Star temperature

The temperature of a star refers to the temperature at its surface, also called the photosphere. It is measured in kelvins (K), the standard unit for temperature in astronomy. A star’s temperature tells us a lot about its physical properties and where it stands in its evolutionary stage.

Astronomers determine a star’s temperature by analyzing its light spectrum. By studying the color and intensity of the light a star emits, scientists can estimate how hot the surface is. Cooler stars shine more in the red and infrared range, while hotter stars emit more blue and ultraviolet light. This is why red stars are cooler and blue stars are hotter.

A typical red dwarf has a surface temperature of around 3,000 K. A larger, Sun-like star has a temperature of about 5,800 K. A blue giant or O-type star can reach surface temperatures of 40,000 K or more.

In the Stellar Catalog, star temperatures are listed in kelvins (K) and often shown in comparison to the Sun to give context.