| Subject | has specie | has width | has wavelength | occurs in | has definition | 
|---|
| color |  |  |  |  |  | 
| luminosity |  |  |  |  | Total radiant energy output per second (absolute brightness, usually expressed in ergs s-1 or in magnitudes). L = 4πR2σT4 (see Stefan's law). | 
| magnitude |  |  |  |  | A measure. on a logarithmic scale, used to indicate the brightness of a celestial object. A 1-magnitude difference in brightness between two stars corresponds to a difference in luminosity by 100.4 or 2.51; 5 magnitudes corresponds to factor of 100 in luminosity. | 
| spectral feature |  |  |  |  | A feature in the spectra of a celestial object which occurs at a specific wavelength or range of wavelengths |