Transcript: Stellar luminosity is a fundamental property of stars. It’s the amount of energy radiated each second. Absolute brightness is another word for this. Really we’re talking about the energy radiated at all wavelengths which is technically called the Bolometric luminosity. Since most stars emit most of their radiation in visible light, visible or visual luminosity and Bolometric luminosity are usually almost equal. However, this is not true for very cool or very hot stars.