Photometric variability and spectral features of the protoplanetary nebulaLSII+34 degrees 26=V1853 Cyg

We present photoelectric and spectroscopic observations of the protoplaneta ry object V 1853 Cyg, a B supergiant with an IR excess. Over two years of i ts observations, the star exhibited rapid irregular light variations with a mplitudes DeltaV = 0.(m)3, DeltaB = 0.(m)3, DeltaU = 0.(m)4 and no correlat ion between color and magnitude. Its mean magnitude has not changed since t he first UBV observations in 1973 (Drilling 1975). Low-resolution spectrosc opic observations show that the spectrum of V 1853 Cyg in 2000 corresponded to that of a B1 - B2 star with T-eff similar to 20000 K. High-resolution s pectroscopic observations confirm the conclusion that the profiles of absor ption and emission lines are variable. We identified the star's spectral li nes and measured the equivalent widths of more than 40 lines. The star's ra dial velocity is <V-r> = -49 +/- 5 km s(-1), as measured from absorption li nes, and ranges from -50 to -85 km s(-1) for different lines, as measured f rom shell emission lines. The velocity of the dust clouds on the line of si ght determined from diffuse interstellar bands (DIBs) and from interstellar Na I lines is <V-r> = -16 +/- 5 km s(-1). The P Cyg profiles of the He I l ambda 5876 Angstrom and lambda 6678 Angstrom lines suggest an ongoing mass loss by the star. An analysis of the observational data confirms the conclu sion that the star belongs to the class of intermediate-mass protoplanetary objects. (C) 2001 MAIK "Nauka/Interperiodica".