Abstract
We have obtained for this nebula high dispersion lUE spectra in the short and long wavelength ranges and with different exposure times. We have measured the emission line intensities and analyzed them. The density derived fiom different ions confirm that the nebula has no systematic density variations. The collisionally excited lines of [Mg V] 2783 and 2928 are present, but no measurable Mg II 2795 and 2803 appear in emission. We derived ionic abundances and a value for the depletion of magnesium in the gaseous component of the external parts of the nebula. From the long wavelength exposures we have measured the expansion velocity for different ions, and we find an increasing expansion velocity with decreasing ionization degree. We have obtained the velocity field and we find that it is compatible with predictions, in the literature, for a nebula under isothermal expansion into vacuum. We derive for the object a kinematical age of ∼ 3100 years. A wavelength dependence of the asymmetry of the blue and red components of the lines is measured. We analyze a possible interpretation for this dependence.
