How do you determine the temperture of a star and what is the formula?

Answer 1

Looking at the colour of a star gives an indication of the temperature, but accurate measurements are done by looking at absorption lines in the star's spectrum. These are dark lines where light is being absorbed by the material in the star, and they're dependent on temperature.

Answer 2

It's determined from their color.

http://www.smv.org/jims/l6a.htm

Answer 3

depending on a stars temperature it will emit light at certain wavelengths, ie...color. so if you know a stars color preciesly, you will also know its temperature!!!! i hope this helps!!!!!!