JulianO

Thanks for the feedback all! Glad the maths didn't scare you!

Might just feature 😉

No pressure then, probably better finish writing it then!! 😃

It's one of the top simulations around, along with the Durham based Eagle project. They use different simulation codes, but derived from the same base. 

Happy to give some talks if you are still looking, I have a few - let me know.

Julian

Both Hertzsprung and Shapley tried to calibrate based on nearby Cepheids for which there were known parallax measurements. There were a lot of issues to solve about extinction and so on before a firm equation for the distance was worked out, and of course there was then the issue of Cepheid II's!

The Cepheid variable relationship was worked out by Henrietta Swan Leavitt  observing Cepheids in the Magellanic Clouds. This is a smallish (astronomically speaking) cluster of stars a ways outside our galaxy, so to all intents and purposes are more or less all at the same distance. A bit like observing the lights of Manchester from London, they're all about the same distance away.  

So if there is a relationship between their brightening and dimming and their luminosity, you can tell that the relationship is pretty much fixed.

It turned out there is a little more to it in the case of Cepheids, but that's mostly what it is.

So once you have calibrated this and worked out how this equates with distance, you have a convenient yardstick