What is the general between surface temperature and brightness of an main sequence o a star?

In main sequence stars, there is a direct relationship between surface temperature and brightness, often described by the Hertzsprung-Russell diagram. Stars that are hotter (with higher surface temperatures) emit more energy and are therefore brighter. O-type stars, the hottest and most luminous on the main sequence, exhibit this trend, as they have surface temperatures exceeding 30,000 K and can be thousands of times more luminous than the Sun. Consequently, as you move from cooler to hotter stars in the main sequence, both temperature and brightness increase.