corecollapse

Core collapse refers to the rapid gravitational collapse of the iron core of a massive star at the end of its nuclear burning life. When the core mass approaches the Chandrasekhar limit, electron degeneracy pressure can no longer support it, and the core collapses within milliseconds.

During collapse, the inner core reaches nuclear densities and stiffens, causing a hydrodynamic bounce that launches a shock wave into infalling matter. The shock loses energy and stalls, but a delayed neutrino-heating mechanism, aided by multidimensional flows, can revive it and produce a successful supernova explosion. If revival fails, the star may collapse into a black hole with little optical display.

Massive stars above roughly 8–10 solar masses undergo core collapse. Progenitor envelopes determine the supernova type: Type II retain hydrogen, Type Ib/c have lost most or all of their hydrogen (and helium) envelope, often via winds or binary interactions.

Core-collapse supernovae radiate across the electromagnetic spectrum; SN 1987A provided the first neutrino detection from such an event, confirming core-collapse theory. Observations of spectra and light curves distinguish Type II, Ib, and Ic. Outcomes include neutron stars or stellar-mass black holes; remnants enrich the interstellar medium with heavy elements via ejected material and contribute to galactic dynamics.

Modeling requires 3D simulations with accurate neutrino transport; the exact explosion mechanism remains an area of active research. Rotation, magnetic fields, and turbulence influence the outcome and may vary among progenitors, contributing to diversity in observed explosions and remnants.