Stellar Death
When a star more than 8 times the Sun's mass exhausts its nuclear fuel, it faces a catastrophic end. Over millions of years, it has fused hydrogen to helium, helium to carbon, and progressively heavier elements in concentric shells — like a cosmic onion. But when the core reaches iron, fusion stops producing energy. In less than a second, the iron core collapses from the size of Earth to a sphere just 20 kilometers across.
The Bounce and Explosion
The collapsing core reaches nuclear density and rebounds violently — like a rubber ball hitting concrete. This bounce sends a shockwave outward through the infalling stellar material. Meanwhile, the newly formed neutron core releases a flood of neutrinos carrying 99% of the gravitational energy. The shock, energized by neutrino heating, blasts through the star's outer layers at 10,000 km/s. The simulation above lets you watch each phase unfold.
Cosmic Alchemy
In the extreme temperatures and neutron fluxes of the explosion, rapid neutron capture (r-process) nucleosynthesis creates elements heavier than iron — from gold and platinum to uranium and beyond. A single supernova can eject several solar masses of these elements into interstellar space. Every heavy element on Earth was forged in ancient supernovae — we are literally made of stellar debris.
The Remnant
What remains after the explosion depends on the progenitor's mass. Stars between roughly 8 and 25 solar masses leave behind a neutron star — an ultra-dense remnant spinning rapidly and emitting radio pulses. More massive progenitors may produce black holes, sometimes without a visible explosion at all. The expanding debris forms a supernova remnant like the Crab Nebula, visible for tens of thousands of years.