HIGH-RESOLUTION SPECTROSCOPY OF V1853-CYGNI (LS II-DEGREES-26) - BIRTH OF A PLANETARY-NEBULA(34)

High-resolution optical spectra are discussed for the high-latitude B- supergiant V1853 Cyg (LS II +34-degrees-26), which has been identified recently as a hot post-AGB star with far-infrared IRAS colors similar to those of dusty planetary nebulae. Spectra obtained on eight nights between 1993 August and November reveal strong emission lines of Halp ha, beta, and gamma, as well as a variety of profiles (absorption, emi ssion, P Cygni) for the He I lines. A photospheric spectrum of absorpt ion lines, fairly typical of B1-2 supergiants, is present, but the lin es are asymmetric and their shapes and equivalent widths vary signific antly on a night-to-night basis. The velocity of the absorption lines varies by approximately 40 km s-1. Emission lines from permitted (C II , N II, Si II, and Fe III) and forbidden ([N II], [O I], [S II], and [ Fe II]) transitions are visible at a constant radial velocity over the observing interval. This object may be in the process of becoming a p lanetary nebula.