SIMBAD references

We present results of the medium resolution spectral observations of a variable A-e star DD Ser. In 1984-1986 the star was found to have a normal double emission Hα-line with equivalent width of emission component EW Hα_e=13.3±0.5Å. In 1991 a drastic Hα-line profile, as well as photometric variations, were detected. Analysis of the reconstructed profile of the emission line absorption component implies that a dense gas-dust cloud has most likely emerged on the line of sight at the moment of the spectral observations. Quantitative characteristics of the absorption profile variation are given.