Structure of the hot object in the symbiotic prototype Z Andromedae during its 2000-03 active phase

Aims. To investigate structure of the hot object in the symbiotic prototype Z And during its major 2000-03 active phase. Methods. Analysis of the far ultraviolet, optical low- and high-resolution spectroscopy and ${\it UBVR}$ photometry. Reconstruction of the spectral energy distribution (SED) during the outburst. The Raman scattering process. Results. At the initial stages of the outburst the hot object was characterized by the two-temperature spectrum (a warm stellar radiation and a strong nebular emission) with signatures of a mass-outflow at moderate (~100-200 km s -1 ) and very high ( ≈ 1000-2000 km s -1 ) velocities. The corresponding structure of the hot object consists of an optically thick, slowly-expanding disk-like material encompassing the accretor at the orbital plane and a fast optically thin wind over the remainder of the star. The disk-like shell persisted around the central star until 2002 August as was indicated by the eclipse effect. Then, a significant dilution of the optically thick material and evolution of a fast wind from the hot star, concentrated more at the orbital plane, were detected. A striking similarity of [$\ion{Fe}{vii}$] λ 6087 and Raman λ 6825 profiles at/after the dilution of the disk suggests their origin within the interaction zone where the winds from the binary components collide.