on its axis and emits pulses of radio energy as it spins, creating a beacon of the sort that betrayed the locations of Tycho's and Kepler's supernovae. It resembles nothing so much as a giant atomic nucleus — as if the real business of the star, the conjuring of nuclei, was now at last monumentalized as a colossal nuclear tombstone.
—Timothy Ferris, Chapter 14, "The Evolution of Atoms and Stars" from Coming of Age in the Milky Way
Iron
Iron spells death, and death deliverance. The iron core grows like a cancer in the heart of the star, damping nuclear reactions in all that it touches, until the star becomes fatally imbalanced and falls victim to a general collapse. If the mass of the core is a tenth to two or three times that of the sun — here we draw on research by Gamow, Baade, Robert Oppenheimer, Fritz Zwicky, and others — the core rapidly crystallizes into a steely sphere, a "neutron star." Smooth as a ball bearing and smaller than a city but as massive as the sun, a neutron star spins rapidly on its axis and emits pulses of radio energy as it spins, creating a beacon of the sort that betrayed the locations of Tycho's and Kepler's supernovae. It resembles nothing so much as a giant atomic nucleus — as if the real business of the star, the conjuring of nuclei, was now at last monumentalized as a colossal nuclear tombstone.
—Timothy Ferris, Chapter 14, "The Evolution of Atoms and Stars" from Coming of Age in the Milky Way