Data description: the diagonal crosses represent HST FOS spectrum, the open triangles represent IUE spectrum, the open stars denote optical and IR photometry from Gillett et al. (1989), the filled stars denote DENIS photometry, the filled squares denote WISE photometry, the filled triangles represent Spitzer IRS spectrum, the open hexagons denote IRAS photometry and the filled hexagons denote Akari photometry. Model SEDs fit to the observed data for (a) 1/r2 radial density profile with amorphous carbon grains (long-dashed line in green) (b) 1/r2 radial density profile with graphite grains (short-dashed line in blue) (c) amorphous carbon model with a modified density function taking the nebular interaction with the halo gas (solid line in red). The modelled central star spectrum is given in dotted lines. A model of the field star spectrum is given (dot–dashed line in magenta). Input stellar spectrum is shown as a dotted line in blue.
