Disentangling of composite spectra.

A novel technique for the reconstruction of the individual spectra of the components of well detached binaries is presented. The method requires a set of composite spectra at different phases. It is based on a singular value decomposition (SVD), the appropriate method of treating a linear problem which is both overdetermined and rank deficient. The algorithm also yields precise radial velocities, even at phases where the lines are severely overlapping, e.g. near conjunction. This is a great advantage for the construction of radial velocity curves, especially the determination of system velocities and orbit eccentricities. The quality of the reconstructed spectra is demonstrated using CCD spectra of the B0.5 type binary V453 Cygni. The spectrum of the primary taken during total eclipse in the secondary minimum matches perfectly with the spectrum reconstructed from a set of seven composite spectra at different phases out of eclipse. We conclude, that spectra which are reconstructed by means of the disentangling algorithm are well suited for quantitative spectroscopic work.