spectral feature

The term spectral feature is a catch-all for any recognizable feature (i.e., detail) of a spectrum. If it provides specific evidence of some characteristic of the source, the term spectral signature applies. It might refer to an emission line or absorption line, or the line shape, or a spectral band. Examples include a Balmer jump, a vegetation red edge or a Compton hump. Some lines are common in galaxies and recognizable even when redshifted, offering a means to estimate distance using the Hubble constant.

The phrase spectral feature extraction is used in discussions of computer techniques aimed at analyzing spectra, allowing and population groupings and examples of specific phenomena to be selected from extensive survey data. Machine learning (ML) methods are of interest.