The central star of S 216.

Abstract

Optical and high-resolution ultraviolet spectra of LS V + 46 21, the postulated central star of the large, nearby planetary nebula S 216, have been analyzed. From modeling the line profiles, this star is found to have an effective temperature of about 90,000 K, surface gravity log g of about 7, and a He:H ratio of about 0.01. These are as expected from published data on the nebula, and provide confirmation that it is a planetary. The ultraviolet data reveal a spectrum rich in lines of Fe VI and Fe VII, whose excitation potentials require a photospheric origin. LS V + 46 21 is currently the brightest member of the DAO class of white dwarfs and planetaries. Low-resolution IUE SWP spectra of three others (A 7, A 31 and PW 1) have also been analyzed, two of which reveal metals. This suggests that the spectrum of LS V + 46 21 may be typical of many DAOs.