What function do instruments like the Cosmic Origins Spectrograph (COS) serve aboard the Hubble Space Telescope?

Breaking light into constituent colors to reveal critical physical information.

The Hubble Space Telescope employs tools categorized as either cameras or spectrographs. Instruments like COS fall into the latter category. Rather than creating visual images, spectrographs perform deep analysis by dispersing the incoming light beam. This separation into a spectrum allows astronomers to examine the patterns of lines superimposed on the rainbow. Analyzing these patterns provides crucial physical characteristics of the source material, such as chemical composition and radial velocity, which are distinct from the morphological data provided by imaging instruments.