30 years of optical spectroscopy from the symbiotic binary PU Vulpeculae

Since its discovery in 1932, there has been a great atempt to explain the variety of physical properties observed in symbiotic stars, explosive binary systems whose spectrum shows red giant and planetary nebula characteristics simultaneously. I expose in this talk a spectroscopic analysis of the symbiotic star PU Vul, span over 30 years of observations. The system harbors a red giant and an accreting white dwarf. There is also a nebula surrounding the system, generated by a wind from the red giant and the ejected material by the white dwarf during the 1979's outburst. I introduce a study of the evolution of the system, through the analysis of line fluxes, temperatures and luminosities. I also propose a geometrical model to explain the evident changes in the spectrum.