What is the typical lifecycle of a star and how are different types of stars related?

Question

What is the typical lifecycle of a star and how are different types of stars related?

Answer 1

Star condenses from hydrogen gas.

Star heats to dull red from heat of compression.

If large enough, nuclear fusion, with hydrogen becoming helium.  This usually takes billions of years.  If not large enough, the star becomes a brown dwarf.  If the star is large enough, its color will depend on temperature, which in turn depends on size.  Small = red dwarf, Large = blue-white.  We're in-between at the average yellow.

The star runs out of hydrogen, and is now helium. If the star is very small, fusion stops, and the star will turn from red to brown.  Otherwise, fusion of helium into carbon starts.  If the star is very large, gravity will prevent the star from swelling, and this phase will go by quickly, in millions of years.  For average size stars, helium fusion will result in bloating, slowing this phase down, and taking another billion years or so.

At some point, the helium is used up.  If the star is large enough, fusion resumes with carbon fusing to iron.  This almost always immediately causes the star to explode.  That's why there are so many carbon/iron meteorites.

If the star is large enough, some or all of the star will hold together, and the carbon will get used up.

If the star is large enough, iron will fuse to lead.  Again, most stars will blow up during this process.

If the star is large enough, lead will fuse to neutronium.  Again, most stars will blow up during this process.  Neutronium is unstable outside of billions of Gs, so it will decompose into who-knows-what, but looks like mostly hydrogen to me.

If the star is large enough, one theory states that the next stage is strange matter.

If the star is large enough, the neutronium or strange matter is converted to a black hole.

Over googles of years, the black hole will dissolve to sub-atomic particles.

The first few stages take billions of years.  The last few take milliseconds.  Incomplete burning/fusing of H, He, C, Fe, and Pb result in all the other elements.