"yellow" and "white" are a bit subjective .
And what most would call "white" is not .The human eye sees things in a very broad range
with what the sun is as white about 5800 K
it is really yellow with about 6500 K as white
D65 VS. D55
so we call something yellow white , and "see" it as white but it is not
color theory fun,fun,fun....http://en.wikipedia.org/wiki/Color_theory
what the REAL color ( temp in K or in angstroms ) is,is NOT what we "see"
and different people will "see" the SAME color as different colors so.
then again i spent many years in photographic darkrooms processing color film and prints
remember "film" you actually had to put a role of this stuff in a camera
stars are measured as the temp. of the surface for Sol that is about 5777 Kelvin ( reference 0 k is equal to -273 C and 100K is -173 C )
then you have the corona at about 1 Million K
the surface temp is do to the energy AND the size the surface area .The larger the surface area for a given energy output the "cooler" the temp
a red giant though burning He and Ar, O2 or carbon is hotter in the core BUT is a cool star at the surface
a blue giant burning H2 only and BIG is very compact ( less surface area ) is Hotter
this is just a quick run down from what i learned in school years ago
do a bit of research on your own , at some point a "light bulb" will go off and the " aah haa " moment