The Fate of the Stars
All scenes › Chapter 3 A heavy star: supernova and neutron star
A core choked with iron
Layers like an onion, and an iron center that gives way
View in 3DA core choked with iron
Inside, the supergiant is layered like an onion. From the outside in: hydrogen, helium, carbon and oxygen, silicon, and iron piling up at the very center. Joining iron together gives off no energy. When the iron core grows to about the size of Earth, it can no longer hold up its own weight, and in less than a second it collapses to the size of a city.
Why?A star gets its energy by joining light elements into heavier ones. But this ladder ends at iron. With no more heat coming out, the push that held up the center is gone.
Learn moreThe last step, turning silicon into iron, takes only about a day. The collapsing core falls inward at about a quarter of the speed of light. The screen shows this moment very slowly.
- When
- About 12 million years old
- Star we are watching
- Inside the red supergiant
- Size · state
- Iron core at the center: about the size of Earth
Read more
Wikipedia: Silicon-burning process · Wikipedia: Type II supernova
More in the series
Lifetimes and sizes are typical values from models of how stars change (approximate). The black hole horizon size and the teaspoon masses are calculated with official constants. Sizes, distances and speeds in the 3D view are a rough sketch.