Ultraviolet spectra of planetary nebulae. II. The young PN IC 4997.

Abstract

Observations of the planetary nebula IC 4997 made with the International Ultraviolet Explorer satellite are analyzed in conjunction with visual photoelectric observations. The extinction to the nebula and the electron temperature and density are deduced from the relative intensities of lines emitted by O(+) and O(2+) ions. The relative abundance of C and O is found to be similar to the solar value, whereas the abundances of these elements relative to H are substantially less than solar. The effects of the variability of the nebular emission are considered and found to be only marginally significant.