Star temperature from B-V color

[poiuy]

Homework Statement

I need to know how to calculate the temperature of a star from it's B-V color

Homework Equations

B = -2.5log(F440)+C
V = -2.5log(F550)+C
B-V = -2.5log(F440/F550)

The Attempt at a Solution

Really no idea, all my textbooks say that B-V color is used to measure temperature but none of them say how. I also can't find anything linking flux ratios to temperature.

Any help appreciated :)

 

[mgb_phys]

From my list of handy astronomy values
B-V = -3.684 log(T) + 14.551 (for log(T) < 3.961)
B-V = 0.344 (log(T))^2 -3.402 log(T) +8.037 (for log(T) >3.961)

Note that B-V is also called the color-index of a star.

These are experimental fits to the HR diagram for some cluster - you can probably derive it from Planck's law + stefan-boltzmann if you know the filter bandwidth.