Storey, P. J.; Sochi, Taha
Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, UK.
The continuum spectrum of the planetary nebula Hf 2-2 close to the Balmer discontinuity is modelled in the context of the long-standing problem of the abundance and temperature discrepancy found when analysing optical recombination lines and collisionally excited forbidden lines in nebulae. Models are constructed using single and double Maxwell-Boltzmann distributions as well as kappa-distributions for the energies of the free electrons. New results for the necessary continuum and line emission coefficients are presented calculated with kappa-distributed energies. The best fit to the observed continuum spectrum is found to be a model comprising two components with dramatically different temperatures and with a Maxwell-Boltzmann distribution of electron energies. On the basis of a chi2 analysis, this model is strongly favoured over a model with kappa-distributed electron energies.
SAO/NASA ADS entry –> http://adsabs.harvard.edu/abs/2014MNRAS.440.2581S