An Etymological Dictionary of Astronomy and Astrophysics

A spectral line energy distribution which plots the intensity of each → carbon monoxide (CO) transition as a function of the upper J number. This type of → diagram is a powerful diagnostic tool, where models show that these CO ladders have very different shapes depending on the type of excitation (i.e. photon dominated region, PDR or X-ray dominated region, XDR) as well as density and radiation environment.

See also: → carbon monoxide (CO); → ladder.