Ultraviolet and optical spectroscopy of CN 1-1 (= HDE 330036).

Ultraviolet and optical spectra of Cn 1-1 are presented. This stellar object has strong emission lines superposed on the absorption spectrum of an F5 III-IV star. It has been called both a symbolic star and a planetary nebula. Optical spectra taken over a period of two years do not show any variations in radial velocities. The radial velocities of the absorptionand emission-line spectra appear to be the same. The ultraviolet and optical spectra did not show variations in appearance over the period of observations. The interstellar extinction and distance are estimated by various methods, and values of c = 0.4 and d = 450 pc are adopted. The emission-line region is characterized by high-electron density and temperature and by enhancements over solar values in C/O and N/O. It is proposed that Cn 1-1 is a dense planetary nebula involved in a binary system. If so, the enhancements in abundances derived from the observations suggest that the planetary nebula is associated with a relatively massive progenitor star.