Posted by nichola on .
I have two stars A = 7150K and B = 4850K.A is 20 times brighter than B.
Assuming L/Lv is the same for both stars find the ratio ofthe radii of A and B.
I have the equation R/R= (L/L)^1/2(T/T)^2.
I can do this for each star in terms of solar masses but i am unsure which temperature goes in the numerator/denominator?
Is (L/Lv)^1/2 sqr root 20?

Astronomy 
bobpursley,
luminosity is proportional to r^2*temp^4
so if are comparing r, then
r^2 prop Luminosity/T^4
so in your
Ra/Rb= sqrtLa/Lb) * (tb/ta)^2
= sqrt (20) * (4850/7150)^2