Temperature plays a crucial role in determining the appearance of a star, primarily influencing its color and luminosity. Stars emit light across a spectrum of wavelengths, and their surface temperature dictates the peak wavelength of emitted light according to Wien's Law. Generally, hotter stars emit more light at shorter wavelengths, appearing blue or white, while cooler stars emit light at longer wavelengths, appearing red or orange.
For example, consider the stars Sirius and Betelgeuse. Sirius, the brightest star in the night sky, has a surface temperature of around 9,940 K, which gives it a blue-white appearance. In contrast, Betelgeuse, a red supergiant, has a surface temperature of about 3,500 K, resulting in its characteristic reddish hue. The difference in temperature not only affects their color but also their overall luminosity; Sirius is one of the most luminous stars, whereas Betelgeuse, despite being large, appears less bright from our perspective due to its greater distance.
In summary, the temperature of a star profoundly influences its color, luminosity, and overall appearance, with hotter stars appearing blue and cooler stars appearing red.