Astro dot point: Cluster age from H-R diagram? (1 Viewer)

[DebuOfCourse]

There's a dot point towards the end of the Astrophysics syllabus:

Explain how the age of a globular cluster can be determined from its zero-age main sequence plot for a H-R diagram.

I've asked my tutor, my teacher, other people but everyone's given me a very practical answer to this but not theoretical.

Has anyone got a decent "WRITTEN" response to this question please?

Thanks.

- Dev

 

[Dangar]

-On a H-R diagram the turn-off point (the highest remaining point of the main sequence) can be used to infer the age of a globular cluster.
-As a cluster ages the main sequence shortens from the top as stars progressively evolve into red giants in order of mass.
- The lower the turn off point the older the cluster
-e.g. O. B, and A stars evolve and move off the main sequence first, so if the H-R diagram shows that the cluster has no O, B or A stars we know that the cluster is at least approx 10 million years old.

Hopes this is 'decent'...

 

[DebuOfCourse]

Well first of all, it does help and it IS in writing so thanks Danger. Appreciated.
Whether it's decent or not, I wouldn't have a clue. Do you think it would satisfy....oh I don't know....say a 4 - 6 mark question? I can't tell whether it does or doesn't. I'm not even sure if you're able to get questions like that, but I figured it was possible since it's an "explain" dot point.

 

[Dangar]

I guess if it was a 4-6 mark question you would have to explain why the O, B and A stars evolve faster in greater depth. i.e. they have a greater mass therefore they consume their fuel at a faster rate etc.