Stellar Masses for use with GURPS SPACE?

[cvannrederode]

Originally Posted by Agemegos

Those figures are missing the effect of stellar age.

You touched on it a later, but the age of a star has big impact on where it lies on the H-R diagram. Stars on the main sequence tend to move up and to the left as they age (getting brighter and hotter) and helium "ash" builds up.

Our sun will then shoot up and to the right as it grows to it's first red-giant phase, then move along the "horizontal branch" before hitting the asymptotic-giant-branch red giant phase. The first burns hydrogen around a inert core of helium, the second is now burning helium into carbon.

This chart shows all the parts of the H-R diagram a 1 solar mass star will touch in its life-time.

Long story short, the chart you give just gives a snap shot of real stars at their current age. It is excellent for giving real data on what real stars are like, but you can't use the chart to say what a 1.5 solar mass star will be, without also knowing how old the star is.