What are the stars with the highest and lowest temperatures?

Stars have different colors, and colors mainly reflect their surface temperatures. The sun is a yellow star with a surface temperature of about 10000℃ and a white color. Altair and Vega are both white stars. When the temperature is as high as 25000 ~ 40000℃, the color of the star is blue. Orion ι is one of the hottest stars, and its surface temperature is as high as 40000℃, so it is a typical blue star.

The pulse variable star Tsukuji (O) is a red star with a surface temperature of only 2000℃, which can be regarded as one of the lowest temperatures. But even the coldest star has a surface temperature enough to melt gold and steel into liquid. As for Orion, which is more than 20 times hotter than it, it is hard to imagine how hot it is.