The planetary nebula NGC 7009.

Abstract

IUE observations of the planetary nebula NGC 7009 and its central star are presented and used to derive the physical properties of the system. Low-resolution spectra were obtained by the SWP and LWR cameras using the large aperture centered on the nucleus and 6.5 arcsec NE of it. When combined with optical line ratios, the UV data indicate an electron temperature of 9500-9700 K for the O III zone, 12,700-15,400 K for the Ne IV zone, 10,800-13,400 K for the O II zone and 12,700 to 13,000 K for the N II zone, depending on the value adopted for the logarithmic extinction at H-beta. Relative abundances with respect to hydrogen of 0.00029 for C, 0.00030 for N, 0.00052 for O and 0.000096 for Ne are then obtained, and it is noted that while carbon and oxygen are essentially solar, nitrogen and neon are overabundant by factors of 3 and 2.5, respectively. The nebular continuum is found to be dominated by atomic continuum with no evidence of light scattered by dust particles. The stellar continuum is consistent with a black body of temperature 100,000 to 150,000 K shortwards of 2200 A, and one of much lower temperature longwards of this value.