At night, the stars are bright and dark, and their colors are red, orange, yellow and blue. In fact, the light emitted by each star contains light of various colors. For example, a prism can decompose the sunlight into "seven colors" like a rainbow. Stars look different in color because some colors of starlight are stronger. For example, the yellow light emitted by the sun is relatively strong and looks yellow; When the blue light emitted by Rigel is relatively strong, it is blue; The red light emitted by Betelgeuse is relatively strong, which shows red, and so on.
The experience of daily life tells us that the temperature of blue flame is high and that of yellow orange flame is low. The same principle applies to stars in the sky: different colors of stars reflect different surface temperatures, and the color and surface temperature generally have the corresponding relationship shown in the table:
Every star is a hot plasma ball, and the central part is undergoing violent thermonuclear reaction. The huge amount of energy released there is transmitted to the star surface through radiation, convection and other processes, making the star glow. Due to the difference of age, mass and metal content, the surface temperatures of different stars vary greatly, and the corresponding colors are also different. If stars are photographed, the color difference of different stars will be more significant due to the long-term accumulation of starlight. It is these colorful colors that "reveal" the secrets of many internal physical properties of stars to us.