On the identification of absorption lines with small red shifts in the spectra of quasistellar objects

The reliability of identifications of narrow absorption lines with small red shifts is analyzed statistically on the basis of literature data on spectra with high spectral resolution for 38 quasi-stellar objects. The identifications were made using a reference spectrum including the most pronounced lines of the interstellar medium. Particular attention is devoted to the case of quasi-stellar objects in the region + or - 10 deg from the supergalactic equator or coincident in position on the celestial sphere with high-latitude high-velocity hydrogen clouds, and also situated at small angular distances from nearby galaxies. It is shown that in the majority of cases identifications with the line pairs of Ca II and Na I are random