A Spectroscopic Study of PU Vulpeculae

High-dispersion spectra of a peculiar object, PU Vulpeculae obtained at Okayama in the period from 1979 through 1989, were analyzed regarding both the absorption and emission lines by a ``curve of growth" method with an assumption of resonance fluorescence. Most of the emission lines including forbidden lines of [Fe II] are distributed on the linear part of the curve, and the emitting region is considered as being optically thin. Although the estimated atmospherical parameters of this object agreed with those of an F supergiant until 1982, an anomaly in the chemical composition appeared in and after 1983. This anomaly can be related to a line weakening of Fe II, Sc II and Sr II relative to Ti II, which is probably due to a filling effect of the emission lines. The profile of the H Balmer lines was analyzed with a Gaussian decomposition scheme; the radial velocities of these components and those of metallic lines suggest that the emitting region comprise an expanding envelope and an accretion disk. A geometrical model based on a binary hypothesis is presented.