Back to Volume
Paper: Three-Dimensional Photoionization Modelling of the Hydrogen-Deficient Knots in the Planetary Nebula Abell 30
Volume: 313, Asymmetrical Planetary Nebulae III
Page: 276
Authors: Ercolano, B.; Barlow, M.J.; Storey, P.J.; Liu, X.-W.; Rauch, T.; Werner, K.
Abstract: We have constructed a photoionization model, using the 3-D Monte Carlo code MOCASSIN for one of the hydrogen-deficient knots (J3) of the born-again planetary nebula Abell 30. The model consists of spherical knots, comprising a cold, dense, hydrogen-deficient core with very high metal abundances. The inner core, occupying 9.1% of the total volume of the knot, is surrounded by a less dense hydrogen-deficient and metal-enriched gas envelope, with less extreme abundances. The envelope of the knot might have been formed by the mixing of the knot material with the surrounding nebular gas.

The chemical abundances inferred from our modelling of the central core region and of the envelope of the knot are, at least qualitatively, in agreement with the abundances derived by the empirical analysis of Wesson et al. (2003), although the discrepancies between the core and the envelope abundances that we find are less dramatic than those implied by the ORL and CEL empirical analysis. Our models also indicate, in agreement with the empirical analysis of Wesson et al. (2003), that the C/O ratio in the two regions of the knot is less than unity, contrary to theoretical predictions for born-again nebulae (Herwig et al., 2001).

Back to Volume