ASTRO 001H Study Guide - Midterm Guide: Neon Neon, Carbon-Burning Process, Crab Nebula
Document Summary
Do not become planetary nebulas or white dwarfs. Their great mass compresses their helium cores and heat them to carbon fusion temps. Oxygen cores compress and heat to fuse to neon. Neon cores compress and heat to start to fuse to silicon. Silicon compresses and heats to fusion temps. Iron core is under tremendous pressure and at very high temps. But the iron nucleus is very tightly bound and nuclear fusion cannot occur. The formation of iron signals the end of a massive star"s life. Such tremendous pressure on iron nuclei causes a new reaction: protons and electrons merge into neutrons. Sphere of iron turns into a sphere of neutrons. Core radius drops to about that of earth about 6 miles. With nothing to support the star, it collapses, bouncing out, and shatters the star in a supernova explosion. Crab nebula - 1054 a. d, founded by chinese astronomers.
