Line tomography is the use of double-peaked spectral line shapes of recognizable emission lines from a disk to determine the radial position of the line's source and thus placement of the disk's constituents as well as hints to the temperatures at various radii. Presuming an approximately Keplerian disk, the Doppler shifts and radial velocity implied by the line's double peak provide a clue to the line's source's distance from the host star. This technique is of interest for protoplanetary disks, and planet formation. Used over time, it can also reveal information about the progression of accretion events.
Line tomography (analysis of double-peaked line shapes) has been used for some time for analysis of ejecta such as planetary nebulae and from cataclysmic variable stars.