An ultraviolet study of NGC 7662.

Abstract

Spectroscopic observations obtained by the IUE of the planetary nebula NGC 7662 are discussed. Physical conditions in the central regions of the nebula are determined from the intensities of the O III and Ne IV lines, resulting in an electron temperature profile which increases with the ionization potential of the ions, in agreement with predictions from detailed models. Direct determinations of the relative atomic abundances with respect to H of C, N, O and Ne from the UV observations yield values of 0.00047, 0.000090, 0.00053 and 0.00090, respectively, which are in agreement with values obtained from a detailed model of ionization structure and thermal balance, and with solar abundances, with the exception of neon. The nebular continuum is found to be essentially of atomic origin, with no significant dust grain contribution, and that of the central star indicates a blackbody temperature of 80,000 K.