A model for the planetary nebula NGC 7027.

Abstract

Extensive photoionization modeling of NGC 7027 is presented using the most recent observations available. The effects of the differential extinction caused by the local dust cloud are considered and corrections are made to large-aperture line fluxes. Abundances are derived from a large number of collisionally excited and recombination emission lines. The abundances of this nebula are found to be very similar to the average of galactic disk type II and III planetaries. An attempt is made to model the thermal dust emission of this object, including the contribution to grain heating by absorption of the nebular emission lines. Both the photoionization and dust emission models reproduce the total observed emission using a non-LTE model atmosphere at T(eff) = 140,000 K with a luminosity of 10,000 solar luminosities at 1 kpc as the ionizing source. The evolution of the central star is discussed.