AST2002 Chapter Notes - Chapter 12: Planetary Nebula, Cno Cycle, Ant-Zen
Document Summary
Contraction and enough mass will allow gravity to keep working and the temperature and pressure to keep rising. Protostar + temperature hot enough for hydrogen fusion -> true star (of the main sequence) Gravitational equilibrium: where core generates enough energy to = energy lost on surface due to radiation. Massive stars do everything faster, including contracting, forming, and dying. Stars with higher mass than sun shorter lifetimes; opposite is true as well. No more h in the core -> no more nuclear fusion -> no more energy to replace the radiation -> (cid:272)ore (cid:449)o(cid:374)"t (cid:271)e a(cid:271)le to resist gra(cid:448)ity -> shrinkage. Additionally, gravity will be weakened at the surface, which will allow mass to escape via stellar wind. Once all the he converts into ca, fusion will cease again -> shrinkage again because of gravity. Will expand again with he fusion in shell around inert carbon core. At this point, the star is a double shell-fusion star.
