colour temperature

Color temperature is a concept used in physics to describe the color of light emitted by a blackbody radiator at a specific temperature. It's a measure of the relative amounts of radiation in different wavelength regions.12

For stars, color temperature is related to their spectral characteristics and can be determined by comparing their magnitudes in different color bands (like B and V). This helps astronomers understand the star's surface temperature, with hotter stars emitting bluer light and cooler stars emitting redder light. The effective temperature, a fundamental measure of a star's temperature, is derived from its total energy output and radius, relating it to the radiation of a blackbody.2