Life Cycle of a Star
Prostars: The First Cycle
1. Gravity pulls gas and dust inward toward the core.
2. Inside the core, temperature increases as gas atom collisions increase.
3.Density of the core increases as more atoms try to share the same space.
4. Gas pressure increases as atomic collisions and density (atoms/space) increase.
5. The protostar’s gas pressure RESISTS the collapse of the nebula.
6. When gas pressure equals gravity, the protostar has reached equilibrium and accretion stops
The Main Sequence
Death of a Star
Low Mass Stars: The helium core runs out, and the outer layers drift of away from the core as a gaseous shell, this gas that surrounds the core is called a Planetary Nebula. The core left behind is known as a white dwarf.
Medium Mass Stars: Shrinks to neutron star. Supernova happens when a neutron star is created. Neutrons prevent further collapse. The size of a neutron star is about that of a large city. Medium mass stars become explosive supernova. Supernova explosions happen because the core has formed a very stiff neutron star and the in-falling outer layers rebound off of it. After this phase, the star becomes a white dwarf.
More Massive Stars: The highest mass stars have cores that shrink into a point. Before they collapse, they may momentarily create a neutron star and the resulting supernova explosion. Space warps around the object that it leaves a black hole.
A Star's Light
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