Contemplating the stars

Warning, Mummy brag heading your way:
I set Joel a task this morning.
I had been looking at diagrams of star lifecycles to show the kids, but they all seemed to be a little different from each other depending on which website or book I looked at. I suspect some were out of date, others simplified, or being used to demonstrate one particular aspect of the process.
Either way, as usual, I was not satisfied with anyone else's answer, so I decided to make my own.
Except Joel knows far more than me about such things, so I delegated the job.

I was MOST impressed with the resulting diagram he came up with, using a simple graphics package.
Here it is.

Click on image to get a bigger readable version.