Lbol

Lbol, or bolometric luminosity, is the total power emitted by an astronomical object across all wavelengths. It is an intrinsic property that does not depend on distance, unlike apparent brightness.

In practice, Lbol is determined by integrating the object's spectral energy distribution (SED) over all frequencies and correcting for interstellar extinction. When direct integration is not possible, bolometric corrections based on measurements in a finite band or color indices are used, relying on assumed SED shapes.

For stars, Lbol relates to radius and effective temperature by L = 4πR^2σT_eff^4, connecting Lbol to stellar structure and evolution. For the Sun, Lbol is about 3.828 × 10^26 watts, or 1 Lsun. Astronomers express Lbol in solar units, typically as log(Lbol/Lsun) or as a multiple of Lsun. For galaxies and active galactic nuclei, Lbol represents the integrated energy output of the system, including infrared emission from dust reprocessing.

Uncertainties arise from distance estimates, extinction corrections, and incomplete wavelength coverage, which can bias bolometric corrections. Lbol is widely used to characterize energy budgets, place stars on the Hertzsprung–Russell diagram, and study accretion and feedback processes in compact objects.