The planetary nebula IC 3568 : a model based on IUE observations.

Abstract

The planetary nebula IC 3568 has been observed at both low and high dispersion with the IUE satellite. The spectrum of the star shows strong P Cygni profiles due to an 1840 km/s stellar wind. The nebular spectrum shows lines of He II, semi-forbidden C III, C IV, semi-forbidden N III, and semi-forbidden O III. The spatial distribution of the gas has been derived from a 6 cm VLA map. An ionization model is presented which fits the observed optical and UV line fluxes well. The abundances of C, N, O, Ne, and S are determined to be about half the solar values. The far-UV flux of the central star in the 912-228 A range can be represented by a Hummer and Mihalas model atmosphere with an effective temperature of 50,000 K. The flux at wavelengths below 228 A, however, is 35 times greater than the value given by the Hummer and Mihalas atmosphere.