Technically, our sun is white... it's color is
our definition of white.
Compared to other stars though, it is only yellow. Some stars are so hot that their visible light emission is in the blue range while others are so cool that they appear orange or red.
There is no such thing as a "green" star though. There are illusions caused by stars of two different colors being (visibly to us) very close together, and their combined colors mimic green... a lot like blue and yellow paint mixed together.
Example:
Viewing star color involves the additive primary color spectrum (red, green and blue) instead of the subtractive primary spectrum (magenta, cyan and yellow). This is the same as a computer monitor or TV set.
To make colors other than red, green or blue, two of these are mixed together. For example, red plus green = yellow. Red plus blue = magenta and green plus blue = cyan.
So, as a black body radiator increases in temperature, it's apparent color will change from dull red to bright red, then to yellow (as a result of combining green and red), then finally blue, violet and ultraviolet.
Although there IS green emission, because it's mixed with either red or blue, we can never see PURE green from a black body radiator (although it IS in there... as proven by the fact that using a prism to split "white" sunlight yields the full visible color spectrum, including pure green.
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