Abstract: The Optical Spectrum of HR 4049.

High-resolution optical spectra (UES/WHT) of the extreme metal-poor post-AGB star HR 4049 were obtained at four different orbital phases. The spectra cover the wavelength region from 3650A to 10850A at a resolution of R=52000. These observations are supplemented with four high-resolution spectra of the NaI D1 & D2 and CaII K lines at R=~105 (CAT/CES). The optical spectrum shows 217 spectral lines: the Balmer series (H{alpha} – H35), the Paschen series (P9 -P23), NI, OI and numerous CI lines. We show that the lines of H{alpha}, H{beta}, H{gamma} and NaI D show significant changes in profile between different observation dates. Nine components were identified in the profile of the NaI D lines of which three are circumstellar and six interstellar. The stronger CI lines are asymmetric and we derive a post-AGB mass-loss of {dot}(M)=6±4×10-7M{sun}/yr from the asymmetry. The [OI]6300A line has been detected in emission at the system velocity and we argue that the emission is from an almost edge-on disk with a radius of about 20R*.