Spectral variation and the expanding envelope of PU Vulpeculae.

The peculiar variable star PU Vul showed significant spectral changes in 1982. The mean radial velocity of absorption lines changed from +30 km s^-1 in May to -50 km s^-1 in November. Strong emission lines with P Cygni profile of Hα, Fe I, Fe II, Ca I, Ba II, Sc II, and La II were detected on a high dispersion spectrum taken in November 1982. The mean radial velocity of the emission lines in the spectrum is about +30 km s^-1. The blue-shift of the absorption lines and the emergence of the emission lines suggest the presence of an expanding envelope. This object probably entered an active period in 1982. Some points of similarity between PU Vul and the peculiar F type supergiant ρ Cas are pointed out.