Review

#02

An accretion disk is a flattened ``pancake'' of gas orbiting a star. It is formed ultimately through conservation of angular momentum, as gas tries to fall down onto the central star via gravity.

#04

It runs out of material to burn via nuclear fusion.

#06

Refers to the condition that the density of stellar gas is so large, electrons are literally driven into the nucleus to make neutron-rich matter. Essentially neutrons live ``shoulder-to-shoulder'' to resist the compressive effects of gravity wanting to collapse the star.

#15

The fusion of iron does not yield energy, but requires external energy.